巴黎協定的擁護者預計，盡管美國總統特朗普決定退出，變革仍會繼續，大量新興低碳能源技術會將石油、天然氣和煤炭之類傳統碳氫化合物趕進歷史的垃圾箱。要迎接能源業的嶄新未來，我們需要合適的“動力”，巴黎協定正是這個作用：要實現理想中的降低碳排放目標，唯一的途徑是替換碳氫化合物。

實際上，所謂的大量選擇不過三種：生物燃料、風力發電和太陽能電池。一些環保人士將核能也納入其中。這些都不是什么新發現：世界上第一次核裂變反應是在1939年，第一塊光伏電池于1954年問世，風力發電機的歷史可以追溯到中世紀，至于生物燃料的主要元素乙醇，人類在有史料記錄以前就會合成。

巴黎協定的支持者認為，只要政府制定宏偉的計劃，就能坐等能源科技重復“摩爾定律”，像計算機領域一樣（摩爾定律是指，芯片的處理能力每兩年翻一倍）。可惜他們要失望了，能源業發展不會如他們所愿。

人類利用燃料可不是把幾個人送上月球，更像是把全體地球人遷往月球，還得定居下來。擺脫重力實現太空移民的耗資簡直無法計算。但如今專家們大贊硅谷綠色能源企業，認為其意義堪比顛覆傳統固話的手機，以及顛覆傳統出租車行業的優步。

遺憾的是，大規模生產能源和產生信息的發展趨勢截然相反。以飛機為例。如果能源業發展也遵循摩爾定律，如今一輛滿載的波音777從紐約飛到日本應該只用消耗一只蒼蠅重的燃料。工程師和數學家可以在字節上做文章，讓計算機運行速度更快，所占空間更小。可人類或者現實世界的物體只在科幻小說里才能任意縮小。

過去十年，技術進步大幅降低了太陽能和風能的成本。即使美國政府提供超過千億美元補貼扶持，風能和太陽能的產量十年間也只增加了十倍，分別僅占在全美能源總量的0.3%和0.2%。

還記得生物燃料么？十年前硅谷傳奇人物維諾德?科斯拉曾預計： “未來25年，所有汽油都能被替代。”如今，美國40%的玉米作物都用于煉制乙醇汽油，卻僅能供應全國約5%的交通運輸。不論是在美國還是其他國家，沒人再提起類似預測。

但還有人固執地認為，多投入資金，多提供補貼和撥款、多給稅收優惠政策或者推行嚴格的排放標準，就會讓太陽能和風能的成本再便宜十倍。技術是會逐漸進步，但也總有極限。每次燃油效率才提高幾個百分點，飛機渦輪制造商都要拿出來吹噓一番，正是因為現在的機械已經接近熱能轉化為動能的熱力學極限。

太陽能發電板和風力渦輪發電機也是同樣處境。這兩類產品的核心技術已經沒有重大提升的空間，所以回報都在遞減。（幾百年前生物燃料就有過類似經歷）。生物燃料生產的基本要素——混凝土、鋼鐵、玻璃鋼、硅、電線和玻璃早已實現大規模量產，所以沒什么規模效益可挖掘。

假如我們希望能源業來一場不同以往的革命，需要的是物理學領域新發現。而且只能寄望于基礎研究突破，不能再靠補貼陳舊的技術自欺欺人。

當前，全世界將近80億人口，經濟體量也已達80萬億美元，碳氫化合物能源的供應量超過80%，全球98%的交通都要靠石油燃料。巴黎協定改變不了現狀，美國參不參與都一樣，只有物理學革新才能真正實現改變。而理論科學進步需要的條件跟各國簽署協定之類完全兩碼事。或許是該靜下心追求真正的科學了。（財富中文網）

本文作者馬克?米爾斯是美國智庫曼哈頓政策研究研究所高級研究員。

譯者：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.