全世界的電動車數(shù)量龐大而且不斷增多，如果車主下班后立刻給這些電動車充電，汽油車和柴油車的減少給環(huán)境帶來的預(yù)期有利影響將會被抵消掉一大部分。而等到晚上睡覺時再給電動汽車充電，則會使減少污染變成一種再普通不過的行為。

一種選擇可以給未來的世界帶來更潔凈的天空、更清潔的能源以及更可靠的電力系統(tǒng)。另一種選擇則會帶來更多使用化石燃料的發(fā)電廠、更高的電價，而且為了滿足醫(yī)院、學(xué)校等地的用電需求，電網(wǎng)也會承受更大的壓力。

倫敦研究機構(gòu)BMI Research電力和可再生能源行業(yè)分析師丹尼爾·布倫登說：“關(guān)鍵問題不是電動汽車讓電網(wǎng)負擔(dān)增加多少，而是什么時候增加。電動車要么變成一個巨大的問題，要么變成一件強大的工具。”

2017年，電動乘用車銷量首次突破100萬輛。對電動車今后增長的預(yù)期存在巨大差異——埃克森美孚預(yù)測到2040年全球電動車總量將增至1億輛，彭博新能源財經(jīng)預(yù)計的數(shù)字則為5.4億輛，而且電動車將占汽車總銷量的一半以上。

彭博新能源財經(jīng)分析師科林·麥克科拉徹爾指出，即使按最高預(yù)估值計算，要滿足新增電動車的需求，全球發(fā)電量也只需要提高5%。如果電網(wǎng)運營商、監(jiān)管部門和車主能在時間方面協(xié)調(diào)一致，這樣的增幅甚至都不需要修建新的發(fā)電廠。

這是因為電力市場結(jié)構(gòu)獨特，隨著人們打開或關(guān)上電燈以及用電器，電力需求每分鐘都會發(fā)生起伏。電力消費通常在晚上和上午達到高峰，午夜時處于最低點。

布倫登指出，如果車主下班回家后就給電動車充電，晚間用電高峰就會變得“更高”，而且就算新增電力需求不多，也有可能需要增加裝機容量，而新增裝機容量很可能必須以化石燃料發(fā)電廠的形式出現(xiàn)。由于這些發(fā)電廠的所有者得償還債務(wù)，同時每天只運轉(zhuǎn)一小段時間，所以他們要的電價一定會更高。

布倫登說：“你對脫碳的貢獻就不會像你希望的那么多，而且為了讓這些后備發(fā)電能力隨時都可以投入使用，你還得掏腰包，這就會加大你的電費負擔(dān)。”

不過，麥克科拉徹爾認為還有另一條途徑。如果車主能在非高峰時段給電動車充電，也許就根本不需要新建發(fā)電廠，而且非高峰時段還是某些可再生電力資源最充裕的時候，比如風(fēng)力最大的晚上以及日照最強的白天。

麥克科拉徹爾說：“大家根本不需要什么新裝機容量為大量電動車提供電力，前提是有效率地給它們充電。”

研究咨詢機構(gòu)Wood Mackenzie亞太地區(qū)電力和可再生能源行業(yè)咨詢主管馬克·哈金森說，如果配備了雙向充電裝置，車主甚至有可能讓他們的電動車變成微型電力交易商，他們可以在電價最低的時候充電，然后在高峰時段把電力賣還給電網(wǎng)。

布倫登指出，他能預(yù)見到優(yōu)步等部署幾千輛自動駕駛電動車的公司將借助人工智能來決定盈利水平最高的載客、充電和賣還電力的時間。

這樣的未來需要企業(yè)的投資和監(jiān)管決策，以便為更完善的充電基礎(chǔ)設(shè)施提供支持。它還需要自由的電力市場，通過動態(tài)定價來鼓勵在非高峰時段給電動車充電。

公用事業(yè)行業(yè)對此反響不一。布倫登說，作為全球最大電動車市場，中國尚未制定任何鼓勵電動車主優(yōu)化充電時間的政策。

另一方面，日產(chǎn)汽車已經(jīng)在用它的電動車為丹麥風(fēng)力發(fā)電行業(yè)提供緩沖；南加州愛迪生公司提出為用戶提供“超優(yōu)惠”日間非高峰電價，以鼓勵他們在中午給電動車充電——每天中午，涌進加州電網(wǎng)的廉價太陽能電力是如此之多，以至于州電網(wǎng)運營商有時不得不關(guān)閉太陽能電站。

2月2日，南加州愛迪生公司負責(zé)監(jiān)管事務(wù)的高級副總裁卡羅琳·蔡在加州帕拉奧圖的彭博新能源財經(jīng)移動未來峰會（The Future of Mobility Summit）上說：“充電的最佳時間是中午，此時所有太陽能電站都在向電網(wǎng)輸送電力。”（財富中文網(wǎng)）

譯者：Charlie

審校：夏林

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Put simply, if the world’s drivers plug in an increasingly large EV fleet right after work, it could undo many of the environmental benefits expected from fewer cars running on gasoline and diesel. Cutting pollution could come down to an act as unexceptional as waiting until bedtime to charge the minivan.

Down one path lies a future world with cleaner skies, cheaper energy and more reliable electricity systems. The other has more fossil fuel-burning generators, higher power prices and additional strain on the grids keeping lights on everywhere from hospitals to schools.

“The key question isn’t how much demand electric vehicles add to the grid, it’s when does it add it,” said Daniel Brenden, a senior power and renewables analyst at BMI Research in London. “EVs are either going to be huge problem or a huge tool.”

Sales of electric passenger vehicles surpassed 1 million for the first time in 2017. Forecasts for future growth vary wildly: Exxon Mobil Corp. expects the global fleet to swell to 100 million vehicles by 2040, while Bloomberg New Energy Finance sees it reaching 540 million units by then, with more than half of all cars sold being powered by electricity.

Even at the high end of estimates, global electricity production would need to increase by just 5 percent to meet the new vehicle demand, said Colin McKerracher, an analyst with Bloomberg New Energy Finance. The new generation may not even require new power plants if grid operators, regulators and drivers can get on the same page as far as timing goes, McKerracher said.

That’s because of the unique structure of the power market, in which demand ebbs and flows minute-by-minute during the day as people flick their lights and appliances on and off. Consumption typically peaks in the evening and morning, and is at its lowest in the middle of the night.

If drivers plug in their cars when they get home from work and add to that evening peak, even the modest amounts of new generation needed will likely require building more capacity, and that likely will have to be in the form of fossil fuel-fired plants, Brenden said. And because the owners of those plants will have to pay down debt while only operating a short time of the day, their rates will have to be higher.

“You’re not contributing to decarbonization as much as you’d like, and you’re paying to keep that backup generation ready, so you’re adding to your electric bill,” Brenden said.

There’s another option, though, McKerracher said. If drivers can charge their vehicles during off-peak times, they may be able to do so without requiring new generation at all. Off-peak hours also coincide with the time when some renewable power sources are at their strongest — at night when the wind blows hardest and during the day when the sun shines brightest.

“You don’t need a whole lot of new generating capacity to electrify a lot of the fleet, provided they’re charged in an efficient way,” McKerracher said.

Drivers could even use their electric cars to become miniature power traders if they install two-way chargers, filling up their batteries when power rates are the cheapest and selling back to the grid if they’re plugged in during peak hours, said Mark Hutchinson, head of power and renewables consulting in Asia Pacific at Wood Mackenzie Ltd.

Brenden said he could envision a company such as Uber Technologies Inc. employing thousands of autonomous EVs using artificial intelligence to decide the most profitable times to give rides, charge their batteries and resell electricity.

Such a future will require investments by companies and regulatory decisions that support more sophisticated charging infrastructure. It will also need liberal power markets with dynamic pricing to encourage off-peak charging.

The response from utilities has been mixed. China, home to the largest EV market, hasn’t created any policies incentivizing optimal plug-in times, Brenden said.

On the other hand, Nissan Motor Co. already uses its electric cars to buffer wind power in Denmark, and Southern California Edison proposes offering customers “super” off-peak daytime rates to encourage plugging in during mid-day, when so much cheap solar energy floods the California grid that the state system operator sometimes has to shut down solar plants.

“The best time to charge is going to be in the middle of the day when all of that solar is on the grid,” Caroline Choi, senior vice president of regulatory affairs for the company, said February 2 at the Bloomberg New Energy Finance The Future of Mobility Summit in Palo Alto, California.