Geothermal power, like many renewable sources of power, is more readily available in some geographical locations than others. For example, Iceland has a lot of surface level geothermal activity, and produces nearly 20% of its electricity and heats more than 85% of its homes using this resource. But Iceland is one of just over 20 countries around the world that utilize geothermal power.

Geothermal resources have been used for centuries for bathing and heating. It wasn’t until 1904 that the first geothermal power generator was tested in Italy. The first commercial geothermal power plant was built in the same location in 1911. New Zealand built the second commercial plant nearly 50 years later, in 1958. Most of these early power plants relied on existing steam vents. Hot Dry Rock (HDR) geothermal power was developed by pumping water down into the porous hot rock a few kilometers below ground. The resulting steam powers generators and is recollected as water to be pumped into the ground again. Enhanced Geothermal Systems (EGS) use cold water or chemicals to create the cracks and pores necessary to generate sufficient steam and therefore power. As EGS technologies continue to improve, the energy potential for geothermal can reach 2,000 ZJ as reported by an MIT study in 2006. The study predicted that this would be enough to sustain the worlds present energy consumption for several millennia.

Like solar and wind, geothermal power utilizes a free source of energy with very little harmful emissions. Unlike solar and wind, geothermal power is fairly constant and unaffected by the weather, allowing it to be easily used for base load power generation. It is considered nearly sustainable since the heat extraction is small relative to the total heat reservoir. Geothermal power is already economically competitive in some geographic locations and can often scale to provide large generation capacity. The largest dry steam field in the world is at The Geysers, north of San Francisco, CA, which can produce 1,360 MW of electricity. One of the power plants at The Geysers is pictured on the left.

There are some drawbacks to geothermal power. Geothermal fluids are corrosive and realtively low temperature (compared to steam). The lower temperature causes less efficient transfer to power. Trace amounts of toxic elements such as mercury and arsenic may also be present, so the fluids must be disposed of properly. Some systems such as EGS can cause land stability due to the injection of water. Some plants emit low levels of carbon dioxide, nitric oxide and sulfur, but at roughly 5% of the level of fossil fuel plants. Most of these emissions can be captured and sequestered back in the earth to drop the emission levels to less than 0.1%. While the overall geothermal source is relatively limitless, some local cooling may occur. Care must be taken to design plants at sustainable production levels, allowing their heat reserve to replenish from deeper in the earth’s mantle.

Like most of the renewable sources I have looked at, geothermal is probably not the single answer to the problem. However, it appears to be a viable solution for large base load power generation which can be supplemented with various other renewable sources. My next challenge is to start a head-to-head comparison of the various energy sources to really see how they stack up over a full life cycle assessment; or maybe I’ll take the easy way out for now and jump into transportation alternatives. Check back to find out!

“We’re borrowing money from China to buy oil from the Persian Gulf to burn it in ways that destroy the planet. Every bit of that’s got to change.”

The former vice president alludes to some of the potential solutions with the following factoids:

• Enough solar energy reaches the earth every 40 minutes to supply 100% of the worlds energy needs for a year.
• Enough wind blows through the Midwest corridor to supply 100% of the US energy needs.
• Geothermal is another relatively underutilized source of energy.

Mr. Gore’s ultimate challenge was this:

“Today I challenge our nation to commit to producing 100 percent of our electricity from renewable energy and truly clean carbon-free sources within 10 years.”

He likened this challenge to Kennedy’s challenge to land a man on the moon and return him safely in 10 years. Mr. Gore makes reference to falling prices of the specialized silicon for solar cells, the continuing performance increases in the semiconductor industry and the rising prices of oil as indicators that now is the time when we can meet a challenge such as this. Mr. Gore also notes some of the obstacles to reaching this goal, such as the need for a Unified National Grid for power distribution and a switch to an all electric vehicle fleet. He also stresses the need for an increased commitment to efficiency and conservation.

The speech includes some specific steps to get us moving in the the right direction. One of his key objectives is to sharply reduce payroll taxes and start taxing carbon emissions. Mr. Gore summed this up with “tax what we burn, not what we earn.” Another objective is for the US to rejoin the global community and lead efforts to secure an international treaty to cap CO₂ emissions.

Personally, I think this is the call to arms we really need to get moving. Unfortunately, unlike JFK in the 60’s, Mr. Gore is not the President of the United States of America. It remains to be seen what sort of influence this former VP and noble prize winner will have on the next administration. Will anyone running for the presidency or any of the top offices in the Congress be bold enough to take up this challenge?

“We must now lift our nation to reach another goal that will change history. Our entire civilization depends upon us now embarking on a new journey of exploration and discovery. Our success depends on our willingness as a people to undertake this journey and to complete it within 10 years. Once again, we have an opportunity to take a giant leap for humankind.”

For more information, join the WE campaign at wecansolveit.org. You can find the text of the full speech here.

While wind has wider distribution and better availability throughout the day compared with solar, it is intermittent. Typical wind farms generate energy at about 20-40% of their theoretical maximum output. The ratio of actual production to the theoretical max is called the capacity factor. For example, a 1 MW wind turbine with a 35% capacity factor will produce 0.35 MW on average. This still leaves the need for either overproducing and storing energy during peak product or reverting to an alternative energy source during low wind periods.

In addition to intermittency, there are some environmental concerns for wind power. While no greenhouse gases are emitted during the operation of wind turbines, there is some concern that due to the intermittent nature of wind generation, the quick-start back up generators may be more polluting than the standard fossil-fuel plant they are replacing. Also, wind farms require large, unobstructed areas of land. There is also a concern that these wind farms have a negative impact on wildlife, especially birds and bats. While some studies have shown significant impact to bat populations in especially sensitive areas, most studies show that the impact on birds is fairly negligible. Another potential concern is whether noise produced by wind towers at sea could pose a risk to ocean mammals.

It doesn’t seem likely to me that wind can solve all of our energy generation needs. It does seems like a good complement to other alternative energy sources. Perhaps a combination of well placed wind farms and solar farms could meet most of the world’s energy needs. It seems like we would still need to make some major improvements in energy storage and transmission for this to come about. I certainly hope we will all start to feel the winds of change…

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

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.

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.

The latest presentation by Al Gore on Climate Crisis (running time 0:27:54), from TED.com. I ran across this video on AlternativeEnergy.com.

One of the guest speakers was San Jose’s mayor, Chuck Reed. He discussed the city’s “Green Vision” which is a 15 year, 10 point plan for the city.  Some key point he mentioned are to create 25,000 clean tech jobs, reduce per capita energy use by 50%, and receive 100% of our electrical power from clean renewable sources. The mayor also challenged the solar industry to come up with a way to deliver residential solar energy at zero cost to the end consumer.

Another guest speaker was David Rodgers of the Department of Energy. One of his key points was the effort by the CCTO and the DoE to duplicate the CCTO in other regions across the country. Marc mentioned that requests have come in for help establishing similar competitions all over the world. It would be nice to see this focus on clean tech start-ups gain some serious momentum.

Tomorrow, March 29, 2008 from 8 to 9 pm is Earth Hour. Earth Hour in an event where millions of people around the world will make a statement about climate change by turning off their lights for one hour. Earth Hour was created by the World Wildlife Fund in Sydney, Australia in 2007. In one year it has grown to more than 200 cities around the globe, including 100 cities in North America.

Unfortunately, I only just heard about this event through a mass mailing from the World Wildlife Fund’s Earth Hour. I have already signed up on the Earth Hour website. There’s no Earth Hour event in my home town of San Jose, CA, but maybe I can help organize one for next year…