Challenges of energy transition needed to meet decarbonisation targets set up to address climate change

Gautam Kalghatgi

（Department of Engineering Science, University of Oxford, OX1 3PJ, U.K.）

Abstract: There is widespread belief that climate change poses an “existential threat” and drastic and rapid cuts in greenhouse gas (GHG) emissions and hence fossil fuel use are needed to cope with it. However,empirical evidence shows that humanity has coped well with the past rise in temperature caused substantially by human activities. Moreover, fossil fuels supply 85% of global energy needs and replacing just 60% of these with carbon-free energy will require the world to build new capacity of around 9.4 TW CO2-free continuous power. Simultaneously, the existing energy infrastructure has to be dismantled e.g. oil, gas, coal, aviation, steel and cement industries have to be largely shut down. Such change is unlikely to happen, particularly as poorer countries try to grow their economies and continue to use fossil fuels so that global GHG levels are not likely to come down. It is perhaps better to recognise this reality and make societies more resilient to the effects of climate change. The paper will focus on transport, particularly, battery electric vehicles to illustrate some of the challenges. The focus is also on the policies in the U.K. but the general points are applicable to most other countries.

Key words: climate change; energy transition; greenhouse gas (GHG) emissions; decarbonisation; new energy; transport energy

1 Introduction

There is widespread concern about climate change, the term that encompasses the impacts of global warming caused by the increase in greenhouse gases (GHG) such as carbon dioxide(CO2) methane and nitrous oxide (N2O). The Intergovernmental Panel on Climate Change (IPCC)[1]established in 1988 under the auspices of the United Nations, has been providing the world with the evolving knowledge on climate change through its assessment reports. It is now accepted that the earth has warmed by about 1.1 C since 1900 and it is “extremely likely”,according to the IPCC, that global warming between 1951 and 2010 was caused entirely by human activity. The burning of fossil fuels-coal, oil and natural gas-which provide most of the energy requirements of the world increases CO2and methane increases primarily because of agriculture and land use. There is widespread belief that unless “something is done”, the world will go through an “existential crisis”. As a result,several initiatives calling for drastic cuts in GHG emissions are gaining traction. For instance, the U.K. government has legally committed to “net zero” GHG by 2050[2]. “ Net zero”means that the amount of GHG produced is balanced by the amount of GHG removed. Natural sinks such as the oceans and land biosphere already remove around 55% of GHG produced.Other technological methods for GHG removal such as carbon capture and storage (CCS) are being researched and developed but they are not yet ready for deployment at scale and have huge requirements for land and energy[3]. In practice, it really requires very significant reduction in emissions of GHG to meet net zero targets. Indeed, there is some opinion that the current level of 412 ppm (1 ppm equivalent to 1.8 mg/m3) of CO2in the atmosphere is already too high and this needs to be brought down to 350 ppm which will require the world to stop using fossil fuels completely[4]. The Green New Deal (GND)which has strong support amongst many leading politicians in the U.S. has ambitions to eliminate fossil fuel use by 2030[5].

The speed and extent by which global GHG emissions need to be reduced depends on how serious and dangerous climate change is perceived to be. At the same time, in many countries,energy policy is very much influenced by the need to ensure sufficient affordable energy to allow growth of prosperity and reduction of poverty. On the one hand there are pressure groups like the Extinction Rebellion[6]who believe the “emergency on planet earth” is so severe that GHG need to go to net zero by 2025. However, there are also more balanced voices[7-8]which say that such alarmism is not justified and humanity will cope with the problems posed by climate change. There are other very important matters which have been traditionally of concern of the environmental movement such as clean air, clean water, safe food and biodiversity which need to be tackled. An equally important goal should be to reduce global poverty because most environmental problems cannot be solved when people are poor[7-8]. So, the question really is how does the world respond to the challenges posed by climate change.

This paper first considers if there is indeed a “climate emergency” leading to “an existential crisis” and comes to the conclusion that the crisis is not so bad that the world has to completely and almost immediately give up fossil fuels. However, since there are many such initiatives being proposed, the paper discusses the challenges posed by rapid decarbonisation and the energy transition that would be required. It also discusses transport which is the most difficult to decarbonise and more particularly, the prospects of achieving such decarbonisation through battery electric vehicles. These discussions are often focussed round the U.K. in the paper but the general points are relevant to other countries as well. Finally, there is a concluding discussion.

2 How serious is the “climate emergency”leading to an “existential crisis”?

The central premise appears to be that “science” says that the world is rapidly heading towards disaster and there is an“existential crisis” and a “climate emergency”. How has humanity coped with the warming of 1.1 C over the past century and what does the empirical evidence say about the impacts of this warming?

· All objective/empirical measures of human development such as absolute poverty levels, life expectancy, share of the population that is undernourished, education,child mortality have been improving significantly and consistently, particularly in poorer countries, over the past many decades[9-11].

· World food production (and per capita food consumption,productivity per acre, daily supply of calories) has been increasing consistently over the past few decades[9,12]. The International Grains Council (IGC) is forecasting record total grains production in 2020-2021[13]. In fact, the world produces roughly 25% more food than is actually needed by its current population[7].

· A related point is that the earth is ‘greening'. From a quarter to half of Earth's vegetated lands have shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide. Such greening is expected to mitigate global warming by increasing the carbon sink on land and altering biogeophysical processes, mainly evaporative cooling[14-16].

· Deaths attributed to natural disasters (drought, floods,extreme weather, extreme temperature, landslides, dry mass movements, wildfires, volcanic activity and earthquakes)have declined by over 95% over the past century[9,17].This is because of increased prosperity and development which enable societies to become more resilient though the financial losses caused by natural disasters have increased for the same reason.

· According to the IPCC AR5, Ch4, there is little or no empirical evidence to suggest that the incidence of tropical and extra-tropical storms, floods and droughts have increased in recent decades. The more recent IPCC report (on Global Warming of 1.5 C) does not alter these conclusions but says that there is evidence now of increased incidence of warm days and nights. However, this report also projects that such extreme weather events will increase based on model projections. The empirical evidence is discussed by Roger Pielke Jr. in his book[18].

· There is a lot of justified concern about deforestation and forest fires. Global warming is expected to makes forest residue more likely to burn by making it drier. However, hot dry conditions, do not automatically mean fire - something needs to create the spark and actually start the fire[19]. In fact, empirical, statistical evidence does not show a uniform global trend that there is an increase in wildfires[20-21]though there appears to an increase in the frequency and extent of forest fires in some places like California. However, the immediate causes for this is very likely to be bad forest management e.g. allowing forest residue to build up and increased accidental or deliberate setting of fires.

· There is also a lot of concern about sea level rise. However,sea levels have been rising consistently since the mid19th century but there have been reports that they are rising faster in recent years. There are very credible assessments of data that show that the current level of rise of 3 mm/year is not abnormal[22].

· There are other issues which have more impact emotionally such as the belief that the polar bears will go extinct because of climate change. However, polar bear populations have been increasing or are stable apart from in a handful of locations. Polar bear numbers are at least three times higher than in 1960[23-24].

· As an aside, it is not uncommon to hear of CO2as a pollutant or even a poison but the concentration of CO2in one's nostril when one breathes out is around 40 thousand ppm (72.0 g/m3) or 100 times that in the atmosphere; in a closed lecture room it is around 1000 ppm (1.8 g/m3). So how can it be a poison? Without CO2, there would be no photosynthesis and no green plants.

Thus, humanity has coped very well with the warming of the past century. The world is a far better place in almost all countries not affected by war, compared to the past though there are great many problems associated with poverty, disease and unequal distribution of resources in many parts of the world. However, these are not caused by climate change. As economies have grown and prosperity has increased, humanity has been able to cope with natural disasters and there is no real empirical evidence that such weather extremes have increased over the past century. There will be consequences of further increases in global temperature because of human activity but it is reasonable to expect that the world will be able to cope with such consequences as it has done in the past.As economies grow further, and people get richer especially in poor countries, they will be better able to cope with these changes. However, economic growth and poverty reduction cannot happen unless there is access to affordable energy. So,one quite justifiable view is that climate change is just one of the many challenges facing humanity and is not going to lead to an imminent collapse of the world. It is not possible to stop using fossil fuels in the short to medium term since they provide most of the energy needed by modern societies. In most developing countries growth and energy security which can lead to a reduction in poverty and an improvement in the overall wellbeing of the population, drive energy policy.

It is now fairly common to ascribe incidence of any storm,flood, forest fire, drought, excessive snowfall and other misfortune to climate change. Even if evidence emerges in the future with more data that this is indeed the case, what would be the best policy to tackle these problems? Clearly effective action to make societies cope with and eventually resilient to such extremes would be a top priority. Thus, if one is worried about floods, one would build better flood defences and stop building in flood plains. Though efforts should continue to reduce global GHG levels, as we discuss below, the task is extremely challenging and eliminating GHG emissions is not likely to be possible in the short to medium term. Even if the world eliminates GHG emissions, extreme weather will not disappear - there will always be a need to adapt and be resilient to such events.

In summary, we can argue that though climate change is real, it does not pose an imminent “existential crisis” and that humanity will cope with the challenges posed by climate change and that the world should adopt sensible policies to tackle real energy and environmental problems which make people's, especially poor people's, lives better. There should be more focus on “no regrets” adaptation policies such as better flood defences, reduction in waste in the use of energy and resources and preservation of forests rather than primarily on GHG reduction. However, it is fair to say that a large number of influential people across the world disagree,many very passionately, with this view. People holding such a view are commonly called “deniers”, “delayers” and “fossil fuel industry shills” who are delaying actions needed to tackle climate change. In fact, most western governments,particularly in Europe, are already changing their policies on the assumption that the dangers of climate change are serious enough to require an elimination of their GHG emissions. So,what are the challenges of the energy transition required by such policies?

3 Challenges posed by the energy transition required by zero carbon targets

In this section, we focus on the U.K., which is an advanced industrialised nation and has committed to a net zero GHG target by 2050 but is also small in the context of global energy consumption. The broad analysis shown below can then be adapted for any country. Table 1 shows the primary energy use in 2019 in exajoules by the source of energy, for China, the U.S.,India, U.K and the world[25].

The total U.K. primary energy consumption was 7.84 EJ in 2019 of which 6.21 EJ or 79.2% was from fossil fuels; wind and solar contributed 3.5% of the total energy used. Let us assume that the U.K. will require only 60% of current fossil fuel energy use, 3.73 EJ, to be replaced by CO2-free energy production because losses in electrification are lower than losses when combustion is involved and also because of greater efficiency in the use of energy. The Table on p 9 of Ref. [26]shows that in the U.K, final energy consumption, which shows what is available for use, was 74.5% of the total primary energy consumption. So, of 6.21 EJ of fossil fuel energy only 4.63 EJ can be expected to be available for use. To achieve this via electricity, the U.K. will need to generate 5.03 EJ of electricity because the electricity transmission and distribution losses for the U.K. are 8%[27]. However, we are assuming that in fact, the U.K. will need only 3.73 EJ of new CO2-free electricity. The additional reduction could come about because electric devices are more efficient and because of policies implemented to save energy overall and lifestyle changes such as more walking and cycling. It would also allow a margin for CO2emissions which are impossible to reduce, to be offset by removing such emissions using natural sinks like growing trees or engineered sinks like carbon capture and storage. The assumption that only 60% of current fossil fuel use has to be replaced by CO2-free electricity generation is optimistic, perhaps unrealistically so, particularly since many initiatives to decarbonise such as hydrogen and e-fuel production, carbon capture and storage and the dismantling of existing energy infrastructure will increase energy demand. To generate 3.73 EJ (1.037 PWh) of CO2-free energy, the U.K. will need to build 118 gigawatt,GW of continuous power generation. This is equivalent to 39 nuclear power stations of 3 GW capacity each or around 110 thousand wind turbines of 3 MW each, assuming a capacity factor of 0.35[28]. The capacity factor has to be used because the wind does not always blow and on average, only 3.5 MW is delivered for an installed capacity of 10 MW. The scope for large growth in the U.K. for inland wind or hydro power is limited. Solar, though coming down in cost, has a very low capacity factor of around 0.1. So, wind power will need to be primarily offshore and transmission and distribution losses might be greater than the 8% taken above. Wind and solar will also require storage systems such as batteries to store energy when more energy than needed is produced. A single 3-MW wind turbine needs, from Table 5 in Ref. [29], 310 tonnes of steel, 9 tonnes of copper, 1 200 tonnes of concrete (120～150 tonnes of cement), 2 tonnes of rare earth metals, 20 tonnes of fibre glass, 28 tonnes of other plastics and aluminium and large amounts of oil[30]to build. Hence there will be an initial spike in GHGs as the massive new energy infrastructure is built and existing infrastructure is dismantled. Will this not hasten the “existential crisis” ? The capital cost of an offshore wind turbine is expected to be between $4 400 and $6 000 (USD)per kW[31]. So, 110 thousand 3-MW turbines will cost between$1.4 and $2 trillion.

There are also significant environmental impacts associated with wind or solar energy. For instance, wind energy can reduce,fragment, or degrade habitat for wildlife, fish, and plants and the spinning turbine blades often kill birds and bats[32]. Birds of prey such as eagles and falcons are particularly affected and wind turbines are now effectively the apex predator of such birds, some of which are rare, and have a ripple effect on the entire eco system around them[33]. Disposal of wind turbines at the end of their life of about 20 years, particularly of the blades which are made from un-recyclable plastic will be a growing problem. Solar panels contain toxic materials like cadmium and lead and also glass and these pose a serious environmentalproblem especially on their disposal at the end of their life of about 25 years[7,34-35].These environmental problems,especially at the end of life of wind and solar energy systems will only become more acute as these renewables spread.

Table 1 Primary energy use in 2019 in selected countries and the world by energy source shown in exajoules, EJ (1018 joules) [25]

Simultaneously, the existing energy infrastructure has to be dismantled. For instance, the U.K. has an estimated 26 million gas boilers installed[36]. These are expected to be converted to electric (heat pumps) heating by 2050. The electricity distribution network has to be rebuilt at great cost, estimated at ￡466 billion, to accommodate these changes[37]. Are there enough heating engineers and electricians in the U.K. to implement this? Are households expected to bear the cost of conversion or is the government going to pay for this? The net zero target will involve decarbonising transport, supposedly by eliminating internal combustion engines (ICEs). If transport is to rely only on battery electric vehicles and hydrogen (see next section), huge investment will be needed to build the required infrastructure e.g. provide 2 million public and 20 million private charging points. What is the cost of replacing internal combustion vehicles with these new technologies? Is all this even sensible from energy, environment and efficiency points of view? In fact, many initiatives could be either ineffective or counterproductive on a life cycle basis e.g. switching transport to battery electric vehicles if large batteries are required and energy used in battery manufacture and to run the car is not sufficiently decarbonised. In addition, greenhouse gas (GHG)emissions from agriculture need to be taken to zero. Also,the steel, aviation and cement industries which are extremely difficult if not impossible to decarbonise will need to be largely shut down by 2050[38].

Clearly, if all this has to be achieved in less time e.g., by 2030,the task will be even more challenging. For a start, there will not be sufficient time to bring about big changes in lifestyle and improve energy efficiency sufficiently so that more than 60% of energy provided by fossil fuels currently will need to be replaced by CO2-free energy. In other words, more than 39 nuclear plants of 3 GW or 110 thousand wind turbines of 3 MW each will need to be built in a shorter period of time in the U.K.

From Table 1, we can calculate that, to replace only 60% of current fossil fuel use, China, U.S.A, India or the World would need to install new continuous CO2-free electricity generation of 2.296, 1.500, 0.590, 9.366 TW respectively. Again, the assumption that only 60% of fossil fuel currently used needs to be replaced is unrealistic. Actually, demand for energy will increase as most developing economies strive for growth and increased prosperity and as many decarbonisation initiatives such as developing a hydrogen economy, carbon capture and storage and dismantling the existing energy infrastructure are implemented in the more developed countries. Even with this assumption, the world will have to build the equivalent of over 3 100 nuclear power stations of 3 GW each or over 8.9 million wind turbines of 3 MW each (capacity factor 0.35) at an average cost of 15 million U.S. dollars each. At the same time,use of natural gas and oil has to be unless it is combined with carbon capture and storage stopped (will Russia, Saudi Arabia and the U.S. agree?), surface transport has to be decarbonised,meat and dairy farming has to be stopped (will India agree to cull the cows?), aviation, steel and cement industries have to be largely shut down because they are very difficult to decarbonise. All this is not going to happen by 2050 if we consider the world as a whole. So, if the world as a whole does not decarbonise, the efforts of the U.K. (or countries like the U.K.) which accounts for only around 1.3% of global fossil fuel use and hence CO2emissions, will make little difference to global GHG but at great economic and environmental cost.We now consider transport in greater detail particularly focusing on whether internal combustion engines are “dead”and in the future, transport will be powered by batteries and perhaps hydrogen fuel cells.

4 Transport

Transport of goods and people is central to modern life.Globally, transport contributes around 25% CO2emissions but 14% of GHG including other gases such as methane,the same share as livestock farming for meat and dairy[39-40]. Discussion of transport power systems, energy and fuels can be found in Ref. [41-47]. Currently 99.8 % of transport is powered by internal combustion engines (ICE) and 95%of transport energy comes from petroleum-based fuels - the other 5% is from bio sources and natural gas[42-45]. We will again focus on the U.K. because some of the transport policies of the U.K. may be adopted in other countries and the issues discussed below will be equally relevant in such countries.

There is widespread belief that battery electric vehicles (BEVs)which do not have an ICE and get all their energy from the electricity grid should and will replace ICE vehicles (ICEVs).The idea is that if electricity generation is CO2-free, the transport sector can also be decarbonised. Also, since BEVs do not produce any pollutants during use, unlike ICEVs, they can help improve air quality where it is a problem e.g. in urban centres. Another alternative proposed is to produce hydrogen using renewable electricity and then use it in fuel cells to power vehicles. There are also possibilities for developing ‘ lowcarbon' fuels which can help reduce the carbon footprint of transport. However, all these alternatives start from a very low base and face very significant environmental and economic barriers to unlimited growth as discussed in Ref. [45]. Essentially it is a problem of scale. Firstly, BEVs can realistically only power light duty vehicles (LDVs) which account for 45%of global transport energy use. The battery size and weight needed for heavy duty transport and aviation would be too large for realistic, practical electrification of such transport.For instance, with the current technology, a battery which carries the same energy as the aviation fuel carried by a midrange jet such as the Airbus A320 Neo, would weigh 19 times the maximum take-off weight of the plane[45]. Currently the world has around 1.3 billion LDVs expected to go up to 1.7～1.9 billion by 2040 while at the end of 2019, the number of BEVs in the world was around 4 million, more than half of them in China and mostly small cars. So, BEV numbers have to grow by a factor of 300 even to replace the current number of LDVs in the world. The battery capacity needed will have to grow much more than 300-fold if bigger LDVs with longer ranges which require bigger batteries also have to be replaced by BEVs. Such an enormous increase in battery capacity requirements would lead to huge, currently unsustainable,environmental and materials requirement problems[45]but would address only 45% of transport energy use.

Several governments are planning to ban the sale of ICEVs in pursuit of their CO2targets. We will discuss the issues surrounding large scale deployment of BEVs and focus on the U.K. to explore the implications of the proposed bans on the sales of ICEVs.

The U.K. government is considering banning the sale of any new vehicle carrying an internal combustion engine starting from 2035 and maybe even by 2030. This ban will include hybrid electric vehicles (HEV) such as the Toyota Prius and also plug-in hybrid electric vehicles (PHEV). Thus, from this date, only full electric vehicles i.e. battery electric vehicles(BEV) and vehicles equipped with fuel cells and running on hydrogen will be allowed to be sold. This initiative is explicitly part of the plan to decarbonise transport.

4.1 Environmental impact of BEVs

BEVs are not zero CO2vehicles[45]. BEVs do not offer a very significant benefit over ICEVs in terms of CO2unless the energy for manufacture and use is CO2-free. The energy needed to manufacture BEVs, is greater for BEVs compared to ICEV of a similar size because of the higher energy required for battery manufacture, and disposal at the end of life[48-53].There are many life cycle assessments (LCA) comparing BEVs with ICEVs. However, there is a great deal of leeway in the assumptions one can make. For instance, to calculate the embedded CO2associated with battery manufacture, first the CO2intensity of mining, processing the materials and assembly of the batteries has to be established and currently most of these activities take place in countries which use energy which is not from renewable sources and has a high carbon intensity and in the literature, there are values of CO2eq mass ranging from 49 to 200 kg/kWh of battery capacity. The product of this CO2intensity and battery size in terms of kWh gives the total embedded CO2in kg. This total value then has to be distributed over the life/distance travelled of the BEV, which has been variously assumed to be between 150 000 km to 250 000 km to express the impact of the embedded CO2in terms CO2eq mass g/km which can have very different values depending on the assumptions made. The CO2impact during use of the BEV is the product of carbon intensity of the electricity grid expressed as CO2eq mass g /kWh and the energy use by the BEV expressed as kWh/km to get the impact in terms of CO2eq mass g/km. Even if the electricity used is generated from renewables like wind and solar and the average carbon intensity of power generation is very low, the extra electricity demand from BEVs has to be met with marginal (backup) electricity generation which can quickly respond to changing demand.This usually relies on fossil fuels, especially if nuclear power is not in favour, and has a very much higher carbon intensity than the average value. However, many BEV proponents take the average carbon intensity for power generation and this results in a lower value (in terms CO2eq mass g /km) for the in-use CO2impact of BEVs. Then one has to add the CO2impact of the manufacture of the BEV without the battery and the disposal of the BEV at the end of its life; these assumptions also can be different. In summary, the calculated CO2impact of a BEV over its life in terms of CO2eq mass g/km can have very different values depending on the assumptions made but it is not zero though for small BEVs in the U.K. it will be lower than for an ICEV. As battery size increases, to enable bigger cars and longer range, BEVs could in fact have a larger CO2footprint than an equivalent ICEV even if the electricity used to run them becomes increasingly CO2-free.

The impact on human health (human toxicity potential, HTP)associated with mining of metals, water and eco-toxicity associated with batteries is very significant[49-52]and is estimated to be three to five times worse than for ICEVs where it arises from exhaust pollutants[49-51]. Again, the bigger the battery, the worse the impact. This emissions impact of BEVs is exported to where the mining takes place and materials are processed (e.g. the Democratic Republic of Congo, for cobalt;China, Chile for lithium) and cannot be ignored if battery capacity needed increases by many hundred-fold. Mining also requires moving large quantities of earth and rock - on average 500 times the weight of the battery[53]. Thus a 75 kWh battery in a Tesla Model 3, which weighs 480 kg could require 240 tons of rock and earth moved.

4.2 Infrastructure and material requirements

Very large investments will be needed to build new public infrastructure for charging and CO2-free electricity generation to enable a mass conversion to BEVs. In the U.K., around 43%of LDVs (～16 million) have no access to garages[54]and park on the street. Over 2 million public charging points, placed near where people usually park rather than at more remote charging areas will be needed to overcome “charging anxiety”and persuade people to buy BEVs. Subsidies to encourage people to buy BEVs will continue to be needed till their upfront costs come down sufficiently. For instance, the cheapest Nissan Leaf, a BEV, costs ￡29 000 while the cheapest Nissan Micra, comparable in size, is ￡14 000 in the U.K. The Nissan Leaf is most likely to be around 30% better for GHG on a life cycle basis but the Micra has a longer range and can be refuelled in about 5 minutes using the existing infrastructure.A recent paper by Toyota[55]concluded that even the most optimistic scenarios considered did not show BEVs reaching purchase price parity by 2030 compared to a ICEV. At some later date, the U.K. government will need to recoup lost fuel taxes including VAT which currently contribute over ￡32 billion to the public purse. There are very challenging problems associated with providing additional electric power to a large number of BEVs both at the micro and macro level[37,56]and the distribution network will need to be significantly altered. There will be serious questions about the availability of materials needed for battery production. For instance, to replace all LDVs in the U.K. with BEVs will require two times the total annual world cobalt production, nearly the entire world production of neodymium, three quarters the world' s lithium production and at least half of the world's copper production during 2018[57].

4.3 The realistic CO2 impact by 2030 of switching to BEVs in the U.K.

The U.K. has around 37 million cars and vans[58]which account for about 55% transport energy use. Converting all of these to BEVs, will not mean a reduction of 55% in transportrelated CO2. A recent IEA study[48]suggests that, on average,for a mid-sized car, GHG emissions are around 25% lower for a BEV compared to its ICE equivalent. So, making an allowance for various uncertainties and assuming that even big LDVs are replaced by BEVs, even if all of the 37 million cars and vans were converted to BEVs at very great cost, 15% ～20 % of GHG associated with transport would be saved.

At the end of 2019 U.K. had around 100 thousand BEVs or fully electric vehicles ～ 0.3% of LDVs[59]. So, BEV numbers have to increase at least 300-fold to replace all current LDVs.To account for bigger cars and longer range, available battery capacity has to increase by a factor very much greater than 300. Let us assume that the number of BEVs increases a hundred-fold to an improbable 10 million by 2030 (27% of current LDV numbers). Even after this improbable increase,after huge investments, 75% of the cars and 85% of transport energy will be used in ICEs in the U.K. In 2019, 37 800 BEVs were sold in the U.K[59]; at this rate it will take 263 years to reach 10 million. So, even if these 10 million BEVs reduce CO2on average by 25% compared to the ICEVs they have replaced, the overall reduction in transport related CO2in the U.K. will only be only be 3.7% (0.27 x 0.55 x 0.25) of the total.A reduction in fuel consumption of ICEVs of 5% would result in a bigger reduction in CO2/GHG. By 2030, it is likely that the improvements in ICEVs will easily lead to such reductions in CO2by 2030.

In fact, here is much scope for far greater improvements[47]- fuel consumption could be reduced by 50% in a gasoline powered ICEV through better combustion and control systems,partial electrification and reduction in weight. However, this will require continuous development. Sustainability of transport can only be ensured by improving ICEVs in terms of efficiency and exhaust emissions since they will be substantially driving transport in the medium term[46-47]. Note that this will not require any investment in new infrastructure. Indeed, in the short term, HEV offer a readily available technology to bring about a significant reduction in fuel consumption and hence CO2emissions of about 20% in gasoline engines but HEVs are also included in the proposed ban.

4.4 Impact of the proposed ban on the sales of ICEVs

Banning the sale of new ICEVs by 2030 will ensure that any improvements not in the market before the proposed ban will not be available in the U.K. So, a consumer in the U.K. will not be able to buy, say a new Japanese model in 2031 which might be better than what was available in 2030. It will also stop all research and development in the U.K. on ICEs well before the ban and lay waste to quite a strong capability in this area and throw many young and talented scientists and technologists out of work. It will thus remove the biggest and the easiest opportunity to improve the sustainability of transport by denying the best ICEV technology to U.K. customers even while ICEVs will continue to dominate transport for decades to come. The possibility of making the largest and the easiest impact on the sustainability of transport will be lost while the conversion to BEVs will have had only a small impact on the overall CO2footprint of transport. In fact, if the general public is not persuaded to buy BEVs in large numbers by 2030, because of charging anxiety and high up-front costs,and car manufacturers are not allowed to sell ICEVs, the U.K.auto industry will be destroyed with all the implications for employment.

4.5 BEVs and air quality

Of course, BEVs have no exhaust pollutants such as particulates, unburned hydrocarbons (UHC) and nitrogen oxides (NOx) which affect air quality which affects human health. The impacts on human health of BEVs are associated with the mining of metals and battery manufacture are exported to where these activities take place from where the vehicles are used. The general public would support measures to improve air quality because it affects them more directly and immediately and perhaps matters much more to them than GHG mitigation.Modern (Euro VI) diesels with modern after-treatment systems are capable of comfortably beating the most stringent NOxrequirements[47,60]; this was confirmed in 2019 by testing 13 Euro 6 diesel cars of different models in Germany in real driving conditions[60]. With modern particulate diesel filters,the exhaust particulate levels are near zero[47]and other sources such as tyre-wear become important. BEVs will be heavier because of the weight of the batteries and hence particulate emissions from tyre wear will be greater for BEVs compared to equivalent ICEVs. In fact, with fully warmed up after-treatment systems, the particulate level could be lower in the exhaust than in the intake for the most modern diesels and for ultra-low emissions (ULEV) gasoline engines UHC could be lower in the exhaust[61]than the intake in heavily polluted areas (e.g. Delhi for particulates and LA freeways for unburned HC).

Nevertheless, BEVs can play an important role in improving local air quality, though the most modern ICEVs are also be capable of meeting very stringent emissions standards. If the spread of BEVs is being promoted because they can help with urban air quality, different policies need to be instituted e.g. banning of vehicles that do not meet strict emissions regulations from city centres. Some of these policies exist in some form or the other e.g. low emissions zones. However,current policy is built around decarbonising transport and by 2030, BEVs on their own are likely to make little difference to CO2/GHG emissions, comparable reductions in CO2are most likely to happen because of improvements in ICEVs by this time without the need for new infrastructure.

All available technologies, including ICEVs, BEVs, fuel cell vehicles (FCVs) and alternative fuels should be continuously improved and used to improve the sustainability of transport.Banning the most common of these technologies i.e. ICEVs will not be sensible. However, all these technologies need to be assessed on an honest life cycle analysis to ensure that they deliver what they promise and do not have unintended counterproductive consequences. Policies instituted on environmental arguments have often proved to be either ineffective or counterproductive or have other unwanted consequences. Some examples are burning biomass for power and biofuels, particularly biodiesel, for transport[45].

5 Concluding remarks

An assessment of empirical data shows that humanity has coped well with the warming of about 1.1 C over the past century caused by human activity, mainly the burning of fossil fuels. During this period almost every measure of human well-being such as life expectancy, children' s health and per capita calorie intake have improved significantly, particularly in poorer countries. Of course, there are still pockets of deprivation, disease, exploitation, threats to biodiversity and unequal and unfair global use of resources but not because of global warming. There is no statistical evidence that floods,droughts, storms, forest fires have increased in the past half century or so. Food production and global greening, which can absorb CO2and mitigate its effects, have increased.Extreme events such as floods, storms, droughts, forest fires and excessive snowfall will always exist and even if evidence emerges that global warming makes these worse, societies have to be made resilient to such events. This is particularly true in poorer countries. “ No regrets” adaptation measures such as better flood defences and better forest management have an immediate and direct effect in coping with such events. So, the focus should also be on such adaptation and on reduction of waste in the use of energy and resources. Other environmental and developmental issues like provision of clean water, safe and sufficient food and shelter and ensuring biodiversity are of immediate concern and can only be ensured if global poverty levels are reduced. This requires affordable energy. So, a balance has to be struck between reduction of GHG and adopting measures to cope with climate change. Of course, such a view is very strongly and passionately opposed by a large body of influential opinion which is focussed very strongly on a quick and drastic reduction of GHG, particularly on the elimination of the use of fossil fuels which produce CO2.In fact, many governments, particularly in the West, already have policies built round a reduction of GHG. For instance,the U.K. government is required by law to go to net zero GHG by 2050. Any proposed changes to the energy infrastructure must be assessed honestly on a life-cycle basis to ensure that they really provide the benefits that are promised and have no unintended consequences.

The energy transition needed to reach net zero GHG by 2050 is extremely challenging and transport is the sector that is most difficult to decarbonise. All the alternatives to the current energy infrastructure start from a very low base and face very significant environmental and economic barriers to the sort of growth that will be required if net zero is to be achieved. The scale of the problem is very large. For instance, to replace just 60% of current fossil fuel use, the U.K. will have to install 118 GW of new continuous CO2-free energy generation. This is equivalent to around 39 nuclear power plants of 3 GW each or 110 thousand wind turbines of 3 MW each (assuming a capacity factor of 0.35). At the same time, the existing energy infrastructure has to be dismantled - by 2050 the use of gas and oil has to be almost eliminated and aviation, steel, cement industries along with livestock farming have to be largely shut down. Needless to say, a target to achieve such a transition by 2030, will be even more challenging.

To replace 60% of the fossil fuel use in the world would need installation of around 9.4 TW of new CO2-free energy generation and this is not going to happen. If, as will almost certainly be the case, not enough countries follow the U.K.'s“l(fā)eadership”, It would be better to recognise that there will be little change to global GHG levels and focus on “ no regrets”policies to reduce waste in the use of energy and resource efficiency and on measures to adapt to climate change such as better flood defences. Such realism would involve recognizing that internal combustion engines will dominate transport globally for decades to come and that banning the sale of new ICEVs, including HEVs (a particularly senseless policy), from 2030 will condemn the U.K. to forgo any new developments in ICEV technology from the date of the ban and remove the biggest and easiest opportunity to improve the efficiency and environmental impact of the U.K.'s transport sector. It will also shut down research and development in ICE in the U.K.from well before the ban and throw many talented scientists and engineers out of employment and pose a real danger to the automotive industry if sufficient number of people are not persuaded to buy BEVs by 2030.

Of course, if the British government is really serious about its net zero goal, concrete, time-bound initiatives with clear budget and engineering targets to achieve this have to be set and implemented. Such targets could include, in the next 10 years - reducing energy consumption by 13% and at the same time building 133 GW nuclear plants or 37 thousand offshore 3 MW wind turbines; replacing 10 million gas boilers; building 700 thousand public and 7 million private charging points for BEVs; rebuilding the electricity distribution network appropriately; reducing steel, cement, aviation and livestock farming by a third ...The work has to start immediately and would then have to continue at the same pace for the following two decades. This would force the U.K. government to focus on the implications of what has been promised.

Since no such detailed plans addressing the true scale of the task have been announced, it is almost certain that the net zero GHG by 2050 will not be met in the U.K.