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1. Introduction

Current energy policies in affluent western countries are based on the assumption that climate change poses an imminent “existential threat”. The term, “climate change” covers the impacts of global warming caused by the increase in greenhouse gases (GHG) such as carbon dioxide (CO2) methane and nitrous oxide (N2O). Evolving knowledge on climate change is summarized by The Intergovernmental Panel on Climate Change (IPCC) established in 1988 under the auspices of the United Nations, through its assessment reports [1]. 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 the dominant contribution to global warming between 1951 and 2010 was from human activity. CO2 from human activities results from the burning of fossil fuels -coal, oil and natural gas- which supply most of the primary energy used by the world, though natural processes are also extremely important in the CO2 cycle. Methane, which is much more potent than CO2 as a greenhouse gas, increases primarily because of agriculture and land use and leakages from the natural gas infrastructure. Many governments see this to be a threat and are bringing in policies to “eliminate” man-made GHG to combat this perceived threat. For instance, the U.K. has committed, by law, to go to “net-zero” GHG by 2050 [2]. Some pressure groups like Extinction Rebellion, demand that the use of fossil fuels be eliminated by 2025 [3]. Many major corporate entities, including oil majors, have announced their own “net-zero” plans.

“Net zero” means that the amount of GHG produced is balanced by the amount of GHG removed by industrial efforts such as carbon capture and storage (CCS) which are not yet ready for deployment at scale and have huge requirements for land and energy [4] or by natural sinks such as the oceans and forests. In the last resort, emissions will have to be “offset” e.g., by planting trees to absorb the CO2 or by buying carbon credits from entities which have reduced their emissions by more than they needed or committed to. In practice, an almost complete elimination of GHG emissions is required to meet net zero targets. A corollary to this is the conviction that everything must be electrified, with the assumption that the electricity will be produced from CO2-free sources.

However, the evolution of energy systems is complicated (Fig. 1) and is determined by different drivers which are also different in different countries. For instance, in many countries, particularly in developing nations, economic growth and access to affordable energy is considered at least as important as climate change. Fig. 1 is a simplistic illustration; there could be even more boxes and more complex interactions between the boxes. Equally importantly, as the war in Ukraine has amply demonstrated, geopolitics can have a profound effect on energy systems. In many western countries, these complexities are not given sufficient consideration and climate change dominates the narrative in setting energy policy. The scale of the problem and the environmental, economic, materials requirement, technical and societal barriers to a sufficient expansion of alternatives to replace existing energy systems, at the rate required, do not always appear to be properly appreciated. Often, there is also wishful thinking and an appearance of a lack of honesty or a sense of reality in the proposals and discussions on these matters. In the discussion below, the focus is often on the U.K. but the arguments are equally valid for other regions. Vaclav Smil's book [5]is essential reading on matters of energy, resources, food and environment in a world with a growing and energy hungry population. Also, in this paper, the focus is on the transition needed to meet “net zero” targets and not on the scientific accuracy or the uncertainties in climate models which form the bases of energy policy; an excellent discussion of these issues can be found in Ch.4 of Koonin [6] and Ch. 6 of Smil [5].

2. Challenges of the energy transition required by net-zero targets

The global energy demand is very large. The sources for primary energy and electricity generation for 2021 in exajoules, EJ (1018 joules) for the World, China, U.S.A, India and the U.K sourced from the BP Statistical Review of World Energy [7] are summarized in Table 1 which also lists the installed solar and wind capacity in GW for 2021. It should also be noted that these data are for “traded energy” which can be tracked. There is perhaps an additional 5-10% of energy used by the global poor who rely on wood, cow dung and other sources but aspire to move to fossil fuels for their energy needs. Increasing global population will also inevitably increase the demand for energy.

Table 1. Primary energy and electricity sources in exajoules, EJ (1018 joules) and installed wind and solar capacity in GW for 2021 [7]. Electricity generation converted to EJ from TWh. 1 EJ= 277.8 TWh.

Country	World	China	U.S.A	India	UK
Oil, EJ	184.21	30.6	35.33	9.41	2.5
Natural Gas, EJ	145.35	13.63	29.76	2.24	2.77
Coal, EJ	160.1	86.7	10.57	20.09	0.21
Total fossil fuel, EJ	489.66	130.93	75.66	31.74	5.48
Actual delivered Wind, EJ	6.7	2.36	1.38	0.245	0.232
Actual delivered Solar, EJ	3.72	1.177	0.594	0.246	0.045
Nuclear, EJ	25.31	3.68	7.4	0.4	0.41
Hydro, EJ	40.26	12.25	2.43	1.51	0.06
Other, EJ	29.5	7.253	5.306	1.289	0.953
Total Primary Energy, EJ	595.15	157.65	92.97	35.43	7.18

Electricity Generation
Installed wind capacity, GW	824.9	329	132.7	40.1	27.1
Installed Solar Capacity, GW	843.1	306.4	93.7	49.3	13.7
Total electricity generated, EJ	102.47	30.72	15.86	6.173	1.116

Other includes bioenergy, geothermal etc.

Fossil fuels supplied 82.3% of global energy use in 2021 and the share of wind and solar of this total was 1.75% though this share is different in different countries; it is 3.86% of the total primary energy in the U.K. Fig. 2 shows electricity generation as a fraction of the total primary energy. In the U.K., electricity accounts for about 16% of primary energy. Thus, even if electricity generation is fully decarbonized, it will have a much smaller impact on total CO2 emissions. It should also be noted that U.K. accounts for only 1.1% of global fossil fuel use. If other countries like China and India do not also give up fossil fuels, U.K.’s commitment to net-zero GHG will not have much effect on global GHG levels.

There was a reduction in global energy consumption because of the COVID pandemic but as the world economy has bounced back, global oil [8], natural gas [9] and coal [10] consumption appear to have recovered to meet or exceed 2019 levels. The total energy consumption in 2021 was about 2% higher than in 2019 mostly because of increases in China [7]. However, aviation was badly hit and has not fully recovered from the massive reduction because of the COVID pandemic though it is expected that demand for aviation jet fuel will continue to increase [11] and recover to pre-pandemic levels in the next few years.

Fig. 3 shows the share of wind and solar in electricity generation. On average, wind and solar supplied around 10% of global electricity in 2021 though the share was very much higher in the U.K.- around 25%. Wind and solar are variable renewable energy (VRE), intermittent sources. The ratio of the actual energy supplied on average to the theoretical energy if the VRE operated continuously at full rated capacity is defined as the capacity factor, CF. Fig. 4shows the capacity factors for wind, solar and (wind+solar) from the data in Table 1.

Thus, on average across the world, in 2021, wind supplied only 25.8% of electricity that would be expected if it operated at its full installed capacity continuously. Similarly, wind and solar together supplied only 25% of U.K. electricity in 2021 (Fig. 3) though there was almost enough wind and solar installed power capacity to supply all its electricity if they generated electricity at rated power continuously. To ensure continuous supply of electricity when wind and solar fail to produce the needed electricity, there must be sufficient back-up generation capacity from nuclear or hydro or gas or coal. Also, as the share of such variable sources in energy generation increases, there will be times when they generate more energy than required and this needs to be stored for use when they produce less energy than needed. Even though the cost of wind and solar has been apparently falling rapidly, domestic electricity prices are generally higher in countries with more installed wind and solar capacity [12]; primarily because they do not supply electricity when it is needed and the system costs including transmission and storage are high.

Table 2 lists the average daily demand during 2022 for liquid fuels for transport and other oil products from IEA [13]. The Table also shows these data in terms of the volume of liquid fuels needed. The world uses, on average, around 11 billion litres of gasoline, diesel and jet fuel every day. There are around 1.3 billion light duty vehicles, cars and vans, and 380 million heavy duty commercial vehicles in the world and these numbers are expected to increase, mostly in non-OECD countries like China and India [14]. Fig. 5 shows the energy content of the liquid fuels listed in Table 2 as a fraction of global primary energy use of 595 EJ. The total annual energy content of gasoline, diesel and jet fuel which power transport, is 135 EJ, 22.7% of the global primary energy consumption.

Table 2. The daily average demand for liquid transport fuels and other oil products in 2022. Note: MBOE – million barrels of oil equivalent. 1 EJ equals 163.4 MBOE or 277.8 TWh.

Empty Cell	Million barrels of oil equivalent, MBOE	Energy, exajoules, EJ	Volumetric lower calorific value, MJ/litre	Fuel Volume, billion litres
Gasoline	26.26	0.1607	32.5	4.94
Diesel/Gasoil	28.12	0.1721	36	4.78
Jet/Kerosene	6.2	0.0379	35	1.08
Residual Fuel Oil	6.2	0.0379	38	1.00
Other	32.75	0.2004
Total	99.53	0.6091

2.1. Energy substitution requirements

Let us arbitrarily assume that the world will need to replace only 60% of current fossil fuel energy use of 489.7 EJ (Table 1) by CO2-free energy; the rest coming from efficiency improvements, lifestyle changes and offsetting, e.g. by planting trees to absorb man-made CO2. This is extremely optimistic because all the initiatives for energy transition such as building new alternative generating capacity, upgrading building stock and dismantling existing infrastructure will require a lot of fossil fuel energy. Even with this assumption, the world will need to build around 9320 GW of continuous CO2-free electricity generation capacity. This would be equivalent to around 3110 nuclear power plants of 3 GW each, of the size of Hinkley Point C which has taken over 20 years to build in the U.K, or around 23300 GW of new wind capacity assuming a much-improved average capacity factor of 0.4. Under the same assumptions, the U.K. and the U.S. would need to build 279 GW and 3840 GW respectively of new wind capacity to replace 60% of their current fossil fuel use. Large hydroelectric projects which require large areas of land and displace established communities face significant opposition; the scope for expanding these is limited anyway. There is strong resistance to new nuclear power as well in many quarters. Often, there is also resistance to large onshore wind installations from surrounding communities. Other CO2-free technologies like geothermal and tidal power are either limited in scope or not ready for large scale deployment. Hence, offshore wind and solar, in sunny climates, offer the best chance for new CO2-free energy in the near term. The capital cost of offshore wind, the primary practical path for U.K. to increase its CO2-free electricity generation, is estimated to be 4000-6000 USD/kW [15] in the U.S. and around £4000/ kW in Europe [16] from actual experience. Assuming a figure of £4000/ kW, to install 279 GW of wind, the capital costs could be over £1 trillion in the U.K. The real operating costs are also very high, much higher than commonly assumed, especially for offshore wind [16]. The cost of the necessary back-up and storage to ensure continuous supply of electricity will add very significantly to the capital costs. The scale is again large. For instance, the largest battery storage project in the U.K. by Intergen is expected to have a capacity of 640 MWh [17] and cost £200 million. It will be sufficient to supply London's peak power requirement of 8 GW for less than 5 minutes. Apart from the enormous financial requirements, there are serious concerns about fire and explosion hazards of such industrial scale battery storage [18] which will have to be addressed. Hence, battery storage alone will not be able to ensure uninterrupted supply of electricty if wind and solar are to be the sole providers of electricity and there is limited scope for other storage technologies such as pumped hydro and back up from fossil fuel sources will be necessary.

2.2. Environmental and material requirement impacts of wind and solar

The material and environmental costs associated with a large-scale shift to wind and solar are very significant. To build 23300 GW of wind capacity needed to replace simply 60% of global fossil fuel use would roughly require, using data in Table 5 in [19], 2,500 million tons (metric tons) of steel, 12,000 million tons of concrete, 70 million tons of copper (global copper production was 21 million tons in 2021 according to US Geological Survey), 1.1 million tons of rare earth metals, 163 million tons of fiber glass, 220 million tons of other plastics and aluminum and large amounts of fossil fuel energy [20]. Wind turbines are now considered the apex predators of some rare birds of prey such as eagles and falcons, kill other birds and bats and can degrade habitat for wildlife, fish, and plants [21]. This can have a ripple effect on the entire eco system around them [22]. 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. The disposal of toxic materials such as cadmium and lead and glass in solar panels at the end of their life of about 25 years poses a serious looming environmental problem [23,24]. As the deployment of wind and solar increases, with simultaneous decommissioning of nuclear and coal plants, the severe challenges posed to the stability and the integrity of the electricity grid will become ever more pressing and come to the fore [25].

2.3. Other examples where the scale of the problem does not seem to be appreciated or honestly assessed

Currently there is a lot of interest in electro fuels, e-fuels, made from CO2 and hydrogen using renewable energy, to decarbonize transport. The energy conversion efficiency for making e-fuels, starting with fully renewable electricity is only around 44% [26,27]. The current annual fuel demand for jet fuel alone is around 14 EJ – Table 2. The world will need to provide an additional 32 exajoules of CO2-free energy annually to run aviation on e-fuels. This is the equivalent of over 1000 GW of additional continuous electricity generation or over 2500 GW of wind power (capacity factor of 0.4). Similar arguments can also be made about hydrogen [14] from electrolysis of water, though the conversion efficiency, starting from renewable electricity, is better than for e-fuels. All the other issues around storage, distribution and safety have to be addressed if hydrogen is to be considered for aviation [14]. Of course, as the share of intermittent (wind and solar) electricity generation increases, there will be excess electricity available sometime and can be used to make e-fuels or hydrogen but in relation to what is needed, this is bound to be negligible for a very long time to come. However, such initiatives open a path to “store” this excess electricity (rather than say batteries) and should be seen as enablers to the spread of intermittent sources like wind and solar rather than as a “solution” to the transport problem. Similarly, biofuels are also not suitable for aviation, even if sufficient quantities can be manufactured in a carbon-neutral way though there is a lot of research in this area. If they are oxygenated, their gravimetric energy density would be around 16% lower than that of aviation fuel and either payload or range will be compromised.

Rough calculations can also be made about offsetting CO2 emissions by growing trees as follows. For guidance, we can use figures from a carbon offsetting website [28] which says 192 trees should be planted to offset 3 tons of CO2 and this will require 0.12 hectares of land. The annual demand for aviation (jet) fuel is 2263 MBOE from Table 2. So global aviation produces 990 million tons of CO2(according to U.S. EPA, 1 barrel of oil equivalent is 437.8 kg of CO2) and so to “offset” this will need around 39.6 million (990 × 0.12/3) hectares of forest to be planted. Thus, to offset the CO2 emissions from aviation alone, which accounted for only about 10% of transport energy used (Table 2) in 2021, will require an area slightly larger than Germany (35.7 million hectares), to be planted with trees every year. Indeed, for aviation to go to net-zero, it needs to be shut down for all practical purposes.

Also, corporations and other entities are promising to go to “net zero”, without setting out clear plans or considering basic realities. One example is the desire that British military aircraft should aim to hit the net-zero target by 2040 [29]another is the plan by the U.S. military to have electric armored vehicles [30]. These plans are not practical given the size of the batteries needed and the difficulties of charging them in a combat zone. For instance, the maximum takeoff weight of a Euro fighter (Typhoon) aircraft is 21,000 kg and it carries 4000 kg of fuel [31] with an energy content of 49 MWh. A lithium -ion battery pack with the same energy content would weigh around 13 times the maximum takeoff weight of the aircraft, assuming an energy density of 180 W/kg for the battery pack. A light armored vehicle (L-ATV) weighs 4667 kg with a range of 300 miles and has dimensions of 6.2 m length, 2.5m width [32]. Extrapolating from the Tesla S long range car (2100 kg weight, 100 kWh battery, 300 miles range), the L-ATV will need a battery of at least 220 kWh capacity. Under “peak sun”, modern solar panels produce 150 W per square meter [33]. So, if the LATV has to be charged by solar energy, it has to be parked under “peak sun” for about 95 hours to charge the battery even if its entire top surface is covered by solar panels (220/[0.15 × 6.2 × 2.5]) – impossible to arrange in a combat zone. Or else, a dedicated charging infrastructure has to be set up in combat zones. In any case, with large batteries, the greenhouse gas emissions reduction, if any, will be very small on a life cycle basis because of the large amount of energy needed for battery manufacture – see section 3.1.

2.4. Other requirements of net-zero commitments

In addition to replacing fossil fuels with CO2-free electricity, far greater efforts will be needed to dismantle the existing energy infrastructure safely, improve building stock and transform society to reduce energy consumption. For instance, in the U.K. 22 million homes have gas central heating [34] with at least 26 million gas boilers installed overall [35]. These are supposed to be converted to electric heating (heat pumps) as part of the net-zero target. There might not be enough trained heating engineers and electricians in the country to implement this by 2050. It is also very expensive, currently costing between £10,000 and £20,000, depending on the size and location of the property for the full system installation; most householders might not be able to afford such conversion. Also, utility is degraded – heat pumps cannot supply hot water nearly instantly as gas boilers can and a storage tank with an electric immersion heater might be needed for hot water supply. The size of the radiators might need to be increased because of the lower water temperature from heat pumps and insulation might need to be enhanced to maintain adequate heating. Many countries plan to decarbonize transport by eliminating the internal combustion engine (ICE) but this is unlikely to deliver significant reductions in CO2 but will have huge environmental and economic consequences as discussed in the next section. There are very large challenges and costs of rebuilding the electricity distribution network, at the micro level, required by such changes are discussed in [25,36]. Also, GHG emissions from agriculture need to be taken to zero. For instance, globally, livestock farming for meat and dairy contributes about 7 gigatons of CO2 equivalent or 14% of global GHG including gases such as methane [37,38], the same share as from all transport. Ultimately, the steel, aviation and cement industries which are extremely difficult if not impossible to decarbonize will need to be largely shut down [39] and oil, and gas production and distribution and the refining industry will need to be safely dismantled. At the global level, Saudi Arabia, Russia and other oil and gas producers must be persuaded to give up their main source of income; India, with the highest number of livestock in the world [40] and where cows are worshipped, has to cull most of the cattle.

2.5. What are the prospects for the reduction of global GHG levels?

The world will need to build new CO2-free energy capacity of 294 EJ which is 28 times the energy currently supplied by wind and solar, to replace just 60% of fossil fuel used globally in 2021 (Table 1). Also, as discussed in the previous section, many other actions which require a complete overhaul of how societies are organized and run must happen to reach net-zero GHG. Developing countries will need to rein in their plans for economic development which need fossil fuel energy.

However, currently, many big nations seem to be focusing on energy security and economic development. COP 26 in Glasgow in November 2021 called for a commitment “phase out” coal but many countries did not accept this wording [41]. For instance, India has vast reserves of coal and also has ambitious plans for wind and solar. Even as the share of coal in supplying energy declines, coal use is expected to increase in absolute terms, as India's overall energy demand grows [42]. Indeed, India's coal production rose 8.6% to 777.2 million tons during the year ending March 2022 [43]. Similarly, China is expected to see its coal output grow further in 2022 after hitting a record last year [44]. In many countries, the increase in the contribution from wind and solar is more than made up by fossil fuel use as the overall demand for energy increases. The energy supplied by wind and solar together in China increased to 3.54 EJ in 2021 compared to 2.27 EJ in 2019 [7] – an increase of 56%; however, over the same period, fossil fuel energy increased by 8.47%. Similarly, in India, even though the contribution of wind and solar increased by 24%, that of fossil fuels increased by 2.4% between 2021 and 2019. Saudi Arabia recognizes that global oil demand is not decreasing and in fact plans to increase production in the coming years [45]. National oil companies like Saudi Aramco, Sinopec and Rosneft, already control 75% of production and 90% of known oil reserves. These companies will become even more powerful if independent oil companies like Shell, ExxonMobil and BP shrink under the current anti-fossil fuel narrative in the west. Even in countries like the U.K. with deeper commitment to net-zero targets, in the absence of concrete plans and the urgency required for the vast transformation of the energy system and society, the net-zero target does not seem achievable. Similarly, all the commitments from major corporations to net-zero targets, without concrete steps to achieve them, are not credible.

So even though there is a desire and some efforts to reduce GHG emissions, the scale of the problem is very large. This will require detailed engineering plans with proper time targets and honest cost and environmental assessments, and the work has to start immediately. Such plans would clarify the scale of the challenge and the very rapid changes required in society. Currently, such plans do not exist. As the IEA says, the world is still far from the kinds of energy policies and investments that would put global emissions into a structural decline towards net-zero by 2070– let alone by 2050 [46]. The U.S. Energy Information Administration [47] projects that in absolute terms, the demand for oil, gas and coal will be higher in 2050 than it is currently though renewables will have grown faster.

Thus, combustion of fossil fuels will continue to be central to supplying energy to the world up to and beyond 2050 and must be continuously improved. It is almost certain that global GHG levels will not come down significantly in spite of some efforts and a lot of rhetoric in some quarters. There is no prospect of reaching net zero GHG at the global level for the next several decades.

We now discuss transport policy, with focus on the U.K., which highlights many of the issues discussed above.

3. Decarbonization of transport

More discussion of transport power systems, energy and fuels can be found in references 14, 48, 49, 50, 51. Currently 99.7 % of global transport is powered by internal combustion engines (ICE) and 95% of global transport energy comes from petroleum-based fuels [14].

There are different degrees of electrification but only battery electric vehicles(BEVs) do not have an internal combustion engine (ICE) and get all their energy from the electricity grid. Plug-in hybrid electric vehicles (PHEVs) have a limited range on battery alone but also have an on-board ICE to charge the battery. Conventional hybrid electric vehicles (HEVs) like the Toyota Prius are “self-charging” and all their energy comes from the onboard fuel powering the ICE; hybridization simply improves the efficiency of the engine/transmission system. There is widespread belief that BEVs are “zero emissions” vehicles and that they can and will and should replace ICE vehicles (ICEVs) completely. The other alternative to ICEs to power transport is to use fuel cells powered by hydrogen produced using renewable electricity. However, this technology is not ready for the mass market and there are great difficulties associated with the production, distribution and on-board storage of hydrogen for it to be a true alternative fuel for transport [14]. There are also many possibilities for developing ‘low-carbon’ fuels which can help reduce the carbon footprint of transport which are being researched. However, all these alternatives start from a very low base and face very significant environmental and economic barriers to unlimited growth and cannot sustainably replace around 11 billion liters (Table 2) of petroleum-based liquid fuels that the world consumes daily.

BEVs can realistically only power light duty vehicles (LDVs), cars and vans, which account for around 45% of global transport energy use [14,50]. The battery size and weight needed for heavy duty long-distance transport, large marine transport and aviation would be too large for full electrification to be practical, desirable, or even possible [14]. For instance, with the current battery technology, for a medium-range jet such as the Airbus A320, a lithium-ion battery pack with the same energy capacity as of the aviation fuel carried would weigh around 19 times the maximum take-off weight of the aircraft [14]. Currently the world has around 1.3 billion LDVs, expected to go up to 1.7-1.9 billion by 2040 [48]. The U.K has around 36 million cars and vans (light goods vehicles) [52] and at the end of 2021 the number of BEVs, was around 0.36 million [53]. So, BEV numbers have to grow by a factor of at least a 100 to replace even the current number of LDVs. The battery capacity needed will have to grow much more than 100-fold if bigger LDVs with longer ranges which require bigger batteries also are to be replaced by BEVs. This would lead to huge, currently unsustainable, environmental and materials requirement problems as discussed below. For comparison, by the end of 2021, the world had around 12.5 million BEVs, which accounted for around 70% of plug-in vehicles [54]. More than half of these were in China.

The U.K. government has announced a ban on the sale of any new vehicle carrying an internal combustion engine from 2030 though the sale of hybrid electric vehicles (HEVs and PHEVs), which carry an ICE will be allowed till 2035 [55]. Only BEVs and vehicles equipped with fuel cells and running on hydrogen will be allowed to be sold after 2035. Other governments have also announced plans for similar bans on the sale of new ICEVs.

3.1. Environmental impact of BEVs

BEVs do not offer a very significant benefit over ICEVs in terms of CO2 unless their use and manufacture is with energy that is CO2-free. Battery manufacture needs much more energy compared to ICEs in similar size cars [14,56]. So, a full life cycle analysis [57] is needed for an honest assessment of the impact of electrification. Even if renewables provide a large share of the electricity, the extra electricity demand from BEVs has to be met with marginal (backup) electricity generation which can quickly respond to changing demand [14,58]. This usually relies on fossil fuels, especially if nuclear power is not in favor, and has a very much higher carbon intensity than the average value. The CO2 impact of a BEV during use depends on the carbon intensity of the electricity grid which will be very high if coal is a dominant source of electricity generation as in India and China. In addition, even with modern, efficient combined cycle coal-plants, the NOx emissions levels will be significantly higher than for modern ICEVs except that this emissions burden is shifted on to poorer communities living near the peaker plants. In India, by going fully electric, though 2-wheelers might show a reduction in GHG, 4-wheelers will increase GHG in most areas [59]. There are many life cycle assessments (LCA) comparing BEVs with ICEVs but the results depend on the assumptions made. For instance, the embedded CO2 associated with battery manufacture depends on the CO2intensity of mining, processing the materials and manufacture and assembly of the batteries that is assumed. Currently most of these activities take place in countries which use energy which has a high carbon intensity. A review [60] on CO2 production from battery manufacture gives a range of 61-106 kg CO2 eq/ kWh. A recent estimate from China, where over 70% of the batteries are made, is 125 kg CO2 eq / kWh of battery capacity [61]; a BEV with a 60 kWh battery will start with a deficit of 7.5 tons of CO2 eq, before it has driven a single kilometer. In the U.K. the CO2 impact of a small BEV will be lower than for a comparable ICEV on a life cycle basis, but not zero. As battery size increases, to enable longer range and/or bigger vehicles, BEVs could in fact have a larger life cycle CO2 footprint than an equivalent ICEV even as the electricity used to run them becomes increasingly CO2-free [62].

The impacts on human health – human toxicity potential (HTP), water and eco-toxicity associated with mining of metals needed for batteries are very significant. HTP is estimated to be three to five times worse than for ICEVs where it arises from exhaust pollutants [[63], [64], [65]]. These health and environmental impacts of BEVs are exported to where the mining takes place and materials are processed (e.g., the Democratic Republic of Congo, for cobalt; Chile for lithium). The bigger the battery, the worse the impact. Mining also requires moving large quantities of earth and rock - on average 500 times the weight of the battery [66]. Thus a 40 kWh battery in a Nissan Leaf, which weighs around 300 kg could require roughly150 tons of rock and earth moved. These issues, which are currently ignored, will inevitably come to the fore if battery capacity is to be increased more than a hundred- fold.

3.2. Infrastructure and material requirements

Only 22% of cars in the U.K. have access to garages [52]. Over 2 million public charging points, placed near where people usually park, will be needed to overcome “charging anxiety” [51]. One estimate [67] suggests that the U.K. will have to invest between £8bn and £18bn in the electric vehicle (EV) charge point infrastructure by 2030. Up-front costs of BEVs are very high. 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. A recent study by Toyota [68]concluded that BEVs would not reach purchase price parity by 2030 compared to a ICEV even under the most optimistic scenarios considered. Indeed, as demand for battery materials increases, their price increases making it very difficult for battery prices to come down [69]. Direct and indirect subsidies will continue to be needed to encourage people to buy BEVs till their up-front costs come down sufficiently – a regressive transfer of money to the rich who can afford expensive BEVs. Also, the Nissan Micra has a longer range and can be refueled in about 5 minutes using the existing infrastructure. The Leaf is most likely to be around 30% better for GHG on a life cycle basis in the U.K. but this is not visible to the ordinary driver. So currently, BEVs are not particularly attractive to the average individual customer. There are arguments that when fuel prices are high, the total cost of ownership (TCO) of BEVs will be lower than for an equivalent ICEV. However, such arguments assume that electricity prices will not rise in the future and in any case, most people consider the up-front costs and other issues like ease of charging rather than TCO, when they buy a car. At some later date, the U.K. government will also need to recoup lost fuel taxes including VAT which currently contribute around £40 billion to the public purse every year.

There are very challenging problems associated with providing additional electric power to a large number of BEVs both at the micro and macro level [36,70]. Let us assume that the number of BEVs increases from the current 0.36 million to an improbable 10 million by 2030 in the U.K – around 28% of current LDV numbers. Let us further assume that around 10% of these decide to charge in the evening at the end of the working day. Even with a 7 kW, Level 1 charger, an additional 7GW of power, equivalent to more than two Hinckley Point nuclear power station has to be built to meet this extra power demand. In fact, the U.K. government has legislated that new EV chargers to be installed after May 30, 2022, have to be pre-programmed to be disabled at peak electricity demand times. [71]. This will further inconvenience BEV drivers. The electricity distribution network, particularly the final connections to households, will need to be very significantly altered [36,70].

The availability of materials needed for battery production will be of increasing concern if the battery capacity needed is to be increased by over a hundred-fold in addition to batteries that might be needed for storage to support the spread of wind and solar. For instance, one study estimated that the U.K. alone will require two times the total annual world cobalt production, nearly the entire world production of neodymium, three quarters of the world's lithium production and at least half of the world's copper production during 2018 to replace all the LDVs with BEVs [72]. There is much faith in the “circular economy” where battery materials will be recycled. However, it is extremely difficult and energy intensive to recover critical metals from lithium-ion batteries given their complexity and weight and it is very unlikely that they will be significantly recyclable even in the near future [72]

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

Cars and vans (light goods vehicles) account for about 70% of transport energy use in the U.K. [73] (from Table 3B in [73], plus aviation assumed at 12% of total) and BEVs are not zero-CO2 vehicles on a life cycle basis. A recent IEA study [74]suggests that GHG emissions for a mid-sized car are around 25% lower for a BEV compared to its ICE equivalent, on average, on a life cycle basis in Europe.

So, if there are 10 million BEVs by 2030, 28% of all cars and vans, the reduction in transport related CO2 in the U.K. will be around 4.9 % (0.28 × 0.70 × 0.25) of the total CO2 from transport if these 10 million BEVs reduce CO2 on average by 25% compared to the ICEVs they have replaced. Over 70% of the cars and vans will be using ICEs in the U.K. even after this huge increase in BEV numbers in 2030. Replacing 10 million gasoline cars with HEVs would result in a similar reduction in fuel consumption, CO2/GHG without requiring any new infrastructure at a much lower up-front cost to the consumer. 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 [49,50] Partial electrification as with self-charging hybrid electric vehicles (HEV) like the Toyota Prius which have much smaller batteries and where the energy comes from the ICE but is more efficiently utilized, offers a readily available technology to bring about a significant reduction in fuel consumption and hence CO2 emissions of about 25% in gasoline engines without requiring any new infrastructure. In fact, HEVs offer the best practical prospect to lower GHG rather than BEVs [14,56,59].

3.4. BEVs and air quality

BEVs produce no exhaust pollutants unlike ICEVs such as particulates, unburned hydrocarbons (UHC) and nitrogen oxides (NOx) which can affect human health. The impacts on human health of BEVs are exported to where mining activities take place from where the vehicles are used. Modern (Euro VI) diesels with modern after-treatment systems can comfortably beat the most stringent NOx requirements [50]. The particulate level could be lower in the exhaust than in the intake for the most modern diesels with fully warmed up after-treatment systems in the more polluted areas. For ultra-low emissions (ULEV) gasoline engines UHC could be lower in the exhaust than the intake in heavily polluted areas [50]. The exhaust particulate levels are near zero with modern diesel particulate filters and other sources such as tire-wear become important [75]. These will be greater for BEVs because they weigh 25-30% more than comparable ICEVs because of the weight of the battery [76]. As BEV numbers increase in the future, their impact on particle emissions will need to be reassessed.

Different, more effective policies such as banning vehicles that do not meet strict emissions regulations from city centers have to be instituted if urban air quality is the primary concern. However, current U.K. policy is built around decarbonizing transport and BEVs on their own are not likely to make a significant difference to CO2/GHG emissions on a life cycle basis by 2030 but require large investments in new infrastructure.

3.5. Impact of the proposed ban on the sales of new ICEVs

Even if the U.K. government wishes to promote BEVs, banning the sale of new ICEVs does not make sense. Such a ban will ensure that, even though transport will be largely dependent on internal combustion engines for decades to come, any improvements not in the market before the proposed ban will not be available to customers. A customer in the U.K. will not be able to buy, say a new ICEV in 2031 which might be better than that 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. If people are not persuaded to buy BEVs in large numbers by 2030, because of charging anxiety, lack of utility 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.

The number of BEVs will certainly rise rapidly, especially with all the current government encouragement and they have an important role to play in the future. However, batteries cannot and, to avoid an environmental and economic catastrophe, must not become the sole source of power for transport. All available technologies, including ICEVs, BEVs, fuel cell vehicles (FCVs), self-charging hybrids, alternative fuels should be deployed and continuously improved to improve the sustainability of transport [56]. However, all these technologies need to be assessed on an honest life cycle analysis to ensure that they really deliver what they promise and do not have unintended counterproductive consequences.