Could the transition drive emissions up?

One question that comes up quite regularly about the energy transition is the amount of energy, and therefore emissions, required for the transition itself. This is the energy required for making solar PV modules, wind turbines, batteries and so on. Further up the supply chain there is also the energy required for the additional minerals, such as the lithium, nickel, cobalt and copper found in an electric vehicle (EV). These not only have to be mined, but also go through extensive industrial transformation and refining processes to make the actual materials required for the end use. Today, most of these processes use oil, coal and gas for energy, giving rise to carbon dioxide emissions.

Perhaps the most energy intensive part of the energy transition is the manufacture of lithium-ion batteries, now being widely deployed in EVs. Some commentators have even questioned the effectiveness of the EV as a mitigation route, particularly when the battery is made in China (currently a heavy reliance on coal for energy) and the vehicle is driven in a country with a high electricity emissions intensity (e.g. a country like Poland still largely dependent on coal fired power stations). The problem with this argument is that transitioning in a series of steps (e.g. first decarbonise the electricity supply, then start deploying electric cars) would take decades longer than transitioning in parallel steps (i.e. decarbonising the electricity supply at the same time EVs are deployed). Nevertheless, the parallel approach could drive up emissions in the short term, the question is by how much?

The manufacture of batteries for EVs provides a good example of the problem. In a recent article, MIT report that the Tesla Model 3 holds an 80 kWh lithium-ion battery and the CO2 emissions for manufacturing that battery would range between 3120 kg (about 3 tons) and 15,680 kg (about 16 tons), depending on the manufacturing location. The article notes that the vast majority of lithium-ion batteries—about 77% of the world’s supply—are manufactured in China, where coal is the primary energy source. That means most batteries are currently made with CO2 emissions at the higher end of the range, although as battery factories spring up across the world and particularly in the EU and US, that picture will change.

Bringing together a few assumptions about battery manufacture, EV deployment and embedded CO2 in both manufacture of EV batteries and driving EV cars, it is possible to get a back-of-the-envelope view of the scale of the issue. I will assume the following;

  • EV production rises from current levels (some 7 million vehicles per year) to all EV production globally by the mid-2030s (i.e. no more internal combustion engine cars are built after that time). This is an aggressive transition, but probably the minimum that is required for a 1.5°C goal.
  • Higher CO2 emission battery manufacture is currently at 77%, but the share declines to 40% by 2060 and the higher CO2 emissions also fall by 75% over the same timeframe as the manufacturing system decarbonises.
  • Lower CO2 emissions manufacture is therefore 23% now, but rises to 60% by 2060 and the manufacturing CO2 emissions fall to zero by 2050. Decarbonising industry to such an extent will require a variety of technologies, with carbon capture and storage playing a critical role.
  • The 80 kWh battery delivers 300 miles of range and the average vehicle travels 10,000 miles per year.
  • The electricity supply which EVs use is on average 0.4 tonnes CO2 per MWh now, falling to zero by 2060. The actual global average grid intensity is higher than 0.4 today, but EVs tend to be driven in lower intensity regions at the moment, e.g. the EU, California etc.
  • An EV produced today has a 15 year life.
  • The EV mitigates emissions from internal combustion engine vehicles at a rate of 120 gms/km. As a simplification, this doesn’t change throughout the calculation. It assumes that smaller cars are replaced earlier and that the average fleet efficiency of internal combustion vehicles improves over time.
  • The battery represents a net increase in car manufacturing emissions with other emissions in the manufacturing process about the same for both EVs and internal combustion vehicles.

The calculation is for net-emissions, which is;

[Battery manufacturing emissions] + [Indirect EV emissions during driving] – [Gasoline / Diesel emissions backed out by EVs] = Net Emissions

What we see from the charts below is that global passenger car emissions rise before they start falling when net-emissions cross the zero line. This happens in 2035. Clearly the year in which this happens depends on the assumptions made, with the CO2 from internal combustion vehicles not being used being a key determinant. For example, if this is raised to 180 gm CO2/km, the crossover point is around 2030.

The outcome certainly points to the longer term benefit of the EV transition, with global cumulative emissions over 25 Gt lower in 2060 than they would otherwise be. This is a material reduction when thinking about a 500 Gt carbon budget for 1.5°C. However, it also highlights an issue with the current global goal to reduce emissions by 45% by 2030 relative to 2010, as set out in the Glasgow Climate Pact; the EV revolution that we are currently in the midst of is unlikely to contribute to that reduction. If anything, it could make the task even more difficult.

In a post some time back I noted that the only real opportunities for change which could make a material difference to global CO2 emissions by 2030 are where replacement technologies are already being manufactured at scale or where governments are prepared to create social change. This quickly reduces the options to only three major opportunities: 

  • Significantly curtailing coal-fired power generation through replacement with renewables; 
  • Replacing internal combustion engine vehicles with electric vehicles; and 
  • Ending deforestation. 

Passenger vehicle emissions account for 4 Gt, or 10%, of global CO2 emissions today. If change in this sector can’t deliver any net reductions by 2030 and potentially adds to global emissions, then it calls into question any possibility of a 45% reduction in 8 years. Almost perversely, if EV production could be ramped up in the short term, the problem for 2030 gets worse while the longer term net global cumulative emissions picture gets better.

None of the above is to meant to argue against an EV transition, it is clearly the right way to go. But like many other aspects of the energy transition, it is more complex than it looks.