Image Credits: Pavel L Photo and Video/shutterstock.com
In an ideal world, vehicles such as cars and trucks, would be powered by zero-emission fuels like electricity. In the real world, however, electric cars have a limited range on a single charge – anywhere between 186 and 300 miles - and there is a lack of suitable public charging infrastructure along the extensive stretches of motorways and highways of the world. This has caused a shift in thinking towards an alternative, specifically e-fuels.
E-fuels are electricity-based carbon neutral fuels that can power compressed natural gas (CNG) vehicles. Carbon neutrality is achieved when the emissions produced by the vehicle equal the carbon footprint of the fuel – the amount of carbon dioxide emissions created in producing said fuel.
E-gas is also known as synthetic methane, and is exactly the same as the methane naturally produced over millions of years, just much, much quicker and in the laboratory. An electric current is passed through water during electrolysis and the hydrogen and oxygen that make up water are split. It is hoped that hydrogen could be used a fuel for cars in the future, but this is still under investigation, so for now, the hydrogen is reacted with carbon dioxide which undergoes methanation to form methane.
As the resulting methane is identical to natural methane, it can enter the natural gas network with no modifications. From here it is distributed to homes, businesses and CNG stations. In natural gas-powered vehicles, the methane is mixed with oxygen from the air in an internal combustion engine and burned to release energy, carbon dioxide and water vapour. Methane is therefore one of the cleanest burning hydrocarbons, and any contaminants in the natural gas would have been removed at the source.
As the price of petrol continues to increase, there is the potential that we will see more vehicles running on natural gas. It is approximately 30% cheaper than petrol and has fewer emissions; there is a 70-90% decrease in carbon monoxide, a 75-95% reduction in nitrogen oxides and a 20-30% decline in carbon dioxide emission. It therefore has a lesser impact on air quality and will help slow the progress of global warming.
However, it is more expensive to purchase and there are still replenishing issues as there are few refuelling stations open to the public. E-fuels are also considered too inefficient and expensive to power the fleet of cars and trucks on the roads, but experts suggest that their use in aviation might help the sector in the fight against climate change. Only a limited amount of e-fuels could be used, and the electricity used to make the fuel would have to come from renewable sources – such as wind farms – in order to make the process much cleaner, and for it to meet the strict sustainability criteria set by the industry if it is to contribute to lowering aviation emissions. It is therefore considered a supplemental measure and one that is likely to be expensive.
Furthermore, production costs are high and it is difficult to realistically scale-up the production process to meet future power needs and such a method has never been demonstrated at a commercial level. Despite this it should still be considered in areas where there really is no alternative, such as the aviation industry.
E-fuels are an intermediate technology – they are not the solution and they do still contribute to the warming of the planet, but they absolutely have an important role to play in meeting future demand for fuels. While they require electricity to produce, the use of wind farms to provide power is thought to be the likely candidate to help offset the carbon footprint. As the price of wind and solar power falls, it’s likely that the electrification of road transport will occur, but while we wait for that to happen, e-fuels will plug the gap as an alternative fuel.
References and Further Reading
- How carbon neutral e-fuels work
- E-fuels too inefficient and expensive for cars and trucks, but may be part of aviation's climate solution – study
- E-fuels may be an option for aviation but not road transport, study finds
- Electric car range; how far will they really go on a single charge?