Fuel cells

Wednesday, January 08, 2014

Tags :  alternative-energy

The phrase ‘quiet revolution’ is often used to describe significant but gradual change that is accepted without fuss. The advent of electric transport and motorsport feels like this, but the on-track result will also be quiet, and concerns about the lack of noise has given rise to synthetic noise generators for electric road vehicles to mimic the sound of various types of engines.

Batteries made from lithium-ion fuel cells are the most popular way to store the energy on electric cars and indeed on IC engine-electric hybrids, although there are those who prefer supercapacitors. The other alternative, especially for pure electric motorsport, is the fuel cell. These can perhaps be imagined as a cross between an engine and a battery, although they aren’t especially closely linked to either. The similarity to an engine is that while we still flow fuel into a fuel cell – in this case hydrogen – the output is electrical rather than kinetic energy, which is similar to a battery. The conversion to a more useful kinetic energy is achieved via an electric motor.

The use of fuel cells has been limited to date, although there has been a notably impressive Land Speed Record car, the Buckeye Bullet, which uses fuel cells and which holds the electric-powered record at more than 303 mph (487 kph) for the flying kilometre. It was mentioned in a previous RET-Monitor article, which also mentioned the Green-GT, another hydrogen fuel-cell powered car that unfortunately proved to be an no-show at Le Mans and has not been heard of since.

One arena where fuel cell-powered cars compete with other electric and IC-engine cars though is Formula Student. Delft University, for example, has competed in Formula Student with great credit, and has used its experience to create its sixth car, the Forze VI. The aim of the car is twofold – to compete in the Caterham Cup against a field of IC-engined cars and to be the fastest hydrogen-powered car around the famous Nurburgring Nordschliefe circuit.

That would be no mean feat. An Aston Martin Rapide with an engine configured to run on either gasoline or hydrogen ran a full lap of the Nurburgring on hydrogen in 2013. The estimated power output of the Aston was about 500 hp (375 kW). At 260 hp (190 kW), the Forze VI car has around half of this power but also weighs around half of the Aston’s 1600 kg and is much smaller, so may have less drag. Delft estimates the top speed to be about 137 mph (220 kph).

The beauty of a fuel cell vehicle is the energy storage density, although hydrocarbon fuels have a large advantage over batteries for this very reason. I have yet to see a car that can go 600 miles on batteries, but I see hundreds of gasolines and diesels every day that will do just that. And if there is a 600-mile battery car out there somewhere then I bet it wouldn’t be able to put in a repeat performance five minutes after draining its batteries. The Forze VI car has a fuel tank that  holds only 3kg of hydrogen. Although the tank itself and the associated plumbing may be heavy, I also bet it would be lighter than a comparable battery.

Written by Wayne Ward

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