The electricity generated by solar photovoltaic panels has probably just surpassed the amount of energy used to make them, researchers say.
The rapid growth of the solar power industry over the past decade may have exacerbated the global warming situation it was meant to soothe, simply because most of the energy used to manufacture the millions of solar panels came from burning fossil fuels.
For the first time since the boom started, the electricity generated by all of the world’s installed solar photovoltaic (PV) panels last year probably surpassed the amount of energy going into fabricating more modules, according to Michael Dale, a postdoctoral fellow at Stanford University’s Global Climate & Energy Project (GCEP).
Related article: Making Recyclable Solar Cells from Trees
With continued technological advances, the global PV industry is poised to pay off its debt of energy as early as 2015, and no later than 2020.
“This analysis shows that the industry is making positive strides,” says Dale, who developed a novel way of assessing the industry’s progress globally in a study published in Environmental Science & Technology. “Despite its fantastically fast growth rate, PV is producing—or just about to start producing—a net energy benefit to society.”
The achievement is largely due to steadily declining energy inputs required to manufacture and install PV systems, according to co-author Sally Benson, GCEP’s director. The new study, Benson says, indicates that the amount of energy going into the industry should continue to decline, while the issue remains an important focus of research.
“GCEP is focused on developing game-changing energy technologies that can be deployed broadly. If we can continue to drive down the energy inputs, we will derive greater benefits from PV,” she says. “Developing new technologies with lower energy requirements will allow us to grow the industry at a faster rate.”
Energy in to get energy out
The energy used to produce solar panels is intense. The initial step in producing the silicon at the heart of most panels is to melt silica rock at 3,000 degrees Fahrenheit using electricity, commonly from coal-fired power plants.
To be considered a success, PV panels must ultimately pay back all the energy that went into them, says Dale.
As investment and technological development have risen sharply with the number of installed panels, the energetic costs of new PV modules have declined. Thinner silicon wafers are now used to make solar cells, less highly refined materials are now used as the silicon feedstock, and less of the costly material is lost in the manufacturing process.
Increasingly, the efficiency of solar cells using thin film technologies that rely on earth-abundant materials such as copper, zinc, tin, and carbon have the potential for even greater improvements.
To be considered a success—or simply a positive energy technology—PV panels must ultimately pay back all the energy that went into them, says Dale. The PV industry ran an energy deficit from 2000 to now, consuming 75 percent more energy than it produced just five years ago. The researchers expect this energy debt to be paid off as early as 2015, thanks to declining energy inputs, more durable panels and more efficient conversion of sunlight into electricity.
Related article: Suntech Bankruptcy Bad News for Solar
2 percent by 2020?
If current rapid growth rates persist, by 2020 about 10 percent of the world’s electricity could be produced by PV systems. At today’s energy payback rate, producing and installing the new PV modules would consume around 9 percent of global electricity.
However, if the energy intensity of PV systems continues to drop at its current learning rate, then by 2020 less than 2 percent of global electricity will be needed to sustain growth of the industry.
This may not happen if special attention is not given to reducing energy inputs. The PV industry’s energetic costs can differ significantly from its financial costs. For example, installation and the components outside the solar cells, like wiring and inverters, as well as soft costs like permitting, account for a third of the financial cost of a system, but only 13 percent of the energy inputs. The industry is focused primarily on reducing financial costs.
Continued reduction of the energetic costs of producing PV panels can be accomplished in a variety of ways, such as using less materials or switching to producing panels that have much lower energy costs than technologies based on silicon.
The study’s data covers the various silicon-based technologies as well as newer ones using cadmium telluride and copper indium gallium diselenide as semiconductors. Together, these types of PV panels account for 99 percent of installed panels.
Where’s the sunshine?
The energy payback time can also be reduced by installing PV panels in locations with high quality solar resources, like the desert Southwest in the United States and the Middle East.
“At the moment, Germany makes up about 40 percent of the installed market, but sunshine in Germany isn’t that great,” Dale says. “So from a system perspective, it may be better to deploy PV systems where there is more sunshine.”
This accounting of energetic costs and benefits, say the researchers, should be applied to any new energy-producing technology, as well as to energy conservation strategies that have large upfront energetic costs, such as retrofitting buildings. GCEP researchers have begun applying the analysis to energy storage and wind power.
By. Mark Golden
"As environmental science has advanced, it has become apparent that the human appetite for animal flesh is a driving force behind virtually every major category of environmental damage now threatening the human future: deforestation, erosion, fresh water scarcity, air and water pollution, climate change, biodiversity loss, social injustice, the destabilization of communities, and the spread of disease." ~ Worldwatch Institute, "Is Meat Sustainable?"
“If every American skipped one meal of chicken per week and substituted vegetables and grains... the carbon dioxide savings would be the same as taking more than half a million cars off of U.S. Roads.” ~ Environmental Defense Fund
"The livestock sector emerges as one of the top contributors to the most serious environmental problems, at every scale from local to global. The findings of this report suggest that it should be a major policy focus when dealing with problems of land degradation, climate change and air pollution, water shortage and water pollution, and loss of biodiversity... The impact is so significant that it needs to be addressed with urgency." ~ United Nation Food and Agricultural Organization's report "Livestock's Long Shadow"
“It’s not a requirement to eat animals, we just choose to do it, so it becomes a moral choice and one that is having a huge impact on the planet, using up resources and destroying the biosphere.” ~ James Cameron, movie director, environmentalist, new vegan
I find it interesting that scrutiny from energy experts suggests the solar energy sector has the capacity to produce more than it consumes. For me it raises some questions that I'm sure many in the industry have the answers to.
What does the same qausi 'life-cycle assessment' and raw costings style of scrutiny indicate when applied to the non renewables sector (which obviously includes nuclear)?
Can any of the non renewable energy generation methods ever be said to pay back their energy (r & d, creation, deployment, operation, maintenance and dismantling etc) as renewables do/will?
As the energy generation costs of renewables continue to reduce while non renewables increase, when is the inevitable crossover point anticipated?
How would the industries compare economically, now and future, if both received NO subsidies of any sort and operated from an identical perspective?
I would greatly appreciate if someone could provide or point me in the direction of answers.
All the best,