Dec

10

How Clean is Solar Power?

Solar Panels

Renewable energy sources like Solar Photovoltaic (PV), hydro, and wind power are vital today.  The Photovoltaic (PV) effect was identified by a French physicist, Edmund Bequerel in 1839. First PV in 1954 was expensive, but in 1975s the costs decreased by 20% (for every doubling incapacity). In 1976 people paid $80 (around 75 euros today) for one Watt-peak (Wp) unit, and today is around 64-67 US cents.

There have been concerns around the energy needed to make solar panels. The creation of solar silicon panels goes through a melting and purifying phase (Silicon’s melting point is 1,414°C, around 124°C less than iron). Silicon melted in electric furnaces uses electricity produced by burning fossil fuels, and also emits carbon dioxide. A new solar panel thus starts with a carbon-debt. This debt has to be cleared out for the panel to be a part of the solution from a greenhouse-gas-saving perspective.

Dr Wilfried van Sark, from Utrecht University, Netherlands, and his colleagues have put together a new paper (Nature Communications) report. They calculated the energy required to make solar panels installed worldwide during 1975-2015, vis-à-vis the carbon-dioxide emissions associated with producing that energy. They also studied the solar panels’ energy since installation and corresponding prevention of carbon dioxide emitted in the atmosphere.

The study team used the International Energy Agency data, an autonomous intergovernmental body, to estimate the number of solar panels installed worldwide. The team found that the carbon dioxide emitted during the manufacturing depends on where-and-when it was made. Therefore, in China, a panel would cost double the greenhouse-gas emissions than in Europe, as China relies more on fossil fuels for generating power. The benefits of solar panel installations, therefore, would be greater in China than in Europe.

The team observed that solar panels had 400-500 gm of carbon dioxide per kilowatt-hour of energy produced in 1975, which today is around 20 gm (estimated as 30 years, regardless of when a panel was manufactured). The time needed for a solar panel to produce energy vis-à-vis its creation time has reduced to two-years from 20-years. More panels lead to more efficiency. Another observation was every doubling of the world’s solar capacity, the energy required to make the panel fell by 12% and the associated carbon-dioxide emissions by 17-24%. Thus, the global break-even may have been in 1997, or under more pessimistic assumptions be set in 2018.

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