别急着捧绿色能源 看看特朗普背弃巴黎气候协定的真正原因

巴黎协定的拥护者预计，尽管美国总统特朗普决定退出，变革仍会继续，大量新兴低碳能源技术会将石油、天然气和煤炭之类传统碳氢化合物赶进历史的垃圾箱。要迎接能源业的崭新未来，我们需要合适的“动力”，巴黎协定正是这个作用：要实现理想中的降低碳排放目标，唯一的途径是替换碳氢化合物。

实际上，所谓的大量选择不过三种：生物燃料、风力发电和太阳能电池。一些环保人士将核能也纳入其中。这些都不是什么新发现：世界上第一次核裂变反应是在1939年，第一块光伏电池于1954年问世，风力发电机的历史可以追溯到中世纪，至于生物燃料的主要元素乙醇，人类在有史料记录以前就会合成。

巴黎协定的支持者认为，只要政府制定宏伟的计划，就能坐等能源科技重复“摩尔定律”，像计算机领域一样（摩尔定律是指，芯片的处理能力每两年翻一倍）。可惜他们要失望了，能源业发展不会如他们所愿。

人类利用燃料可不是把几个人送上月球，更像是把全体地球人迁往月球，还得定居下来。摆脱重力实现太空移民的耗资简直无法计算。但如今专家们大赞硅谷绿色能源企业，认为其意义堪比颠覆传统固话的手机，以及颠覆传统出租车行业的优步。

遗憾的是，大规模生产能源和产生信息的发展趋势截然相反。以飞机为例。如果能源业发展也遵循摩尔定律，如今一辆满载的波音777从纽约飞到日本应该只用消耗一只苍蝇重的燃料。工程师和数学家可以在字节上做文章，让计算机运行速度更快，所占空间更小。可人类或者现实世界的物体只在科幻小说里才能任意缩小。

过去十年，技术进步大幅降低了太阳能和风能的成本。即使美国政府提供超过千亿美元补贴扶持，风能和太阳能的产量十年间也只增加了十倍，分别仅占在全美能源总量的0.3%和0.2%。

还记得生物燃料么？十年前硅谷传奇人物维诺德•科斯拉曾预计： “未来25年，所有汽油都能被替代。”如今，美国40%的玉米作物都用于炼制乙醇汽油，却仅能供应全国约5%的交通运输。不论是在美国还是其他国家，没人再提起类似预测。

但还有人固执地认为，多投入资金，多提供补贴和拨款、多给税收优惠政策或者推行严格的排放标准，就会让太阳能和风能的成本再便宜十倍。技术是会逐渐进步，但也总有极限。每次燃油效率才提高几个百分点，飞机涡轮制造商都要拿出来吹嘘一番，正是因为现在的机械已经接近热能转化为动能的热力学极限。

太阳能发电板和风力涡轮发电机也是同样处境。这两类产品的核心技术已经没有重大提升的空间，所以回报都在递减。（几百年前生物燃料就有过类似经历）。生物燃料生产的基本要素——混凝土、钢铁、玻璃钢、硅、电线和玻璃早已实现大规模量产，所以没什么规模效益可挖掘。

假如我们希望能源业来一场不同以往的革命，需要的是物理学领域新发现。而且只能寄望于基础研究突破，不能再靠补贴陈旧的技术自欺欺人。

当前，全世界将近80亿人口，经济体量也已达80万亿美元，碳氢化合物能源的供应量超过80%，全球98%的交通都要靠石油燃料。巴黎协定改变不了现状，美国参不参与都一样，只有物理学革新才能真正实现改变。而理论科学进步需要的条件跟各国签署协定之类完全两码事。或许是该静下心追求真正的科学了。（财富中文网）

本文作者马克•米尔斯是美国智库曼哈顿政策研究研究所高级研究员。

译者：Charlie

Paris advocates assert that, despite President Donald Trump’s decision to pull out of the agreement, we face an inevitable transition to a multitude of new low-carbon energy technologies that will consign hydrocarbons—oil, natural gas, and coal—to history’s dust heap. All we need to birth the new energy future are the right “incentives,” which Paris provides: The only way to meet aspirational carbon emissions reductions is to replace hydrocarbons.

This so-called multitude of options actually distills to just three things: biofuels, windmills, and solar panels. Some environmentalists include nuclear fission as well. There’s no new physics here: The first fission reaction was in 1939, the first photovoltaic cell was created in 1954, windmills date to the Middle Ages, and making alcohol (the dominant biofuel) predates recorded history.

But, say Paris supporters, all we need are moonshot government programs to see energy tech emulate the “Moore’s Law” progress that happened in computing (the doubling in computer power every two years). Yet to their inconvenience, the physics of energy won’t cooperate.

Fueling humanity is not like putting a few people on the moon. It’s like putting everybody on Earth on the moon—permanently. No amount of money obviates the costs of fighting gravity. But pundits in awe of Silicon Valley’s prowess analogize today’s green energy companies to the disruption of landline phone businesses after the advent of cell phones or the disruption of taxis by Uber.

Unfortunately, the physics of energy production scales in exactly the opposite direction of the physics of information production. If aircraft, for example, followed Moore’s Law, a loaded Boeing 777 could reach Japan from New York by burning a housefly’s weight in fuel. Engineers and mathematicians can trick bytes to go faster and slip into ever smaller spaces, but only in science fiction are similar tricks possible with physical objects or humans.

Better technology has brought solar and wind costs down dramatically in the past decade. And, fueled by over $100 billion in subsidies, while wind and solar have increased 10-fold over a decade, they still supply, respectively, just 0.3% and 2% of America’s energy.

Remember biofuels? Ten years ago Silicon Valley legend Vinod Khosla famously predicted that with biofuels there is "no doubt that 100% of our gasoline use can be displaced in the next 25 years." Now, despite 40% of America’s corn crop used distilled into alcohol, that supplies barely 5% of U.S. transportation. No one expects America or the world to get anywhere close to Khosla’s forecast.

But there is a stubborn idea that more money—subsidies, tax incentives, grants, or enforced standards—will make solar and wind 10 times cheaper yet again. While all technologies get better over time, they also approach physics’ limits eventually. Aircraft turbine manufacturers brag about single-digit percentage gains in fuel efficiency precisely because those machines are near thermodynamic limits in converting heat to thrust.

Solar cells and wind turbines are now in the same boat. There are no game-changing advances left in the core technologies; both are now on the curve of diminishing returns. (Biofuels crossed that Rubicon centuries ago.) Nor are there big gains in economies of scale for the underlying components—concrete, steel, fiberglass, silicon, wires, and glass are all already in mass production.

If we want a different energy revolution, we’ll need new discoveries in the physical sciences. That can only emerge from basic research, not from more subsidies for yesterday’s technologies.

Meanwhile, the world’s nearly 8 billion people and $80 trillion economy depend on hydrocarbons to supply over 80% of global energy; oil fuels 98% of transportation. Meaningful changes to this status quo won’t come from the Paris agreement with or without the U.S., unless there’s a revolution in physics. And the latter will require very different priorities. Perhaps it’s time to chase real science.

Mark Mills is a senior fellow at the Manhattan Institute.