Air pollution and carbon neutrality aren't the same thing

A lot of people get this wrong, even high-level conversations I had with ministers and experts, they don’t understand the real meaning of some technology or process being carbon neutral or pollutant and its effects on society.

Let’s start with an example: e-fuels. E-Fuels are hydrocarbon-based fuels like gasoline but the technology to make them involves capturing CO2 of the air and adding the hydrogen with energy obtained from renewable sources. So, you take all your carbon from the air and create “artificial” gasoline. Then you burn this gasoline inside a combustion engine which then releases back all the CO2 to the atmosphere again. The whole process is carbon neutral, considering the whole production chain is carbon neutral. Carbon is captured here and burned there. But it generates a very similar amount of pollution where it is burned. If you are cycling behind a car using e-fuels or traditional fossil-fuel, the effect on your lungs is as bad as it can get. That is due to the high temperature combustion generating small particulate matter, nitrous oxides, carbon monoxide etc… Actually, the higher the engine efficiency the higher is the combustion temperature and therefore higher pollution.

Now the opposite, an electric car being charged by a coal production plant. Coal is dug up from the ground and burned into a thermo electric power plant. Coal is very carbon dense, that why it is black, and the hydrogen ratio is low. Burning all this coal generates a lot of CO2, a greenhouse gas, but also electricity. The carbon is released to the atmosphere while the electricity is used to charge the car. The car drives around a city with zero emissions, which is extremely good in a dense urban area, pollution free. But all that electricity had been generated by a lot of greenhouse gas emissions, therefore not carbon neutral.

What is best?

The best is generating the electricity by renewable sources and having vehicles in dense urban areas emission-free, for the best human health and quality of life for society. Of course, this isn’t suitable for all applications, and each different use case needs a specific technology which, sometimes, can be a compromise. Jet fuel is an example. It is not ideal to have planes burning so much kerosene at the upper layers of the atmosphere but no zero-emission technology exists to replace the power and energy dense turbines that makes the plane fly. Solution? Maybe bio-fuel. Cheaper than e-fuels, soya hydrogenated vegetable oil might be a great solution to keep the planes flying at a carbon neutrality compromise. For large container ships, maybe SMRs, small nuclear reactors, could provide fuel for 10-20 years at zero carbon and zero emissions.

What about hydrogen?

Hydrogen will be part of the solution. Hydrogen combines with oxygen to generate water vapor. It can be combined by using a fuel-cell or a combustion engine. If fuel-cell technology is used then it is pollution free. If you burn H2 at high pressure and temperature (combustion engine), it will produce some toxic pollution like nitrous oxide. The problem with hydrogen is how you produce it. Today most H2 is used by taking methane (CH4), getting those juicy H4 out of methane and releasing the C (carbon) in the air. This isn’t carbon neutral clearly and it is called gray hydrogen. To produce green hydrogen, you need to break the water molecule H2O with lots of electricity. The process is extremely energy-dense and in many cases it would just be better to send that electricity directly to batteries.

As you can see, we don’t have a silver bullet – a unique all wonder solution – for our carbon neutrality and air pollution problem. A combination of technologies and uses must be developed side by side so we can decrease our impact on the planet and human health while providing faster, better, and improved quality of life for all world’s population.