这是减缓气候变化所能采取的最重要一步

风能和太阳能发电正以创纪录的速度在全球范围内扩张，这使得更多的人能够从清洁的可再生能源中获得电力。这是个好消息。

更好的消息是：我们可以做得更多。通过对能源创新的投资，我们能继续扩大在现有技术（例如可再生能源）上已经取得的成果，这将有助于加快从化石燃料向未来可靠且负担得起的无碳电力的转变。

这将是一个惊人的成就，也是我们可以采取的最关键一步，从而防止全球变暖而带来的最坏影响。

原因如下：虽然发电是造成气候变化最大的单一因素——造成25%的温室气体排放，且每天都在增长——但它在解决方案中起到的作用更大。有了清洁的电能，我们能做的不仅仅是为我们的家庭照明与电网供电。我们将解锁无碳能源的一个来源，帮助为产生其它75%温室气体排放的经济部门提供动力，包括交通业、建筑业和制造业。想想电动汽车和电动巴士，家庭和企业中安装的零排放加热和制冷系统，以及使用更多清洁能源生产产品的能源密集型工厂吧。

那么，如何才能实现零碳发电的目标呢？

我们必须解决两个挑战。第一个挑战在意料之中。我们需要在利用太阳能与风能方面下更大功夫。多亏了太阳能电池板、风力涡轮机和其他技术不断下降的价格，部署可再生能源系统比以往任何时候都更便宜。

第二个挑战可能不那么明确，且更加困难。我们需要在技术上取得重大突破，让我们甚至在无风天、多云天和夜间，也能够为电网提供清洁能源。

通常情况下，你需要把像天然气这样在必要时可以迅速并可靠地发电的化石燃料当作可再生能源的后备军。但为了实现零碳排放，我们需要找到一种方法，将更多的清洁能源作为储备。

尽管我希望有一个一击必中的方法，但现实并非如此。今后几年需要的是兼具多样化与灵活度的能源解决方案（像瑞士军刀般的能源工具箱）支持可再生能源发电的未来，从而满足我们的需求。其中部分解决方案已经存在，其他的则需要更多创新。所有这些都可以帮助我们完成到低成本、无碳能源的转型。随着美国越来越多州通过100%无碳电力标准，它们正逐渐认识到这一点。

以下是我们转型到清洁电力所需的三个关键解决方案：

1. 改良的能源储存系统：太阳和风是极好的能源。我们需要解决的一个大挑战就是找到一种方法储存这些能源，让我们在太阳落山和风停后可以使用它们。我们现在已经能够将能源储存几个小时——就像锂离子电池一样——这个技术每年都在变得愈加便宜。

我们没有的是：将可再生能源储存数天，数周，或数月的可靠并能广泛使用的办法。我们需要为季节性的变化 (当冬天白昼很短时) ，或者更糟糕的情况做好准备，比如长时间的云层覆盖或者几个星期甚至几个月没有风。

幸运的是，有很多创造性的思路正在解决这些挑战。我是突破能源基金（BEV）的投资者，我们正在支持一些探索储存能源方法的公司。以下是一些关键的创新领域:

• 水力：当今最常见的能源储存形式是抽水蓄能，它利用电动机将水抽到山上的水库中。当水从水库中释放出来时，水向低处流动，通过水电涡轮产生电能。这种方法的挑战在于，它只适用于高海拔或低海拔的地区。由 BEV 投资的一家名为Quidnet的新公司正在尝试一种不同的技术，这种技术成本更低，而且地势平坦的地区也适用。Quidnet公司的系统使用可再生能源将水抽入地下水井，产生巨大的压力。当需要能量时，压力就会被释放出来，把水推上井，通过涡轮机产生电能。

• 电池：你可以笔记本电脑、手机或电动汽车中找到的那种锂离子电池，是发展最快的储存解决方案之一。但它们最适合短期存储。Form Energy是一家由BEV投资的公司，它们正在开发一种比锂离子电池成本更低且储存时间更长的新型电池。

• 蓄热：蓄热技术有潜力为电网提供灵活可靠的备用能源。在熔盐中储存热量是最有效的方法之一。由BEV投资的 Malta, Inc.已经开发出一种熔盐热能技术，它的工作原理类似于热泵。可再生能源将以热能的形式储存在熔盐中。在放电模式下，该系统会像热力发动机一样运转，并利用热能发电。

• 零碳燃料：还有其他令人兴奋的潜在储存解决方案，包括利用风能和太阳能生产的零碳燃料，这些燃料可以转化为电能，或用于为其他部门进行去碳化。

2. 碳捕获、封存与核能: 我经常听说，随着太阳能和风能变得更廉价，以及能源储存方面出现的新突破，这些能源足以让我们实现无碳电网。但是，由于世界必须在消除碳排放的需求与经济增长之间取得平衡，我们也应该考虑哪些解决方案是最负担得起的。麻省理工学院（MIT）研究人员2. 最近的一项研究发现，通过混合使用清洁能源解决方案——包括核能和碳捕获与封存技术（CCS）来支持可再生能源，可以比单独使用可再生能源产生无碳电力便宜多达62% 。

核能已经是一个无碳电力的来源，其发电量约占世界总发电量的10% 。它还是补充可再生能源的一种非常可靠的清洁能源来源。但高成本和安全问题减缓了核能的发展。通过对核能的创新，我们可以创造出新一代核能——这种能源将更安全，废物排放量更少，且成本更低。

有几种核能技术应当加以探索。其中一个是我帮助创办的泰拉能源公司（TerraPower），它使用一种安全、防止核扩散，几乎不产生废物的方法——行波堆。为了使这些创新成为现实，我们需要各国政府——特别是美国——加快步伐，承诺为核能研究提供新的资金，并表明核能在未来将有一席之地。

达成零碳电力的另一种方式是碳捕获、利用与封存，它可以分离并永久储存发电厂排放的二氧化碳污染物，以防止它们进入大气层。这项技术对那些可再生能源潜力不大的地方，或者淘汰并更换现有发电厂成本太高的地方来说尤其重要。

3. 高压长距离输电线路: 风能和太阳能等可再生能源通常远离于能源需求最大的城市或工业区。将可再生能源的供应与需求连接起来，将需要我们建立能够在非常长的距离上负担大量电力的输电线路。与目前美国大多数电网用于输电的交流电输电线路相反，高压直流（HVDC）输电技术将有助于我们把可再生能源纳入全球电力供应。然而，扩张高压直流输电线路不仅需要对我们的电网进行投资，还需要国家和地方政策来支持它们的建设。

气候变化很容易让你感到力不从心和无从下手。例如，去年全球温室气体排放量再次上升，这再次提醒我们，如果我们想要阻止地球变暖最可怕的场景，我们就必须迅速采取行动。

尽管如此，当我了解到所有为了应对这一挑战而产生的奇思妙想时，我仍然乐观地认为，有了可以正确结合并即刻实施的解决方案和创新技术，我们能够走出一条通往无碳未来的道路。

The most important step we can take to reduce climate change

Wind and solar power generation is expanding around the globe at record rates, allowing more people to get their electricity from clean, renewable sources than ever before.  This is great news. 

And here’s better news: We can do even more. By investing in energy innovations, we can build on the progress we’ve made deploying current technology like renewables, which will help accelerate the transition from fossil fuels to a future of reliable and affordable carbon-free electricity. 

This would be an incredible achievement and the most important step we can take to prevent the worst impacts of global warming. 

Here’s why: While electricity generation is the single biggest contributor to climate change—responsible for 25 percent of all greenhouse gas emissions and growing every day—it’s an even bigger part of the solution. With clean electricity, we can do more than light our homes and power our grid. We’ll unlock a source of carbon-free energy to help power the sectors of the economy that produce the other 75 percent of greenhouse gas emissions, including transportation, buildings, and manufacturing. Think electric cars and buses; emission-free heating and cooling systems in our homes and businesses; and energy-intensive factories using more clean power to make products. 

So, what will it take to reach the goal of zero carbon electricity generation?

We must solve two challenges. The first challenge will come as no surprise. We need to do more to harness the power of the sun and wind. And thanks to falling prices for solar panels, wind turbines, and other technologies, deploying renewable energy systems is more affordable than ever before. 

The second challenge is probably less obvious and more difficult. We need big breakthroughs in technologies that will allow us to supply the power grid with clean energy even during windless days, cloudy weather, and nighttime. 

Usually, you back up renewable sources with fossil fuels like natural gas that can quickly and reliably provide power when it’s needed. To reach zero carbon emissions, however, we need to find a way to use more clean energy sources as a backstop.

While I wish there could be a single, magic bullet solution this problem, there isn’t one right now. What will be required in the years ahead is a diverse and flexible mix of energy solutions – a Swiss army knife of energy tools - to support a future of renewable energy generation to meet our needs. Some of these solutions already exist. Others will require more innovation. All can help us make the transition to low-cost, carbon-free power. This is something a growing number of states across the U.S. are recognizing as they adopt 100 percent carbon-free standards for electricity.

Here are three key solutions we’ll need for the transition to clean electricity:  

1. Improved energy storage systems: The sun and the wind are incredible energy sources. Finding ways to store that energy to use after the sun sets and the wind stops blowing is a big challenge we need to solve. We do have ways to store energy for a matter of hours– like lithium ion batteries – that are becoming cheaper every year.  

What we don’t have are reliable and widely useable ways to store renewable energy sources for days, weeks, or months. We need to be prepared for seasonal changes (when we have short days during the winter) or worse case scenarios when there are long periods of cloud cover or no wind for weeks or months.

Fortunately, there’s a lot of creative thinking to solve these challenges. I am an investor in a group called Breakthrough Energy Ventures (BEV) that is backing a number of companies exploring ways to store energy.  Here are some key areas of innovation:  

• Hydro: The most common form of energy storage today is pumped hydro, which uses electric motors to pump water uphill to a reservoir. When the water is released from the reservoir, it flows downhill and generates electricity through hydroelectric turbines. The challenge with this approach is that it only works in geographies with high elevations and low elevations. A new company called Quidnet Energy, supported by BEV, is trying a different approach that is lower cost and can be built in flat areas. Quidnet’s system uses renewable energy to pump water into underground wells, creating huge amounts of pressure. When that energy is needed, the pressure is released, pushing the water up the well and through a turbine, generating electricity. 

• Batteries: Lithium-ion batteries, like you would find in a laptop, mobile phone or electric car, are one of the fastest growing storage solutions. But they work best for short-duration storage. Form Energy, a BEV-backed company, is creating a new class of batteries that would provide long-duration storage at a lower cost than lithium ion batteries. 

• Thermal storage: Thermal-powered storage technologies have the potential to offer a flexible and reliable power backup for the grid. One of the most effective ways to store heat is in molten salt. Malta, Inc., a BEV company, has developed a molten salt thermal technology that operates like a heat pump. Renewable energy stored as heat in molten salt. In discharge mode, the system works as a heat engine, using heat to produce electricity.

• Zero-carbon fuels: There are other exciting potential storage solutions as well, including zero-carbon fuels produced with wind and solar power that can be turned back into electricity or used to decarbonize other sectors.

2. Carbon capture and storage and nuclear: I often hear that lower cost solar and wind power along with the emerging breakthroughs in energy storage mean that these sources will be enough to get us to carbon-free power grid. But because the world must balance the need to eliminate carbon emissions with economic growth, we should also consider what solutions would be most affordable. A recent study from researchers at MIT found that supporting renewable energy with a mix of clean energy solutions— including nuclear and carbon capture and storage (CCS)—would make carbon-free electricity up to 62 percent cheaper than using renewables alone. 

Nuclear power is already a source of carbon-free electricity, producing about 10 percent of the world’s power. It would also serve as very reliable source of clean energy to complement renewables. But high costs and safety concerns have slowed the growth of nuclear power. With innovations in nuclear power we can create a new generation of nuclear energy that would be safer, produce less waste, and be lower cost. 

There are several nuclear technologies that should be explored. One of them, a company I helped start called TerraPower, uses an approach called a traveling wave reactor that is safe, prevents proliferation, and creates very little waste. To make these innovations a reality, we need governments – especially the U.S. – to step up and commit new funding for nuclear energy research and demonstrate that there is a future for nuclear energy. 

Another way we can get zero-carbon electricity is carbon capture, utilization, and storage, which separates and permanently stores CO2 pollution from an energy plant’s exhaust to keep it out of the atmosphere. This technology is especially important in places where there isn’t good renewable energy potential, or where it would be too costly to retire and replace existing power plants.

3. High-voltage, long-distance transmission lines: Renewable power resources like wind and solar are often located far from the cities or industrial areas where energy demand is the greatest. Connecting our renewable energy supply with demand will require us to build transmission lines that can handle large amounts of power over very long distances.  High-voltage direct current (HVDC) transmission technology—as opposed to the alternating current power lines most electric grids in the US use today for transmission—would help us integrate renewable energy into our world’s power supply. Expanding HVDC lines, however, will not only require new investments in our power grids, but also supportive national and local policies to support their construction.

It’s easy to be overwhelmed by climate change and what to do about it. Global greenhouse gas emissions, for example, went up again last year – another reminder that we must act quickly if we want to prevent the worst-case scenarios of our warming planet.

Still, as I learn about all the creative thinking underway on this challenge, I am optimistic that with the right mix of solutions we can deploy right now and new innovations we can build a path to a carbon-free future. 

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