Electric power plants produced 17,320 terawatt-hours (TWh) in 2005. In 2030, the world is projected to need about 33,264 TWh—nearly double the amount of 2005. (Source: 2009 EIA International Energy Outlook Report.)
Can you imagine a field planted with silver balloons as far as the eye can see or a hillside covered with silver balls? This is what Cool Earth out of Livermore, California envisions in the very near future. The solar collection concept is not new but the concentrator is different from anything seen before.
The orb-shaped sunlight concentrators are what make Cool Earth’s design unique. The orb is 8 foot in diameter and uses Mylar plastic as the cover, much like the metallic balloons you buy for your children.The bottom half is a highly reflective surface and the upper half is clear to allow in sunlight. The air used in the orb is increased or decreased according to outside air temperature. This allows the orb to change it’s shape in order to keep the sunlight on the solar cell at the precise focal point needed to produce maximum power.
Unlike traditional flat-panel solar cell systems, newer higher efficiency cells allow CPV systems to generate the same amount of electricity using 300 to 400 times less solar cell material from a concentrated source. This reduces the cost and brings the cost per watt down to around one dollar per watt.
This brings the cost almost equal to the cost of producing electricity using natural gas. The orb shape and lack of elaborate metal support structures helps to drive the cost down even further.
The orbs are attached to a tracking system to track the daily and seasonal passage of the Sun. They use water to cool the photovoltaic cells instead of large, material-intensive heat spreaders and sinks used by most other CPV companies. The inflated orb is lightweight, will survive 125 mph winds, and can produce electricity in winds up to 40 mph.
Initially, they are planning to focus on building utility-scale power plants that can provide 10 to 30 megawatts—enough to power a small city. Later they are planning to build smaller plants "off grid" for rural, developing areas.
With each orb generating about 1 kilowatt of electricity, space will be the only limiting factor. The initial system will require around 1/5 square mile to contain an array that will have the potential to produce10-megawatts. They are in the initial installation phase and will be completed this year.
Michael
