Harvesting Solar Energy from Space从太空捕获太阳能

马泰奥·切里奥蒂/文　陈俭贞/译

The idea of space-based solar power （SBSP）—using satellites to collect energy from the sun and “beam” it to collection points on Earth—has been around since at least the late 1960s. Despite its huge potential， the concept has not gained sufficient traction1 due to cost and technological hurdles.

太空太陽能是指利用卫星从太阳收集能量，并将其“传送”到地球上的收集点。这一概念至少在20世纪60年代末就出现了。然而，尽管潜力巨大，由于成本和技术难题，太空太阳能尚未获得足够的关注。

Can some of these problems now be solved？ If so， SBSP could become a vital part of the worlds transition away from fossil fuels to green energy.

目前能否解决部分成本和技术难题？如果可以，太空太阳能可能成为全球能源从化石燃料向绿色能源过渡的关键一环。

We already harvest energy from the sun. Its collected directly through what we generally call solar power. This comprises different technologies such as photovoltaics2 （PV） and solar-thermal energy. The suns energy is also gathered indirectly： wind energy is an example of this， because breezes are generated by uneven heating of the atmosphere by the sun.

我们已经从太阳获得了能量。直接收集自太阳的能量就是人们通常所称的太阳能，涉及光伏发电和太阳热能等不同的技术。太阳的能量也可以被间接收集，风能就是一个例子，因为风是由太阳对大气的不均匀加热产生的。

But these green forms of power generation have limitations. They take up lots of space on land and are limited by the availability of light and wind. For example， solar farms dont collect energy at night and gather less of it in winter and on cloudy days.

然而，这些绿色发电方式具有局限性。它们占据了陆地上的大量空间，并且受到光和风的可获得性限制。例如，太阳能发电场在夜间不收集能量，在冬季和阴天收集的能量较少。

PV in orbit wont be limited by the onset of night. A satellite in geostationary orbit （GEO）—a circular orbit around 36，000 km above the Earth—is exposed to the Sun for more than 99% of the time during a whole year. This allows it to produce green energy 24/73.

在轨的光伏发电不会受到夜幕降临的限制。地球静止轨道是一条距离地球约3.6万公里的圆形轨道，在静止轨道上的卫星一年中99%以上的时间都受太阳照射，因此可以全天候生产绿色能源。

GEO is ideal for when energy needs to be sent from the spacecraft to an energy collector， or ground station， because satellites here are stationary with respect to the Earth. Its thought that theres 100 times more solar power available from GEO， than the estimated global power demands of humanity by 2050.

当需要将能量从航天器传输到能量收集器（或称地面站）时，由于其上的卫星相对地球静止，地球静止轨道是理想的选择。据估计，地球静止轨道上可获得的太阳能超过全球人类能源需求预估值（截至2050年）的100倍。

Transferring energy collected in space to the ground requires wireless power transmission. Using microwaves for this minimizes the energy lost in the atmosphere， even through cloudy skies. The microwave beam sent by the satellite will be focused towards the ground station， where antennas convert the electromagnetic waves back into electricity. The ground station will need to have a diameter of 5 km， or more at high latitudes. However， this is still smaller than the areas of land needed to produce the same amount of power using solar or wind.

将太空中收集的能量传输到地面需要无线能量传输。使用微波传输可以最大限度地减少大气中的能量损失，即使在多云天气也是如此。卫星发射的微波束将会对准地面站，地面站的天线再将电磁波转换回电能。地面站的直径需要达到5公里，在高纬度地区则需要更大的直径。然而，这仍然比使用太阳能或风能产生同样电力所需的土地面积要小。

Evolving concepts

不断发展的概念

Numerous designs have been proposed since the first concept by Peter Glaser in 1968.

自1968年彼得·格拉泽首次提出太空太阳能概念以来，人们已经提出了许多设计方案。

In SBSP， the energy is converted several times （light to electricity to microwaves to electricity）， and some of it is lost as heat. In order to inject 2 gigawatts4 （GW） of power into the grid， about 10 GW of power will need to be collected by the satellite.

在太空太阳能中，能量被多次转换，从光能依次转化为电能、微波能，再从微波能转化为电能，其中部分能量以热能的形式损失。向电网注入2吉瓦的电力，卫星需要收集大约10吉瓦的电力。

A recent concept called CASSIOPeiA5 consists of two 2km-wide steerable reflectors. These reflect the sunlight into an array of solar panels. These power transmitters， approximately 1，700 meters in diameter， can be pointed at the ground station. It is estimated that the satellite could have a mass of 2，000 tonnes.

近日，“仙后座太阳能卫星”的概念被提出，该卫星由两个2公里宽的可操纵反射器组成。反射器将太阳光反射到太阳能电池板阵列，这些电力传送器直径约1700米，可以朝向地面站。据估计，卫星的质量可能达到2000吨。

Another architecture， SPS-ALPHA6， differs from CASSIOPeiA in that the solar collector is a large structure formed by a huge number of small， modular reflectors called heliostats， each of which can be independently moved. They are mass-produced to reduce cost.

另一种结构“任意大型相控阵太阳能卫星”与“仙后座太阳能卫星”的不同之处在于，它的太阳能收集器是一个由大量名为“定日镜”的小型模块化反射器组成的大型结构。每个反射器都可以独立移动，并且可以通过大量生产而降低成本。

In 2023， scientists at Caltech7 launched MAPLE， a small-scale satellite experiment which beamed8 a tiny amount of power back to Caltech. MAPLE proved the technology could be used to deliver power to Earth.

2023年，加州理工学院的科学家们发射了一颗名为“枫树”的小型实验卫星，“枫树”向加州理工学院传回了少量的能量，证明该技术可以用于向地球输送能量。

National and international interest

国内与国际关注

SBSP could play a crucial role to meet the UKs net-zero target by 2050—but the governments current strategy does not include it. An independent study found that SBSP could generate up to 10GW of electricity by 2050， one-quarter of the UKs current demand. SBSP provides a secure and stable energy supply.

太空太陽能可能对英国实现2050年净零排放目标起关键作用，但政府并未将其纳入现行战略。一项独立研究发现，到2050年，太空太阳能可以产生高达10吉瓦的电力，相当于英国当前需求的1/4。太空太阳能是安全稳定的能源供应。

It will also create a multi billion-pound industry， with 143，000 jobs across the country. The European Space Agency is currently evaluating the viability of SBSP with its SOLARIS initiative. This could be followed by a full development plan for the technology by 2025.

太空太阳能还将创造一个价值数10亿英镑的产业，在英国创造14.3万个就业岗位。欧洲航天局目前正在通过“索拉里斯”计划评估太空太阳能的可行性。到2025年，这项技术可能会有一个完整的发展计划。

Other countries have recently announced the intention to beam power to Earth by 2025， moving to larger systems within the next two decades.

其他国家近日也宣布了到2025年将电力传输到地球的计划，并在今后20年内转向更加大型的系统。

A massive satellite

巨大的卫星

If the technology is ready， why is SBSP not being used？ The main limit is the enormous amount of mass that needs to be launched into space， and its cost per kilogram. Companies such as SpaceX and Blue Origin are developing heavy-lift launch vehicles， with a focus on reusing parts of those vehicles after they have flown. This can bring the cost of the venture down by 90%.

如果技术已经具备，为什么不使用太空太阳能呢？主要的限制在于需要发射到太空的巨大重量，以及每公斤重量的发射成本。太空探索技术和蓝色起源等公司正在研发重型运载火箭，专注于重复使用发射后的火箭部件，这样可以使发射成本降低90%。

Even using SpaceXs Starship vehicle， which can launch 150 tonnes of cargo into low Earth orbit， the SBSP satellite will require hundreds of launches. Some components， such as long structural trusses-structural elements designed to span long distances-could be 3D-printed in space.

太空探索技术公司的“星舰”火箭可以将150吨物品发射到近地轨道，但即便使用“星舰”，太空太阳能卫星也需要数百次发射。某些部件可以在太空中3D打印，例如长结构桁架这种用于长距离的结构元件。

Challenges and risks

挑战与风险

An SBSP mission will be challenging—and risks still need to be fully assessed. While the electricity produced is fully green， the impact of the pollution from hundreds of heavy-lift launches is difficult to predict.

太空太阳能任务将富有挑战性，并且存在仍待充分评估的风险。虽然产生的电能完全是绿色的，但数百次重型运载火箭发射所产生的污染影响难以预测。

Additionally， controlling such a large structure in space will require substantial amounts of fuel， which involves engin-eers working with sometimes very toxic chemicals. The photovoltaic solar panels will be affected by degradation， reducing efficiency over time from 1% to 10% per year. However， servicing and refueling could be used to extend the satellites lifetime almost indefinitely.

此外，在太空中控制如此之大的结构将需要大量的燃料，为此工程师有时会接触到剧毒的化学物质。由于降解的影响，光伏太阳能电池板的效率将随着时间的推移每年下降1%到10%。然而，维修保养和补充燃料几乎可以无限期地延长卫星的寿命。

A beam of microwaves powerful enough to reach the ground could also harm anything that got in the way. For safety， then， the power density of the beam will have to be restricted.

强烈到足以抵达地面的微波束同时会损伤传输路线上的一切物体。因此，为了安全起见，必须限制微波束的功率密度。

The challenge of building platforms like this in space may seem daunting， but space-based solar power is technologically feasible. To be economically viable， it requires large-scale engineering， and therefore long-term and decisive commitment from governments and space agencies.

在太空中建造太空太陽能的平台似乎是一项艰巨的挑战，但这在技术上是可行的，其经济上的可行性则有赖于大型工程，因此需要政府和航天机构坚决的长期投入。

But with all that in place， SBSP could make a fundamental contribution to delivering net zero by 2050 with sustainable， clean energy from space.

但当一切准备就绪，作为来自太空的可持续清洁能源，太空太阳能可以为2050年实现零排放做出重大贡献。

（译者为“《英语世界》杯”翻译大赛获奖者）

1 gain traction流行，受到人们关注。  2 photovoltaics 光伏发电，缩写PV，一种利用半导体界面的光生伏特效应而将光能直接转变为电能的技术。

3 24/7 全天候，指一天24小时一周7天不间断，读作twenty-four seven。

4 gigawatt吉瓦，缩写GW，功率单位，1吉瓦=10亿瓦。  5 其中大写字母分别代表Constant、Aperture、Solid-State、Integrated、Orbital Phased Array，中文意思为“恒定孔径的、固态的、集成的轨道相控阵”。  6英文全称为Solar Power Satellite via Arbitrarily Large Phased Array，中文意思为“任意大型相控阵太阳能卫星”。  7加州理工学院，英文全称为California Institute of Technology。  8 beam发射（电波）；播送。