A team of students from my hometown's university, that proved last year they could run a small miniature car on formic acid, has now upscaled their design.
Eindhoven is now the first city in the world to have a city bus that runs on formic acid.
Formic acid is interesting, because it's a good energy carrier, and contrary to hydrogen, can be stored at room temperature without needing pressure tanks.
It also is not flammable, and cannot explode. It's nicknamed 'Hydrogen 2.0' by the student team. It is also CO2-neutral.
Formic acid can be created by having CO2 and H2 react with each other. It can then be easily stored in plastic tanks. To turn it into power for an electric engine, two steps are nescessary. First a reformer (catalyst) turnes the formic acid back into CO2 and H2, then the latter is used by fuel cells to produce water and electricity.
Up until recently, it was hard to produce the hydrogen fast, and in meaningful quantities. With another invention from Eindhoven University, namely that adding ruthenium to the catalyst vastly increased performance, the students had no trouble upsizing their engine prototype to a size that can drive a city bus.
"One of the main challenges was to create a reliable reformer, one that doesn't break every week. The reformer that drives the bus now, has been performing without falure for three months now during the test phase. In our lab, we have a similar reformer that has been running non stop for 2 years now.
Another big challenge was increasing reformer speed, so it could be made smaller. Our first prototype had a volume of 200 liters. Our current design is only 20. It produces enough hydrogen per minute to allow the fuel cells to provide 10 to 15 kW netto output."
Now this isn't strong enough to drive the bus. However, it is enough to keep the bus' batteries charged over the course of the day. With a tank of 300 liters of formic acid, the action radius of the electric bus increases from 80 to 300 kilometers. This means in practice, that the city busses will no longer need to return to loading stations to reacharge their batteries during their daily schedules.
The main benefit of formic acid, is that it can be tanked easily. This makes it suitable for normal cars as well. With 50 liters of formic acid, an electric car would be able to drive about 250km. Gas station owners who want to supply formic acid don't need to invest 1.5 million like they would need for hydrogen service. For a mere 30-40k existing tanks and pumps can be refitted.
There's still challenges though. For instance, a lot of energy is lost in the transition. the so called 'wheel to wheel ratio' of formic acid is about 33%, meaning that two thirds of the energy put into the system is wasted. Still better than hydrogen though, which has a wheel to wheel ratio of 25%.
Another big advantage is that formic acid tanks can be shaped and molded into any desired form. Contrary to hydrogen tanks, which need to be cylindrical to withstand the huge 700 bar pressure. This restriction has made it hard to fit fuel tanks for more than 5 liters of hydrogen into a car. Obviously, formic acid tanks allow for much more design freedom.
Author
Topic: Tech News. Automation, Engineering, Environment Etc (Read 265515 times)