Concentrating solar power with a Stirling engine

In January 2010, Teserra Solar and Stirling Engine Systems showcased the Maricopa Solar plant in Arizona. This is the first commercial project for the SunCatcher concentrating solar power technology designed and manufactured by Stirling Engine Systems.The innovative and highly-efficient SES SunCatcher is a 25-kilowatt solar power system which uses a 38-foot, mirrored parabolic dish combined with an automatic tracking system to collect and focus the sun’s energy onto a Stirling engine to convert the solar thermal energy into grid-quality electricity. Developer Tessera Solar has created a 1.5 megawatt power plant out of 60 SunCatcher solar thermal devices.

SunCatcher has a number of advantages including the highest solar-to-grid electric efficiency, zero water use for power production, a modular and scalable design, low capital cost, and minimal land disturbance. SunCatcher was designed and developed in America, through a public-private partnership with the U.S. Department of Energy. The SunCatchers unveiled at Maricopa Solar were manufactured and assembled in North America, mostly in Michigan by automotive suppliers.

Now that the plant is up, Stirling will be able to compare the results its gets from its Stirling engines from heliostat prototype power plants erected by eSolar in Southern California and BrightSource Energy in Israel as well as parabolic trough systems that have already been commercially deployed. Parabolic companies, BrightSource and eSolar collect solar heat on mirrors and use it to heat fluid. The warmth causes the fluid to expand, which creates pressure that gets exploited to crank a turbine.

The Company has publicly quoted a fully-installed cost for grid-scale plants of $2.8 million per megawatt.

Read more here… or here…

Joule Solar Fuel

While producing biofuels from feedstock has drawn heavy criticism, much money and research is being put into next generation biofuels. The world’s largest oil company, Exxon Mobil, that has shunned other forms of renewable energy, has poured billions into next generation biofuel R&D.

One of the most exciting innovations in this field is Joule, a Massachusetts based company.

Joule produces biofuels by mimicking photosynthesis. Their SolarConverter, that facilitates the production process, contains a mixture of brackish water, nutrients, and genetically engineered organisms. Carbon dioxide gas is fed into the mixture, and the device is designed to expose the organisms in the mixture to the sun. The organisms are photosynthetic, meaning that they absorb light energy and carbon dioxide to form compounds. Joule has engineered its organisms to secrete ethanol and hydrocarbons and chemicals.

The organisms mimic photosynthesis and uses sunlight and carbon dioxide to produce liquid fuels and chemicals. According to the company they can produce up to 20 000 gallons (75 700 litre) per acre per year. They are also price competitive with oil at around US $50 per barrel.

Cellulosic biofuels made from wood or grass and algae-based methods reduce water and land needs, but they are currently more expensive than fossil fuels or have yet to become commercially viable.

Another company doing similar work to Joule is Amyris. Amyris uses synthetic biology to create microbes that metabolize sugar and churn out long hydrocarbon chains that are better known as diesel fuel.

Original article: Kevin Bullis. Technology Review. 27 July 2009. Read more…

Direct Carbon Fuel Cells

The Direct Carbon Fuel Cell (DCFC) converts fuel to electricity directly rather than burning it to boil water to make steam to turn a turbine, to turn a generator, to produce electricity. The DCFC can convert solid fuels to electricity at 70% efficiency and reduce CO2 emissions by 50% without sequestration.

A Fuel Cell is an electrochemical device that efficiently converts a fuel’s chemical energy directly to electrical energy without burning the fuel. However, instead of using gaseous fuels, as is typically done, DCFCs use aggregates of extremely fine (10- to 1,000-nanometer-diameter) carbon particles distributed in a mixture of molten lithium, sodium, Yttrium-stabilized zirconium or potassium carbonate at a temperature of 600 to 850°C. The overall cell reaction is carbon and oxygen forming carbon dioxide and electricity.

The reaction yields 80 percent of the carbon–oxygen combustion energy as electricity, yet no burning of the carbon takes place. DCFCs provide up to 1 kilowatt of power per square meter of cell surface area — a rate sufficiently high for practical applications.

The overall process of producing electricity in a DCFC from biomass gains efficiency by its simplicity. It involves only two steps: (1) drying (and/or pyrolysis, or hydrothermal carbonization) to obtain char, and (2) feeding the resulting fuel directly to the DCFC.

If the carbon feedstock for the fuel cell were to be derived from biomass, and the CO2 captured and sequestered, super-efficient carbon-negative electricity would be generated. That is: electricity the use of which results in the active removal of CO2 from the atmosphere

DirectCarbon, a company spun out of Stanford University in 2006, are currently trying to commercialise this technology. Great progress has also been made at the Max Planck Institute in Germany and the University of Queensland in Australia.

For more information read here orhere.

More renewable energy sources added to REFIT

Biomass, biogas and three varieties of solar power technology were on Friday added to the list of renewable energy sources that qualify for feed-in tariffs to be paid by Eskom.

The tariffs, known in South Africa as Refit, are set to top up earnings of independent power producers (IPPs). They are determined by the National Energy Regulator of SA (Nersa).

The latest tariffs are

• R3.13 a kilowatt-hour for concentrating solar power without storage;
• R3.94 for grid-connected solar photovoltaic systems producing more than 1 megawatt;
• R1.18 for solid biomass;
• 96c for biogas; and
• R2.31 for concentrating solar power with six hours of storage.

It estimated that the cost of generating electricity from coal would more than triple from 51.9c a kilowatt-hour this year to R1.66 in 2030, while the cost of power from nuclear sources would increase from 72c a kilowatt-hour to R1.76.

Meanwhile, the cheapest renewable generation technology in two decades would be landfill gas at 75c a kilowatt-hour, down from 90c currently, Nersa forecast. The next cheapest source would be biogas at nearly 87c a kilowatt-hour, against 93c currently.

Wind and biomass were projected to be the next cheapest in 2030 at about 89c a kilowatt-hour, down from R1.25 and R1.18, respectively.

Original article: Ingi Salgado. Business Report. 2 November 2009. Read more…

World’s largest solar project planned in Sahara

If just 0.3% of the Saharan Desert was used for a concentrating solar plant, it would produce enough power to provide all of Europe with clean renewable energy. That is why 20 blue chip German companies are gathering in July 2009 to discuss plans and investments to create such a massive project. Both the meeting and project are being promoted by the Desertec Foundation, which is proposing to erect 100 GW of concentrating solar power plants throughout Northern Africa.

The red squares in the map to the right represent the land area necessary to meet the energy demand of the world, the EU and MENA in 2005. The last square represents the land necessary for the proposed project to generate 100 GW of concentrating solar power. The project being proposed by Desertec would not all be situated in one location, but scattered throughout politically stable countries. Taken as a whole, the project qualifies as the world’s largest solar installation – 80 times larger than the PG&E and BrightSource project planned for the Mojave Desert. The power generated would be transported over high-voltage DC lines across the Mediterranean Sea to Europe, where it would supply 15% of the energy demand. The project is still 10-15 years from going online, but that’s why major players are getting started now.

Read more

Hydrogen car to be ‘open-source’

The manufacturer of a hydrogen car unveiled in London recently will make its designs available online so the cars can be built and improved locally.

The Riversimple car can go 80km/h and travel 322km per re-fuelling, with an efficiency equivalent to 127 kilometers per litre. The company hopes to have the vehicles in production by 2013. Next year, it aims to release 10 prototypes in a UK city which has yet to be confirmed. Riversimple has partnered with gas supply company BOC to install hydrogen stations for the cars in the city where the prototypes are launched.

The car is an amalgam of high-efficiency approaches in automotive design. Its four motors are powered by a fuel cell rated at just six kilowatts, in contrast to current designs that are all in excess of 85 kilowatts – required because the acceleration from a standing start requires a great deal of power.
Read more

Video: Mr W

Could energy success backfire in the end?

A very thought-provoking article from the New York Times that challenges us to think into the potential effects of success in solving our energy / climate challenge. The core question is whether we would be responsible enough in our attitudes and values to handle the consequences of abundant
(renewable) energy.

Original article: Andrew Revkin. The New York Times. 10 February 2009. Read more…

Renewable feed-in tariffs announced

In a much anticipated move, NERSA has approved feed-in tariffs for renewable energy that will encourage investment by private power producers.

“The approved REFIT guidelines will create an enabling environment for achieving the government’s 10,000 GWh renewable energy target by 2013 and sustaining growth beyond the target,” Thembani Bukula, regulator member for electricity regulation, said in a statement.

The following tariffs have been agreed for South Africa:

• R1.25 for each killowatt hour produced from wind,
• R0.94 for the same from hydro,
• R0.90 rand for electricity from landfill gas and
• R2.10 for power from concentrated solar.

These rates are significantly higher than the R.60 – R0.74 range proposed in a December ’08 consultation paper.

According to NERSA the tariff will be reviewed every year for the first five years and every three years after that. Tariffs will only apply to new projects.

Student Invents Solar-Powered Fridge for Developing Countries

Proving once again that the best ideas are often the simplest, 21-year-old student/inventor/entrepreneur Emily Cummins has designed a brilliant portable solar-powered refrigerator that works based upon the principle of evaporation. Employing a combination of conduction and convection, the refrigerator requires no electricity and can be made from commonly available materials like cardboard, sand, and recycled metal.

Simply place perishable foods or temperature-sensitive medications in the solar refrigerator’s interior metal chamber and seal it. In-between the inner and outer chamber, organic material like sand, wool or soil is then saturated with water. As the sun warms the organic material, water evaporates, reducing the temperature of the inner chamber to a cool, 6 ºC [43 ºF] for days at a time!

Original article: Daniel Flahiff. Inhabitat. 12 January 2009. Read more…

Next Page »