Solar plants do not produce any emissions when generating electricity. It is therefore quite easy to think that they are completely green and emissionless. But are they?
There is currently no single and simple measure of what is “green”. To some, green means no emissions. To others, they mean that it is environmentally sustainable. There’s no single definition to what being “green” means. Let’s settle on one we can agree on: being environmentally sustainable. Environmental sustainability is currently commonly measured from the emissions (CO2, other greenhouse gases and other pollutants), energy consumed, or the resources used, including water consumed.
In examining whether solar energy is really green, we will consider the energy and environmental impact from four key stages of their lifecycle:
- The first stage is the extraction of raw materials used to produce the solar panels.
- The second stage is production or the conversion of those raw materials to components of solar plant, such as the panels, inverters, cables and the frame.
- Thirdly, is the transportation from the factories to the site. The fourth stage is the operations and maintenance stage where the solar plant is generating electricity.
- Lastly, is the end of the life of these solar power plants where we will need to consider disposal or recycling.
What is the Environmental Cost of Solar Plants?
Let’s compare the energy “cost” of solar plants against the energy generated throughout its lifecycle. The energy payback time is the number of years it takes for the solar plant to generate enough energy to offset (payback) the energy it uses throughout its lifetime. Research shows that currently, the estimated energy payback time for solar plants is about 2 years. With an average lifespan of, say, 20 years, it means that solar plants generate 18 years of extra electricity than it costs to make them.
Another consideration is the environmental footprint from the location of the solar plant itself. It is no secret that solar plants require a large amount of land. In the implementation of large-scale solar plants, these plants are typically located on land that could have alternate uses These alternate uses include economic or agricultural uses, or as tree covers with environmental benefits. If the plants displace trees from the land, then the plants would have prevented the absorption of up to 2.6MT of CO2 per year per acre.
What about the benefits?
On the other hand, 1 acre of solar panels can generate about 1.3GWh of electricity per year, depending on location and multiple other factors. This electricity is likely to displace about 705MT of CO2 emission per year on average, assuming that it displaces electricity generated from coal and gas fired power plants.
This reduction of CO2 emissions is equivalent to removing 20 cars from the road for a period of 20 years! Electricity generated from solar plants is clearly a greener alternative to fossil fuels. However, it should not just end here. More needs to be done to further improve the sustainability of solar energy.
What else can we do?
For one, we can do more to encourage the proliferation of solar panels on roofs or on areas such as bus-stop shelters and sheltered walkways, or areas that are already developed. These will utilise non-productive spaces (rooftops) to generate energy, instead of using land that can have alternative commercial or agricultural uses, or as forest covers.
Another aspect that needs to be seriously considered is the end-of-life treatment of the solar plants. Currently, there are no clear guidelines and regulations for the decommissioning of solar plants. How should the panels and equipment be disposed or recycled? While imposing some kind of guidelines and regulations will increase the cost of solar power, but these are necessary to improve the environmental sustainability of our energy sources.
Lastly, solar plants only generate electricity during the daytime, meaning we likely will still need to generate electricity using fossil fuels at night. Current technologies for storage of electricity in mass quantities, for example batteries or green hydrogen, are expensive. With further development of these technologies and further mass deployments will make them more affordable. These should be considered in-tandem with renewable energy sources like solar.