Australian company Green and Gold Energy has put a solar appliance called a Sun Cube on the market. The Sun Cube is an interesting and simple concept. It’s effectively a box with Fresnel lenses on one side and triple junction solar cells on the other. The appliance is mounted on a dual axis tracking system to ensure that the assembly is always pointed at the optimal location to absorb and focus sunlight onto the cells and the whole deal is controlled with an on-board microprocessor.

Here’s a picture of the appliance:


Recently GGE has announced that they’ve been able to get 35.4% efficiency from these units, see the graph below for data on the experiment. Update: May 14, 2007: the efficiency graph has been removed from Sun Cube’s web site, thus we are unsure if this claim still stands. We have contacted Green and Gold Energy directly and asked them to comment on this entry and contribute any material they see fit to assist in clarification.

Update to the Update: May 15, 2007: Greg Watson, CEO of Green and Gold Energy responded immediately to our inquiry. In a nutshell, G&G have changed business strategy from distributed solar installations to concentrated solar installations with utilities. This change was prompted in part as a means to better manage their intellectual property. Mr. Watson says he knows the change in strategy has caused some grief among early adopters, but this is the direction the company needs to pursue.


This could be a good option for home installations, we’ll watch GGE and the SunCube with interest.

“The Department of Energy has not requested funds for geothermal research in our fiscal-year 2008 budget,” said Christina Kielich, a spokeswoman for the Department of Energy. “Geothermal is a mature technology. Our focus is on breakthrough energy research and development.”

This has been widely reported since December, 2006 and is appalling as geothermal power is in no way “mature” and there are still several breakthroughs required to realize the vast potential of harvesting heat from the earth including:

• Deep drilling to 10km
• Warm water harvest (25-75C)
• Engineered geothermal systems

With the change from the mid-term elections, there is still hope the Department of Energy position can be modified on this issue.

Steve Years jogged my memory about solar thermal over the weekend with his blog entry about a 64MW facility coming online in Nevada this year.

Solar Thermal Plant operations illustration


As you can see from the illustration above, this is a binary power system where heat is transferred to a working liquid that carries heat to water which is then vaporized into steam and cycled through a turbine sent to a condenser for cooling and then it starts the cycle again. Since the sun only shines so much, there is a natural gas boiler that takes over at night and when weather conditions aren’t appropriate to enable a steady flow of energy to consumers.

Map of appropriate solar-thermal regions of the globe


Not only are solar thermal systems ready for primetime, they’ve been working for some time. The largest operator is Florida Power and Light who operates the largest plant, the 310MW Solar Electric Generation Systems (SEGS) is a set of 7 array plants in the Mojave Desert in California. Obviously this isn’t a 100% renewable system, but it is a step in the right direction combining natural gas with sunlight to do the heavy lifting during peak consumption.

The costs of solar thermal systems are still relatively high, around $3.9M per MW in the Nevada Solar One 64MW project. The technology is competitive with “clean coal” technologies, though it’s still a far cry from the $0.75M per MW for natural gas fired generation. But it’s a great step forward from photovoltaic systems that still cost somewhere north of $8M per MW.

One has to wonder if the solar thermal folks should be talking to the binary geothermal bunch and the chemistry already completed allowing power to be generated from 75 degree centigrade resources, that has to be more cost effective than the 400 degree centigrade solar thermal design specificiation.

Techconnect, an organization connecting technology to the business world, is sponsoring this conference. It looks to have a rich set of participants from the venture and clean technology entrepreneurial communities. If you’re local, this is a good forum to attend. The conference details are available at the event web site.

Cleantech 2007 is a multi-disciplinary and multi-sector conference on global sustainability addressing advancements in traditional technologies, emerging technologies and clean business practices. The mission of Cleantech 2007 is to bring together the entire cleantech ecosystem with the goal of accelerating the flow of technologies from the research phase to the viable market phase. We do this by linking scientists, engineers and researchers with potential business, financial and government partners. The Cleantech ecosystem enables a growing set of knowledge-based technologies, products or services designed to improve operational performance, productivity or efficiency while reducing costs, inputs, energy consumption, waste or pollution.

Much has been made of this technology for extracting the carbon dioxide from the emissions of coal fired electricity generation plants. The basic premise is that the waste gas is circulated through chilled ammonia which “captures” the carbon dioxide which is then pressurized and stored for reuse. The French power company Alstom is the inventor of this process which it claims is less expensive and feasible at utility scale.

Alstom and American Electric Power have agreed to collaborate on a 30MW proof-of-concept that will capture flue gas from AEP’s 1,300MW Mountaineer Plant located near New Haven, West Virginia. The PoC should be complete by late 2008. After the results are evaluated, AEP and Alstom may proceed to two other projects at utility scale with a 200MW capture facility on a 450MW AEP plant in Oklahoma.

Ideas for what to do with all the excess carbon dioxide include using it as a pressurization agent in enhanced oil recovery and storing the gas in stable salt domes (like present natural gas and strategic petroleum reserve facilities.) Other approaches are to use and enhance natural carbon processing ecosystems like plant mass and the ocean to reduce carbon dioxide levels.

As a matter of practicality, these are reasonable steps to take given that 50% of the US electrical power is created by burning coal and reducing the impact of that activity is a very good thing. But, it’s not sufficient, it needs to happen in concert with conservation as well as increasing the non-fossil fuel generation of electricity. As carbon sequestration becomes mandatory, that should help push the price of coal burning generation facilities to levels where renewable generation technologies are more cost effective. That’s just the catalyst needed to start vast change in the way we generate our electric power.