What the U.K.’s Target of Net Zero Emissions Would Really Entail

In 2019, Britain’s Conservative government toughened existing climate-change legislation by setting the country the target of net zero carbon emissions by 2050 (the previous target had been 80 percent). There are other yet more ambitious proposals, providing for full decarbonization at even earlier dates, such as Extinction Rebellion’s 2025 and the Green Party’s 2030. In addition, other policies such as banning the sale of new cars and vans with internal-combustion-engines from 2030 are under serious consideration by the government in order to decarbonize transport as part of the overall CO₂ target. As discussed below, the challenges of the energy transition required are enormous enough to seem unsurmountable and don’t seem to be sufficiently appreciated by those who set the targets. The scale of the challenge is great. A schedule, a budget, and engineering targets need to be put in place, and the work needs to start immediately, if the government is serious about meeting the targets for zero carbon emissions. It won’t be easy.

Target: Zero Net Carbon Emissions by 2050Fossil fuels, coal (7.9 mtoe, million tonnes of oil equivalent), oil (68.5 mtoe) and gas (875.6 TWh, or 75.3 mtoe) supplied 151.7 mtoe, or 79.6 percent of the primary energy used in the U.K. in 2019, while wind and solar accounted for 3.47 percent of the total primary energy-use (BEIS).

How much additional CO₂-free energy will the United Kingdom need to generate by 2050 to replace fossil fuels?
Let us assume that by 2050 the United Kingdom will need to replace only 60 percent of current fossil-fuel energy use (91 mtoe, or 1,058 terawatt hours (TWh) by CO₂-free energy, thanks to greater overall energy efficiency. Even on this extremely optimistic assumption, the U.K. will need 121 gigawatts (GW) of new continuous CO₂-free power generation, equivalent to 40 nuclear plants of 3 GW each or to 100,000 offshore wind turbines of 3 MW each, given a capacity factor of 0.4 — i.e., 10 MW installed capacity will deliver only 4 MW on average because it is not available all the time. 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 0.1. Wind and solar will also require storage systems to cope with intermittency. Incidentally, 1,610 GW of new continuous CO₂-free power generation will be needed for the U.S. to replace 60 percent of its current fossil-fuel use.

The existing energy infrastructure has to be dismantled
According to PHAM News, an estimated 26 million gas boilers are installed in the U.K. These are supposed to be converted to electric (heat pumps) heating by 2050. Are there enough heating engineers and electricians in the country to implement this? Are households expected to bear the cost of conversion, or is the government going to pay for this? The enormous challenges of rebuilding the electricity-distribution network required by such changes have been discussed by Mike Travers in The Hidden Cost of Net Zero: Rewiring the U.K., a report from the Global Warming Policy Foundation. He estimates that the total cost will run up to £466 billion, much of which might have to be borne by households.

Net zero will also involve decarbonizing transport, supposedly by eliminating internal-combustion engines (ICEs). This will also require huge investments in new infrastructure (as discussed below) but is not likely to deliver significant reductions in CO₂. In addition, greenhouse gas (GHG) emissions from agriculture would also need to be taken to zero if climate change is the real concern. Globally, livestock farming for meat and dairy contributes about 14 percent of global GHG, the same share as from all transport. The relevant percentages are likely to be similar for the U.K. Also, the steel, aviation, and cement industries, which are extremely difficult if not impossible to decarbonize, will need to be largely shut down by 2050.

The energy transformation required will lead to an initial spike in CO₂
This large-scale transformation of the U.K. infrastructure will require huge amounts of fossil fuels, other materials, and mining requirements for materials needed. Will all this not hasten the “existential crisis”? For instance, according to National Wind Watch (admittedly a skeptical observer of the industry), a single 3-MW wind turbine needs 335 tons of steel, 4.7 tonnes of copper, 1,200 tons of concrete (120–150 tons of cement), 2 tonnes of rare earth metals, 40 tonnes of unrecyclable plastic, and large amounts of fossil fuel energy to build. The capital cost of an offshore wind turbine is expected to be between $4,400 and $6,000 per kW. So, 100,000 3-MW offshore wind turbines will cost between $1.3 and $1.8 trillion. Any large-scale increase in wind, solar, and battery manufacture will come with its own enormous environmental challenges, particularly those associated with mining the materials needed and end-of-life disposal.

Can and will most of the rest of the world follow this decarbonization path?
In 2019, the world used 581 exajoules (EJ) of energy (13,880 mtoe). Of that, 84 percent was supplied by fossil fuels. Wind and solar chipped in with 1.33 percent. Once again we assume (not very realistically) that only 60 percent of 488 EJ (293 EJ) needs to be replaced by CO₂ -free energy. This still will require 9291 GW of continuous CO₂-free power generation. That’s equivalent to building 3,100 nuclear power plants of 3 GW each, or 7.74 million wind turbines of 3 MW each (capacity factor of 0.4). At the same time, use of natural gas and oil has to be stopped (will Russia, Saudi Arabia, and the U.S. agree?), surface transport has to be decarbonized, meat and dairy farming has to be stopped (will India agree to cull the cows?), and, again, the aviation, steel, and cement industries will have to be largely shut down This is not going to happen by 2050. The U.K. accounts for just 1.3 percent of global fossil-fuel use. So, if most of the rest of the world does not follow U.K.’s “leadership” in this area, all Britain’s efforts will have been in vain.

Current U.K. Transport PolicyThe British government is considering a ban on the sale of any new car or van carrying an internal combustion engine starting in 2035 or even 2030. This ban would include hybrid electric vehicles (HEV) such as the Toyota Prius and even plug-in hybrid electric vehicles. Only full electric vehicles —  i.e., battery electric vehicles (BEVs) and vehicles equipped with fuel cells and running on hydrogen — would be allowed to be sold. This initiative is explicitly part of the plan to decarbonize transport. The proposed ban on HEVs is particularly senseless. HEV technology is mature and can reduce fuel consumption by up to 25 percent in gasoline-fueled cars (although by far less in diesel cars).

BEVs do not offer a significant benefit over internal-combustion-engine vehicles (ICEVs) in terms of CO₂ unless the energy for manufacture and use is CO₂-free. Such manufacture is not likely to happen by 2030, since the mining and processing of the materials needed to produce batteries takes place outside the U.K., in countries — e.g., China, Chile, and the Democratic Republic of Congo — that are not likely to decarbonize any time soon. It’s worth noting the health risks that come with that mining required for a BEV are expected to be worse than for a similar-sized ICEV, where the health impact is associated with exhaust pollutants such as particulates, carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (UHC). The larger the battery, the worse these environmental impacts. A modern diesel car with a particulate filter has almost no particulate emissions, and tire wear becomes the most important source of particulates. A BEV will weigh more than a comparable ICEV because of the weight of the battery and hence, thanks to tire wear, will actually generate more particulate emissions. It should be remembered that the British government promoted diesel vehicles for a long time because of their far lower carbon footprint. They fell out of favor because of their higher NOx and particulate emissions. However, modern diesel cars are capable of meeting the most stringent exhaust-emissions standards while delivering very high efficiency

Commercial road transport and aviation cannot and should not be run on batteries, because the size and weight of batteries would be too large¹. Meanwhile, to convert all passenger cars and vans in the U.K. would require around 2 million public charging points and 21 million private (home) charging points. A large investment in charging infrastructure, additional electricity generation, and a rebuilding of the electricity-distribution network would be needed to enable wide deployment of BEVs.

Even if we assume a (very unlikely) hundredfold increase in BEV numbers to 10 million by 2030, around 75 percent of cars and vans and 85 percent of all transport in the U.K. will still be run on internal combustion engines (ICE). Even if they reached 10 million in total number, BEVs would save at best about 5 percent of CO₂ generated by transport, and at great cost. A similar or even greater reduction in CO₂ is very likely to be obtained simply through improvements in ICEV by 2030 thanks to further development in combustion, control, and aftertreatment systems aligned with partial electrification and reduction in weight. And this will require no new infrastructure.

Banning the sale of new ICEVs will deny the U.K. access to any continuing improvements in global ICEV technology after the proposed ban even as ICEVs continue to dominate transport. To take one example: A British consumer would be unable to buy a new Japanese car that considerably improved on what was available in 2030. A ban will also stop R&D in this area in the U.K (an area in which the U.K. has a strong capability) well before such a ban comes into force, and it will throw a lot of very highly talented and educated engineers and scientists out of work. It will remove the biggest and the easiest opportunity to reduce fuel consumption (CO₂) and pollutant emissions from transport. If the public are not persuaded to buy BEVs in large numbers by 2030, and if auto companies cannot sell ICEVs from that date, Britain’s auto industry, a critical sector of the U.K. economy, will collapse. It would be a spectacular case of self-harm. All available technologies, including BEVs, ICEVs, and novel fuels, where they make sense, need to be deployed and continuously improved to mitigate transportation’s environmental impact.

ConclusionThe energy transition needed to reach net zero carbon by 2050 is extremely challenging, and transport is the sector that is most difficult to decarbonize. 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 by the target date. The proposed changes 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. If, as will almost certainly be the case, not enough countries follow the U.K.’s “leadership,” it would be better to recognize that there will be little change to global GHG levels and to focus instead on efforts to improve energy and resource efficiency and on measures, such as better flood defenses, to adapt to climate change. 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 onward will condemn the U.K. to forgo any new developments in ICEV technology and remove the biggest and easiest opportunity to improve the efficiency and environmental impact of the U.K.’s transport sector.

Of course, if the British government is really serious about its net zero goal, concrete, time-bound initiatives with clear budget and engineering targets have to be set and implemented. Such targets could include, in the next ten years, reducing energy consumption by 13 percent and at the same time building 13 3-GW nuclear plants or 33,000 offshore 3-MW wind turbines; replacing 10 million gas boilers; building 700,000 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; and the list doesn’t stop there . . . 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 government to focus on the implications of what has been promised.

Clearly, since no such targets have been announced, it is almost certain that the government will miss its goal to get to net zero carbon emissions by 2050. Meanwhile, vast sums of money and resources will have been spent for little gain and perhaps quite a bit of environmental harm, and a great deal of industrial production will have been outsourced. Soon there will be a realization that net zero will remain out of reach. After that will come the time for creative CO₂ accounting, offsets, and apportioning of blame.

Gautam Kalghatgi is a fellow of the Royal Academy of Engineering, the Institution of Mechanical Engineers, and the Society of Automotive Engineers. He is currently a visiting professor at Oxford University and has held similar professorial appointments at Imperial College, Sheffield University, KTH Stockholm, and TU Eindhoven. He has 39 years of experience in combustion, fuels, engine, and energy research.