STIRLING ENERGY: CONCENTRATING SOLAR

Solar energy is still struggling with cost. Photovoltaic panels take a long time to pay for themselves. Thin film is not as efficient and not thoroughly tested. Consumers are unwilling to afford something more expensive than their car and regard it as a necessity, like a refrigerator, when their refrigerator already gets electricity.

The City of Berkeley, CA, has devised an ingenious method of financing its citiens' solar installations for them and getting its money back via property taxes. (See BERKELEY BREAKTHROUGH SOLAR FINANCE PLAN PASSES)

That’s the best way consumers are likely to get around the cost issue.

Big solar players are bypassing the consumer and building huge solar thermal plants that do not require silicon-based photovoltaics at all. Cambridge Energy Research Associates (CERA), one of the most respected energy-consulting firms in the world, calls solar thermal the likely next high-growth energy resource in the world and predicts there will be 5,000 megawatts by 2020.

The biggest problem with solar thermal isn’t solar thermal, just like the biggest problem with wind energy isn’t wind energy. Without new, smart transmission systems to get the power from the plants to the population centers, these New Energies can’t move forward. The cost of building new transmission must always be considered.

Fortunately, big players see the opportunity in building new transmission. In many places around the U.S. new transmission is being built or being planned. People like Warren Buffet, Bill Gates and Boone Pickens are investing. The big players see what Stirling Energy’s Bruce Osborn sees: "I guarantee there will be issues and challenges. But that's just part of business…[Still,] you don't have to worry about the fuel supply. It's free…"

Osborn w/Stirling Energy Systems concentrators at Sandia National Laboratories. (Picture from USA Today - click to enlarge)

There are a variety of concepts. Ausra likes parabolic mirrors to capture the light and focus it. ESolar uses flat mirrors and concentrating towers. Stirling Energy’s design – giant colletors, each with its own engine to rotate it across the sky tracking the sun – may be highly efficient. But the design has many moving parts, which makes each solar collector more expensive and potentially fragile.

In the early days of oil there was enormous distrust of the incipient science of petroleum geology. The oil men used to say that the only way to really find out if there was oil in the ground was to ask Dr. Drill. In the solar energy game, the only way to really find out if a collector works is to ask Professor Sun.

Stirling Energy takes on the solar power challenge
Julie Schmit, January 24, 2008 (USA Today)

WHO
Stirling Energy Systems (CEO Bruce Osborn, co-founders David Slawson and Harry Braun, key investor Robert Nissenbaum, chairman Robert Clark), San Diego Gas & Electric (SDG&E) (Michael Niggli, COO), Southern California Edison (SCE)

WHAT
Stirling Energy is installing a small solar thermal plant which it hopes will be a prototype for two of the biggest solar thermal installations (800 megawatts and 950 megawatts) in the world.

WHEN
- SDG&E and SCE signed an agreement in 2005 for all of Stirling Energy’s power for w0 years but the project has yet to be approved by CA regulators.
- The current version of the Stirling engine was developed by McDonnell Douglas in the mid 80s, sold to SCE and eventually to Stirling Energy in 1996.
- Plans call for 2 more prototypes in 2008, 2 in 2009, 40 for an installation in CA’s Mojave desert in 2010 and then there will be a production ramp up.

Another view of the Stirling Energy concentrators. (click to enlarge)

WHERE
- Stirling Energy is based in Phoenix, AZ
- The prototype system will be in Albuqueque, NM
- The huge plants would be in CA

WHY
- The Stirling dishes are 40-feet in diameter. They are geared to rotate across the sky, tracking the sun. Each one generates enough electricity for 10 to 15 average homes.
- The CA installation would generate enough electricity to double U.S. solar energy output and power a million homes.
- The engine that drives the system is based on (and named for) an 1816 patent of Rev. Robert Stirling, a Scottish clergyman, who was trying to make something safer than steam engines with explosive boilers.
- Stirling has been developing financing and perfecting its technology with government engineers at Sandia National Laboratories in New Mexico for the last 2 years. They have cut steel 40% and made the collectors strong enough to withstand lightning strikes and bullets. They have optimized spacing to maximize productivity and minimize land use. Each prototype costs $225,000 but mass production could bring the cost down to $50,000.
- The planned production ramp up is expected to produce 80 collectors/month after 2010 and 80/day eventually. The modular nature of the collector allows for fast production as well as reconfigurations as needed.
- Barry Butler, materials science expert and former Stirling employee, in written testimony to California energy regulators said the technology won’t be scalable before 2020 and maintenance costs will always make it too expensive.

A different concentrating solar concept: A specially constituted liquid runs in pipes through a field of parabolic mirrors that concentrate the sun. The heated liquid flows to a plant where it boils water into steam that drives a turbine. (click to enlarge)

QUOTES
- Osborn, Stirling Energy: "This is something that hasn't been done before…We're not aware of any showstoppers. … No fatal flaws."
Niggli, SDG&E: "They clearly have the technology. It's a matter of whether they can get the cost out…"
- Osborn, on mass production: "It's not like you build the shuttle, launch it and it works or it doesn't…Nothing will stop us cold in our tracks."