Source: economist    2011-06-14  我要投稿   论坛   Favorite  

To put that in perspective, in 2010 the UN Environment Programme estimated that for the world to have a reasonable chance of limiting global warming to less than 2°C, carbon-dioxide emissions should be reduced to 44 billion tonnes by 2020. With business as usual, emissions would be between 54 billion and 60 billion tonnes. If countries took the most ambitious of the courses of action that they have outlined to the UN, the figure comes down to about 49 billion tonnes, leaving an “emissions gap” of 5 billion tonnes that seems highly unlikely to be bridged. So the 2 billion tonnes saved by nuclear power is not vast, but it is significant.


That said, a complete withdrawal from nuclear energy is not on the cards. Though China, which has 77 reactors at various stages of construction, planning and discussion, has said it will review its programme in the aftermath of Fukushima, few expect it to stop entirely. China has a great appetite for energy, which will continue to grow. For now its energy sector is highly concentrated on coal, but so that the country can both diversify and clean its air China’s latest five-year plan aims for growth in all sorts of non-coal energy, including wind power, gas and nuclear. Adverse public opinion and the additional cost of capital caused by uncertainties over regulatory approval have much less salience in China than elsewhere.


Some other countries will also go ahead: Russia says it sees no reason to stop work on ten reactors that are in development. But there could still be a widespread withdrawal from the technology by OECD countries, caused by national changes in policy or stiffer local opposition. And grand though China’s ambitions are, for now OECD countries produce more than 80% of the world’s nuclear electricity.


Analysts at Société Générale, a French bank, argue that if these rich countries built no more reactors and allowed existing ones to close at the end of their planned lives, an extra 860m tonnes of carbon a year would be emitted, on average, from 2010 to 2030. This may underestimate the impact on the system as a whole, because nuclear plants and large dams are the only broadly reliable sources of baseload electricity that do not burn fossil fuels. Although renewable capacity has been added quickly in some countries, you cannot be sure that the wind will blow or the sun will shine to order. A fair part of this can be smoothed out if the various sources are linked into an electric grid that is sufficiently large, robust and smart, but that does not obviate all the need for baseload.

法国兴业银行(Société Générale)分析师提出:如果这些富裕国家不再建造更多的反应堆,并让现有反应堆在其设计寿命到期后关闭的话,在2010至2030年间,平均每年将额外排放8.6亿吨碳。这或许低估了它对整个体系带来的冲击,因为在不燃烧化石燃料的基本电力负载来源中,只有核电站和大坝基本可靠。尽管一些国家的可再生能源产能已在快速增长,但人们却不能确定风和阳光能够按需而至。如将不同能量来源联入一张足够庞大、稳健、智能的电网,则此问题能有一大部分得到解决,但这并不会完全消除对基本负载的各种需求。

Most studies assume that in a fully decarbonised electricity system the baseload would come either from nuclear or from fossil-fuel plants fitted with carbon capture and storage (CCS) technology. However, CCS has yet to be demonstrated on anything like the necessary scale, so deploying enough of it to replace existing and expected nuclear plants is a tall order. And a public that was turning against hubristic nuclear engineering might also object to the large-scale storage of a potentially asphyxiating gas beneath the ground, which CCS requires. This “numby” (not under my back yard) attitude has already affected some pilot projects.



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