Do you know about the Climate Security Act? It is a bipartisan bill introduced to the Senate in 2007 by Senator Lieberman (I-CT) and Senator John Warner (R-VA). It is the most comprehensive global warming bill to make it out of committee. Read more about it and send a letter to your Senators from National Wildlife Federation’s Climate Action Center.

Surf around on the NWF page to learn more about topics like the Arctic Refuge and the Everglades.

Last night I attended a panel titled “Clean Technology - Sustainable Growth: Innovating and Implementing in the Developing World.” The panel was at Santa Clara University and sponsored by the California Clean Tech Open and the university’s Engineers Without Borders student chapter. Outside the theater there were some displays set up showcasing some of the SCU Engineers Without Borders projects, including the low pressure solar distillation apparatus pictured on the right. Other displays showed low cost building insulation derived from denim and pictures from previous projects.

The main assembly began with a presentation by an SCU-EWB co-chair, Yasemin Kimyacioglu, about the low pressure solar distillation project. The apparatus uses an array of solar tubes and coper pipe to pre-heat the water. An electric powered vacuum allows the water in the pressure cooker to boil at 57 degrees Celcius, rather than the normal 100 degrees. The purified steam runs through a condensing coil which utilizes the original contaminated water as a coolant. The prototype is nearly complete and testing will begin soon. There are still some technical hurdles to overcome before deployment, such as elimination of the contaminants from the pressure chamber.

The panel began immediately following the SCU EWB presentation. It was moderated by R. David Hague, VP of Business Development at GreenMountain Engineering, a consulting firm focused on renewable energy and clean technology. The panel included:

• Patrick Freeburger - Co-founder of BuildFast, winner of the CCTO 2007 prize for Green Building
• Rebeca Hwang - Co-VP BASES Social E-Challenge and Judging Chair for CCTO
• Dr. Ashok Gadgil - Senior Staff Scientist at Lawrence Berkeley National Laboratory
• John Rockwell - Managing Director, Element Partners, a clean technology investment firm

The bulk of the panel session centered around the problems with deploying clean technologies in the developing world. One of the main problems is a difference in values. Each panelist had a personal anecdote illustrating the common misunderstanding of the problems people in the developing world face. For example, Ms. Hwang described a project to deploy water filters in Nicaragua only to find the local men would rather spend their money on beer. Dr. Gadgil told of an unsuccessful attempt to utilize cheap, single family open space housing plans in Afghanistan, where extended families live together with separate areas for the men and women.

Mr. Rockwell pointed out that the only way to be successful in the developing world is to figure out how to make money. Mr. Freeburger described how his company, BuildFast, changed their business model from building complete housing solutions to providing key materials and knowledge to local builders. Dr. Gadgil pointed to SELCO in India as a good example of meeting the needs of the local people. They provide renewable energy solutions to Indian homes and businesses which could not normally afford them. They are able to replace kerosene lighting with CFLs powered by batteries charged by solar arrays. The service provides pre-charged batteries and the lighting solution delivered where needed replacing kerosene with a clean, more affordable, better lighting solution.

Understanding the culture, the value and needs are more important in many ways than the technology. You can be the foremost authority on water decontamination, but unless you really understand the local situation, your solution will probably not be successful. You are simply adding to the junkyard of Western technologies in the third world, as Dr. Gadgil called it. Sometimes you need to learn before you can teach.

Solar Energy covers a broad spectrum of energy from the Sun. Light and heat are the primary forms of this energy. They can be used directly or converted to other forms of energy such as electricity. The Sun is also indirectly responsible for other forms of renewable energy such as biomass (photosynthesis), hydroelectricity (evaporation), wind (thermal variation) and waves (from wind). All told, the Sun is responsible for more than 99% of the available renewable energy on Earth.

The total solar energy absorbed by the Earth’s atmosphere, oceans, and land masses is approximately 3850 ZJ (10²¹ Joules). The total worldwide energy consumption in 2004 was 0.471 ZJ. The picture above on the left shows the solar radiation breakdown. The picture on the right shows the average insolation at the Earth’s surface. The black dots on the right-hand picture indicate the total land area required to replace the entire world energy supply with solar cells. So the energy is is there, the question is, how do we make use of it?

For the sake of this article, I will focus on solar power, or the the conversion of solar energy into electricity. There are two primary methods of converting the Sun’s energy to electricity: photovoltaics and concentrators.

Solar Photovoltaic (PV)

For solar photovoltaic (PV), solar cells make use of the photoelectric effect (picture on right) to generate electricity. This effect refers to the process where a material is exposed to electromagnetic radiation causing it to emit electrons. Solar cells have been around since 1883 and were commonly seen a the power sources for satellites and later calculators.

Most modern solar cells are based on silicon or some similar semiconductor material. The cells are often joined into modules with a glass sheet on the top which provides protection for the cells while allowing light to pass through. The amount of electricity produces by a module depends on the materials used and sometimes a lens is used to direct more light to the individual solar cells. Multiple modules are used in conjunction to produce more electricity. Large farms of panels can be installed in open areas with lots of direct sun. For maximum effectiveness, the panels can be mounted on platforms capable of tracking the Sun.

PV modules or panels are becoming more common on commercial and residential buildings. They are typically installed on the roof at an angle to catch the most sunlight possible. The panels produce direct current electricity which is passed through an inverter to create alternating current which can be fed directly to the building’s electrical grid.

Solar Concentrators

The idea behind solar concentrators is to focus the heat from the Sun to drive more traditional means of electrical generators such as steam turbines. This generally means reflecting the light into a concentrated beam. The beam is then used to super heat the working fluid which in turn drives an electric generator. To maintain maximum heat, the concentrators use complex tracking systems. While there are many different implementations of solar concentrators, the most common forms are solar trough, parabolic dish and solar towers (pictured on right). The solar trough makes use of a linear parabolic reflector which concentrates light on a tube of working fluid located at it’s focal line. The parabolic dish focuses on a single point of working fluid, but can track the sun on both axes. A solar tower uses a large array of tracking mirrors to focus light on a central tower containing the working fluid.

Problems with Solar

While solar power has a lot of potential, there are some problems as well. One of the biggest problems for solar is availability,that is to say, the sun is not up 24 hours a day, and the skies are not always clear. There is plenty of solar energy available to produce extra power for use at night, but the technology to store the power is sorely lacking. Transmission could be another issue, where you need to get power from a sunny desert to a cloudy coastal town. The transmission issue exists even for traditional power generation, but is exacerbated by a more limited number of locations to install a solar plant. PV systems can eliminate the transmission issue all together since they can be installed at the end use site. Even then, the storage problem remains and becomes more pronounced if the location does not have adequate sunlight to begin with. Another issue for PV is the availability of the semiconductor material.

I believe solar will be a big part of the future energy equation. It seems almost crazy not to take advantage of the most abundant source of clean energy around. We need to keep improving the conversion technologies as well as push for better storage and transmission solutions. As for which of the solar technologies will win, I think they both have an important role. PV can be used in area with good sunlight to keep homes and businesses off the grid. Good local storage systems can keep a home running through the night. Solar concentrators with improved transmission technology can supply power to areas with insufficient sunlight. Perhaps power storage can be as simple as an underground steam reservoir which is heated in the day and used to power the generators at night or on cloudy days.

The sun is the largest power plant in our galaxy, let’s use it as best we can.