Block’s Indicator of Sustainable Growth

by Ray Block

 The US Department of Energy is proactive in encouraging energy efficiency and renewable energy. It is a model in action for governments around the world, which not only want to preach about the need to reduce greenhouse gases, but also achieve something positive about it in a practical way.

 

My attention was drawn to two recent examples:

Ø      Adding solar energy to coal fired power plants.

Ø      Encouraging research and development in solar air conditioning. 

 

Adding solar energy to coal fired power plants

 

While carbon capture and storage (CCS) is a great goal to reduce greenhouse gases from electric power stations, it is highly unlikely that the research will have been commercialised before 2015-2020. As the energy efficiency and renewable energy service of the US Department of Energy says: CCS “will probably have limited value for coal fired power plants that are operating today.”

 

R&D by the Electric Power Research Institute (EPRI) is studying the potential to add solar power to existing power plants. An electric utility operating in Colorado, Nebraska, New Mexico and Wyoming, along with a utility headquartered in North Carolina is evaluating the potential to add solar thermal energy systems to the utilities’ power plants in Prewitt, New Mexico and Roxboro, North Carolina.

 

EPRI is also studying the potential to add solar thermal energy systems to natural gas fired power plants in Kingman, Arizona and Las Vegas, Nevada.

 

Solar thermal is a US technology involving building fields of mirrors adjacent to a power plant, to focus the sun’s heat and boil water into steam, which is integrated into the steam cycle of the coal fired power plant. The aim is to either reduce the coal usage or to increase the electric power production. The net balance is to reduce the carbon intensity of the power produced at the plant.

 

Encouraging research and development in solar air conditioning

 

The US Energy Independence and Security Act of 2007 created funding through 2008 to 2012 for a new solar air conditioning R&D program, the aim being to develop and demonstrate multiple new innovations and mass production economies of scale. “Solar air conditioning will play an increasing role in zero energy and energy-plus building design.”

 

Multifunctional solar devises (all in one solar panels and solar thermal) harvest both light and heat from the sun.  Traditional solar PV (photovoltaics) cells “only harvest light and are only around 23 per cent efficient in converting PV to electric power. Solar thermal systems collect heat and are about 48 per cent efficient at best.” 

 

The quote comes from a solar thermal start up Chromasun, which will market itself as a specialist in air conditioning. It was co-founded by Peter Le Lievre, a former CEO of solar thermal specialist, the Australian start up Ausra, which migrated to California.

 

Cleantech Media (March 16 2009) reports that Chromasun’s prototype device claims a 75 per cent efficiency. Mass production is expected to be in the March quarter 2010.

 

The solar air conditioner contained in a sealed box unit is operated with mirrors, measuring 0.3mm thick. It is essentially a utility scale solar thermal plant, the mirrors tilting with the sun, along with receivers and a concentrator. At the same time, it is a solar PV plant in miniature.  The unit has a US cost payback of two to four years.

 

Geographically, the unit is more suitable for dry heat regions, as in the US south west, Southern Europe, North Africa and Middle East, South and West Australia. By comparison, the unit is less efficient in humid heat conditions.

 

In Californian peak energy cost terms, the Chromasun unit is very competitive, compared with electrical and natural gas air conditioners.

 

 

 

 

 

 

 

 

 

Posted under Climate Change, Global Warming, Low Carbon Economy, Renewable Energies