Thursday, November 03, 2005

Fuel Cells - Why should i care?

I said i was going to post a little something on fuel cells. The wiki entry is here and isn't too bad for an initial overview.
You can talk about fuel cells in a number of ways:
  • The chemistry/engineering of getting them to work
  • The electricity network/markets as they exist right now and how FC's fit into this
  • As an enabling technology for the prophesied 'hydrogen economy' (you may guess my leanings on this one)
Most FC summaries focus mainly on one of these topics and sprinkle in a little of the other two as a way of justifying the major point. Each of these topics is worthy of a post itself - so that's what i'm gonna do.
The bullet points above can just as easily be asking 3 different questions, namely, how do they work? how will they compete/complement? and why should i care?
I'm going to start with the last one, since if you can't convince someone something is worth doing, you should think twice about wasting their time telling them how you did it...

For this post, just visulise a FC as being something that converts a fuel into electricity on a continuous basis. We should care about fuel cells for 2 main reasons as far as i can tell:
  1. They can potentially be far more efficient users of fuel for generating electricity than other combustion methods
  2. They can be readily distributed to where the user's are
Point 1 hinges on the fact that as far as we can tell, economic growth and standard of living both correlate with carbon emmissions (even if you discount Global Warming as an issue, burning coal/nat gas is still emmitting loads of gunk into the atmosphere). If we are to accept that the other 3/5 of the world that doesn't have a first world standard of living are going to catch up in the 21st century, we need to be smarter in how we deliver their infrastructure. There are some truley horrendous estimates of how much coal China is going to be burning by 2050, but given their growth rate, what else can they do?
Point 2 is a little more subtle - something like two thirds of the cost of getting a unit of electricity (kWh) into your house to use is actually the cost of getting it from the power station to your street. FC's (and other technologies) that allow you to generate your power at the point of consumption, are great because they automatically avoid these transmission and distribution losses (which are actually equivalent to CO2 emmisssions at the power station, just because this energy is lost on the way doesn't mean it wasn't generated in the first place). FC's are particularly well suited for distributed generation because some of their attributes include running quietly (it's a solid state device at heart), having few if any (visual or smog related) emmissions and they don't suffer from 'economies of scale' arguments like power stations i.e. they're just as 'efficient' when designed for 1 kW as 250 kW.
If you are looking for an analogy as to how a DG system might work, just look to how the telephone industry has been shaken up by cell phones and the internet, how the music industry is suffering because its business model hinged on mechanism rather than content and how television is changing from 1 channel-1 time-many viewers to any program-any time-parallel viewers. These are all industries that were very mature and have had to deal with a shock to their system driven primarily because customers started to move to the head of the supply-chain rather than sitting around at the end waiting for stuff. A DG electricity system is likely to behave in a similar manner for some part of the market segment over the next 25 years.
How are they fuelled? This is an extremely vexacious issue and one that is often glossed over in FC stories/articles. It is in fact the achilles heel of the whole system. DG stationary power sources that can tap into an existing natural gas network get around this problem but anyone that says 'water is the only product' is pulling a fast one - hydrogen isn't mined, it's made. Making hydrogen in significant quantities is very, very energy intensive and you have to burn loads of fossil fuels to make it. When people talk about a hydrogen economy, they always put in the caveat that the hydrogen needs to be made in a renewable fashion for it to really work. But this is the crux of the issue, there is no current way of making hydrogen sustainably in significant quantities. As for using biomass to turn into hydrogen to run cars... that's stupid, just burn the biofuel directly - it was good enough for Otto Diesel in 1870 and it's good enough now.
So where does that leave us? FC's are a good addition to the tech arsenal since they can more efficiently use the fossil fuels we have in a potentially cleaner way and they are able to be deployed and used in a chaotic and distributed fashion - these two reasons are all that are needed in my opinion to warrant the investment in research that is needed to bring these to market.
Completely emmission free power generation is a problem for my grandkids, i'll settle for >50% efficiency (and that's real efficiency - delta G/delta H, a plague on all your other namby pamby definitions) in my lifetime.


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