I get to learn about lots of different plans for dealing with climate change. It’s part of my job—climate change is the focus of my work with the investment fund Breakthrough Energy Ventures—but it’s just as likely to come up over dinner with friends or at a backyard barbecue. (In Seattle, we get outside as often as we can during the summer, since we know how often it’ll be raining once fall comes.)我了解到许多应对气候变化的不同计划。这是我工作的一部分——气候变化是我在突破能源基金的工作重点但这个话题同样可能在与朋友共进晚餐或在后院烧烤时出现。(在西雅图，我们会尽可能多地在夏天到户外活动，因为我们知道一旦秋天来临，下雨会有多频繁。)
Whenever I hear an idea for what we can do to keep global warming in check—whether it’s over a conference table or a cheeseburger—I always ask this question: “What’s your plan for steel?”每当我听到一个如何控制全球变暖的想法——无论是在会议桌上还是在吃芝士汉堡时——我总是会问这个问题:“你对于钢铁是如何打算的?”
I know it sounds like an odd thing to say, but it opens the door to an important subject that deserves a lot more attention in any conversation about climate change. Making steel and other materials—such as cement, plastic, glass, aluminum, and paper—is the third biggest contributor of greenhouse gases, behind agriculture and making electricity. It’s responsible for a fifth of all emissions. And these emissions will be some of the hardest to get rid of: these materials are everywhere in our lives, and we don’t yet have any proven breakthroughs that will give us affordable zero-carbon versions of them. If we’re going to get to zero carbon emissions overall, we have a lot of inventing to do.我知道这听起来很奇怪，但它为一个重要的话题打开了大门——这个话题在任何关于气候变化的讨论中都值得更多的关注。制造钢铁及其他材料（如水泥、塑料、玻璃、铝和纸张）是温室气体的第三大来源，仅次于农业和发电。它的排放量占总排放量的五分之一，而这些排放会是最难避免的。因为这些材料在我们的生活中无处不在，而我们也还没有任何已被证实的突破性进展，制造出我们能负担得起的零碳材料。如果我们要实现全面零碳排放 ，我们还需要做很多创新。
Steel, cement, and plastic are so pervasive in modern life that it can be easy to take them for granted. The first two are the main reason our buildings and bridges are so sturdy and last so long. Steel—cheap, strong, and infinitely recyclable—also goes into shingles, household appliances, canned goods, and computers. Concrete—rust-resistant, rot-proof, and non-flammable—can be made dense enough to absorb radiation or light enough to float on water. (People sometimes use the terms cement and concrete interchangeably, but they’re not the same thing. You make cement first, and then you mix it with sand, water, and gravel to make concrete.)
钢铁、水泥和塑料在现代生活中无处不在，人们很容易把它们视为理所当然可以获得的东西。钢铁和水泥是我们的建筑和桥梁如此坚固耐用的主要原因。钢材便宜、坚硬，而且可以无限循环使用，还能用于墙面板、家用电器、罐头食品和电脑。混凝土则防锈、防腐蚀、不易燃。它可以被制造得足够厚实来吸收辐射，也可以被制造得足够轻且漂浮在水面上。（人们有时把水泥和混凝土这两个词混用，但它们不是一回事。你需要先制作水泥，然后把它和沙子、水和砂砾混合制作成混凝土。)
The 520 floating bridge near my house sits on 77 concrete pontoons, each weighing thousands of pounds. In his book Making the Modern World, Vaclav Smil estimates that America’s interstate highway system contains about 730 million tons of concrete in the driving lanes alone.我家附近的520浮桥坐落在77个混凝土趸船上，每个趸船重达数千磅。在《创建当代世界》（Making the Modern World）一书中，瓦茨拉夫·斯米尔（Vaclav Smil）估计，仅是美国州际公路系统的行车车道就含有7.3亿吨混凝土。
As for plastics, they have a bad reputation these days—and it’s true that the amount piling up in the oceans is problematic. But they also do a lot of good. For example, you can thank plastics for making that fuel-efficient car you drive so light; they account for as much as half of the car’s total volume, but only 10 percent of its weight! 至于塑料，它们最近名声不好——海洋中的塑料堆积量也确实是个问题。但它们也做了很多好事。例如，你可以感谢塑料使你驾驶的节能汽车如此轻便；它们占据着汽车一半的总体积，但只有汽车重量的10%！
So how do we cut down on emissions from all the steel, cement, and plastic we’re making? One way is to use less of all these materials. There are definitely steps we should take to use less by recycling more and increasing efficiency. But that won’t be enough to offset the fact that the world’s population is growing and getting richer; as the middle class expands, so will our use of materials.那么，我们如何削减我们生产钢铁、水泥和塑料所产生的排放量呢？一种方法是减少这些材料的使用。我们确实应该采取一些措施，通过更多的回收利用和更高的效率来减少其使用量。但这不足以抵消世界人口不断增长且日益富裕的事实；随着中产阶级的扩大，我们对材料的使用量也会增大。
In a sense, that’s good news, because it means more people will be living in sturdy houses and apartment buildings and driving on paved roads. But it’s bad news for the climate. Take Africa, for example: Its emissions from making concrete are projected to quadruple by 2050. Emissions from steel could go up even more, because the continent uses so little now.从某种意义上说，这是个好消息，因为这意味着更多的人将住在坚固的房屋和公寓楼里，出门开车有铺好的平坦道路。但这对气候来说是个坏消息。以非洲为例：到2050年，非洲混凝土制造过程中的排放量预计将翻两番。钢铁制造的排放量可能会增长更多，因为目前非洲大陆极少使用钢铁。
If using less isn’t really a viable option, could we make things without emitting carbon in the first place? That is, in fact, what we’ll need to do—but there are several challenges. First, these industries require a lot of electricity, which today is often generated using fossil fuels. Second, the processes also require a lot of heat (as in thousands of degrees Fahrenheit) and fossil fuels are often the cheapest way to create that heat.如果减少使用并不是一个切实可行的选项，我们是否可以从一开始生产时就不排放碳呢？事实上，这就是我们需要做的，但也存在一些挑战。首先，这些行业需要大量的电力，而现在通常使用化石燃料来发电。其次，这个过程也需要大量热量(比如数千华氏度)，而化石燃料往往是产生这种热量最廉价的方式。
Finally—and this might be the toughest challenge of all—manufacturing some of these products involves chemical reactions that emit greenhouse gases. For example, to make cement, you start with limestone, which contains calcium, carbon, and oxygen. You only want the calcium, so you burn the limestone in a furnace along with some other materials. You end up with the calcium you want, plus a byproduct you don’t want: carbon dioxide. It’s a chemical reaction, and there’s no way around it.最后，这可能是最艰巨的挑战——其中一些产品的制造过程包含排放温室气体的化学反应。比如，要制作水泥，首先要从石灰石开始，石灰石中含有钙、碳和氧，而你只想要钙，于是你把石灰石和其他一些材料一起放在炉子里烧。最终你会得到想要的钙，以及你不想要的副产品：二氧化碳。这是一个化学反应，是怎么也无法绕过去的。
All three are tough challenges, but don’t despair. Scientists and entrepreneurs are trying to solve these problems and help make zero-carbon materials that will be affordable around the world. Here are a few of the innovative approaches that I’m especially excited about:虽然以上三个挑战都很艰巨，但请不要绝望。科学家和企业家正试图解决这些问题，并制造出全世界都能负担得起的零碳材料。下面是一些让我感到兴奋的创新方法:
The idea here is to suck greenhouse gases out of the air. I think this is probably the approach we’ll have to take with cement; rather than making it without emissions, we’ll remove the emissions before they can do any damage. There are two basic approaches: One is to grab the greenhouse gases right where they’re created, such as at a cement plant (that’s called carbon capture); the other is to pull them from the atmosphere, after they’ve dispersed. That’s called direct-air capture, and it’s a big technical challenge that various companies are trying to solve. Mosaic Materials, for example, is developing new nano-materials that could make direct-air capture much more efficient and cost-effective.这个办法的创意是从空气中吸收温室气体。我认为这可能是针对水泥将必须采取的方法——与其让生产过程不排放温室气体，不如在排放物造成损害之前就消除它。有两种基本的方法：一种是在温室气体产生处就捕获它们，比如水泥厂(这叫做碳捕获)；另一种是在温室气体散开后，再将它们从大气中捕获，这就是所谓的直接空气捕获，是一个许多公司都在试图解决的巨大技术挑战。例如，马赛克材料公司（Mosaic Materials）正在研发一种新型纳米材料，这种材料可以使直接空气捕获更加高效且更具成本效益。
We may be able to replace fossil fuels with electricity in some industrial processes. Boston Metal, the company profiled in the video above, is a great example; they’re working on a way to make steel using electricity instead of coal, and to make it just as strong and cheap. Of course, electrification only helps reduce emissions if it uses clean power, which is another reason why it’s so important to get zero-carbon electricity.我们也许可以在某些工业过程中用电力代替化石燃料。上面视频中介绍的波士顿金属公司（Boston Metal）就是一个很好的例子。他们正在研究一种用电力代替煤炭来生产钢铁且使其同样坚固而便宜的方法。当然，电气化只有在使用清洁能源的情况下才有助于减少排放，这也是获得零碳电力如此重要的另一个原因。
Some industrial processes can’t easily be electrified because they require too much heat. One possible alternative is to get the heat from a next-generation nuclear plant. (As I’ve mentioned before, a company that I helped start, TerraPower, uses an approach called a traveling wave reactor that is safe, prevents proliferation, and creates very little waste. ) We also might be able to get the heat using hydrogen fuels, which can be made using clean electricity and don’t emit any carbon when they’re burned. Hydrogen fuels exist today, but they’re expensive to make and transport, so companies are trying to drive the cost down and make hydrogen fuels available at scale. The Swedish steelmaker SSAB plans to build the world’s first fossil fuel-free steel plant powered by hydrogen, which will running as a pilot project next year. ThyssenKrupp and ArcelorMittal also recently announced projects in this area.有些工业过程很难利用电力实现，因为它们需要的热量太多。一个可能的替代方案是从下一代核电站获取热量。(正如我之前提到的，我帮助创办的一家公司泰拉能源使用了一种叫做“行波堆”的技术，这种方法安全，可防止核扩散，而且产生的废物很少。)我们也可以用氢燃料获得热量，清洁电力可以制造出氢燃料，它们在燃烧时不排放任何碳。如今氢燃料已经存在，但制造和运输成本都很高，因此企业正试图降低成本，并大规模生产氢燃料。瑞典钢铁制造商SSAB计划建造世界上首个以氢气为动力的无化石燃料钢铁厂，这将在明年作为试点项目运行。蒂森克虏伯(ThyssenKrupp)和安赛乐米塔尔(ArcelorMittal)最近也宣布了该领域的项目。
On its own, recycling steel, cement, and plastic won’t be nearly enough to eliminate greenhouse gas emissions, but it will help. The best book I’ve read on recycling—yes, I’ve read more than one!—is called Sustainable Materials With Both Eyes Open, and I highly recommend it.就其本身而言，回收钢铁、水泥和塑料还不足以消除温室气体的排放，但它也会有所帮助。我读过最好的一本关于回收利用的书——是的，我读过不止一本!——叫做《可持续材料：睁开双眼》，我强烈推荐。
I’m optimistic about all these areas of innovation—especially if we couple progress in these areas with smart public policies. Companies need the right incentives to phase out old polluting factories and adopt these new approaches. If all of these pieces come together, we will have a climate-friendly plan for cement, as well as steel, plastic, and the other materials that make modern life possible.我对所有这些创新领域都感到乐观，尤其是在将这些领域的进展与明智的公共政策结合起来的情况下。企业需要适当的激励措施来逐步淘汰旧的污染型工厂，从而采用这些新方法。如果能将这些利好都结合在一起，我们就将有一个针对水泥、钢铁、塑料和其他现代生活所需材料的气候友好型计划。