Is the future of cars green?

Andreas Wilson-Späth

Does the future of transportation involve an inexhaustible fuel that produces pure water vapour as its only emission?

Toyota thinks so. After two decades of development, the Japanese motor giant recently unveiled the Mirai, the world’s first mass-produced hydrogen fuel cell car, which is on sale in limited numbers in Japan now and will be released in the US and Europe next year.

The ‘hydrogen economy’ has long been a feature of futurist writings, but until now, there has been scant evidence of it becoming a reality. Cars powered by hydrogen may change this, as other major manufacturers, including Hyundai, Audi, Honda, Renault, Nissan, Ford and Daimler are all involved in developing their own versions.

How does it work?

A fuel cell vehicle is propelled by an electric motor, just like a conventional electric car. Instead of powering that motor with electricity from a bank of batteries, however, the electricity comes from a series of fuel cells arranged in a so-called stack.

Inside the fuel cells, oxygen from the air is combined with hydrogen and in the resulting chemical reaction, electricity is generated. The compressed hydrogen fuel is stored in bulletproof onboard tanks and the only emission from the reaction is water vapour – no noxious gases or climate changing greenhouse gases.

Hydrogen benefits

Hydrogen fuel cell cars have a number of advantages over electric vehicles:

? A superior range of well over 450 kilometres when fully tanked up on hydrogen – that’s two or three times further than a typical electric vehicle will go without a recharge.

? A much faster refuelling time. Filling up the Mirai is as quick as filling a conventional petrol powered car. Recharging an electric vehicle takes much longer – typically hours although times are decreasing with improved technology.

? The potential to scale up the technology to power larger vehicles like truck, busses, forklifts and heavy machinery, which is not generally an option with electric vehicles.

In addition to this, the hydrogen fuel cell can be used as an autonomous source of electric power even when the car is parked. The Mirai comes with an optional ‘out’ port that allows owners to plug their home into their car if necessary (provided it’s wired appropriately). With full fuel tanks, a Mirai can supply the electrical power needed to run an average home for about a week.

Some way to go

How close is the nearest hydrogen filling station to your home? Not particularly? Thought so!

That’s the most obvious practical problem in making hydrogen fuel cell cars a viable proposition: the infrastructure for manufacturing and distributing the fuel is essentially non-existent.

But that may change pretty quickly. California is planning to build a network of 100 hydrogen filling stations in the next ten years (currently there are only ten demonstration sites in the state). Germany, Japan, Korea, the UK and Denmark have made similar commitments.

Building hydrogen fuel cell cars is still quite expensive – if you can get one, a Mirai will currently set you back anywhere between about R650 000 and R900 000. In addition, there is no clarity as to how much hydrogen fuel will cost.

But is it really green?

Hydrogen is extremely abundant on Earth, but unfortunately it is very rarely found in the pure state required for fuel cells. Hydrogen fuel needs to be manufactured.

Regrettably, not all hydrogen fuel is created equally and that’s the crux of the matter when evaluating it from an environmental perspective.

Currently, almost all hydrogen is made by stripping atoms of the element out of natural gas, generating carbon dioxide as a waste product. Obviously that’s not a viable scenario for anyone who cares about the planet. We’re trying to get away from using fossil fuels in our cars, not find new ways to market them.

There is a cleaner alternative, however. Electricity generated using renewable energy sources like solar and wind power can be used to extract hydrogen out of water. The technology is still in its infancy, but holds a lot of promise. Denmark is planning to use its excess wind energy in this way. The hydrogen created serves as a green energy storage medium which can be used to power fuel cells in cars or wherever else electricity is needed.

- Andreas is a freelance writer with a PhD in geochemistry. Follow him on Twitter: @Andreas_Spath
 
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