Geothermal Heat Pumps

Geothermal Heat pumps use the energy stored in the earth's surface to provide heating or cooling depending on the ambient temperature of the surroundings. The temperature a few feet below the earths surface is shown to be constant year round between 50 and 60 degrees Farenheit. The heat pump uses this temperature difference to operate, providing cooling for the house in the summer and heating for the house in winter times. Geothermal heat pumps are usually used in a central air conditioning system. The major challenges to implementing such a system are the initial expense for installation and choosing the type of piping system to use for heat exhange. The energy needed for operation is used to pump and pressurize the water and blow air into the house, in addition to that geothermal systems are designed to last a very long time, at least 25 years but if properly maintained 50 years is possible.

Photovoltaics with a difference

I was always told photovoltaics were expensive and that sometime in the future, technological advances would make them affordable to use, it seems like that time is near. The major costs for conventional solar panels were in the areas of acquiring the high quality silicon needed as well as high production costs and low utilization of the materials. Recent advances in technology has allowed for companies to create photovoltaic products that does not use silicon and whose production costs are slashed and material utilization increased greatly. The most promising technology right now is CIGS ( Copper Indium Gallium Selenide) ink technology where the photovoltaic ink is printed onto a special material. The company at the forefront of implementing this technology is Nanosolar, however several other companies are beginning to enter this area including Konarka, Miasole, Solopower and Solyndra. Most have just started large scale production and products will not be on the market for at least another year. The only downfall of this technology is its efficiency, the highest efficiency attained in lab tests approached 20 % and for applications efficiencies will be around 13%, however a 5% decrease in efficiency is small compared to a production cost a half or less of the conventional cost

The Power of the Sun

Most of us have heard about photovoltaic panels, but not about solar air conditioning. The technology behind solar air conditioning is actually quite old, however we have not been able to put it to good use until now, mainly because of the lack of adequate equipment. There is an Austrian company called Solar Installation + Design (SOLID, www.solid.at) that specializes in implementing these systems, their projects include installations on the Arnold Schwarzenegger Stadium in Austria and also in certain structures that will be used in the 2008 Beijing Olympics, among other places. It uses an absorption chiller in conjunction with special solar panels, heat exchangers and pumps to cool the air. I was able to be at one of their presentations and learn more about their systems and these are a couple things I was told.

• Solar Air Conditioning is geared to supplying a commercial space with cool air.
• It can be retrofitted to an existing central air conditioning ducting system.
• If needed it can provide hot water as well.
• Only uses electricity for pumps and fans, which can be supplied by photovoltaics or other renewable sources if needed.
• Cheaper to implement than Photovoltaics (in cost installed per kW supplied)
• Usually does not require much roof space for installation.
• Payback period ranging from 5-10 years.
• Minimum useful life of 25 years.