Monday, November 16, 2015

We hear solar energy mentioned when climate change is discussed. How do we know how how solar fits into this?

Solar energy, itself, does not release greenhouse gases (although the energy required to make solar panels, themselves, often does--the precise "cleanness" depends on the specific technology, but modern technologies are cleaner than the status quo). At the same time, they absorb energy and pump it other places in the form of electricity (and, ideally, don't reflect much back to space). Consequently, solar panels change the energy distribution in their immediate vicinity. Computer models are used to predict the effects of solar cells on their local environment. Aixue He et al. recently published a paper discussing these effects. This paper was then picked up by the Washington Post. Solar panels, themselves, lower temperatures in their immediate vicinity. They absorb energy from their surrounding and convert it to electricity, which is sent into cities and towns. Those areas, then, use the electricity, often in ways that release more heat, resulting in warming of urban areas. It is important to note that these temperature increases are much less than those predicted without the use of solar or other clean energy sources.

It is important to note that precipitation is also affected by air temperature. Cold air can't hold as much moisture. If deserts are colder, they are often drier. Solar panels, where they are set up, decrease the local temperature, which A. He et al.'s study suggests would slightly reduce cloudiness and precipitation. It only takes a 2 C temperature decrease to reduce precipitation by 20 % in desert regions. For these reasons, it was found that placing solar panels in a mixture of urban and desert regions minimizes many of the local environmental impacts of solar cells.

The moral of the story is that no matter what you do, the environment is effected. It is just a question of degrees and in what way things are affected. 

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