There has been a great deal of publicity about air pollution from motor cars and the threat it poses to health and life. Here we examine the dangers and what is being done to improve air quality. Topics covered are:
- Vehicle Emissions and Health
- Engines and Exhausts
- Petrol Engines
- Diesel Engines
- Hybrid Engines
- Liquid Petroleum Gas (LPG)
- Natural Gas (Methane) and Hydrogen
- Electric Cars
- Batteries for Electric Vehicles
- The Future
- Some Chemistry Equations
- Further Resources
- Site Index
If you wish to go directly to any of the topics above, click on the heading in blue.
This chapter will examine the effects of air pollution, with particular reference to car exhausts, the different types of engines and what can be done to reduce exposure. Quite often in the piece, I use Jaguar cars as my example and I am well aware that for most people, they are a brand outside their range. I choose them because they are what I like to drive and because I get sent material about their specifications. They are also made in Britain.
Vehicle Emissions and Health
Air pollution from road vehicles is held to be responsible for thousands of premature deaths each year. Figures quoted include 5,000 deaths a year in 2012,1Traffic pollution kills 5,000 a year in UK 13,000 a year again from 2012,2Air pollution ‘kills 13,000 a year’ says study 25,000 a year in 2016 from NICE, 3Drive smoothly to reduce harmful effects of air pollution, says NICEand various other figures such as 9,500, 14,000 and 29,000 a year. A figure of 40,000 deaths a year also comes from 2016 from the Royal College of Physicians4Every breath we take: the lifelong impact of air pollution. Royal College of Physicians but this is for all forms of pollution and not just from traffic. It attributes about 23,000 deaths to road traffic.
These figures are so varied that their accuracy must be doubted. Not all air pollution is from traffic. I searched PubMed, a source of millions of peer reviewed papers in scientific and medical journals but I was unable to find any that gave calculations for such figures. The Royal College of Physicians was the only source that indicated how its figures were derived. Even NICE did not do that. However, from the papers I found, it did seem clear that vehicle exhaust, especially small particles and nitrogen dioxide, does have an adverse effect on health although some papers examined rather extreme conditions, such as using diesel engines down a mine.
It is easy to stratify risk in terms of cigarettes smoked per day or alcohol units drunk per week, but levels of pollution and duration of exposure are much more difficult to quantify. Researchers look at where people live and the incidence of diseases that are susceptible to pollution such as heart and lung disease and then examine measured levels of pollution in those areas. This is unreliable and does not take into account social class, occupation or even smoking habits, all of which have an effect. Nevertheless, the figures are still worrying and cannot lightly be dismissed.
Newspapers love reporting doom and gloom but we should not believe that we have never had it so bad or that bad air is a recent problem. In 1306, King Edward I banned the burning of sea coal because of air pollution. Even before the coal-fuelled Industrial Revolution, tanneries, butcheries and sewage made their presence known through the air. In past centuries, the cities of Great Britain have grown with industries in the east and the desirable housing in the west because the prevailing wind is from the south-west. In big cities, especially London, horse-drawn vehicles clogged the streets. Tens of thousands of tons of horse manure were shovelled from the streets of London every year. An article in The Times of 1894 predicted that in 50 years time, by 1944, the streets of London would be under 9 feet of horse manure. We were saved by the internal combustion engine.
A street scene from late 19th century London. Traffic is congested with horse-drawn vehicles. Crossing the street was unpleasant and dangerous
Air quality in the UK is improving. We burn less coal and have improved the chemistry of diesel so that sulphur dioxide emissions have decreased by 98% over the past 30 years. Nitrogen dioxide emissions, which are largely from car exhausts, have reduced by 50 per cent over the same period, despite the presence of many more vehicles on the road. Just 30 years ago, waste incineration was the largest source of pollution in the UK, but the sector has managed to reduce its emissions by 99.8%.5(Mark Broomfield. Every Breath You Take: A User’s Guide to the Atmosphere)
Before the Clean Air Act of 1956, even on a clear summer day there was a haze over London and when smog struck, beds were put up along the centre of hospital wards to cope with the number of admissions. In addition to general pollution, smoking was much more common then than now. Newer cars are cleaner too, but we do have a problem that has been previously underestimated, and it needs action. London’s air quality, though bad, has been getting steadily better. The average concentration of PM10s is about 20% less than it was 20 years ago and the average concentration of nitrogen dioxide is 30% less.6Dash for gas could solve the diesel crisis Particles such as PM10s and gases including nitrogen dioxide will be explained below.
Pea soup fog was a regular occurrence before the Clean Air Act. The smog of 1952 killed thousands of people in London alone
Numbers help to assess the scale of a problem but it is clear that the figures from the Royal College of Physicians are on the “generous” side, meaning that they may well be rather higher than is actually the case and boosted for political effect and impact. This is probably true for most estimates, especially the higher figures. However, even if they are significantly inflated but we accept a figure as low as 6,000 to 7,000 premature deaths a year from traffic emissions, and 10,000 may be more realistic, this represents at least four to five times the figure of 1,784 deaths in 2018 due to road traffic accidents. After a very satisfactory decline, road deaths have remained almost unchanged since 2010.7Department of Transport. Reported road casualties in Great Britain: 2018 annual report
It is easy to attribute a death to an accident but more uncertain to attribute it to pollution. However, if pollution really kills several times as many people as road traffic accidents each year, it demands attention. It may be that pollution from motor vehicles kills 10 times as many people as road traffic accidents. This has to be a cause for concern.
A paper from Canada examined the incidence of three neurological conditions related to proximity of major roads.8Living near major roads and the incidence of dementia, Parkinson’s disease, and multiple sclerosis: The correlation with dementia received much publicity but none was given to the lack of correlation for either Parkinson’s disease or multiple sclerosis. This seems to have been a well conducted investigation involving large numbers. It showed that those who lived within 50 metres of a major road had a higher risk than those who lived between 50 and 100 metres and the risk reduced with distance until there was no excess after 300 metres. This stratification of risk is indicative of a true association although there is no mechanism proposed to link association with causation.
It has been suggested that pollution from cars has an adverse effect on mental wellbeing similar to bereavement in magnitude.9Mental cost of diesel fumes like a bereavement The study from the University of York looked at findings from a national survey where 60,000 people living around England had been asked to rate how satisfied or dissatisfied they were with their lives on a scale from one to seven. These results were then compared with annual mean nitrogen dioxide exposure for every part of the country, broken up into individual square kilometres, as well as traffic flows. However, I regard the methodology as suspect, and I would not take this very seriously. I wonder if living in areas of high pollution may be a feature of social class and if people are just happier living in the country.
There is good evidence that air pollution is harmful to health and that it causes premature deaths, not just in the elderly with pre-existing disease but also in younger, vulnerable people such as those with asthma.10A review on the human health impact of airborne particulate matter It affects not just the respiratory system but the heart and circulation too. The main pollutants from engine exhausts are small particles and oxides of nitrogen. Nitric oxide combines with oxygen in the atmosphere to form nitrogen dioxide which is very toxic.
The small particles, which are largely carbon, are often referred to as PM, meaning particulate matter, with a number after them. The particles are often called PM10 or PM2.5. The former are particles about 10 microns in diameter, the latter around 2.5 microns or less. A micron, abbreviated to µ or µm, is a millionth of a metre or a thousandth of a millimetre. These particles can be inhaled deep into the lungs. Inhalation of small particles is the basis of inhalers for asthma. A series of scientific papers is available from Environment International.11Human health and particulate matter air pollution Particles can cause inflammation and enter the blood stream. The small particles seem to be very important in causing not just lung disease but arterial disease too. This leads to heart attacks and strokes.
Another toxic product is ozone (O3). People used to say, quite wrongly, that we could smell the ozone at the seaside, and it had health-giving properties. Ozone levels at the seaside are no higher than elsewhere. The gas is odourless, colourless and toxic. Hydrocarbons, which are largely unburned fuel, can act as a catalyst to convert oxygen to ozone, especially with ultraviolet light. This contributes to damage to the respiratory system. When I looked for a picture relating to ozone, I was shocked at the number of advertisements promoting ozone as a health-giving or therapeutic product. I wonder how much ozone is actually in their product. There are a lot of dangerous people and a great many scammers out there.
Incompletely burned fuel produces carbon monoxide which is harmful. It displaces oxygen from the haemoglobin in red blood cells, having 210 times the affinity of oxygen. Hence, blood that is exposed to 21% oxygen and 0.1% carbon monoxide in the lungs will be about 50% oxyhaemoglobin and 50% carboxyhaemoglobin. Oxyhaemoglobin is how blood carries oxygen and blood leaving the lungs should have nearly 100% oxyhaemoglobin. Carboxyhaemoglobin is when it has taken on carbon monoxide instead of oxygen. It seems to have an adverse effect on the process of atheroma that leads to coronary heart disease and stroke. Carbon monoxide is much more of a problem with petrol than diesel as the latter burns at a much higher temperature. Some kinds of hydrocarbons are also carcinogenic.12Motor Vehicle Emission Controls: Fuel Types Sulphur dioxide is not mentioned as modern petrol and diesel fuels both have low sulphur nowadays. Carbon dioxide is not a pollutant but a basic nutrient for plants for photosynthesis.
A study from the University of Surrey found that those who travelled by bus were exposed to rather more pollution than those who went by car. Diesel buses on average produce three times as many particles per mile as diesel cars but they typically carry 20 times as many people.13Commuters warned of new air pollution risk People who use buses spend time waiting at bus stops and spend longer on the journey than car drivers. The study found that passengers on the London Underground’s District Line, whose trains have closed windows, were exposed to far lower concentrations of particles than those on trains with open windows. Particle levels were much higher on trains with open windows in deep tunnels. Levels of pollutants in the morning peak were up to 43% higher than in the afternoon peak.
A paper from Leicester examined air pollution, looking at other factors that may influence a deterioration in lung function.14Air pollution, lung function and COPD They used UK Biobank data on 303,887 individuals aged 40–69 years, with complete and valid lung function measures. They found that people living in areas with PM2.5 concentrations above World Health Organization guidelines of ten micrograms per cubic meter (10 µg/m3), had a COPD prevalence four times higher than among people who were exposed to passive smoking at home. The prevalence was half that of people who have ever been a smoker. They found that outdoor air pollution exposure is directly linked to lower lung function and increased COPD prevalence. People exposed to higher levels of pollutants had lower lung function equivalent to at least a year of ageing. Air pollution had approximately twice the impact on lung function decline and three times the increased COPD risk on lower-income people compared to those on higher-incomes who had the same air pollution exposure but why this should be needs further investigation. Other factors which increased risk of lung function deterioration were smoking status and obesity. Why deterioration in lung function should be worse with low income and obesity is not explained.
The average PM 2.5 level in the UK is 12.1. Qatar and Saudi Arabia have emissions ten times that level. China and Singapore may be improving but India and the Middle East have far to go.
Delhi is the most polluted capital in the world. In November 2019, there was a dense smog that led to 5 million children being given face masks, the public were advised to stay indoors, and more than 30 flights were diverted because the pilots could not see well enough to land. The air quality index level in Delhi reached 1,200, which is 24 times the recommended safe limit of 50. Above 300 is considered hazardous. Of the 30 most polluted cities in the world, 22 are in India.
Dr Michael Mosley walked around London wearing a device to monitor air pollution for a BBC television programme and then he took a taxi back to King’s College. Pollution levels were highest when he was in the taxi. It is not the vehicle that the person is in that causes the problem but the vehicle in front. Perhaps we should change the ventilation system on our cars to recycle the air when we are in traffic but I am unaware of any data on this.
A review of 95 million US Medicare claims examined a long list of conditions and the risk of even short-term exposure to airborne particles. The conclusion was that air pollution causes problems, even at levels below the World Health Organization’s guideline. This confirms the view that there is no safe lower limit for air pollution. 15 Short term exposure to fine particulate matter and hospital admission risks and costs in the Medicare population An accompanying editorial said that the problems of air pollution should be seen as a matter of urgency. 16The health effects of fine particulate air pollution
Nowadays, few can be unfamiliar with the problems of plastics in the oceans. They degrade to small particles but do not break down chemically. They have been found in plankton, which is at the bottom of the food chain, and so everything that we eat from the sea probably contains microplastics. However, they are also found in the air and are breathed in. They may come from the laundering of synthetic fibres. They seem to get everywhere and even rain falling on mountainous regions, far from cities, contains significant amounts of microplastics. They are unrelated to motor vehicle emissions and their significance for health is uncertain, so I shall not dwell on them.
Engines and Exhausts
Catalytic converters improve the quality of exhausts as shown in the chart below.17Motor Vehicle Emission Controls: Fuel Types Petrol cars without catalysts have been given a relative value of 100 for comparison except for particulate matter that is given as 100 for diesel and 0 for petrol. It seems strange that diesels with a catalyst are not included as modern cars have them.
|Type of Engine||Petrol without catalyst||Petrol with catalyst||Diesel without catalyst|
|Oxides of Nitrogen||100||23||31|
Even without a catalytic converter, diesel cars produce rather less carbon monoxide and hydrocarbons than a petrol engine with one. The catalyst reduces oxides of nitrogen from petrol engines by more than 75% bringing them down to just below a diesel engine without one. It would be interesting to know what happens in a diesel with a catalyst. A catalyst does not get up to temperature and start operating properly until a diesel car has done about 5 kilometres. For a petrol, car the distance is about 10 kilometres. Hence short journeys such as the school run may be especially troublesome. However, modern catalytic converters may warm up rather sooner.
People who sit in cars outside schools with the engine running, like the getaway driver outside a bank who is waiting for the robbers to emerge, are probably polluting the atmosphere even more than they think, if they think. Unless they have driven several miles already, the catalytic converter will not be fully functioning and so they are pumping out exhaust as if they did not have one. They may be more dangerous than bad drivers.
People who sit in cars outside schools with the engine running are poisoning the atmosphere and the catalytic converter is probably not working.
Diesel engines offer lower fuel consumption and lower carbon dioxide emissions. However, diesel engines emit nitrogen oxides and small particles.18Diesel Engines: Design and Emissions These two pollutants are traded against each other in many aspects of engine design. Very high temperatures in the combustion chamber help to reduce the emission of soot but produce higher levels of nitric oxide (NO). Lowering the peak temperatures in the combustion chamber reduces the amount of nitric oxide produced but increases soot formation. Better mixing of the air and fuel is the key to lower emissions.
The nitric oxide is rapidly oxidised to nitrogen dioxide on a time scale of tens of minutes. In rural air, away from sources of nitric oxide, most of the nitrogen oxides in the atmosphere are in the form of nitrogen dioxide. Nitric oxide (NO) and nitrogen dioxide (NO2) are collectively called NOx. NOx combines with hydrocarbons or volatile organic compounds in the presence of sunlight to form low level ozone. This leads to smog formation. NO2 is split by ultraviolet light to give nitric oxide and an oxygen atom, which combines with molecular oxygen (O2) to give ozone (O3). Eventually, NO2 is oxidised to nitric acid (HNO3) which is absorbed directly at the ground, is converted into nitrate-containing particles, or dissolves in cloud droplets. At night, different oxidation processes convert nitrogen dioxide to nitrates.19Nitrogen Oxides (NOx) Air Pollution Information System (APIS)
An American website called “Explain that stuff” has an interesting article on 20Catalytic Converters. The version I used had been updated in 2018. Petrol cars usually have a three-way converter and as shown in the chart, this reduces carbon monoxide about seven-fold, hydrocarbons about six-fold and nitrogen oxides about three-fold. Diesel engines have catalytic converters, but there are differences from how they work in petrol engines. They use two-way rather than three-way catalytic converters. They reduce carbon monoxide and hydrocarbons, which as much lower in diesel exhausts but it does not tackle nitrogen oxides. The catalytic converters on diesel engines reduce particulate matter or soot but only a little. Most of the reduction in soot or particles comes from diesel particulate filters (DPFs). The exhaust from diesel engines is rather cooler than from petrol engines.
When catalytic converters have warmed up, they are very effective at reducing harmful emissions
City diesel is a purer fuel which is widely available and gives a cleaner burn. The main benefit of city diesel is that its combustion reduces particulate emissions by 34 to 84% depending on engine type, duty cycle, test basis and type of particulate measured. An additional benefit of city diesel is that it is a low sulphur fuel, which is necessary for the optimum running of oxidation catalytic converters.21Motor Vehicle Emission Controls As a full tank may allow a car to travel around 500 miles, taking it far from where the fuel was bought, it makes sense that all fuel should be of this quality.
Pollution is not evenly distributed throughout the country. Black carbon levels in the air over Britain range from 0.2 micrograms per cubic metre in the countryside south of Edinburgh to 1.4 in central Glasgow and 7 in some parts of London. Grains of black carbon have been found to help pneumonia and other respiratory diseases to spread into the lungs and grow into thick clumps that ward off antibiotics.22Air pollution creates drug resistant bugs Environmental factors such as high buildings which reduce air movement are important as is the weather. Diesel engines are much more of a problem than petrol. Oxford Street in London is one of the worst places for pollution in the country. It has high buildings and although private cars are excluded, there is a constant stream of buses and taxis, all using diesel engines.
It would seem sensible to encourage pedestrian areas in city centres where shoppers may walk without car exhausts nearby. NICE also recommends the removal or flattening of speed bumps as they make cars decelerate and then accelerate, using more fuel and producing more exhaust. However, poor air quality is not limited to urban areas. Motorways can have very high levels of pollutants and limiting speed to 60mph in busy times has been suggested to reduce emissions.2360mph limit and fines to cut M1 pollution
Modern cars are much cleaner than older ones as is explained by the Department for Transport.24Cars and air pollution Modern cars are also very much more fuel efficient than older cars. When looking for the villains of pollution it is very important to consider the age of the vehicle.
Another type of pollution which is unpleasant and stressful but unlikely to be deadly is noise pollution. Modern cars are quieter than older ones but motorcycles are always noisy. It is probably difficult to get adequate silencing of a motorcycle with such as short exhaust pipe. Nevertheless, I am sure that much could be achieved to make them quieter. There are legal limits for noise emissions for passenger cars and these will be reduced further over the next 10 years.25Noise. Department for Transport Most cars are fairly quiet and if the exhaust pipe is damaged, drivers are so embarrassed by the noise that they soon get it replaced. The problem is the few cars that are specially fitted with exhaust pipes the size of drainpipes so that they can be heard from a very long way away. Sometimes these exhausts are fitted specially but often they are factory built as with the Subaru WRX. Legislation for noise limitation must be enforced. If it is possible to measure gas emissions at a MOT, it should be possible to measure noise too. These cars are very antisocial and unnecessary. Steps should be taken to prosecute offenders.
The matter of emissions is not simply a choice between petrol and diesel. There are several types of fuel and much difference between older and new engines. Each fuel type will be discussed in turn starting with a comparison between petrol and diesel.
Whenever I mention the price of cars in the following sections, they were correct at the time of writing but prices vary with time. They also vary according to the specifications of the model. Fuel prices vary too. I have removed references to manufacturers’ websites because they change so often. Prices are given simply to make a point that one form of engine may be significantly more expensive to buy than another. Used car prices are not even considered.
Petrol used to contain tetra-ethyl lead to reduce premature ignition, but lead-free petrol has replaced this for many years. Lead in the atmosphere from car exhausts is toxic and lead poisons the platinum in catalytic converters.
Petrol is dangerous if the car is in an accident and the fuel tank ruptures. The old four-star petrol was highly inflammable. New unleaded petrol is even more flammable and almost explosive whilst diesel is difficult to burn without a wick. Hence diesel is much safer in a crash and perhaps should be considered more often for young drivers.
Petrol engines are lighter than diesels and are usually used for small vehicles and all motorcycles. Diesel engines usually need to be a little larger than petrol for an equivalent performance and they are more likely to have a turbo as they lean burn less readily. Diesels tend to be more sluggish, but their performance has improved markedly in recent decades to give a much livelier response. Until fairly recently, Jaguar did not make diesels, but now 80% of the sales of the XF range are diesels. However, the Jaguar XF diesels are smaller engines with much greater fuel economy than the petrol engines which are renowned as very high performance but very thirsty. In 2021 a car magazine compared the VW Golf petrol and diesel versions. 26Fuel economy, petrol or diesel?
|VW Golf Match||Petrol||Diesel|
|Engine||1.4 TSI 122hp||2.0 TDI 140hp|
|Value after 3 years||£7,640 (lost 60%)||£9,491 (lost 55%)|
|Fuel economy, urban||34.4 mpg||46.3 mpg|
|Fuel economy, combined||45.6 mpg||58.9 mpg|
There are a number of points from this table. The diesel model often has a rather larger engine to give similar performance and is slightly more expensive new but it still give better miles per gallon of fuel and so is rather cheaper to run. The lower rate of depreciation may not apply more recently as diesel has received so much adverse publicity without giving credit for the major improvement to modern vehicles.
Modern cars are much cleaner than older ones as is explained by the Department for Transport.24Cars and air pollution Modern cars are also very much more fuel efficient than older cars. When looking for the villains of pollution it is very important to consider the age of the vehicle. Not all vehicles are equal.
Although cars are getting more fuel efficient and cleaner, there is a general trend away from small cars to SUVs, which are bigger, heavier and less aerodynamic.28Soaring demand for SUVs exacerbates climate crisis Hence they consume 25% more fuel per mile than a medium-sized car. Sales of SUVs in Great Britain rose from 21% of the market in 2014 to 39% in 2018. This is a worldwide trend. They were responsible for all of the growth in oil demand, of 3.3 million barrels a day, from passenger cars between 2010 and 2018, with total fuel consumption from other types of car falling slightly. The average carbon dioxide emissions from new SUVs, or “dual-purpose” cars, had fallen by more than 43% since 2000. Nevertheless, this move to bigger cars is a problem for emissions. The benefits to air quality from electric cars is being cancelled by these larger vehicles. The article was looking more at carbon dioxide production than noxious emissions but they are both related to fuel consumption.
Diesel engines for cars have been much more popular in continental Europe than in the UK. In the last 30 years diesel has grown greatly in popularity as it gives a far better fuel consumption and old problems such as a sluggish performance and being rather noisy are much reduced. Diesel is very popular with drivers who do many miles a year.
The UK is one of the very few countries in the world that has more expensive diesel than petrol, whilst in many countries it is about 40% cheaper. Nevertheless, diesel cars still tend to be rather cheaper to run because of lower fuel consumption. Diesel engines have improved vastly over the years. New ones are much cleaner and livelier. Diesel is preferred for haulage both because of fuel economy where a large goods vehicle may do about six miles to the gallon and because it tends to be the best engine for traction.
Old diesels often give a puff of black exhaust as they accelerate due to turbo delay. Newer cars are much better. It is totally wrong to look at all diesels as being the same in terms of pollution. There may be wisdom in making diesel emissions more rigorous for MOTs, but a move to ban diesels for cars is wrong. However, it seems that just as with official figures for fuel consumption, figures for emissions in normal use may be rather different from official statistics.
Many new cars, especially diesels, have eco-stop. This stops the engine when the vehicle is stationary with the footbrake applied as in congested traffic or at traffic lights. It is probably rather more important for air quality than for fuel consumption.
Diesel cars have risen greatly in popularity from 14% of road users in 2001 to 38% in 2016 although after recent adverse publicity this is now falling back.
New technology has made new diesels much cleaner. A substance known by the trade name of Adblue can reduce nitrogen oxides, but the engine requires the necessary technology. It is used by modern selective catalytic reduction (SCR) systems. It is often found in large goods or passenger carrying vehicles but also many European cars. Adblue is 67.5% distilled water and 32.5% high grade urea, such as that used to manufacture plastics, cosmetic products or fertilisers.29What is Adblue? Urea used as a synthetic product is typically produced from natural gas although urea is an important constituent of urine. AdBlue is injected into the exhaust stream between the engine and the SCR catalyst. At high temperatures AdBlue turns into ammonia and carbon dioxide. When the nitrogen oxides react inside the catalyst with the ammonia, it forms nitrogen and water.
The AdBlue tank has to be filled so that the SCR system functions correctly. If the Adblue tank is completely empty, the car will not start and a warning appears on the vehicle display that it needs to be filled. It is important to get the balance right or ammonia is emitted from the exhaust. Jaguar has made Adblue systems standard in all their diesels from 2016.
Adblue technology helps to reduce NOx emissions considerably
Diesel particulate filters (DPF) started to appear on cars around 2001. However, they may not be suitable for someone doing mostly urban mileage although most people never have any trouble with them.30Are diesel particulate filters more trouble than they’re worth? Perhaps diesels are best avoided for mostly urban mileage and people who find themselves doing mostly short runs should give the car a good run along dual carriageway at 50mph or more for several miles from time to time. Although diesel burns at higher temperatures than petrol in the cylinder, the exhaust gases are cooler. Diesel engines require innovative changes to make them cleaner but much has been done and an article from the Royal Society of Chemistry is very interesting.31The evolution of catalytic converters
Hybrid engines have either petrol or more rarely a diesel engine but also batteries.32Best hybrid cars to buy. Auto Express These batteries or accumulators store energy as electricity when the vehicle decelerates without braking, and this can then be used later to power the car and reduce fuel consumption. The result is that they can achieve better fuel economy than the conventional engine alone. Hence, they produce less emission and have a cheaper annual road tax. They are often thought to have a poorer performance, but this is only so if they have a smaller conventional engine than the standard model or if they are significantly heavier.33Pros and Cons of Hybrid Cars. However, batteries are very heavy.
The diagram shows that energy goes to the battery as the car decelerates
The price of the hybrid car is rather higher than the conventional model, they tend to be more expensive to repair and not all mechanics can deal with them so it may be necessary to use main dealers more often. I have looked at Toyota as a brand that is well established in hybrid technology. The Toyota website states that the Yaris starts from £11,500 with up to 80.7 mpg whilst the hybrid starts at £15,500 with of 85.6mpg. I am surprised how little there is between the fuel consumption of each and I am very sceptical of that figure of 80.7mpg. The prices for the Toyota Auris are £16,000 and £21,000 respectively with both given a fuel economy up to 80.7mpg but the hybrid has a combined carbon dioxide of 92 grams per kilometre compared with 79 for the hybrid. I find these figures remarkable. The term “up to” is meaningless. Buyers want to know the real-life mpg. As the AA notes, there is often disparity between manufacturer rates and reality.34Can you rely on the official figures? The AA The test conditions do not match real driving. At a steady speed the batteries are not charged or used. Hence the mpg is the same. It is at variable speeds such as with urban driving that the hybrid becomes valuable.
The Department for Transport (DfT) gives the cost of fuel for 12,000 miles for the Yaris as £935 with the 1.2 litres petrol engine whilst for the petrol hybrid it is £644. For the Auris the figures are £897 for petrol, £847 diesel and £683 for the petrol hybrid. The Yaris hybrid is cheaper to run than the ordinary petrol version for 12,000 miles by £291 whilst costing £4,000 more to buy new and the Auris is £214 cheaper per 12,000 miles whilst costing £5,000 more. Hence to recover the increased cost of a new car from the cheaper cost of fuel takes around 165,000 miles for a Yaris and 280,000 miles for an Auris. It is clear that the DfT do not use Toyota’s figures for fuel consumption. It is well known that EU figures do not represent true mpg.35Why the EC figures do not represent true MPG A website comparison between petrol, diesel, hybrid and electric-only cars is concise and says that sometimes diesels can be cheaper to run than a petrol hybrid.36That extra mile. Petrol vs Diesel vs Hybrid vs Electric
The cartoon series South Park had an episode in which everyone started to drive hybrids which they called not the Prius but Pius. The result was a cloud of smug over the area.
Hybrid cars have become quite popular with those who wish to parade their “green credentials” but I wonder how many owners have done the calculations about initial price and the time it takes to recover it from lower fuel consumption. There is also a problem that the batteries may need replacement at some stage and this will be expensive. Battery technology is improving but they are still a technology in its infancy. Some hybrid cars also have “plug-in” facilities rather like an all-electric car so that the batteries can be recharged. The others are often called “self-charging” as if it is a new technology. It is really the same old hybrid without the plug-in.
The battery in a hybrid car is a considerable size and weight and so must add a significant amount to the total weight of the car and hence detract from performance. This is a plug-in Toyota.
If you normally drive on motorways or dual carriageways at a steady speed, a hybrid will not give value. If you do a lot of town driving, it may be significantly cheaper and produce fewer emissions. However, you need to calculate the extra cost versus the saving before purchase. I would say that the vast majority of people who buy a hybrid in the belief that it will save the money are wrong. If they buy them to look good, it is a very expensive policy. I think most owners have just not done the maths.
In recent years, many manufacturers have included hybrids in which the batteries can be charged directly and it can run as an electric vehicle. They are called plug-in hybrid electric vehicles or PHEV. Jaguar have included them in their E-pace and F-pace range. They say that running the E-pace on petrol costs 15.2p a mile but on electricity the cost is 7p a mile. However, the range when fully charged for both E-pace and F-pace is just over 30 miles. This is not much on a long run but it may be significant if you work 10 to 20 miles from home and do a 20 to 40 miles commute each day and charge at home overnight. Using just petrol for a 40 miles commute would cost 40 x 15.2p = £6.08p a day. Using electricity for 30 miles and petrol for 10 miles would cost (30 x 7p) + (10 x 15.2p) = £2.10 + £1.52 = £3.62, a saving of £2.46p a day.
The plug-in hybrid Jaguar E-Pace has a 1.5 litre turbocharged petrol engine instead of the usual 2 litres engine. This is the smallest engine available for an upmarket SUV. However, with the assistance from the electric motor, it becomes the most powerful option overall. The combined petrol-electric source produces up to 309hp and 540Nm of torque which is very powerful.
This all comes at a price. The regular E-Pace start at £32,575 but the cheapest E-Pace PHEV begins at £45,995. It will require a great many short journeys on electric power alone for the fuel savings to start clawing back the plug-in hybrid’s price premium.
Liquid Petroleum Gas or LPG
Liquid petroleum gas or LPG is mostly propane (C3H8) with some ethane (C2H6) and butane (C4H10). It is a gas at normal temperature and pressure, but it can easily be liquefied by compression. LPG can be used with a modified petrol engine. The cold engine starts to run on petrol but when it becomes warm, which happens quite quickly, it switches over to LPG. Proton is the only manufacturer that produces LPG models from new and so it is usually necessary to get a conversion. LPG is available from many fuel stations around the UK and on continental Europe, but they are still the minority. There are 1,600 LPG filling stations across the UK. However, if the car runs out of gas, it can run on petrol. LPG costs considerably less than petrol per litre. The UK has more than 100,000 cars and light-duty vans that use LPG.
LPG has a high-octane rating, along with low levels of volatile organic compounds and it can readily mix with air before combustion. This results in more complete combustion with reduced exhaust emissions. The gas is much cleaner and so less damaging to health as well as reducing engine stress and giving a longer engine life. Electronically controlled gas injection systems optimise performance. LPG is said to produce 75% less carbon monoxide, 85% less hydrocarbons, 10% less carbon dioxide, 40% less nitrogen oxides and 87% less ozone. I presume that is compared with a normal petrol engine.37Dorset LPG
In congested urban traffic, both LPG and CNG outperform petrol powered vehicles on emissions of carbon monoxide (CO). CNG is compressed natural gas which is largely methane (CH4). Indeed, emissions of carbon monoxide from CNG powered vehicles are of the same order as those emitted by diesel vehicles. However, emissions of total hydrocarbons (THC) from CNG vehicles are relatively high. Emissions of NOx and particulates from both LPG and CNG powered vehicles are significantly lower than those from diesel vehicles. CNG also compares favourably with emissions from equivalent sized diesel-engine vehicles.38Motor Vehicle Emission Controls
In the early 2000s, I examined the prospects of an LPG conversion for my Rover 400 two-litre petrol car. I looked at the cost of petrol for 10,000 miles, knowing my mpg. I compared that with LPG that is rather cheaper but I assumed a reduced mpg of about 10 to 15%. At the time of writing petrol is about 118p per litre whilst LPG is usually around 65p a litre. I knew the cost for a conversion and I calculated that it would take around 30,000 miles to recover my outlay. An article in The Guardian from 2012 says that a conversion can cost £2,000 but cheaper systems are becoming available and LPG costs less than half the price of petrol.39Petrol or LPG … do the fuel cost savings add up? That was back in 2012 when petrol was rather more expensive than it is at the time of writing. LPG is variable in price, as is petrol. Petrol price varies with the world price of crude oil and gas price is linked to oil. By and large, I would say that the cost of LPG is 50 to 60% of the cost of petrol.
Before committing myself, I looked at several cars that had been converted. They had a neat job with the bodywork in good condition at the LPG filling valve. The inside of the car and under the bonnet was also neat. I was pleased with the workmanship and how the car ran. My main problem, which I understood before it was done, was the need to install an LPG tank. It was placed where the spare wheel had been under the floor of the boot. They gave me a device to inflate and mend any small hole in the tyre should I get a puncture but usually I drove with the spare wheel in the boot but wrapped in plastic to keep the boot clean. This all adds about 60kg to the weight of the car. There is a control switch, usually by the gear lever or on the dashboard, for the driver to select LPG or petrol operation, and a dual-mode fuel gauge.
The LPG tank is rather smaller than a petrol tank and so will need filling more often. On long journeys I did not have difficulty finding a station that sold LPG either in the UK or on the continent. However, there are three different LPG fuel connectors in Europe. The one for the UK is also used in Holland and the neighbouring part of Belgium but nowhere else; not even the Republic of Ireland. I bought two well machined brass adapters that I could fit to my refill point and this was satisfactory for everywhere I went in Europe. Although the range of a full tank of LPG is rather less than a full tank of petrol or diesel, it is at least 200 miles and everyone needs to stop every three or four hours. No one would reasonably wish to drive the 500 miles afforded by a large diesel or petrol tank without a break. Filling up with LPG takes no longer than petrol or diesel but recharging an electric car requires a stop of a few hours.
Before I changed the Rover 400 for an S-type Jaguar I considered the cost of running a petrol model and getting an LPG conversion compared with buying a diesel. The conversion would be more expensive for a six cylinders rather than four cylinders engine. The LPG would be slightly cheaper than diesel to run but it would take me 99,000 miles to recuperate the outlay. In addition, there are problems such as taking space for a tank. I decided against LPG and did not even consider it when I bought a 2.2-litre Jaguar XF.
LPG would be even more explosive than unleaded petrol if the tank burst but it is very strong although the distribution pipes could be damaged. I have never heard of such dangers in accidents.
Natural Gas (Methane) and Hydrogen
Natural gas and hydrogen are also used at times. They are much more difficult to find at petrol stations in this country than LPG. They are more common on continental Europe but still infrequent. LPG will liquefy at about 30 Barr (atmospheres) of pressure but compressed natural gas (CNG) which is mainly methane (CH4) requires about 100 Barr. Hydrogen is very clean and burns to water only.
However, hydrogen does have problems. An article in The Times about hydrogen fuel described a car being fuelled with hydrogen. It was at 900 barr pressure, which I find incredibly high, and cooled to -40o. The car seemed to fill without incident but the nozzle became frozen and stuck fast and it took 5 minutes to thaw. Fortunately, there was no queue of drivers behind.
Hydrogen burns to just water but, at present, most hydrogen is produced by a process called “steam methane reformation”. This produces hydrogen and carbon dioxide. This is a problem to anyone who is trying to avoid producing carbon dioxide by using hydrogen. There is also the matter of the energy that is put into the process to produce this reaction. Once again, we must think where things come from. There is more about hydrogen in the chapter Alternative Energy.
Biofuels are sometimes used to power vehicles and are often seen as environmentally friendly. The fuel is often ethanol, also known as ethyl alcohol (C2H5OH) and it is derived from plants such as maize.
The fallacy of biofuels is discussed in the chapter Alternative Energy. There is no place for them. Wood burning stoves are often promoted as environmentally friendly but they have been implicated in producing high levels of pollutants, particularly soot and particles.40Wood stove fad is blamed for pollution
Another form of fuel is recycled cooking oil used as diesel. I do not know how clean this is but as the vehicle goes down the road it smells like a chip shop.
Plug-in battery cars run on electricity only. Hence, they do not give any noxious exhaust. However, the tyres on the road produce particulate matter, and so even electric cars are not completely free of atmospheric pollution. We may need to consider the source of electricity generation before regarding them as completely clean, including the loss of power through the distribution system between the power station and the point of charging. For use in a congested area they would appear to have much to commend them. Normally they would be charged at home and then used for a limited distance before recharging.
It is possible to get charging points away from home, but they are not very numerous although this will change. A website for finding charging points is available.41UK Charging points Some hybrid cars can also be charged by plugging in. The cost of electricity is still very cheap compared with petrol. For those obliged to park overnight on the road, charging at home can be a problem. The biggest car charging network is the Polar charge point system, operated by Chargemaster. It charges a £7.85 monthly subscription, giving drivers access to 6,000 charging points, of which 5,000 are free. This represents a very cheap way to run a car, although the initial outlay to buy the vehicle is high. A fee of £7.85 a month is equivalent to about 1½ gallons of petrol at current prices.
The batteries in an electric car are laid low across the chassis to keep the centre of gravity low as they are very heavy
Anyone who thinks of buying an electric car needs to consider facilities for home charging. This may also apply to a plug-in hybrid. The government provides a grant of £500 whilst a basic charging unit can cost around £700 leaving just £200 to be found. However, the price of installation can vary depending on how far the charging point is from the mains supply. Faster charging units can cost around £1,500 minus the £500 grant. It is possible to charge the car with a simple piece of equipment from the supplier, but it will charge more slowly. Modern houses are now often built with car charging facilities. This is sensible as electric cars will become compulsory.
A Tesla on fast charge takes 90 amps. That is a phenomenal current and would require very thick cables. A current of 90 amps from a 220 volts source produces around 20 kilowatts. The charging points cannot be cheap to install. The additional demands on the National Grid after battery cars become normal in 2040 has been calculated as less than 10%.42Electric cars will not be a drain on the national grid However, it has been suggested that simply having six electric cars on charge in one street could seriously disturb mains supply and cause power cuts.43Plugging in six electric cars may cause local power cuts
The length of battery’s power is the major problem for electric cars. Back in 2010, Honda’s chief executive conceded to Autocar magazine that a breakthrough in battery technology was essential to make electric cars viable.44Honda: ‘Electric cars not viable’. Technology is improving. Prices are still rather high. The Nissan Leaf starts at £28,000 for a small to medium hatchback. Perusal of new car prices in Autotrader confirms a typical new price of around £31,000 which is very expensive for a car of this size. It has a range of 155 miles. Its performance has been reviewed.45Nissan Leaf 30kWh review I spoke to someone who had a Nissan Leaf and he was delighted with it. He used to spend £240 a month on diesel. Now he spends £45 a month on electricity. He has it on finance, rather than outright purchase.
In 2020, several new electric cars came on the market with prices just below £20,000, which is still expensive for a small hatchback. However, the range before re-charging is only around 100 miles. This may be satisfactory for commuting or the school run but it is most inconvenient for longer trips. With so many filling stations and so many miles available from a full tank, there is no excuse for running out of petrol or diesel. If a LPG conversion runs out of gas, it can continue on petrol. If an electric car has flat batteries before reaching a charging point, it is a problem. Cars with a longer battery life are also coming on the market but they are also rather more expensive than the traditional equivalent. The distance a car can travel on a fully charge battery should be taken no more literally than mpg for petrol or diesel. Real world driving is different.
Before setting out on a long journey in an all-electric car, it is essential to plan. There are a number of sources of lists or maps of recharging points. The manufacturer’s claims for the distance travelled before needing to recharge is probably rather optimistic. It will depend on driving conditions and the load in the car in the same way as miles per gallon for conventional cars. A have seen a number of motorway service stations with rows of fast-chargers but they are for Tesla and are not available to other makes. Take note of this as you plan. Filling with petrol, diesel or LPG takes a few minutes and then you may want a short toilet break and a coffee. If you have an electric car, it will probably need to be on charge for at least an hour. Have a long lunch. You may also find that all charging points are in use and you have to wait for one to become available. This can make you journey much longer and more frustrating but the worst thing would be a flat battery a long way from a charging point.
An article in The Times stated that the American Automobile Association had found that the range of electric cars decreased by nearly 50% when temperatures dipped to -6oC and fell by nearly 20% when temperatures climbed above 35oC. However, both extremes of temperature are rare in the UK.
Tesla is a specialist electric car manufacturer. Its range depends upon the battery specifications but varies from 253 to 381 miles although some reviewers have cast doubt on these figures under normal driving conditions. It is a rather larger car than the Nissan Leaf and more like a SUV. They seem to be shy about the price on the website but a search of Autotrader shows that new cars are around £75,000 for the model S. They take a considerable drop in price when sold second hand but this may change when the technology becomes established. Whilst a burden to buyers of new cars, it may be a boon to those who buy used cars. Tesla is currently accelerating production of its model 3 cars which are sold on Autotrader at around £45,000 to £60,000.46Tesla ‘out-accelerating the Model T’ The “cheap” Tesla is still very expensive compared with most conventional cars.
Jaguar’s new 4×4, the F-Pace, has had an electric version from the second half of 2018. It is called the I-pace. The range is 500 kilometres or about 310 miles. They call it an electric sports car but it is a 4×4 or SUV which means sports utility vehicle. That is not what I see as a sports car. The website gives answers to a number of pertinent questions about the car and the technology. Electric motors give a very fast acceleration from standing. The Jaguar I-pace boasts 0 to 60mph in 4 seconds. That must be for people in a hurry. Electric cars are also very quiet. As well as being expensive to buy, electric cars currently cost about 50% more to insure.47Electric cars cost 50% more to insure I wonder why this should be. Perhaps the very fast acceleration or the risk of an electric fire raise concerns. The article suggests it is just because the concept is new. A new I-pace is in the region of £60,000 to £75,000 depending on specifications. This compares with around £45,000 to £65,000 for the petrol or diesel F-pace.
The price of electric cars should fall as battery prices tumble.48Falling battery costs to drive electric car sales However, a continuing problem is the weight of the battery compared with traditional engines and fuel. A battery that weighs 550kg has about the same store of energy as 7kg of diesel. A Tesla Model S hatchback with 85kWH of battery weighs 2,590kg. To scale up a battery for a large goods vehicle, it would weigh around 18 tonnes. This would significantly limit the amount of cargo that can be carried as what matters is the total weight of the vehicle. Hence it would need rather more electric vehicles than diesel vehicles to carry the load.
Projections from Tesla
An enormous challenge for the producers of electric cars is the charge that can be held in the battery. Whilst some of the bigger, more expensive ones may boast a range of 300 miles, depending on how they are driven, the smaller, cheaper ones have a range around 150 miles or less. A kilogram of petrol stores about 12,000 watt-hours of energy. A kilogram of a state-of-the-art battery stores a 50th of that. Until this gap is narrowed, it is unlikely that electric cars will truly compete with the petrol kind. For the first team that succeeds in closing that gap, the rewards will be immense.49Car battery of the future faces acid test
As traffic increases, a rising proportion of the PM10s in the London air comes from “non-combustion”. This means things such as the smoke of skidding tyres, and dust particles churned up by vehicles.50Dash for gas could solve the diesel crisis Hence even pure electric engines our not completely clean. Furthermore, electric cars will not solve the problem of congestion and parking.51Electric cars ‘will not solve transport problem,’ report warns
Batteries for Electric Vehicles
Whilst there is a definite “halo-effect” around driving electric cars, we need to look at the mining of the minerals for these batteries for all electric cars, hybrids and the components of mobile phones. Most of it comes from a mineral called coltan. Coltan is an abbreviation from columbite–tantalites and is also known as tantalite. The elements nobium and tantalum are extracted. The niobium-dominant mineral in coltan is columbite, so named after niobium’s original American name, columbium. The tantalum-dominant mineral is called tantalite.
Around 70% of the world’s supply comes from the Democratic Republic of Congo (DRC), one of the poorest, most violent and corrupt places on Earth. It is a well-known irony that any country with “democratic” in its name is anything but democratic. Examples include the Democratic Republic of Korea (North Korea) and the old Democratic Republic of Germany (DDR or East Germany). Cambodia under the Kymer Rouge was called Democratic Kampuchea.
As with so much of Africa, the Chinese are eager to invest and acquire the minerals they need for their economy and exports. They ignore human rights, corruption and environmental concerns. The first two are why so many African leaders like to do business with them. Although the Chinese run enormous mining concerns, they are also eager to buy what is called “artisan” coltan, which means it is mined by local people with hand-tools with no regard for safety and often using child labour.52Congo’s miners dying to feed world’s hunger for electric cars.
There are also considerable environmental concerns about the effects of mining in the DRC with soil erosion, pollution of rivers and a substantial fall in the gorilla population in the region. Some are even hunted and eaten by hungry miners.
The International Consortium of Investigative Journalists, has an article about coltan.53International Consortium of Investigative Journalists. Five things you need to know about coltan
An area that has received less scrutiny is the mining of nickel, which is also crucial for batteries. Nickel is used in most lithium-ion batteries as it helps to provide higher energy density and to improve storage capacity. The demand for nickel for electric cars is expected to rise from 150,000 tonnes in 2020 to 310,000 tonnes in 2025 to 650,000 tonnes in 2030. This will drive the total nickel demand to 3.2 million tonnes a year, from 2.3 million tonnes in 2020. Much of this nickel comes from Siberia and the Russians are often rather sloppy about environmental safety. A group representing indigenous communities in Russia sent a letter to Elon Musk, the CEO of Tesla saying, “We are respectfully requesting that you DO NOT BUY nickel, copper and other products from the Russian mining company Nornickel.” They cited the enormous diesel spill from a Nornickel plant that turned Siberian rivers crimson in the summer of 2020. They alleged that the world’s leading high-grade nickel producer was “a global leader in environmental pollution” and urged Tesla to rule out buying from the miner until it cleaned up its act.54The dirty secret behind your ‘green’ electric car
A major producer of nickel for batteries is the Chinese-owned Ramu project in Papua New Guinea. Ramu hit the headlines in 2019 when a pipeline leak caused a huge spill of toxic slurry into a bay. However, even its normal operations are controversial. The nickel deposit here is of a different type to that in Russia and turning it into a product suitable for batteries requires a process called high-pressure acid leaching which generates 1.5 tonnes of waste for every tonne of ore processed. In Ramu, that waste is disposed of deep at sea, a process opposed by environmental groups, which claim that it remains toxic.
Although this section has focussed on batteries, motors and other technologies are important as they often use rare minerals. This is discussed further in the chapter Alternative Energy. The world had a limited supply of rare elements and much of their mining and processing has been monopolised by the Chinese, with considerable risk to our industry and defence. An article said that a British firm had developed a motor that uses steel rather than rare earth minerals.55British firm cracks electric car motor conundrum This is of great importance and must be supported.
In August 2019, Donald Trump announced on Twitter, in his usual inimitable way, that he wanted to buy Greenland. That was for the USA, not himself. This was to gain access to minerals and to keep out China. Greenland is a self-governing territory under the Danish crown which won rights over its own mineral resources in a 2009 self-rule agreement. The Danish prime minister rebuffed him and he pulled out of a state visit to Denmark. An article in The Times called 56Why Donald Trump wants to buy Greenland: the hunt for elements to undermine China explains the importance of the rare minerals in many fields.
There is far more to be considered with regard to the humanitarian and environmental impact of all-electric or hybrid cars as well as mobile phones. This has only scratched the surface, but I hope that it will make you stop and think about the impact of the technology. What might seem clean and wholesome for us, may have a very different impact in other parts of the world. It is no good having dirty mining for a clean technology.
From the evidence available, it seems clear that toxicity from vehicle emissions is real and that it is related to the level of pollution and the duration of exposure. The major problem areas are where traffic is heavy, perhaps tall buildings reduce wind circulation and there are many pedestrians nearby, although the occupants of cars are also at risk. There does not seem to be a threshold for adverse effects from pollution but risk continues down to zero.
Of the various types of engine used for transport, diesel engines are the greatest source of pollutants except carbon monoxide. However, not all diesels are equal and modern engines are very much cleaner and more efficient than older models. Diesels in the more prestigious cars are cleaner than in cheaper cars. Petrol engines are significantly cleaner although carbon monoxide levels are higher. Other fuels such as LPG are much better, but it is an option that is overlooked. It is almost as if a conscious decision has been taken to ignore LPG. Hybrid cars may reduce fuel consumption and toxic emissions in moderate to heavy traffic, but by and large, they do not live up to expectations. Fuel consumption and emissions are not very much lower than conventional models and it takes a great many miles to recuperate the increased capital outlay. They are not worth the money. Electric engines do not produce toxic emissions although just moving throws up a certain amount of particulate matter.
The problem is severe enough and real enough to require attention. This will not be a quick fix but a sustained programme. Many towns have pedestrianised their shopping centres. This is a wise move. It may also reduce road traffic accidents. People who work in car-washes within multi-storey car parks are in an environment where they are exposed to car fumes whilst there is little movement of air. Drivers and passengers come and go, spending a short time in this environment but those who work for hours a day each day must be exposed to considerable pollution. In the Far East many pedestrians and cyclists wear masks rather like surgical masks. I am not convinced that they are much use in reducing small particle inhalation unless the weave is very tight and there is no reason why they should reduce the level of inhaled toxic gases.
London has a congestion charge which means that road users must pay to use certain roads in central London at busy times. The intention seems to be to improve the flow of traffic rather than to improve air quality. Other British cities have considered a similar tariff but, to my knowledge, none has introduced it. A specific charge on drivers of diesel vehicles to enter cities was suggested in 2016 and introduced in 201757Drivers of toxic diesels must pay to enter cities although diesel engines vary considerably.
London introduced an Ultra Low Emission Zone (ULEZ) in 2017, charging diesel vehicles built before 2016 and petrol vehicles from before 2006 £10 a day which rose to £12.50 in April 2019. According to the the Greater London Authority there were 13,500 fewer cars driven into central London in September 2019 compared with March that year, making a 38% reduction. However, they the system does not distinguish between prestigious cars with good systems and cheaper cars with poorer systems including some which know are totally unsatisfactory. Furthermore, diesel back cabs are exempt from the charge and I suspect that many are rather old with many miles on the clock.
It seems that many people have given up bringing their cars into central London with traffic falling by 9% since the previous year. Nitrogen dioxide average levels have fallen from 85 to 57 micrograms per cubic metre at the roadside in central London over the two years of 2017 to 2019. The target legal level is 40. PM2.5 levels have fallen at a much lower rate as they are produced by all vehicles from tyres, brake and road wear and from other sources, including domestic fires and agricultural pollution. It is hoped that this scheme will be adopted by other cities with high levels of pollution, including Manchester, Bristol, Southampton, Newcastle and Derby.
Encouraging haulage back to the railways from the roads may have some benefits but rail lost out to road haulage when repeated rail strikes put businesses at risk. The activity of rail unions has done nothing to convince businesses to put their viability in the hands of rail unions.
It may seem logical to believe that small diesel cars produce fewer emissions than larger cars and they are less troublesome than large goods vehicles and buses. The converse is true. An article in The Times58Small diesels more toxic than big cars said that new models of cars with an engine size below 1.5 litres emit, on average, 9.3 times the legal limit of nitrogen oxides in road tests by a company called Emissions Analytics, which supplies independent data on the real-world emissions produced by cars. The Emissions Analytics road tests involve realistic speed and acceleration. Cars with engines bigger than 2 litres emit on average 5.8 times the legal limit. Both figures may seem astounding but manufacturers are only required to meet legal limits in laboratory tests. They admit that those tests do not reflect how cars are driven on the road. A 3-litre BMW 5 Series and 4-litre Porsche Panamera both met the legal limit of 80 milligrams per kilometre of nitric oxides but in the same tests a 1.4-litre Volkswagen Polo and 1.4-litre Toyota Auris produced from six to eight times the legal limit. Gallon for gallon, lawn mower engines contribute 93 times more smog-forming emissions than new cars.59How Catalytic Converters Work
In May 2017 it was reported that sales of new diesel cars fell that April by the largest amount since the financial crisis after warnings that they could attract charges to improve air quality. Diesel car sales fell by 27.3% compared with the previous April. The previous year diesel cars were outselling petrol models but in April 2017 diesel made up 44.9% of sales, compared with 51% for petrol and 4.1% for electric cars and other fuels.60Diesel car sales slump as drivers fear emission fees However, it is not new cars that are the problem, especially the more expensive ones. It is the old cars.
In March 2018 the sale of new diesel cars fell by 37% compared with the previous year with petrol cars up 1% and alternative fuel up 5.7%.61UK car registrations plunge in March Because of the outcry, people are not buying new, clean diesels that meet Euro VI specifications and the motor industry is suffering. In 2019, when I renewed the road tax on my Jaguar XF 2.2 diesel, the tax was £155. Had it been a brand-new petrol car with the same CO2 production, it would have cost £205 whilst a brand-new diesel, even with Adblue would have cost £515.62Vehicle tax rates No wonder the motor industry is suffering. New, clean cars have punitive road tax.
Larger cars have more space for pollution controls, reducing pressure on manufacturers to use smaller, less effective systems or risk reducing their effectiveness by squeezing them into a tight space. Large cars are also more expensive, so an increase in cost due to a better system is less marked as a fraction of the final price. Larger diesels are more likely to have selective catalytic reduction systems which involve injecting urea into the exhaust to neutralise the nitric oxide emissions. From September 2017, any new models being put on the market for the first time will have to meet a tougher official test which will include on-road testing.
Even modern diesel cars produce more than twice as much toxic gas as a lorry or bus of the same age.63Diesel cars pumping out twice the toxins of lorries and buses The International Council on Clean Transportation (ICCT) analysed results of “real world” emissions tests by Germany’s vehicle testing agency and a Finnish research centre. The latest diesel lorries and buses produced an average of 210 milligrams of nitrogen oxides per kilometre compared with 500 milligrams per kilometre for new diesel cars.
The reason buses and lorries show lower emissions is that they are subject to much stricter official pollution tests than cars, according to ICCT. The legal limit for new diesel cars is 80 milligrams per kilometre but this only has to be achieved in laboratory conditions. ICCT said that car companies used prototypes that had been specially prepared to do well in the tests. Since 2014 lorries and buses have been subjected to tests on the road of randomly selected vehicles. The weight of the battery required for large electric goods vehicles substantially reduces the load that can be carried and drivers will require more and much longer stops to recharge the batteries. Considering how clean diesel haulage is and the problems of batteries, it seems unreasonable to insist on electric long-distance heavy goods vehicles.
The Channel Island of Sark bans cars but tractors and horse drawn vehicles are permitted. I took this outside the medical centre. Note the Doctor sign above the cab. Perhaps the box on the back is the ambulance for the island.
It was revealed that Volkswagen had cheated emissions tests by ensuring that diesel pollution controls worked in the laboratory but not on the road. An improved test was introduced from September 2017. However, it would still be open to manipulation by prototype cars. It would be much better to measure ordinary mass-production vehicles, obtained from customers driving them in an ordinary way. VW also owns Audi, Skoda and Seat. Jeep, owned by Fiat, has also been accused of cheating the emissions. Both fuel consumption and emissions must be tested under conditions resembling normal driving.
More recently, in 2019, in the wake of the VW scandal, the Driver and Vehicle Standards Agency (DVSA) tested a number of cars sold in 2017 on public roads and on a track against the worldwide harmonised light vehicles test procedure. This is more representative of how cars are actually driven and has been a requirement for all new cars sold since September 2018. The agency said that the Qashqai’s result “was found to be more than 17 times the legislative limit”.64Nissan refuses to improve Qashqai’s toxic emissions It said that the level by which the car exceeded the standard “shows that this vehicle is not sufficiently well designed to control NOx in real world conditions”. It asked Nissan to develop a way of recalibrating the engine software of the cars it had already sold to make them produce less NOx, and Nissan initially agreed to consider this. However, the company later refused, telling the DVSA that it wanted “to focus energy and resources on the new models”.
Another serious cause for concern arose from a Channel 4 “Dispatches” programme.65(Channel 4 Dispatches. Broadcast 9th April 2018) A significant number of heavy goods vehicles employ a device called an emulator. This is a small device which switches off the Adblue. The company does not have the cost of Adblue and if the Adblue system goes wrong it can be rather expensive to repair. The result is that these vehicles emit between three and ten times more nitric oxide than they would have done. The Vehicles Standards Agency is catching such people but they are getting just a requirement to remove the device and report for inspection in the next ten days. Much more severe penalties are available with heavy fines and even removal of the hauliers’ licence but these are not being used. Such devices are readily available on the Internet. The market for emulators in this country is second only to China. There is another system involving computers which is said to hack the Adblue system and this is much more difficult to detect. The NOx emissions will be high but to detect this really needs a rolling road which takes the vehicle up to 50mph. They are expensive and the EU decided that they do not represent a cost-effective value.
A suitable response to the available evidence would be to reduce the proximity of vehicles to people and to encourage less toxic engines in areas of high risk. Both approaches should be followed. Simply banning diesels is not appropriate. For large goods vehicles, they are the engine of choice. Alternative fuels may be encouraged for vehicles that enter areas that currently have high pollution. These vehicles include buses, taxis and delivery vans. Electric motors are clean, but their price and limited range are a problem. Perhaps we need more trams and trolley buses back in our cities. Taxis could look to LPG rather than diesel. An electric black cab is being developed but as it would cost about £35,000, many taxi drivers may feel priced out although the markedly reduced cost of fuel must be important with such a high annual mileage. Many minicabs are hybrids. The company that produces the electric black cabs is expanding into delivery vans, but it is owned by the Chinese and only about a third of the components are made in the UK.66Electric taxi factory expands into vans
We look both ways before crossing the road. We drive with due care and attention, but even the most conservative estimates are that road traffic pollution kills 5 to 10 times as many people as road traffic accidents. In a study in London, more than 250 children at five primary schools wore backpacks containing highly sensitive air sensors for a week on their journey to and from school.67Back-street walk to school cuts pollution exposure Those walking on main roads were exposed to an average level of 143 micrograms of nitrogen dioxide per cubic metre (143µgm-3), compared with 78µg-3 for those who took a back street route. Those travelling by bus or car were exposed to 85µg-3. Hence, avoiding main roads can almost halve the level of exposure. The legal limit is an overall annual average level of 40µg-3. Air pollution monitors installed at 30 schools in London by Environmental Defense Fund Europe found that 90% were likely to have air with levels of fine particles exceeding the World Health Organisation’s guideline limit of 10µg-3.
Jaguar Land Rover, Britain’s’ largest and most successful car manufacturer has seen a large drop in sales and whilst Brexit is one of the problems, the campaign against diesel is certainly an issue. Around 80% of the production is diesel and the new engines are good and clean. They will reduce the workforce by about 1,000.68Jaguar slump costs 1,000 jobs This is one of the few companies in the UK that seem to have invested heavily in electric technology, but it is struggling. Action needs to be taken but the hysteria surrounding motor vehicles and the failure to differentiate between polluting and relatively clean cars will have a devastating effect on our motor industry. Nissan in Sunderland have also experienced problems. Although uncertainties over Brexit have also caused problems, adverse publicity over the internal combustion engine has also had a marked effect. Our motor industry is very important to our economy and the adverse effects of these policies were predictable.
Anyone who can afford to buy an electric car spends a great deal of money on it. Even small electric cars are quite expensive compared with conventional cars of similar size. Bearing in mind that electric car owners are the rich, is it right that the ordinary, long-suffering taxpayer should be subsidising them? We have seen that they can charge up away from home for less than £10 a month. The installation of many charging bays around cities will cost a great deal and it would seem likely that it is not the users who are asked to pay for this. In an article in the Times, Ed Conway admits that he has stopped using the Underground to get to work as the perks of driving an electric car make it much cheaper.69My electric car perks are shockingly generous Is this what we want? He is exempt from congestion charges and in Westminster he gets four hours of parking for the cost of 10 minutes.
People who drive 10 years old small hatchbacks do so because they cannot afford anything else. It is totally unrealistic to suggest that they should buy a new electric car instead.
There was a grant of up to £4,500 against the cost of the car itself, a grant to help pay for a charging point at home, generous capital allowances and in Scotland the government will even grant an interest-free loan. There is also free electricity to charge the car and free parking whilst charging if you pick the right charge point. However, an article in The Times in 2019 said that the number of new electric cars had fallen after the grant had been reduced from £4,500 to £3,500 and incentives for plug-in hybrids were abolished. It said that electric cars cost up to £10,000 more than their petrol or diesel equivalents and the government has acknowledged that the gulf in price is unlikely to close until the mid-2020s at the earliest.70Electric car sales stall after cut to green grants
The BBC found that electric cars were not attractive to most people because of the price but also the range before needing to recharge is too small.71Electric cars not attractive for most people in the UK The Government has announced that all cars should be fully electric by 2040.72Government to announce end of the diesel and petrol car If electric cars were universal, there are many consequences to consider. How to charge a car for people who have to park on the road is a problem.73How do I charge an electric car without a driveway? It has been suggested that the total demand on the National Grid would be only about 10% higher but we are near a critical level now. New cables with a high capacity will have to be laid. The government will have to replace the £30 billion it gathers in fuel duty as well as the VAT on petrol. I wonder how many people think that they can charge their cars overnight from their solar panels. Think about that one.
In November 2020, the Government announced that it was bringing forward to 2030 the date when it would no longer be permissible to sell new petrol or diesel vehicles and that new hybrids would be banned from 2035.74Ban on new petrol and diesel cars in UK from 2030 under PM’s green plan The motivation for this announcement seems to be the usual preoccupation with carbon dioxide emissions rather than toxic gases and particles. It is important to realise that the ban applies to new vehicles only and does not prevent the sale of used cars.
The efficiency of large goods vehicles powered by batteries is questioned. As we have seen, the batteries are so heavy that they considerably reduce the weight of goods that these vehicles can carry and they require much longer stops to recharge than filling a tank with diesel. We have also seen that goods vehicles produce fewer emissions than small cars. A more sensible approach may be to use diesel vehicles for long distance haulage to depots and from there to use electric vehicles to deliver to towns and cities.
The plan also involved five gigawatts of “low carbon” hydrogen production capacity by 2030 and carbon capture to capture and store harmful emissions away from the atmosphere. As we have seen, hydrogen production from natural gas involves the production of carbon dioxide, even if the end product just burns to water and carbon dioxide capture is a technology that has not been developed. It is most unwise to rely on technologies that do not yet exist.
Hybrid cars give some benefit in congested areas but the benefit is small, the extra outlay is large and the number of miles taken to recoup the higher price is unrealistic. There is no place for biofuels. LPG should be encouraged as being much cleaner than diesel or even petrol but without the limitations of a fully electric car or the poor returns for outlay with a hybrid. It would be good if dual fuel cars could be factory produced rather than needing conversions. The motor industry should be encouraged to invest in this duel fuel technology. The main problem is that it requires two tanks for the two fuels, but it might be acceptable to make the petrol tank smaller to accommodate the LPG tank.
The internal combustion engine is by no means the only cause of pollution. Even household products such as shampoo, oven cleaner and detergent have been implicated in producing PM2.5 particles that cause respiratory deterioration.75Volatile chemical products emerging as largest petrochemical source of urban organic emissions. The tendency to blame motor vehicles for all pollution is unjustified as there are other factors too. Particles are very significant, even down to low levels75Americans Still Dying From Air Pollution and so we should look at all sources.
A rational plan has to be based on evidence and honesty. We have seen much dishonesty from the motor industry, especially VW. Even scientists who promote the green agenda prefer post-truth to veracity. Simply ditching diesels, let alone all internal combustion engines, is not a valid or realistic choice. Perhaps road tax should be based on real-world pollution rather than the irrelevance of carbon dioxide emissions but it has to be based on reality, not modified prototypes.
- Encourage low emission vehicles as well as electric vehicles in urban areas but remember that hybrids have internal combustion engines too. The hybrid is a fudge that is very expensive for a limited benefit.
- Electric vehicles are most suited to short, urban journey where petrol and diesel engines may not get warm enough for the catalytic converter to start working. On the other hand, electric vehicles are not really suited to long distance haulage and as the diesel engines on large goods vehicles and buses are among the cleanest, they should be given dispensation.
- Encourage pedestrianised areas.
- We look both ways before crossing the road and we drive with due care and attention. However, if road traffic pollution kills perhaps five to 10 times as many people as road traffic accidents, we should give more consideration to where we walk or drive to reduce our exposure to toxins.
- Make the testing of cars, whether for fuel consumption or emissions, relevant to real use. There should be heavy penalties for the sort of fraud perpetrated by VW. The USA has fined them heavily. Europe has taken no effective action. Take firm action against those who turn off Adblue on large goods vehicles.
- Ban vehicles without catalytic converters and effective pollution reduction mechanisms. New but inadequate cars should not be sold.
- Encourage the production of LPG duel fuel cars.
- Take action against gratuitously noisy cars and motorcycles.
Some Chemistry Equations
Here are a few chemistry equations for those who like them:
At very high temperatures oxygen and nitrogen can combine to form nitric oxide:
N2 + O2 = 2NO
Nitric oxide is oxidised to nitrogen dioxide in atmospheric oxygen:
2NO + O2 = 2NO2
Nitrogen dioxide reacts with water to form nitric acid and nitrous acid:
2NO2 + H2O = HNO3 + HNO2
Nitrous acid is a weak acid that is oxidised in air to nitric acid, aided by ultraviolet light:
2HNO2 + O2 = 2HNO3
In catalytic converters carbon monoxide is converted to carbon dioxide in the presence of platinum and palladium:
2CO + O2 = 2CO2
With a rhodium catalyst nitric oxide and carbon monoxide become nitrogen and carbon dioxide:
2NO+ 2CO = 2N2 + 2CO2
At high temperatures, the urea in Adblue is converted to ammonia and water:
(NH2)2CO + H2O = 2NH3 + CO2
Then ammonia then combines with nitric oxide and nitrogen dioxide to form nitrogen and water:
2NH3 + NO + NO2 = 2N2 + 3H2O
I presume that the equation for “steam methane reformation” to produce hydrogen from methane is:
CH4 + 2H20 = 4H2 + CO2
- Motor Vehicle Emission Controls: Fuel Types. Air quality
Brief and comprehensible
- Nitrogen Oxides (NOx) Air Pollution Information System (APIS)
Comprehensible without a great knowledge of chemistry
- Petrol vs diesel cars: which is better? Adrian Potter for Which? 2019
With the authority of Which?A concise look at petrol, diesel and hybrid cars
- International Consortium of Investigative Journalists. Five things you need to know about coltan
A short but revealing article about coltan for car batteries, mobile phones and more
- Traffic pollution kills 5,000 a year in UK, says study. BBC News
- Air pollution ‘kills 13,000 a year’ says study. NHS Choices
- Drive smoothly to reduce harmful effects of air pollution, says NICE. NICE December 2016.
- Every breath we take: the lifelong impact of air pollution. Royal College of Physicians London February 2016
- Mark Broomfield. Every Breath You Take: A User’s Guide to the Atmosphere. Duckworth Press.
- Dash for gas could solve the diesel crisis. Matt Ridley. The Times 20th February 2017
- Department of Transport. Reported road casualties in Great Britain: 2018 annual report. Issued 2019
- Chen HC, Kwong JC, Copes R et al. Living near major roads and the incidence of dementia, Parkinson’s disease, and multiple sclerosis: a population-based cohort study. The Lancet 4th January 2017
- Mental cost of diesel fumes like a bereavement. The Times 17th April 2017
- Kim KH, Kabir E, Kabir S. A review on the human health impact of airborne particulate matter. Environment International. Volume 74, January 2015, Pages 136–143
- Virtual Special Issue: Human health and particulate matter air pollution. Environment International
- Air quality org. Motor Vehicle Emission Controls: Fuel Types
- Commuters warned of new air pollution risk. The Times 14th February 2017
- Doiron D, de Hoogh K, Probst-Hensch N, et al. Air pollution, lung function and COPD: results from the population-based UK Biobank study. ERJ 9 July 2019
- Wei Y, Wang Y, Di Q, Choirat C, Wang Y, Koutrakis P et al Short term exposure to fine particulate matter and hospital admission risks and costs in the Medicare population: time stratified, case crossover study. BMJ. 2019 Nov 27;367:l6258 [full text]
- Loxham, M, Davies DE, Holgate S T The health effects of fine particulate air pollution. BMJ 2019;367:l6609
- Air quality org. Motor Vehicle Emission Controls: Fuel Types
- Diesel Engines: Design and Emissions. John Pignon 2005
- Nitrogen Oxides (NOx) Air Pollution Information System (APIS)
- Catalytic converters. Chris Woodford. Explain that stuff
- Motor Vehicle Emission Controls: Fuel Types. Air quality
- Air pollution creates drug resistant bugs. Oliver Moody, science correspondent. The Times 3rd March 2017
- 60mph limit and fines to cut M1 pollution. The Times. 22nd January 2017
- Cars and air pollution. Department for Transport
- Noise. Department for Transport
- The Car Expert. Fuel economy – Petrol or diesel? Stuart Masson 5 March 2012.
- Department of Transport table ENV0103 December 2016
- Soaring demand for SUVs exacerbates climate crisis. The Times 14 November 2019.
- What is Adblue? Carbuyer
- Are diesel particulate filters more trouble than they’re worth? Car Magazine 26th August 2011
- The evolution of catalytic converters. Royal Society of Chemistry. 1st June 2011
- Best hybrid cars to buy. Auto Express
- Pros and Cons of Hybrid Cars. Car Direct (American site) 26th May 2016
- Can you rely on the official figures? The AA
- Why the EC figures do not represent true MPG. Honest John
- That extra mile. Petrol vs Diesel vs Hybrid vs Electric
- Dorset LPG
- Air quality org. Motor Vehicle Emission Controls: Fuel Types
- Petrol or LPG … do the fuel cost savings add up? The Guardian. 13th July 2012
- Wood stove fad is blamed for pollution. The Times. 26th January 2017
- UK Charging points – find your nearest on-street point
- Electric cars will not be a drain on the national grid. The Times 29th July 2017
- Plugging in six electric cars may cause local power cuts. The Times. 20th April 2017
- Honda: ‘Electric cars not viable’. Autocar 27th May 2010
- Nissan Leaf 30kWh review
- Tesla ‘out-accelerating the Model T’. The Times 4th April 2018
- Electric cars cost 50% more to insure. The Times 28th July 2017
- Falling battery costs to drive electric car sales. The Times 6th July 2017
- Car battery of the future faces acid test. The Times 13th May 2019
- Dash for gas could solve the diesel crisis. Matt Ridley. The Times 20th February 2017
- Electric cars ‘will not solve transport problem,’ report warns
- Congo’s miners dying to feed world’s hunger for electric cars. Sunday Times 10th March 2019
- International Consortium of Investigative Journalists. Five things you need to know about coltan
- The dirty secret behind your ‘green’ electric car. The Times 7 September 2020
- British firm cracks electric car motor conundrum. Daily Telegraph 28 March 2021.
- Why Donald Trump wants to buy Greenland: the hunt for elements to undermine China. The Times 26 August 2019.
- Drivers of toxic diesels must pay to enter cities. The Times. 3rd November 2016
- Small diesels more toxic than big cars. The Times 28th April 2017
- How Catalytic Converters Work. How stuff works
- Diesel car sales slump as drivers fear emission fees. The Times 5th May 2017
- UK car registrations plunge in March. BBC news 5th April 2018
- Vehicle tax rates
- Diesel cars pumping out twice the toxins of lorries and buses. The Times 6th January 2017
- Nissan refuses to improve Qashqai’s toxic emissions. The Times 23rd July 2019
- Channel 4 Dispatches. Broadcast 9th April 2018
- Electric taxi factory expands into vans. The Times 22nd March 2017
- Back-street walk to school cuts pollution exposure. The Times. 22 October 2019.
- Jaguar slump costs 1,000 jobs. The Times 14th April 2018
- My electric car perks are shockingly generous. Ed Conway. The Times 18th August 2017
- Electric car sales stall after cut to green grants. The Times. 13th May 2019
- Electric cars not attractive for most people in the UK. BBC 21st May 2019
- Government to announce end of the diesel and petrol car. The Times 26th July 2017
- ‘How do I charge an electric car without a driveway?’ And more of your questions answered. BBC 10th July 2019.
- Ban on new petrol and diesel cars in UK from 2030 under PM’s green plan. BBC News 18 November 2020.
- McDonald BC, Gouw JA, Gilman JB, Jather SH, Akhereti A, Capps J et al. Volatile chemical products emerging as largest petrochemical source of urban organic emissions. Science 16 Feb 2018: Vol. 359, Issue 6377, pp. 760-764
- Brown. T. Americans Still Dying From Air Pollution. Medscape News 28th June 2017
This website is now completed, although I shall continue to do updates. The following list shows the sections or chapters. Just click on the topic in blue to go to that part of the site.