Archive for the ‘’ Category
November 30, 2009
From November 30 – December 12, Salud del Sol’s Director of Development, Anna Young, will be participating in the Young Leaders Program of the Global Insitute For Tomorrow, an independent social venture think tank dedicated to advancing understanding of the impacts of globalization.
The Program begins with 4 days of classroom learning in Hong Kong, with participants from around the world, including Malaysia, Australia, Thailand, China and Belgium. Following these classes, participants will travel to Aceh, Indonesia to work in partnership with a local farmers cooperative and the UNDP to create a sustainable business plan for the cooperative.
It will be an incredible experience– check back for updates from Asia!
November 22, 2009
A Brief Overview of Concentrated Solar Power Technology
By Matt Pittinger
Two main types of solar power plants dominate the utility industry today, Photo voltaic power plants (PV) are large arrays of solar panels grouped together to produce electricity. These solar panels, very similar to panels you can put on your house, use light photons that react with a thin layer of silicon to excite electrons and produce electricity. Unfortunately, this technology is still rather expensive.
The technology many utility companies are now using is concentrated solar fields. This is a simpler, more cost effective option for solar power, and can even be more easily utilized in developing countries. Parabolic shaped solar concentrators are U shaped to catch, and reflect the sun into a single focal point. When these concentrators are aligned in a row, thousands of focal points create a line of concentrated solar energy. Placed exactly along this focal line is a tube receptor filled with fluid that is then heated to extremely high temperatures. This fluid can then be used by the power plant to create steam, and turn a turbine to produce electricity. A picture of a solar parabolic concentrator can be seen below.
Image 1: Parabolic Solar Concentrator (Photo from Greenterrafirma.com)
Recently there has been a new development in solar concentrating power using Fresnel lens technology. The Fresnel lens, first developed for light houses to cast a brighter beam of light, is now being used in place of parabolic concentrating troughs. By angling flat mirrors towards a single focal point, a similar focal line can be achieved. And, similar to the parabolic mirror, a receiver filled with fluid can then be heated and used to create steam. This steam then goes through the same turbine generator process to create electricity.
Image 2: Concentrated Solar Fresnel Array (Photo from csposi.org)
There are many benefits to this Solar Fresnel array over the traditional parabolic concentrator. Fresnel lens concentrated solar is much less expensive to build. They do not use the more expensive, curved mirrors to concentrate light. This is a very important aspect for Salud del Sol as a company because it is one of our main goals to promote projects that can be made in the regions that we serve. Parabolic reflectors drive up the cost of a concentrated solar project and they are not as prevalent in developing countries such as Nicaragua. Flat reflectors can be manufactured more easily and cost significantly less.
Another benefit to Fresnel technology over parabolic technology is the wind factor. Parabolic reflectors are larger and tend to catch the wind more easily. These wind gusts cause the focal point to shift, dropping the effectiveness of the solar concentration. A Fresnel array utilizes smaller mirrors which are typically closer to the ground and in turn catch less wind. Also, since the Fresnel mirrors are closer to the ground, they cast less of a shadow. With fewer shadows, concentrators can be put closer together and thus save space. If solar power concentrators interest you, there are many different resources online that can tell you more.
Some of my favorite sites are:
1. www.nrel.gov
2. www.solarbuzz.com
3. www.ases.org
Resources:
1. http://www.nrel.gov/learning/re_csp.html
2. http://greenterrafirma.com/
3. www.csposi.com
4. www.solarbuzz.com
Subscribe to Salud del Sol- MIT Global Challenge Award Winners May 4, 2011 Bill
- MIT Global Challenge Awards Replay May 3, 2011 Bill
- 2011 IDEAS Competition & MIT Global Challenge Awards Celebration April 29, 2011 Bill