The Energy Blog

Emissions from Photovoltaic Life Cycles

A new report has found that thin-film cadmium telluride solar cells have the lowest life-cycle emissions primarily because they consume the least amount of energy during the module production of the four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride (CdTe).

The study, published in the Environmental Science & Technology journal, based on PV production data of 2004–2006, presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions of the four types of PV systems considered. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system.

They found that thin-film cadmium-telluride solar cells had the best life-cycle profile. Even though the process emitted  heavy metal cadmium, it still had a lower overall level of “harmful air emissions” than the other PV technologies in the study.

The report stated that "Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electrity from photovoltaics displaces electricity from the grid."

The fact that Cd-Te technology was found to have the lowest emissions profile is interesting, but the main point, to me, is that all technologies had low emissions profiles, that are insignificant when compared to the emissions of the fossil fuel technologies that they replace. While I do not find it suprising that all solar PV systems have a low emissions profile, I find it suprising that the authors did not include thin-film silicon or copper indium gallium selenide (CIGS) cells in their study.  I assume the overall results would have been the similar, but it woud have given a fairer comparison to the technologies now in use.  One problem with scientific research is that it takes so much time to do the study and get it published that by that time the information is made public it is sometimes outdated.

A Solar Grand Plan

The January 2008 issue of Scientific American has an article titled "A Solar Grand Slam" which outlines a plan in which solar power could end U.S. dependence on foreign oil and slash greenhouse gas emissions by 2050. In a massive switch from coal, oil, natural gas and nuclear power plants to solar power plants, the U.S. could supply 69 percent of its electricity and 35 percent of its total energy by 2050. The four key elements of the plan are:

• A vast area of photovoltaic cells would have to be erected in the Southwest. Excess daytime energy would be stored as compressed air in underground caverns to be tapped during nighttime hours.
• Large solar concentrator power plants, with molten salt storage, would be built as well.
• A new direct-current power transmission backbone would deliver solar electricity across the country.
• $420 billion in subsidies from 2011 to 2050 would be required to fund the infrastructure and make it cost-competitive.

The article goes into quite a bit of detail about how the plan would be implemented and financed.

The plan also states that "If wind, biomass and geothermal sources were also developed, renewable energy could provide 100 percent of the nation’s electricity and 90 percent of its energy by 2100."

This comprehensive study is well done and well worth a read.  I disagree on their definition of what is a vast area of photovoltaic cells, which I find reasonable, especially as their estimate of the land required is very conservative compared to other studies.

I also do not see why so much power has to be provided by solar, as other, just as clean sources, could contribute considerable power, especially in the short run.

Unfortunately their study ended before two recent announcements:

1) That Nanosolar producer of thin-film CIGS solar cells, made using nanoparticle ink and roll-printing technology, has begun production of cells that will sell at $0.99 a Watt when their 430. ,000 Mw production facility in CA and a similar facility in Germany are completed. Costs are reduced because, not only by their production technology, but also because their cells and panels are the first ones to have been designed specifically for utility-scale power generation.

and 2) That Ausra which is providing a 177 Mw thermal solar facility for PG&E has begun construction on a 700 Mw production facility which is scheduled to start delivering equipment in April 2008. Ausra claims that It can generate electricity for 10 cents/kWh now and under 8 cents/kWh in 3 yrs (presumably not including storage, which would add another 2 or 3 cents). They claim that all U.S. electric power, day and night, can be generated using a land area smaller than 8,500 sq miles using their equipment.

Noted in Passing: Solar is the Solution

The current edition of Mother Earth News has an excellent post on why Solar energy is the best solution for our energy needs.

Steve Hollerith writes:  I have been studying our energy options for more than 30 years, and I am absolutely convinced that our best and easiest option is solar energy, which is virtually inexhaustible.

Read this interesting article to see if you agree. 

Thanks to Robert Rapier of the R-Squared Energy Blog for the tip.

Solar Installations up 33% in US in 2006, 41% in World, Solar Capacity only Utilized 62%

In an update on the solar industry Solarbuzz reports that the installation of solar photovoltaic (PV) devices in the United States increased by about 33 percent in 2006 over the previous year. Worldwide PV installations totaled 1,744 megawatts (MW) in 2006, a new record and a growth of 19 percent over 2005. The United States contributed just 8 percent of those installations, or about 140 MW, while Germany led the world market with 960 MW of PV installations, comprising 55 percent of the world's total PV installations for 2006. To supply that market, the global production of solar cells reached 2,204 MW in 2006, a growth of 33 percent over PV production in 2005, while the production of polysilicon a critical ingredient for silicon solar cells increased by 16 percent.

The Photovoltaic Service Program at Navigant Consulting has published a “Pre-Release” of its quarterly PV industry newsletter, Solar Outlook. The feature article in the release is an analysis of 2006 PV technology shipments. The PV industry grew by 41%, the same rate as the CAGR from 2000 to 2006. In 2005, thin film technologies were 6% of total shipments. Thin films increased their share of total to 7% in 2006, and are on track to increase by another percentage point, to 8% in 2007. Many more facts are included in the referenced pdf.

Notice that the Solarbuzz numbers are for global production, while the Navigant numbers are for shipments, perhaps explaining the difference in numbers or it may simply be a matter of discrepencies in data collection.

TOP TEN SOLAR MANUFACTURERS

RANKING	2004	2005	2006
1	Sharp Solar	Sharp Solar	Sharp Solar, 22%
2	Kyocera	Kyocera	Q-Cells, 12%
3	BP Solar	Q-Cells	Kyocera, 9%
4	Shell Solar	Shott Solar	Suntech, 8%
5	Q-Cells	BP Solar	Sanyo, 6%
6	Shott Solar	Mitsubishi Electric	Mitsubishi Electric, 6%
7	Sanyo	Sanyo	Shott Solar, 5%
8	Mitsubishi Electric	Shell Solar	Motech, 5%
9	Isofoton	Motech	BP Solar, 4%
10	Motech	Isofoton	SunPower, 3%
Total Shipments	1049.8	1407.7	1982.4

DOE Selects 13 Projects for Solar Technology Development

U.S. Department of Energy (DOE) Secretary Samuel W. Bodman on February 8 announced the selection of 13 industry-led solar technology development projects for negotiation for up to $168 million (FY’07-’09) in funding, subject to appropriation from Congress.  These projects will help significantly reduce the cost of producing and distributing solar energy.  As part of the cost-shared agreements, the industry-led teams will contribute more than 50 percent of the funding for these projects for a total value of up to $357 million over three years. These cooperative agreements, to be negotiated, will be the first made available as part of President Bush’s Solar America Initiative (SAI), a component of his Advanced Energy Initiative (AEI), announced in his 2006 State of the Union Address. 

These projects enable the projected expansion of the annual U.S. manufacturing capacity of PV systems from 240 MW in 2005 to as much as 2,850 MW by 2010, representing more than a ten-fold increase.  Such capacity would also put the U.S. industry on track to reduce the cost of electricity produced by PV from current levels of $0.18-$0.23 per kWh to $0.05 - $0.10 per kWh by 2015 – a price that is competitive in markets nationwide.

Santa Monica Aims to be "Net Zero" City

John Addison writes in his blog about the city of Santa Monica, CA and its plans to be the nation's first "Net Zero" city. Through energy efficiency, solar and other renewable energy, the city hopes to generate enough clean energy to match its total energy consumption. Two paragraphs from the post and you can read the rest at Cleantech blog.

Solar Santa Monica formally launches a two year program on January 1, 2007. The voluntary program will start with 50 residential and commercial buildings. With the benefit of what is learned from these 50 projects, the program will be made available to all. The 50 buildings will include 30 to 35 residences, 5 to10 business and 5 municipal buildings.

Susan Munves estimated that over 20 years, $1.4 billion is the probable investment required to achieve being a “Net Zero” city. This is likely to offset a utility electric charges which would be higher than the $1.4 billion.

Solar Energy Tax Credit Extended One Year

From the Solar Energy Industries Association via Neal Dikeman in the Cleantech Blog:

"In its waning hours, the 109th Congress today passed legislation that would extend the 30% solar energy investment tax credit (ITC) for homeowners and businesses for one additional year, through the end of 2008."

Neal has some good, bad and ugly comments on this legislation.

Rand: 25% of Energy from Renewables by 2025

The Wall Street Journal reports that a Rand Corp. study shows that if the the falling costs of ethanol, wind power and other forms of renewable energy continue to fall, as they have historically, such sources could supply as much as 25% of the U.S.'s conventional energy by 2025 at little or no additional expense.

This is certainly good news if costs continue to drop as they forecast, the problem they didn't mention is whether the manufacturing infrastructure can expand that rapidly.

The Rand study concludes that because prices for gasoline, natural gas and coal are likely to remain high, their cost advantage over renewables will erode, furthered by the hope that ethanol from farm wastes will be available by 2020.

I would agree that fossil fuel costs will remain high and that would allow cellulosic ethanol to be, not only competitive, but lower in cost than fossil fuels.

Houston, MS High School Wins Dell-Winston School Wins Solar Car Challenge

The Houston, Mississippi (population 4,079) Sundancer solar car team won the Dell-Winston School Solar Car Challenge open division championship trophy at Texas Motor Speedway for the sixth consecutive year. During the challenge’s four days and seven racing periods of three hours each, the Sundancer solar car traveled more than 619 miles (413 laps), at an averaged a speed of almost 30 mph, reached a top speed of approximately 60 mph and completed more laps than any of the 13 other cars competing in the race.

Heating and Cooling from the Sun

Harnessing the heating - and cooling - powers of the sun from PhysOrg.com
Imagine heat radiating from the walls of your home on a cold winter night, or the glass in your home's windows emitting cool temperatures on a scorching summer afternoon. Now imagine these systems operating on an endless supply of affordable energy – the sun. Three years ago a team of Rensselaer Polytechnic Institute researchers began developing an "intelligent" heating and cooling system that made these seemingly too-good-to-be-true scenarios a possibility.

Developed by Steven Van Dessel, assistant professor of architecture at Rensselaer, the patented Active Building Envelope (ABE) system uses a photovoltaic (PV) system to collect and convert sunlight into electricity. That power is then delivered to a series of thermoelectric (TE) heat-pumps that are integrated into a building envelope (the walls,windows, and roof). Depending on the direction of the electric current supplied to the TE heat-pump system, the sun's energy can actively be used to make the inside space warmer or cooler. An energy storage mechanism is also integrated to collect extra energy for use when little or no sunlight is available.