The existing transport system, built around internal combustion engines powered by petroleum-derived liquid fuels, meets an essential need and supports a large number of jobs. The demand for transport energy is very large, at around 105 Terawatt hours (TWh) of liquid fuel energy each day, and is growing; for comparison, in 2016, for the whole year, the consumption of wind and solar energy together amounted to 1292 TWh.
Dismantling such a system abruptly, say by banning the production of internal combustion engines (ICEs), as some politicians suggest, will have extreme economic, social, environmental, and political impacts and is highly unlikely. Every alternative to this system starts from a very low base and faces significant environmental and economic barriers to fast and unrestrained growth.
The forced building of an alternative system either entirely around battery electric vehicles (BEVs) or hydrogen fuel cell vehicles (FCVs) will be hugely expensive and be environmentally damaging if the primary energy system is not sufficiently decarbonized and toxicity impacts associated with the battery supply chain are not properly addressed.
For instance, the available battery capacity will have to increase by many hundredfolds, perhaps over a thousandfold, if all light-duty vehicles (LDVs) in the world are to be fully electric by 2040, but this will only address less than half of the transport energy demand since commercial transport cannot realistically be run on electricity alone on this timescale. More importantly, BEVs are not “zero emission” vehicles – they simply shift their emissions’ impact from the tailpipe to somewhere else.
Electricity generation needs to be sufficiently decarbonized for BEVs to have an advantage over ICEVs on a life-cycle basis in terms of GHG emissions. While this is true in some areas of the world, it will not happen for decades in rapidly growing markets like China and India because coal will remain an important part of the electricity generation mix. Also in such areas, if electricity generation is not sufficiently distant from urban traffic centers, even the impact on urban air quality of pollutants like particulates, NOx, and SO2 would be worse for BEVs compared to ICEVs.
The human toxicity problems associated with the battery supply chain are very serious but are concentrated in places like the Democratic Republic of Congo and China. However, this pollution will have to be addressed if BEV numbers have to grow many hundredfolds. Large prior investments in charging infrastructure and continuing subsidies to persuade people to buy BEVs and in extra electricity generation and grid management will be required if governments wish to force such changes.
Transport will be essentially powered by ICEs till these barriers are overcome, and this could take decades. ICEs are also improving rapidly as better combustion, after-treatment, and control systems are implemented. There will be increasing electrification, particularly of LDVs, but it will be mostly in the form of hybridization to improve the efficiency and performance of vehicles carrying internal combustion engines (ICEs).
As the overall energy system is decarbonized and battery technology improves, there will be an increasing role for BEVs and hydrogen which could replace liquid hydrocarbons in the long run and the required infrastructure will evolve. Alternatives to petroleum-based liquid fuels such as biofuels, natural gas, LPG, DME, methanol, and hydrogen will grow but have their own constraints on fast and/or unlimited growth but could increase their share of transport energy from the current 5% to around 10% by 2040. Future transport will not be limited by the supply of petroleum which has been growing faster than consumption over the past 35 years – current reserves are enough to last the next 50 years at current production/consumption rates.
Currently, BEVs appear to be near the top of the first phase of the hype cycle where expectations are raised by overly positive and irrational enthusiasm for a new technology. The hype is promoted by the media which tends to focus on potentially big stories and decision makers follow the trend rather than carefully assessing the potential of the technology or all the consequences of forcibly implementing it. Quite often, once the difficulties of widespread commercial adoption of the technology and the true consequences become clearer, the hype will suddenly ebb and collapse.
Incidentally, if BEV numbers indeed grow fast, the global demand for gasoline, which mostly powers LDVs, will be further reduced, and the expected gap in demand for middle distillates (jet fuel and diesel) on the one hand and gasoline on the other, will only widen. More oil will need to be processed to meet the increasing demand for middle distillates. There will be a proportionate increase in the supply of low-octane gasoline components, mostly from the initial distillation of oil, which are used for gasoline production.
There is great scope for developing fuel/engine systems like the Gasoline Compression Ignition (GCI) engine which can use such fuels. A GCI engine will be at least as efficient as but less complicated and hence cheaper than the diesel engine and will use fuel components which will be in abundance and hence could be cheaper.
Transport policy should be based on a balanced approach using all available technologies, taking into account local and global environmental and GHG impacts, security of supply and social, economic, political, and ethical impacts. The best chance of significantly mitigating GHG and other impacts of transport lies in improving combustion engines assisted by partial electrification and better control and after-treatment systems. It would be very short-sighted indeed not to invest in improving ICEs since they will inevitably be powering the transport sector, particularly the commercial transport sector, to a large extent for decades to come.
These findings are described in the article entitled Is it really the end of internal combustion engines and petroleum in transport?, recently published in the journal Applied Energy. This work was conducted by Gautam Kalghatgi from Saudi Aramco Dhahran.