晚上给电动汽车充电，能拯救世界

全世界的电动车数量庞大而且不断增多，如果车主下班后立刻给这些电动车充电，汽油车和柴油车的减少给环境带来的预期有利影响将会被抵消掉一大部分。而等到晚上睡觉时再给电动汽车充电，则会使减少污染变成一种再普通不过的行为。

一种选择可以给未来的世界带来更洁净的天空、更清洁的能源以及更可靠的电力系统。另一种选择则会带来更多使用化石燃料的发电厂、更高的电价，而且为了满足医院、学校等地的用电需求，电网也会承受更大的压力。

伦敦研究机构BMI Research电力和可再生能源行业分析师丹尼尔·布伦登说：“关键问题不是电动汽车让电网负担增加多少，而是什么时候增加。电动车要么变成一个巨大的问题，要么变成一件强大的工具。”

2017年，电动乘用车销量首次突破100万辆。对电动车今后增长的预期存在巨大差异——埃克森美孚预测到2040年全球电动车总量将增至1亿辆，彭博新能源财经预计的数字则为5.4亿辆，而且电动车将占汽车总销量的一半以上。

彭博新能源财经分析师科林·麦克科拉彻尔指出，即使按最高预估值计算，要满足新增电动车的需求，全球发电量也只需要提高5%。如果电网运营商、监管部门和车主能在时间方面协调一致，这样的增幅甚至都不需要修建新的发电厂。

这是因为电力市场结构独特，随着人们打开或关上电灯以及用电器，电力需求每分钟都会发生起伏。电力消费通常在晚上和上午达到高峰，午夜时处于最低点。

布伦登指出，如果车主下班回家后就给电动车充电，晚间用电高峰就会变得“更高”，而且就算新增电力需求不多，也有可能需要增加装机容量，而新增装机容量很可能必须以化石燃料发电厂的形式出现。由于这些发电厂的所有者得偿还债务，同时每天只运转一小段时间，所以他们要的电价一定会更高。

布伦登说：“你对脱碳的贡献就不会像你希望的那么多，而且为了让这些后备发电能力随时都可以投入使用，你还得掏腰包，这就会加大你的电费负担。”

不过，麦克科拉彻尔认为还有另一条途径。如果车主能在非高峰时段给电动车充电，也许就根本不需要新建发电厂，而且非高峰时段还是某些可再生电力资源最充裕的时候，比如风力最大的晚上以及日照最强的白天。

麦克科拉彻尔说：“大家根本不需要什么新装机容量为大量电动车提供电力，前提是有效率地给它们充电。”

研究咨询机构Wood Mackenzie亚太地区电力和可再生能源行业咨询主管马克·哈金森说，如果配备了双向充电装置，车主甚至有可能让他们的电动车变成微型电力交易商，他们可以在电价最低的时候充电，然后在高峰时段把电力卖还给电网。

布伦登指出，他能预见到优步等部署几千辆自动驾驶电动车的公司将借助人工智能来决定盈利水平最高的载客、充电和卖还电力的时间。

这样的未来需要企业的投资和监管决策，以便为更完善的充电基础设施提供支持。它还需要自由的电力市场，通过动态定价来鼓励在非高峰时段给电动车充电。

公用事业行业对此反响不一。布伦登说，作为全球最大电动车市场，中国尚未制定任何鼓励电动车主优化充电时间的政策。

另一方面，日产汽车已经在用它的电动车为丹麦风力发电行业提供缓冲；南加州爱迪生公司提出为用户提供“超优惠”日间非高峰电价，以鼓励他们在中午给电动车充电——每天中午，涌进加州电网的廉价太阳能电力是如此之多，以至于州电网运营商有时不得不关闭太阳能电站。

2月2日，南加州爱迪生公司负责监管事务的高级副总裁卡罗琳·蔡在加州帕拉奥图的彭博新能源财经移动未来峰会（The Future of Mobility Summit）上说：“充电的最佳时间是中午，此时所有太阳能电站都在向电网输送电力。”（财富中文网）

译者：Charlie

审校：夏林

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.