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Our BatchGeo world MAP shows the locations of green architecture, green building and renewable energy projects featured on Solaripedia.

Project

Solar Balloons Provide Electric Power

Credits: ©2009 Cool Earth

CoolEarth created an innovative way to harness the sun's energy. Instead of large expensive solar panels or costly concentrating mirrors, the company is using balloons made of metalized plastic films. Half of the balloon is transparent, letting the light in to be concentrated into a small high-efficiency solar panel by the concave interior. Each is two meters across and, depending on the source, estimates vary from 500 watt to 1 kilowatt. They are supported by cables, leaving the ground below clear and limiting environmental impact. This breakthrough solar technology can ultimately produce enough clean energy to address the global energy crisis. This patented concentrated photovoltaic (CPV) technology dramatically reduces the cost and time to develop solar power plants capable of generating massive amounts of clean energy at prices competitive with fossil fuels.

 

Solar balloons from Cool Earth

Because the design uses relatively cheap and readily available components, these solar concentrators from Cool Earth can generate electricity at a cost comparable to that of natural-gas plants. ©2009 Cool Earth

Jaymi Heimbuch spoke with Cool Earth CEO Rob Lamkin about how Cool Earth came up with the idea for a concentrating solar balloon concept.

Cool Earth Solar Getting Started on an Idea
The team didn't want to just take a product that's already out and improve it or tweak it and try to make a lot of money by going just one step further. Instead, they wanted to solve a major problem shared by everyone on earth. They focused the majority of their brainstorming time coming up with how to define the problem. They wondered, is it green house gases? Is it energy security? Is it electricity demand? Looking at overarching problems and figuring out what is really needed helped them to develop the technology.

The

Two Most Abundant Resources
Through research, the team discovered two things. Solar is the only resource abundant enough to address all the issues the team considered to be the biggest problems. To harvest enough solar, the team figured out that we would need 100 miles by 100 miles of the earth's surface covered in solar collection technology to power the entire world on clean renewable energy. Delving into more research, they found that the only material we make in enough abunance to cover this kind of area affordably is thin film plastic.

Playing with Plastic
So, the team went with that material. They tried different shapes, different layouts, and finally came up with the best shap - an air inflated balloon 8 feet across. Half of the balloon is clear, half is coated in aluminum. The sunlight comes through the clear material, bounces off the aluminum and at the focal point, PV material is used to collect the 400x concentrated light. Ultimately, a balloon is about two pounds of plastic that costs about $2. And ultimately, Lamkin says, this is a materials problem. No other material used in solar power generation can be found so cheaply - not mirrors, not metals. But...it's plastic.

But....It's Plastic (?)
Lamkin argues that plastic isn't bad, but what we do with it can be. He points out the Great Pacific Garbage patch as a major example of how we've done wrong by plastic. He says, however, when you use plastic for something like solar power, the pros outweigh the cons. He also notes that manufacturers of thin film plastic can use recycled plastic. While he's not sure right now if Cool Earth Solar can know if they're purchasing thin film made from recycled plastic, he assured me he was going to look into it.

Maintaining the Bigger Picture
The team keeps that big picture goal in mind as they form the company and the product - they constantly remember that they're trying to efficiently and cost effectively solve a global problem of renewable power generation. Their product has been 100% shaped by their desire to see the world off of fossil fuels, minimizing our carbon footprints, and being powered by our most abundant resource by using our most abundant materials.

Regardless of the pros and cons of the solar concentrator balloon, the bigger point here is that the company and its team aren't out to just put another product on the green market to try and make a buck. It is this outlook that other companies should (and many do) maintain if we're going to solve the crises at hand.

Cool Earth Solar currently has prototypes in Livermore, California collecting data, and they hope that by mid-year 2009, they'll build their first commercial power plant somewhere in central California on pre-disturbed land such as fallow farm land.

Info from Cool Earth:
Our technology, which is the basis for our power plants, is "reshaping solar energy" in a very literal way: Most of today's solar energy systems take the form of flat panels or boxes-with-lenses and require large amounts of heavy, expensive materials. Our inflated solar concentrators, on the other hand, are shaped like balloons and are primarily made of inexpensive and free materials. This design approach radically reduces material requirements as well as our plant deployment costs and time.

Our inflated, balloon-shaped concentrators are key to Cool Earth's innovative design. Each 8-foot-diameter concentrator is made of plastic film—the same kind of plastic film used to bag potato chips, pretzels, and so on—with a transparent upper hemisphere and a reflective lower hemisphere. When inflated with air, the concentrator naturally forms a shape that focuses or concentrates sunlight onto a PV cell placed at the focal point. This means we need fewer cells to produce a lot more electricity. In fact, a single cell in our concentrator generates about 300 to 400 times the electricity of a cell without a concentrator.

The inflated structure is naturally strong—strong enough to support a person's weight—and aerodynamically stable, able to withstand winds of 125 miles per hour. Finally, the transparent upper surface protects the PV cell and mirrored surface from the environment, including rain and snow, as well as insects and dirt.

Each concentrator has additional structural components: a small steel strut and a harness. The steel strut, tethered in place, holds the cell at the focal point inside the concentrator and provides a conduit for a small water loop that cools the cell. A lightweight, flexible steel band forms a harness around the circumference of the concentrator and is used to hold and point the concentrator.

The concentrators are suspended with our patented support system, which is based on the architectural principles of tensegrity. (Tensegrity structures stabilize their shapes by continuous tension or "tensional integrity" rather than by continuous compression.) The resulting system of wood posts and steel cables uses a minimum amount of material, has a small footprint, and causes the least disruption to the natural environment of any solar power plant.

 


Resources

Solar Balloons from Cool Earth Video Link

Cool Earth Technology