本文为原文前 6,000 字符的节选翻译，完整内容请查看原文。

Turning a solar power system into its own backup

Rather than directly converting photons into electricity, concentrated solar energy uses mirrors to turn sunlight into heat, which can then be used to drive traditional generating turbines. Up to about a decade ago, there was a case to be made that concentrated solar energy had a bright future, as improvements in heat storage had turned it into a way to generate power around the clock.

聚光太阳能并非直接将光子转化为电能，而是利用镜面将阳光转化为热能，进而驱动传统的发电机组。大约十年前，人们曾认为聚光太阳能拥有光明的前景，因为储热技术的进步使其能够实现全天候发电。

It wasn’t to be. While concentrated solar costs fell enough to compete with nuclear power, the price of photovoltaics plunged, making solar panels the cheapest source of power in most locations. Currently, if you have a good site to generate solar power, then the economics of PV panels are hard to beat.

然而事与愿违。尽管聚光太阳能的成本已降至足以与核能竞争的水平，但光伏发电的价格却大幅跳水，使得太阳能电池板成为大多数地区最廉价的电力来源。目前，如果你拥有一个良好的太阳能发电场地，光伏电池板的经济效益是难以超越的。

That has left us needing to build a mixture of other facilities—typically batteries and natural gas facilities—to handle overnight needs or weather-driven shortfalls. But a small company is promising that it can help avoid the need to build a separate facility. Its version of concentrated solar is designed so that a fossil-fueled backup system shares most of the generating hardware with the solar side.

这导致我们需要建设各种其他设施——通常是电池和天然气设施——来应对夜间需求或天气导致的电力短缺。但一家小型公司承诺，他们可以帮助避免建设独立设施的需求。其设计的聚光太阳能系统让化石燃料备用系统与太阳能侧共享大部分发电设备。

Back to the future? Concentrated solar, also called solar thermal, is pretty simple in principle. Most of the site is covered with heliostats, devices that incorporate mirrors and a motorized tracking system that can keep their focus on a single point as the Sun moves across the sky. The point of focus is in a tower, where sunlight heats a working fluid.

回到未来？聚光太阳能，也称为太阳能热发电，其原理相当简单。场地大部分区域覆盖着定日镜，这是一种结合了镜面和电动跟踪系统的装置，能够随着太阳在天空中的移动，始终将光线聚焦于一点。聚焦中心位于一座塔楼上，阳光在此加热工作流体。

The hot fluid can then be used to power a traditional steam turbine, or its heat can be used to generate power overnight. There are many potential variations, however: different working fluids and methods of heat storage, trough-shaped mirrors that eliminate the need for a tower, and so on. All of those variants are meant to reduce some of the issues inherent to solar thermal: lots of moving parts, potentially corrosive fluids, and so on.

加热后的流体可用于驱动传统的蒸汽轮机，或者将其热量储存起来用于夜间发电。然而，该技术存在许多潜在的变体：不同的工作流体和储热方法、无需塔楼的槽式镜面等等。所有这些变体旨在减少太阳能热发电固有的问题：大量的运动部件、潜在的腐蚀性流体等。

Those issues and the lack of standardization have helped ensure that the costs of these plants haven’t come close to keeping pace with photovoltaics. Without any incentive to generate renewable power overnight, there hasn’t been any way for concentrated solar to compete. Construction of new plants has largely stopped, and a number of sources have simply stopped tracking the economics of it.

这些问题以及缺乏标准化，使得此类电站的成本始终无法与光伏发电相提并论。由于缺乏夜间产生可再生能源的激励措施，聚光太阳能无法参与竞争。新电站的建设已基本停止，许多机构甚至不再追踪其经济性。

So it was a bit of a surprise to hear that India had contracted with a US-based startup called 247Solar to build and operate a small concentrated solar plant. While the plant will be extremely small (1 megawatt) and mix in photovoltaics, the company had a unique angle: The same hardware that is handling the solar thermal output can simply be run using fossil fuels if there is a significant shortfall in renewable generation.

因此，当听说印度已与一家名为 247Solar 的美国初创公司签约，建设并运营一座小型聚光太阳能电站时，人们感到有些意外。虽然该电站规模极小（1 兆瓦）且混合了光伏发电，但该公司有一个独特的切入点：如果可再生能源发电出现严重短缺，处理太阳能热输出的同一套硬件可以直接使用化石燃料运行。

“Our systems are their own backup,” said 247Solar’s Mark von Keszycki. “During times of low solar resource—long duration, bad weather, whatever the case may be—they’re able to burn a variety of fuels.” To understand how this works, it’s best to step back and understand the entire system being built, which includes details about how the 247Solar team hopes to avoid some of the problems faced by other solar thermal systems and provide a great deal of flexibility in terms of how its systems get put to use.

“我们的系统本身就是备用电源，”247Solar 的 Mark von Keszycki 表示，“在太阳能资源不足的时候——无论是持续时间长、天气恶劣还是其他情况——它们都能燃烧多种燃料。”要理解其工作原理，最好先退一步，了解整个系统的构建方式，包括 247Solar 团队如何希望避免其他太阳能热系统所面临的问题，并为其系统的使用方式提供极大的灵活性。

Hot air Like other concentrated solar systems, 247Solar’s will be using a field of heliostats. But the receiver—the hardware that they focus the sunlight on—is distinctive, in that it works with ambient-pressure air. (It’s an updated version of hardware developed by a German company.) Air exits this hardware at approximately 970° C. That air can potentially be used directly for industrial process heat or sent on to the hardware that generates electricity.

热空气：与其他聚光太阳能系统一样，247Solar 将使用定日镜场。但其接收器（聚焦阳光的硬件）非常独特，因为它使用环境压力空气工作。（这是德国公司开发硬件的升级版。）空气从该硬件排出时温度约为 970°C。这些空气可直接用于工业过程加热，或输送至发电硬件。

But in most cases, it will be directed to heat storage. Rather than dealing with molten salts and potential phase transition, 247Solar heats up ceramic pellets roughly the size of a golf ball. Depending on the details of the storage configuration, von Keszycki says that the heat from the storage could be used to generate power for anywhere from nine to 20 hours after the Sun sets.

但在大多数情况下，它会被引导至储热装置。247Solar 不处理熔盐和潜在的相变，而是加热高尔夫球大小的陶瓷颗粒。根据储热配置的细节，von Keszycki 表示，储存的热量可在日落后用于发电 9 到 20 小时不等。

Hours will obviously be shorter if some of the heat is used to generate power during the day, but 247Solar plans to pair its system with photovoltaic installations for daytime generation. Wherever the hot air comes from, it will be sent to a heat exchanger. This is designed as a drop-in replacement for a combustion unit on a traditional turbine to heat up compressed air to drive generation.

如果部分热量在白天用于发电，时长显然会缩短，但 247Solar 计划将其系统与光伏装置配套，以实现白天发电。无论热空气来自何处，它都会被送往热交换器。该装置旨在作为传统涡轮机燃烧室的直接替代品，通过加热压缩空气来驱动发电。

“The heat exchanger does the same job as the combustor did,” 247Solar’s Bruce Anderson told Ars. “It’s in the same place in the turbine assembly as the combustor was: after the compression stage and before the expander.” The initial installation will pair two 200 kW generators; aside from the heat exchanger, everything else is part of a standard off-the-shelf package.

“热交换器执行与燃烧室相同的功能，”247Solar 的 Bruce Anderson 告诉 Ars。“它位于涡轮机组件中与燃烧室相同的位置：压缩阶段之后，膨胀机之前。”初始安装将配备两台 200 千瓦的发电机；除了热交换器外，其他所有部件都是标准的现成组件。

This is the point where the system’s flexibility comes in: It doesn’t care how the air in the exchanger gets heated. So, any of a variety of fuels can be burned to provide the equivalent heat. von Keszycki suggested that adding the capability to the system to burn fossil fuels tacks on less than 10 percent of its total cost.

这就是系统灵活性的体现所在：它不在乎交换器中的空气是如何被加热的。因此，可以燃烧各种燃料来提供同等热量。von Keszycki 指出，为系统增加燃烧化石燃料的功能，其成本不到总成本的 10%。

The air coming out of the heat exchanger is still quite hot, in the neighborhood of 250° C, and von Keszycki called it “a separate usable resource” that could be directed to a variety of applications, including industrial processes and absorption cooling. Again, if intermediate temperatures are needed, it could potentially be mixed with some hot air coming directly from the storage medium, albeit at the cost of generation.

从热交换器出来的空气仍然很热，温度在 250°C 左右，von Keszycki 将其称为“一种可单独使用的资源”，可用于多种应用，包括工业流程和吸收式制冷。同样，如果需要中间温度，也可以将其与直接来自储热介质的热空气混合，尽管这会以牺牲发电量为代价。

Scaling up The first installation will be small, with a pair of 200 kW generators, and so will mostly serve to validate the system’s engineering—Anderson said the biggest worries are “unknown unknowns.” But the system is designed to be modular, and the c

扩大规模：首个安装项目规模较小，配备一对 200 千瓦的发电机，因此主要用于验证系统的工程设计——Anderson 表示，最大的担忧是“未知的未知”。但该系统设计为模块化，且 c