Last year, US energy-related carbon emissions were at the lowest levels since 1994, emitting "only" 5.3 billion metric tons of carbon.
This is largely from declining coal use due to cheap natural gas, lower demand for transportation fuels and a mild winter, says the US Energy Information Agency.
Although we don’t like to think that solar energy contributes to emissions, it does, and there’s good news there too.
To get the solar industry where it is today required huge inputs of electricity, and ironically, most of that comes from coal-fired power plants.
For example, to produce polysilicon – the basic building block of most solar panels – silica rock must be melted at 2,000 degrees Fahrenheit using electricity, commonly from coal-fired power plants.
Does the solar industry consume more dirty electricity than the clean electricity it produces?
Before society can truly benefit from the clean electricity solar produces, they have to pay back all the energy it took to produce the solar panels in the first place.
Stanford researchers believe that tipping point occurred around 2010 and if not, it certainly will by 2015.
"The good news is that the clean electricity from all the installed solar panels has likely just surpassed the energy going into the industry’s continued growth," writes Mark Golden of Stanford University.
As the industry has advanced, it’s required less and less energy to manufacture and install solar PV, according to research at Stanford’s Global Climate & Energy Project.
Much less silicon is used these days to make solar panels and much less of it is wasted in the manufacturing process. Solar cell efficiencies, requiring fewer panels, and thin-film solar leaves out silicon altogether.
At current growth rates, solar could produce 10% of the world’s electricity by 2020.
At today’s energy payback rate, producing and installing all those PV modules would consume around 9% of global electricity, but that could drop to less than 2% if energy intensity rates keep declining.
But for this to happen, the same attention that’s being paid today on reducing financial costs of solar has to be applied to reducing energy inputs to manufacturing.
Accounting for energetic costs and benefits is necessary for any new technology, including energy efficiency upgrades in buildings that have large upfront energetic costs, say Stanford researchers. They are currently applying this analysis to energy storage and wind power.
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