【英语生活】用可再生能源吧

A confession: I have been too complacent about technological fixes for the twin problems of climate change and finite oil and gas reserves. Without looking very closely at the numbers, I figured that if politicians would finally get their act together, and if we avoided some of the more unlucky possibilities (such as the release of methane ice from the oceans), cheap, clean energy would be within our grasp, given suitable research incentives and some technological brilliance.

Looking at progress in computer chips, I dreamt about how cheap photovoltaic solar panels might become over the next 50 years. Solar wallpaper, solar paint – who needs fossil fuels? Most climate-change scenarios look at a 100-year time scale. Surely, in that time, we should have figured out a way to take greenhouse gases out of the atmosphere again.

I still wouldn't rule out such techno-fantasies, but having read a remarkable book by David J.C. MacKay, a Cambridge physicist (you can download it at www.withouthotair.com) I am far more pessimistic about the potential of technology to help us out. In Sustainable Energy – Without the Hot Air, Professor MacKay makes this point very simply by sidestepping the economics altogether. Technological progress and economic growth loosen the corset of cost-benefit analysis, but not the laws of physics. No matter how cheap and efficient solar collectors become, there is only so much solar power available per square metre of land. Hydroelectric energy is constrained by the quantity of rainfall and the height of reservoirs above sea level. The most perfectly designed windmill is limited by the energy of the wind. It would barely be possible to make the numbers add up even if renewable energy generators were free.

To power a modern country through renewable energy requires country-scale facilities – hundreds of miles of wave turbines, solar panels on every roof, and windmills blanketing highlands and coastal waters. Nuclear fission is more promising, but nuclear fuel is also finite. Technological progress will be essential but, barring a breakthrough in nuclear fusion, it will not set us on a path to an energy system purged of fossil fuels.

MacKay defies glib summaries, but it is fair to say that he sees considerable potential in energy-efficiency measures such as light electric cars and better-insulated homes. This is a different kind of issue because it is a decentralised problem.

The challenge is to encourage the right behaviour. Centrally mandated efforts will not do the trick, in part because “the right behaviour” is not a universal constant. Take, for example, the intermittency of wind power. A nation equipped with battery-powered cars could charge up when the wind is blowing and scale back during lulls. Yet on any given day one individual might desperately need a reliable charge for her car. To a central planner this is simply unknowable. Yet a discount for those relying only on intermittent power would encourage people to fit in with the scheme whenever they could.

Governments also have an inglorious history of getting even the basics right. The British still subsidise fossil fuels by charging a bargain rate of tax on domestic fuel. European subsidies for offshore wind power, a technology of little interest to Mexico or China, are likely to do little to transform the world's energy system.

Dealing with climate change will need many small decisions to be made differently. The government cannot micromanage these. This is why a carbon price, whether set through taxes or emissions permits, is needed. It is not so much a nudge as a shove in the right direction.

迄今我仍未放弃这种技术幻想，但阅读了剑桥大学物理学家戴维•麦凯(David J.C. MacKay)的一本非凡之作（你可以从www.withouthotair.com下载该书）之后，我对依靠技术摆脱困境的可能性大为悲观。在《可再生能源——拒绝空话》(我要忏悔：对于借助技术手段解决气候变化和石油天然气资源有限这个双重难题, 我一直过于自满。在没有仔细研究数字的情况下，我以为如果政客们最终能采取一致行动，如果我们能够避开一些更加不幸的可能性（比如海洋冰层甲烷气的释放），再加上适当的研究激励手段和一些技术才能，廉价的清洁能源就将唾手可得。

看到人们在计算机芯片上取得的进展，我梦想着在未来50年光电太阳能电池板或许会变得非常廉价。太阳能壁纸、太阳能涂料——谁还需要化石燃料？大多数对气候变化的设想都以100年的时间为考量范围。在这么长的时间里,我们想必已经再次研究出从大气中分离温室气体的方法。

Sustainable Energy – Without the Hot Air)一书中，麦凯完全避开经济学理论，非常简单地论证了这个观点。技术进步和经济增长解除了成本效益分析法的束缚，但物理学规律的限制仍然存在。不管太阳能收集装置变得多么廉价和高效，每平方米的土地也只能产生那么多的太阳能；水电能源受到降雨量和水库海拔高度的限制；设计最完美的风力发电装置也受到风能的限制。即使可再生能源发电机是免费的，也几乎不可能让供需平衡。

要想利用可再生能源为一个现代化国家供应能源，就需要国家规模的设备——数百英里长的海浪涡轮机、每个屋顶上都覆盖的太阳能电池板以及遍布高原和沿海水域的风力发电机。核裂变发电更有前途，但核燃料也是有限的。技术进步将必不可少，但除非在核聚变技术上获得突破，否则我们无法藉此建立一个没有化石燃料的能源体系。

麦凯反对肤浅的总结，但可以说，他看到了生产轻型电动车和建造隔热性能更好的建筑物等节能措施的巨大潜力。这是截然不同的一类问题，因为它被边缘化了。

挑战在于如何鼓励正确的行为。政府指定的措施无法达到目的，部分因为“正确行为”不是一个恒量。以风能的间歇性为例说明。使用电动车的国家可以在刮风的时候充足电，并在没风的时候相应减少规模。然而，在任何一天，都可能有人迫切需要为自己的汽车寻找可靠的充电来源。对于政策制定者来说，这种情况是不可知的。不过为那些只依靠间歇性能源的人提供折扣，能鼓励人们根据自己的时间安排尽可能地适应这个项目。

各国政府甚至还有把基本原则搞错的不光彩历史。英国政府仍通过对国产燃料征收优惠税率而对化石能源提供补贴。欧洲对近海风力发电——墨西哥和中国对这项技术都不感兴趣——提供的补贴可能对改革全球能源体系没什么帮助。

应对气候变化问题将需要在许多细微决定上做出改变。政府不可能对这些决定进行宏观管理。这就是为什么设定碳排放代价——无论是通过税收还是排放限制——是必须的。这与其说是在鼓励向正确方向迈出一小步，还不如说是强迫迈出的一大步。



译者/君悦