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

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.

太空太阳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 world’s 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. It’s collected directly through what we generally call solar power. This comprises different technologies such as photovoltaics2 （PV） and solar-thermal energy. The sun’s 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 don’t 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 won’t 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. It’s thought that there’s 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 UK’s net-zero target by 2050—but the government’s 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 UK’s current demand. SBSP provides a secure and stable energy supply.

太空太阳能可能对英国实现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.