A story from the Business section of yesterday's Western Mail caught my eye:
Biggest carbon capture test planned for Aberthaw Power Station
By Aled BlakeAberthaw Power Station could host the UK’s biggest carbon dioxide capture pilot project connected to a working power station.
RWE, the power station’s owner, has applied for planning permission to construct a plant capable of testing the capture process on emissions direct from the power station.
At 3 MW in size the plant will be at least eight times the size of existing post-combustion projects in the UK and will operate for twice as long. It will be capable of capturing up to 50 metric tonnes of CO2 per day.
Impressive, eh? Well, that's obviously what RWE would like you to think. All you need to say is "Wales leads the world" and a tame reporter from the local rag (sorry, the National Newspaper of Wales) will lap it up unquestioningly. Aled Blake certainly seems to have re-worked their press release without thinking to put these figures into any sort of perspective.
But as he might not accept it from me, I'll let his fellow reporter Lisa Jones do it instead:
Aberthaw is Wales’ biggest polluter
By Lisa JonesA power station in the Vale of Glamorgan has been revealed as Wales’ biggest polluter.
Aberthaw Power Station tops the league tables of the 10 dirtiest sites in Wales, based on Environment Agency information.
Last year the coastal power station between Barry and Llantwit Major pumped out more than 7.4 million tonnes of carbon dioxide, the gas which is a major contributor to climate change.
It also belched out 28,325 tonnes of nitrogen dioxide and 30,953 tonnes of sulphur dioxide – both gases which help to create acid rain.
We can all do the maths for ourselves. Aberthaw produces over 20,000 tonnes of CO2 per day. This new plant will collect less than a quarter of one percent of it!
This should act as a sobering reminder that the words "clean coal" are, in any practical terms, just gobbledygook. They sound impressive, but will not deliver.
That's not to say that it can't be done. It can be done, but it requires a different approach. What RWE are proposing is to retrofit a post-combustion capture plant. This will be almost useless.
The problem is that, at present, the UK government seems to think that it is possible to retrofit post-combustion capture to any new plant, such as Kingsnorth, by allowing space for it at the design stage. That is not quite as misleading, but nearly as much so. At full scale I'm sure it will capture more than 0.25% ... but still not nearly enough to make a significant difference.
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In my opinion the only way to really make clean coal work is with pre-combustion capture: a process in which the coal is first gassified, the CO2 separated from the resulting syngas, and the hydrogen which remains burnt in very much the same way as natural gas but without producing CO2. Doing it this way also makes the power plant very much more flexible, because the output of electricity can be tailored to suit variations in demand. Burning coal directly only works well for continuous base load generation.
This means that power stations like Aberthaw are hopelessly doomed (it's had a good run for its money, but needs to be put out of its misery sooner rather than later) ... but it also means that new coal power stations such as the one proposed for Kingsnorth are fatally flawed from the outset.
By diverting money into projects of this nature the UK Government is failing to put sufficient emphasis on developing the sorts of technologies that will make a big difference, most notably tidal energy. We in Wales can produce all the electricity we need from renewable sources, but the Assembly can't develop it on any scale because it is not a devolved matter. Instead we are locked into an agenda that suits England's energy needs rather than our own.
2 comments:
Don't be too hard on them. It is only a test. If it works they can scale it up.
Yes, it's only a test. But that was my point: that we're still nowhere near able to talk about using this sort of capture at a large enough scale to make any real difference.
The technology of the process is fine. Although the story doesn't give details, I'd guess it's by a cycle of chemical absorption in one chamber, with the CO2 released in another chamber by heating the mixture up. It then has to be cooled before it can do the cycle over again. The CO2 also has to be cooled or compressed to make it transportable. It takes energy to do this.
This test plant uses 3MW of energy to capture 0.25% of the CO2. If that process were scaled up, it would take 400 times the energy to capture all the CO2, some 1,200 MW. The total output of the plant is only about 1,400MW. It would take 86% of the energy Aberthaw produces!
Now of course there would be economies of scale which would make everything more efficient, but how much more efficient? It is not doing it that's the problem, but doing it efficiently.
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