Monday, December 18, 2006

It's time to get tough on carbon emissions

The Scotsman
December 16, 2006


THERE has been a remarkable increase in public awareness of the problems of climate change over the past six months. Clearly, the evidence is becoming more widely accepted.

Here in Scotland, the Scottish Environmental Protection Agency (SEPA) has found that the average temperature in Scotland is now 1 degree Celsius higher than in 1961, with the largest effect in south-east Scotland in winter. The number of days with air or ground frost has fallen by a quarter and the period of snow cover is reduced. The plant-growing season starts three weeks earlier in spring and ends two weeks later in the autumn. Rainfall is 20 per cent higher for the country as a whole, but with an increase of 60 per cent in winter for the north and west.

If this was all, it might not matter. The prospect of someday growing grapes in the Hebrides has its attractions. But the effects across the world could be calamitous, with increased threat of starvation in Africa, hurricanes in the Caribbean, water shortage in areas affected by drought and rising sea levels, as major icefields in Greenland and Antarctica melt.

If carbon emissions from energy production are to be reduced to a level that removes the threat of further climate change, some very tough decisions are going to have to be taken, and taken urgently.

There is no shortage of targets. The Scottish Executive's target for Scotland is to produce 40 per cent of its energy from renewable sources by 2020. The UK government has a target to reduce carbon emissions by 12.5 per cent on 1990 levels by 2012, and last summer's energy review proposed a reduction of 60 per cent by 2050.

The Stern review said that if carbon dioxide in the atmosphere was to be stabilised by 2050, a reduction of 60-75 per cent in carbon emissions from power generation worldwide would be required. But how are these targets to be achieved?

Scotland is at the forefront of some very interesting developments. A few weeks ago it was announced that a £24 million investment was to be made in a biomass plant to make combined heat and power from wood pellets at Invergordon. This follows a similar decision to build a £90 million plant at Lockerbie, also to make electricity from wood pellets. Such plants are carbon-neutral if the wood burnt is replaced by new forest growth.

Scottish and Southern Energy are to build a 350MW power station to make electricity from hydrogen at Peterhead. This will be a world first at this scale. It will manufacture hydrogen from natural gas, from which the carbon will be separated and sent by pipeline to the Miller field to increase the recovery of oil. By this means carbon emissions, compared with an ordinary power station burning natural gas, will be cut by 90 per cent.

Ocean Power Delivery, a firm based in Edinburgh, has a contract with a Portuguese consortium to build the world's first wave farm using its Pelamis machine. Three machines, built in Lewis, each generating 2.25MW, will be supplied initially with the prospect of further orders if the project is successful.

There is also an interesting small project in the Shetland island of Unst to make hydrogen from sea water using wind turbines. Hydrogen fuel cells will provide electricity when the wind drops, and when the wind is strong increased amounts of hydrogen can be made.

Wind turbines are now a common sight in Scotland, with effects on the environment that are not always welcome. About 600MW of capacity is installed and this is likely to at least double. But they suffer from two major defects.

The variable nature of wind means that their availability is unpredictable, averaging only about 50 per cent of capacity. It is therefore unsuitable for base load power. And some of the windiest locations now being considered involve substantial transmission costs, likely to make them uneconomic.

These developments give some indication of what a future energy system may be like. The Peterhead project may point the way to carbon sequestration on a much larger scale than could be applied to coal-fired power stations. Hydrogen, already used to power buses in Iceland and to be tried experimentally in London, could be developed as a major source of power for transport. But many of these technologies are still at a very early stage and there are many questions to be resolved, not least those of cost and reliability.

The Royal Society of Edinburgh's report, published last summer, pointed out that 90 per cent of Scotland's electricity is generated in five large power stations (see table). Two of these are due to close in the next five years. A third, Longannet, which is by far the largest, may be extended beyond 2020, if equipment is installed to remove the sulphur dioxide, as required by an EU directive to prevent acid rain. But it would still be a major source of carbon emissions.

So at least 2,400MW of new capacity is urgently required, if the economy is not to be put at risk, and twice this amount by 2020.

The more that renewable sources and energy saving can contribute the better, but investment in at least one or two new large plants seems inescapable. Left to market forces, this might be an additional gas-fired station. But, given that the UK is now a net importer of gas and there are questions about security of supply from Russia, it would seem that the choice ought to lie between coal and nuclear. Coal emits twice as much carbon as gas per kilowatt produced. But, if clean coal technology proves practical and if it can be made economic, it might be attractive. Nuclear has advanced a long way since the technology of the existing Scottish power stations. It provides 80 per cent of the power in France, which is among the cheapest in Europe. Decisions on the disposal of waste are essential and deep burial in caverns, as the Finns have decided on, seems the best option.

Nuclear power is likely to be less damaging for the world than coal, unless the latter involves clean coal technology. A decision cannot be put off much longer.

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