重力电池能否解决我们的能源存储问题？

Could a cutting-edge technology that harnesses one of the universe's fundamental forces help solve our energy storage challenge?

这种尖端技术利用一种宇宙的基本力，它能帮助我们解决储能挑战吗？

There is a riddle at the heart of the renewable energy revolution. When the wind blows, the sun shines, and the waves roll, there is abundant green power to be generated. But when skies darken and conditions are calm, what do we do?

可再生能源革命面临一个关键问题。当刮风、阳光照射、波涛滚滚时，可以产生丰富的绿色能源。但当天黑和风平浪静时，我们怎么办？
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The answer, today, is to ramp up conventional power production, supplying the grid by burning fossil fuels. It is a 20th Century solution to a 21st Century problem – one that sits in sharp contrast with plans for carbon neutrality.

当今的答案是提高常规电力的生产，通过燃烧化石燃料为电网提供能源。这是在用20世纪的办法解决21世纪的问题，与碳中和计划形成了鲜明对比。
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A cleaner future will mean focusing on ever-larger lithium-ion batteries, some energy experts say. Others argue that green hydrogen is the world's best hope. And then there are those placing their bets not on chemistry, but the limitless force that surrounds us all: gravity.

有能源专家表示，更加清洁的未来意味着重点发展越来越大的锂离子电池。有人认为，绿色氢能是世界的最大希望。也有人不把希望寄托于化学，而是存在于我们所有人身边的无限之力：重力。

"What goes up, must come down" – this is the immutable Newtonian logic underpinning gravity batteries. This new field of energy storage technology is remarkably simple in principle. When green energy is plentiful, use it to haul a colossal weight to a predetermined height. When renewables are limited, release the load, powering a generator with the downward gravitational pull.

“有升必有降”，永恒的牛顿理论为重力电池提供了依据。这种新兴的储能技术领域在理论上非常简单，当绿色能源充足时，利用它将巨大的重物提升至预定高度。当可再生能源不足时，释放重物，利用向下的引力驱动发电机。
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A similar approach, "pumped hydro", accounts for more than 90% of the globe's current high-capacity energy storage. Funnel water uphill using surplus power and then, when needed, channel it down through hydroelectric generators. It's a tried-and-tested system. But there are significant issues around scalability. Hydro projects are big and expensive with prohibitive capital costs, and they have exacting geographical requirements – vertiginous terrain and an abundance of water. If the world is to reach net-zero, it needs an energy storage system that can be situated almost anywhere, and at scale.

与之类似的是“抽水蓄能”技术，目前占全球高容量储能的90%。利用多余电能抽水至高位，当需要时利用水轮发电机放水至低位。这是一种久经考验的储能系统，但在扩大规模上面临重大问题。水利工程规模浩大，建设成本令人难以承受，地理条件苛刻：地形陡峭、水量充沛。世界要想实现净零碳排放，那就需要一种几乎不受地理和规模限制的储能系统。

Gravity batteries work in a similar way to pumped hydro, which involves funnelling water uphill before releasing it through turbines to generate energy

重力电池的工作原理类似于抽水蓄能，先抽水至高位，再利用水轮发电机放水来产生能量。

Gravitricity, an Edinburgh-based green engineering start-up, is working to make this a reality. In April last year, the group successfully trialled its first gravity battery prototype: a 15m (49ft) steel tower suspending a 50 tonne iron weight. Inch-by-inch, electric motors hoisted the massive metal box skyward before gradually releasing it back to earth, powering a series of electric generators with the downward drag.

总部位于爱丁堡的初创公司“重力都市”（Gravitricity）正在致力于实现这一目标。去年4月，该团队成功试验了首个重力电池原型：15米（49英尺）高的钢塔悬吊一个50吨重的铁块。电动机将这个庞大的金属箱缓慢提升至空中，然后逐渐放回地面，从而利用引力为一组发电机提供能量。

The demonstrator installation was "small scale", says Jill Macpherson, Gravitricity’s senior test and simulation engineer, but still produced 250kW of instantaneous power, enough to briefly sustain around 750 homes. Equally encouraging was what the team learned about their system’s potential longevity.

我们进行了“小规模”的样品安装，“重力都市”公司的试验与模拟高级工程师吉尔·麦克弗森说道，但依然产生了250千瓦的瞬时功率，足以暂时维持大约750户家庭的用电。同样令人振奋的是，团队了解到该储能系统的潜在寿命。

"We proved that we can control the system to extend the lifetime of certain mechanical components, like the lifting cable," says Macpherson. "The system is also designed so that individual components can be easily replaced instead of replacing the entire system throughout its lifetime. So there's real scope for having a decades-long operational life."

“我们证明可以通过控制系统来延长某些机械部件的寿命，比如起重索”，麦克弗森说道。“该系统的设计也使单个部件可被轻松更换，寿命期内无需更换整个系统，所以该系统的运行寿命确实可能长达数十年”。

While the Gravitricity prototype pointed upward, the company's focus is now below ground. Engineers have spent the last year scoping out decommissioned coal mines in Britain, Eastern Europe, South Africa, and Chile. The rationale, explains managing director Charlie Blair, is pretty straightforward: "Why build towers when we can use the geology of the earth to hold up our weights?"

“重力都市”的原型系统朝向高处，但公司现在的重点是地下。去年，工程师考察了英国、东欧、南非、智利的废弃煤矿。总经理查理·布莱尔解释说原理十分简单：“既然可以利用地质来提升我们的重物，那又何必建造高塔呢”？

It seems like a neat solution. The globe is pockmarked with disused mine shafts deep enough to house a full-sized Gravitricity installation, which will stretch down at least 300m (984ft), and possibly much further. There's political will to make it happen too, Blair says, with policymakers keen to tap into public enthusiasm for a so-called "just transition" – the notion of a new, low-carbon economy that secures the livelihoods of fossil fuel workers and their communities. And so, with enough funding, a subterranean prototype (most likely located in the Czech Republic) should be functioning by 2024. First, though, a series of challenges must be overcome.

这看来是个巧妙的办法。废弃矿井遍布全球各地，深度足够容纳全尺寸的“重力都市”系统，深入地下至少300米（984英尺）甚至可能更深。布莱尔说，政坛有这样做的意愿，决策者渴望利用民众对所谓“公正转型”的热枕——这种新型低碳经济理念旨在保障化石燃料工人及其社区的生计。因此在资金充足的情况下，地下原型系统（最可能建在捷克共和国）应该会在2024年投入运行，但首先必须解决一系列挑战。

"We need to look closely at the existing civil structures – the shaft lining, the shaft’s surroundings – and make sure they're absolutely sound and capable of holding up several thousand tonnes," Blair explains. "There are also potential safety issues around methane gas, and the mines being flooded."

“我们需要仔细检查现有的土木建筑——井壁、井的周围环境——确保它们完好无损，具备千吨级的承重力”，布莱尔说道。“同时还存在沼气和矿井被淹的隐患”。

With that in mind, Gravitricity is also looking at sinking its own purpose-built shafts: an endeavour that'll cost more upfront, but promises far greater uniformity further down the line.

考虑到这一点，“重力都市”公司正准备建造自己的专用沉井：这样做的前期成本较大，但未来有望达到更高的统一性。

Energy startup Gravitricity plans to use abandoned mine shafts to generate renewable energy

能源初创公司“重力都市”准备利用废弃矿井生产可再生能源。

Not all innovators see the merits of a below-the-surface solution, however. In a valley in southern Switzerland, the striking steel and concrete prototype from Energy Vault, another leader in the gravity battery space, stands more than 20 stories tall. When green power supply exceeds demand, one of several AI-controlled cranes lifts a pair of 30-tonne blocks upwards. When demand outstrips supply, back down they go, generating enough energy for thousands of homes.

但是，并非所有的创新者都看好地下方案的优势。在瑞士南部的一个山谷，重力电池的另一龙头企业Energy Vault制造出惊人的钢筋混凝土原型，高度超过20多层楼。当绿色能源供大于求时，人工智能操控其中一台起重机将一对30吨的重块向上提起。当绿色能源供不应求时，起重机将重块放回地面，为千家万户提供足够的电能。

With its technology tried and tested – and having received some $402m (£325m) worth of investment – Energy Vault is ready to start a commercial rollout. For that, the company has designed something a little more aesthetically pleasing than the angular Swiss prototype: a modular building dubbed "EVx" that stores thousands of weights on a trolley system.

在技术经过反复试验，并获得大约4.02亿美元投资后，Energy Vault公司准备开始进行商业推广，为此设计出一种比有棱角的瑞士原型稍微更具美感的产品：EVx模块化建筑，它通过滑移系统贮存数千个重块。

"Think of it as a warehouse of energy elevators," says Robert Piconi, Energy Vault's CEO. "When clean electricity is coming in, the blocks – made of recycled material – go up, and when the grid needs supply, they go back down. An EVx with a storage capacity of 100MWh can power around 25,000 homes for a day."

“将它视为一座装有能源升降机的仓库”，Energy Vault公司总裁罗伯特·皮科尼说道。“当清洁电能输入时，使用再生材料制造的重块上升。当电网需要供电时，重块下降返回。EVx的电力存储容量为100兆瓦时，每天能为大约25000个家庭供电”。

Each installation's size and layout will determine its overall storage capacity, but even at the lower end, the buildings will cover dozens of acres. Could this be problematic? No, Piconi says, as the systems are likely to be situated near wind and solar farms far from urban centres.

每座设施的大小和布局决定了电力储存的总容量，但即使在低端，这些建筑也会占地数十英亩。这会造成困难吗？不会，皮科尼说道，因为这些装置可能被建在风能和太阳能发电场附近。

"We won’t have to dig any deep holes either, or have any other big limiting factors on location. Basically anywhere you can construct a 20-storey building will work," he says.

“我们不需要挖任何深洞，现场没有任何其他大的制约因素。任何地方只要能建造20层楼基本是可行的”，他说道。

It's a message that seems to be resonating: Energy Vault's order book is filling up fast, with interest coming in from across Europe, America, the Middle East, Australia, and China. The latter is particularly exciting, says Piconi, who is hopeful that it could signify a change of direction for the world's largest emitter of greenhouse gases.

这个消息似乎得到了响应：Energy Vault公司的订单正在迅速增长，来自欧洲、美国、中东、澳大利亚、中国的客户都表现出兴趣。尤其是中国令人振奋，皮科尼说道，他希望这可能标志着世界最大的温室气体排放国家在方向上的转变。

Balancing the grid

维持电网平衡

That may be wishful thinking, but sooner or later, all countries will have to embrace some form of green energy storage.This includes long duration storage, keeping the lights off for an extended period of time when renewable generation is low, and short bursts of electricity as and when the grid requires additional supply.

这可能是一厢情愿，但各国迟早采取某种形式来储存绿色能源。这包括长时储能，当可再生能源的发电量较低时长时间熄灯，当电网需要额外供电时短时间停电。

This second point relates to a serious problem facing green energy developers: electricity grids were designed to work with conventional power stations, not renewables.

第二点涉及绿色能源开发商面临的一个重大问题：电网的设计初衷是与常规发电站相互协作，而不是可再生能源发电站。

"At all times, the grid needs to be balanced," explains Thomas Morstyn, an electrical engineering expert at the University of Edinburgh. "Operators constantly have to match supply and demand, but that's tricky when you've got something as inherently intermittent as wind or solar, which are susceptible to sudden variations."

“电网随时需要维持平衡”，英国爱丁堡大学的电气工程专家托马斯·莫尔斯廷说道。“运营商必须一直维持供求平衡，但当你面对的是原本就时断时续的风能和太阳能时会很困难，因为它们容易受突发变化的影响”。

The sheer mass of a gravity battery's weight coupled with its incredibly slow descent generates a huge amount of torque, allowing the system to deliver maximum power almost instantaneously. This makes the technology particularly adept at maintaining grid equilibrium, reducing the risk of serious infrastructural damage and blackouts by ironing out second-by-second fluctuations.

重力电池的巨大重量和难以置信的缓慢下降速度产生巨大的扭矩，使该装置几乎瞬间产生最大功率。所以这项技术特别适合维持电网的平衡，通过消除瞬间波动，能够减少基础设施严重受损和停电的风险。

The decommissioned Staříč mine in the Czech Republic – one of the potential sites for Gravitricity’s energy storage plants

捷克共和国废弃的Staříč矿井，“重力都市”公司建造储能装置的潜在地点之一。

What about lithium?

锂怎么样？

Lithium-ion batteries, the type that power our phones, laptops, and electric vehicles, can ramp up equally quickly, however, and have similar round-trip efficiency figures as gravity solutions. The cost of lithium cells has dropped significantly in recent years as well. So why not simply build ever bigger chemical batteries?

我们的手机、笔记本电脑、电动汽车使用的那种锂离子电池可以同样快速地充电，充放电效率数据与重力解决方案类似。近年来，锂电池的成本也大幅下降，那么为何不干脆制造越来越大的化学蓄电池？

In answering this question, it's important not only to consider the upfront expenditure, but the total lifetime cost of a system. Gravity batteries are mechanical contraptions, and as such, they can break. Maybe a cable snaps, or a gearbox jams, or a patch of rust appears. These issues are problematic, but they're not fatal – individual components can be replaced with relative ease. This "repairability" means gravity batteries can last as long as 50 years, says Asmae Berrada, an energy storage specialist at the International University of Rabat in Morocco.

在回答这个问题时，重要的是不仅要考虑前期费用，还要考虑寿命周期的总成本。重力电池是一种机械装置，所以会出现故障。可能电缆断裂，齿轮箱卡住，或者出现锈迹。这些都成问题，但不是致命问题——更换单个零部件比较轻松。“可维修性”意味着重力电池的寿命可达50年，位于摩洛哥的拉巴特国际大学的储能专家阿斯玛·贝拉达说道。

It's a different story with their electrochemical counterparts. "Lithium-ion cells degrade, which means their storage capacity drops irreparably over time," explains Berrada, whose research has found the lifetime cost of lithium batteries to be twice that of mechanical alternatives. "There are also constraints on how many times chemical batteries can cycle every day if you're trying to preserve longevity, which is something gravity systems don't really have to worry about as their parts can be more easily replaced."

电化学电池的情况则不同。“锂离子电池会衰退，这意味着储存容量会随时间衰减”，贝拉达说道，他的研究发现锂电池的寿命周期成本比机械装置高一倍。“如果你想保护化学电池的寿命，它们还受到每天循环次数的限制，重力装置着实没有这方面的担忧，因为它们的零部件更换起来比较容易”。

Add into the mix concerns around human rights abuses, with cobalt mining being lixed to child labour, and environmental damage, and Berrada is convinced that a non-lithium means of storing green energy is essential. Accordingly, she and her team are working on their own water-based gravity battery prototype, funded by the Spanish and Moroccan governments.

另外，人们担忧侵犯人权和环境破坏问题，钴矿开采涉及雇佣童工。贝拉达认为，采用锂以外的方式储存绿色能源至关重要。于是，她和她的团队正在研发基于水的重力电池原型，并受到西班牙政府和摩洛哥政府的资助。

Instead of lifting a large solid weight, surplus green power will be used to move a submerged piston upwards, Berrada explains, with the return journey forcing high pressure water through a generator. Similar systems are under development in California and Germany, while researchers in Nevada are exploring a unique, railway-inspired solution.

剩余的绿色能源不是被用于提升一个巨大的固体重块，而是提升一个水下活塞，贝拉达说道，活塞在回程中迫使高压水流经一台发电机。美国加州和德国也在研发类似的装置，内华达州的研究人员正在探索一种灵感来源于铁路的独特方案。

How many of these will come to fruition, it's impossible to tell. What isn't in doubt is that the world needs bold and creative climate solutions. On this front, there are no silver bullets – but gravity batteries, with their harnessing of a truly infinite, omnipresent force, almost certainly have a role to play.

其中有多少方案会取得成果，我们不得而知。但毋庸置疑的是，世界需要大胆和有创意的气候方案。这方面没有灵丹妙药，但重力电池利用真正无限、无所不在的力量，几乎肯定会发挥作用。

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