Why are solar panels useful?
Greenhouse gases like carbon dioxide (CO2) are trapping heat within the earth’s atmosphere, causing global warming. This is becoming a climate emergency. People all over the world are recognising that we need to do whatever we can to reduce our emissions of CO2. One way to do this is to stop using fossil fuels such as oil and coal, which release lots of CO2 into the environment. Renewable sources of energy should be used instead. Renewable energy does not release CO2 and comes from resources that don’t run out, such as sunlight, ocean waves, and the wind.
One example of a renewable source of energy is the energy from the sun. For years, we have been capturing this energy using solar panels. Solar panels work using something called the photovoltaic effect. They absorb light from the sun and convert it into an electric current. Because they use sunlight, solar panels can only work during the day. This means that to access energy during the night, we need other sources. We often end up having to use fossil fuels for this.
How could we use renewable energy during the night?
Researchers from the University of Maryland in the United States have come up with a device that could be used to produce energy during the night. Thermoradiative cells are similar to solar panels but use different materials, and use a different method to produce energy. Instead of absorbing heat (as solar panels do), thermoradiative cells work by putting heat out into their surroundings. The sky is colder than the surface of the earth. This is because the ground is made of a lot of matter that can absorb heat, whereas the sky is mostly empty space, so there is little that can absorb heat. The difference in temperature means that a thermoradiative cell could generate power by emitting heat into the sky.
How efficient are thermoradiative cells at producing energy?
Under ideal conditions, these thermoradiative cells could generate up to 50 watts of power per square metre over the course of a night. This is approximately enough for a low-power lightbulb. That’s about a quarter as effective as solar panels are during the day. However, thermoradiative cells could also work during the day, if they are pointed away from the sun (or if the sun is blocked out). Due to this, it is a potential option for providing clean power during the night as well as the day. Unfortunately, this device is still very theoretical. More research needs to be done before we know if the idea will actually work, especially at large scales.