Monday, 23 June 2014

Hair dye takes on the fuel crisis?

I have always been highly dubious of hydrogen fuelled cars. Okay, they're nice and eco-green because their only waste product is water. But hydrogen takes up three times as much volume as petrol for the same energy output, there is no hydrogen infrastructure, and (as the Hindenburg demonstrated) you don't want a problem at a filling station with leaking hydrogen. I would much rather we put more effort into battery technology, getting them more energy dense, and making them faster to re-charge.

However I would hate to be considered closed-minded, so I share the STFC's latest idea - instead of hydrogen, use ammonia. Although ammonia itself isn't a fuel, you can 'crack' it to give off nitrogen and hydrogen, which is then used in the usual manner in a fuel cell. Or you can use it as a fuel directly with a bit of hydrogen (see below), though despite the airy hand-waving, I would point out that those NOx gasses they hope they can get rid of are worse greenhouse gasses than CO2.

I still have some issues with this. It's quite a complex process from fuel to energy out because you have to go through a chemical reaction along the way. And I don't know what the energy density of ammonia is (any suggestions?) - and there is still an infrastructure problem, though providing ammonia in filling stations is more on a par with LPG, rather than the harsher conditions of hydrogen supply. So not a whole hearted 'Whey-hey, we've solved it!', but at least a 'Hmm, there might be something in it.'

Take a look at the excitable press release:

UK researchers today announced what they believe to be a game changer in the use of hydrogen as a “green” fuel. A new discovery by scientists at the UK’s Science and Technology Facilities Council (STFC), offers a viable solution to the challenges of storage and cost by using ammonia as a clean and secure hydrogen-containing energy source to produce hydrogen on-demand in situ.

When the components of ammonia are separated (a technique known as cracking) they form one part nitrogen and three parts hydrogen. Many catalysts can effectively crack ammonia to release the hydrogen, but the best ones are very expensive precious metals.  This new method is different and involves two simultaneous chemical processes rather than using a catalyst, and can achieve the same result at a fraction of the cost.

Ammonia can be stored on-board in vehicles at low pressures in conformable plastic tanks. Meanwhile on the forecourts, the infrastructure technology for ammonia is as straightforward as that for liquid petroleum gas (LPG).
Professor Bill David, who led the STFC research team at the ISIS Neutron Source, said “Our approach is as effective as the best current catalysts but the active material, sodium amide, costs pennies to produce. We can produce hydrogen from ammonia ‘on demand’ effectively and affordably.

“Few people think of ammonia as a fuel but we believe that it is the natural alternative to fossil fuels. For cars, we don’t even need to go to the complications of a fuel-cell vehicle. A small amount of hydrogen mixed with ammonia is sufficient to provide combustion in a conventional car engine.  While our process is not yet optimised, we estimate that an ammonia decomposition reactor no bigger than a 2-litre bottle will provide enough hydrogen to run a mid-range family car.”

“We’ve even thought about how we can make ammonia as safe as possible and stop the release of NOx gases,” added Professor David. “This fundamental science therefore has immense potential to change the use of hydrogen as a fuel."

Ammonia is already one of the most transported bulk chemicals worldwide. It is ammonia that is the feedstock for the fertilisers that enable the production of almost half the world’s food. Increasing ammonia production is technologically straightforward and there is no obvious reason why this existing infrastructure cannot be extended so that ammonia not only feeds but powers the planet.

 Speaking about this new development from the team at STFC, Professor David MacKay FRS, Chief Scientific Advisor at the Department of Energy and Climate Change (DECC) said “We believe that there is no single solution to the challenges we face in decarbonising the fuel chain, but this research suggests that ammonia based technologies are worth further consideration and may well play an important part in the future energy landscape. “

Five years ago, Professor Steven Chu, Nobel Prize winner and, at that time, the US Secretary of State for Energy in the Obama administration, sounded a death knell for the hydrogen economy with his statement that, while it takes only three miracles to be declared a saint, it would take four miracles to achieve a hydrogen-based energy economy.  This work from STFC researchers could well be a turning point.

Kate Ronayne, Head of Innovation at STFC said: “This exciting research has the potential to dramatically influence the static and mobile energy solutions of the future. While still at an early stage, this innovative work offers a very elegant solution to some of the major challenges in harnessing the power of hydrogen as a fuel source.”

This has been a Green Heretic production

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