With more and more people becoming environmentally-aware, a lot of people would be interested in carbon neutral fuel that would replace regular carbon-emitting natural gas. That is exactly what Audi have done in introducing their e-fuel, which can be used for a dual fuel engine, but doesn’t burn fossil fuels.
With electric cars having limited range as well as limited charging infrastructure nationwide and longer charging times, the trend for the next few years is still likely to be natural gas, gasoline, or diesel. The e-fuel takes advantage of existing natural gas refueling stations and is also produced using landfill and non-potable water.
The carbon neutral nature of e-fuels means that the amount of carbon dioxide they use up when being produced is the same as they use when being burned, thus, there is no net release of carbon into the environment.
Taking advantage of excess CO2, this is used to manufacture hydrogen which is produced through electrolysis using renewable sources of energy. Then CO2 is combined with the hydrogen to form e-gas, very similar to methane in composition. SInce there already exists infrastructure for natural gas, unlike hydrogen, this is a particular advantage.
Audi is planning to make the A3 TCNG, a car that runs on regular gasoline and e-fuels as well, and is also putting up a Germany-based plant for e-fuel production. However, in the US, Audi has partnered with New Mexico-based Joule to make e-fuel out of non-potable water, non-food crops and microbes in a process where the microbes which are photosynthetic use up sunlight, waste CO2 and contaminated water to make the fuel. This means that the process uses neither valuable agricultural land nor drinking water in the e-fuel production.
This does not mean that e-fuels are totally problem-free. First, there is the problem of price as they are a bit more expensive than their oil-based counterparts. However, Audi is aiming that a $100 per barrel price is reached by 2020 with increased production. Another issue is that of yield. Even with about 8,000 gallons of e-ethanol being produced per acre, which is the leader in terms of e-fuel yield, this is by far only a tiny fraction of the yield of regular gasoline.
Another talking point is that carbon neutral fuels do not actively reduce carbon emission; they only ensure that the net output of greenhouse gases is zero. Despite this, the production of synthetic natural gas may prove to be a key way in helping in the fight against climate change.