Cool Earth Solar Rethinks Photovoltaic Electricity

(12/4/2008) - California start-up Cool Earth Solar (CES) claims that they offer, “A clean energy solution that massively scales to meet the world's power demands at prices competitive with traditional fossil fuels.”  As I have discussed before, this kind of hyperbole is standard fare in promotional literature for clean energy companies.  A simple, “We make solar PV that is price competitive with traditional fossil fuels,” would have been sufficient to grab my attention. 

Price-competitive solar electricity is one of the holy grails of the clean energy industry.  And though the price has come down, it still has a long way to go.  A recently installed 2MW PV plant in L.A. is expected to produce electricity for $0.27 per kWh, compared to $0.08 per kWh for coal (less in other locations).

So when I read that CES was going to produce price-competitive solar PV, my interest (and skepticism) rose.  What new technology would they be touting?  Super-duper-thin-film PV?  Solar panels in space? 

The answer was refreshingly low-tech: balloons. 

In a traditional solar panel, an array of silicon cells is spread out over a large, flat surface exposed to the sun.  Some of the light falling on the cells area is converted into an electrical current.  The more light that falls on a cell, the more electricity it produces.  CES's balloon acts as a concentrator, reflecting solar energy onto a single, small PV cell.  The company says that this single cell will produce 300-400 times as much electricity as it would without the concetrator. 

The top 2/3 of the balloon is transparent, and the bottom third is made of reflective material similar to a potato chip bag.  The air pressure inside the balloon is actively controlled to focus light onto a single, small PV cell. Without this feature, variables like changes in air pressure would reduce the concentrator’s effectiveness.

Though each eight foot wide balloon doesn't produce quite as much electricity as a traditional PV panel of similar size, the materials used are a lot cheaper  Each balloon and the associated support system is built with plastic, aluminum, stamped-steel galvanized parts, wire, mylar, wood and air.  Though the materials will be cheap, it will likely take more manpower to maintain than other power systems.  For example, the company expects to replace the plastic balloons every couple of years.  While the plastic will only cost a few dollars for each, the full time personel required to replace tens of thousands of balloons every year will cost a lot more.

The concentrators will be strung along wire suspended from wooden polls, with a cooling system alongside to prevent the cells from overheating.  While this will allow them to be placed on slopes and other land that won’t work for solar thermal plants, you won’t be able to put them on land that is already occupied.  So don't expect to install Cool Earth Solar concentrators on your rooftop. 

CES plans on building a 1.5MW pilot plant in early 2009.  Assuming everything goes as planned, CES will install power plants rated at 10MW-30MW (10,000-30,000 balloons), and earn money from selling the electricity to utility companies. 

California, at least, should prove to be a very lucritive market.  Not only do they have sun, but utility companies in the state are under the gun to meet renewable energy standards that require them to procure 20% of their electricity from clean sources by 2010, which is why utility companies are bankrolling expensive PV projects. 

CES anticipates that initial power plants will cost about $1/watt, compared to about $5/watt for commercial PV instillations today, such as the one in L.A. that I mentioned before.  Even if it ends up costing $2/watt, I expect CES should have no trouble attracting investment from California utilities looking for cheaper sources of clean energy.

Why We Need Clean Energy That’s Cheaper-Than-Coal

CES says that its electricity will initially be cheaper than energy produced in natural gas-fired generators, which currently produces 20% of America’s electricity, but not cheaper than coal, which produces almost half of the nation’s electricity.  They stress, rightly, that becoming cheaper than goal is the ultimate goal.  Coal is one of the largest sources of greenhouse gases in the world, and electricity produced from coal is relied upon worldwide. 

There is another way to make PV cheaper than coal – raise the price of coal.  Passing a stringent cap-and-trade system or a stiff carbon tax could accomplish this.  In the 2008 election, both candidates said they supported a cap-and-trade system, and Europe has already begun to implement one. 

While these systems might help the Western world curb its emissions, they will not solve the problem of global warming alone.  By definition, global warming requires a global solution.  Even if the United States cut its emissions by 80% (which is the current goal for 2050), emerging economies in China, India, Turkey, Angola, Mozambique, Brazil, and other countries will more than make up the difference if emissions growth is unchecked. 

Lets suppose that by 2050 the United States, the E.U., Russia, South Korea Canada, South Africa, Australia, Japan – the “developed” world – cut its CO2 emissions 95% from 2004 levels.  At the same time, lets suppose emissions from the rest of the world rise by a meager 2% a year.  Under this scenario, worldwide emissions will still rise by 16.5%.  In the real world, emissions in the developing world are rising much faster, and emissions in developed nations haven’t even started to go down.

Cheap and scaleable alternatives to fossil fuels are needed so that every country can cut emissions without asking poorer nations to end dreams of development and increased standards of living.  In the United States, emissions can be reduced the easy way – by using less.  In other countries, there are millions upon millions of people who don’t yet have electricity.  As more and more of the world becomes electrified, we want to make sure that they have the opportunity to do so with clean energy.  

Time will tell whether or not CES can live up to its promises.  No matter what happens, CES’s emphasis on using existing technology and cheap materials is the only way solar PV (or any type of clean energy) is going to become a widespread, worldwide energy source that is accessible to every country.