The Energy Blog

Emissions from Photovoltaic Life Cycles

A new report has found that thin-film cadmium telluride solar cells have the lowest life-cycle emissions primarily because they consume the least amount of energy during the module production of the four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride (CdTe).

The study, published in the Environmental Science & Technology journal, based on PV production data of 2004–2006, presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions of the four types of PV systems considered. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system.

They found that thin-film cadmium-telluride solar cells had the best life-cycle profile. Even though the process emitted  heavy metal cadmium, it still had a lower overall level of “harmful air emissions” than the other PV technologies in the study.

The report stated that "Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electrity from photovoltaics displaces electricity from the grid."

The fact that Cd-Te technology was found to have the lowest emissions profile is interesting, but the main point, to me, is that all technologies had low emissions profiles, that are insignificant when compared to the emissions of the fossil fuel technologies that they replace. While I do not find it suprising that all solar PV systems have a low emissions profile, I find it suprising that the authors did not include thin-film silicon or copper indium gallium selenide (CIGS) cells in their study.  I assume the overall results would have been the similar, but it woud have given a fairer comparison to the technologies now in use.  One problem with scientific research is that it takes so much time to do the study and get it published that by that time the information is made public it is sometimes outdated.

A Solar Grand Plan

The January 2008 issue of Scientific American has an article titled "A Solar Grand Slam" which outlines a plan in which solar power could end U.S. dependence on foreign oil and slash greenhouse gas emissions by 2050. In a massive switch from coal, oil, natural gas and nuclear power plants to solar power plants, the U.S. could supply 69 percent of its electricity and 35 percent of its total energy by 2050. The four key elements of the plan are:

• A vast area of photovoltaic cells would have to be erected in the Southwest. Excess daytime energy would be stored as compressed air in underground caverns to be tapped during nighttime hours.
• Large solar concentrator power plants, with molten salt storage, would be built as well.
• A new direct-current power transmission backbone would deliver solar electricity across the country.
• $420 billion in subsidies from 2011 to 2050 would be required to fund the infrastructure and make it cost-competitive.

The article goes into quite a bit of detail about how the plan would be implemented and financed.

The plan also states that "If wind, biomass and geothermal sources were also developed, renewable energy could provide 100 percent of the nation’s electricity and 90 percent of its energy by 2100."

This comprehensive study is well done and well worth a read.  I disagree on their definition of what is a vast area of photovoltaic cells, which I find reasonable, especially as their estimate of the land required is very conservative compared to other studies.

I also do not see why so much power has to be provided by solar, as other, just as clean sources, could contribute considerable power, especially in the short run.

Unfortunately their study ended before two recent announcements:

1) That Nanosolar producer of thin-film CIGS solar cells, made using nanoparticle ink and roll-printing technology, has begun production of cells that will sell at $0.99 a Watt when their 430. ,000 Mw production facility in CA and a similar facility in Germany are completed. Costs are reduced because, not only by their production technology, but also because their cells and panels are the first ones to have been designed specifically for utility-scale power generation.

and 2) That Ausra which is providing a 177 Mw thermal solar facility for PG&E has begun construction on a 700 Mw production facility which is scheduled to start delivering equipment in April 2008. Ausra claims that It can generate electricity for 10 cents/kWh now and under 8 cents/kWh in 3 yrs (presumably not including storage, which would add another 2 or 3 cents). They claim that all U.S. electric power, day and night, can be generated using a land area smaller than 8,500 sq miles using their equipment.

Noted in Passing: Solar is the Solution

The current edition of Mother Earth News has an excellent post on why Solar energy is the best solution for our energy needs.

Steve Hollerith writes:  I have been studying our energy options for more than 30 years, and I am absolutely convinced that our best and easiest option is solar energy, which is virtually inexhaustible.

Read this interesting article to see if you agree. 

Thanks to Robert Rapier of the R-Squared Energy Blog for the tip.

Solar Installations up 33% in US in 2006, 41% in World, Solar Capacity only Utilized 62%

In an update on the solar industry Solarbuzz reports that the installation of solar photovoltaic (PV) devices in the United States increased by about 33 percent in 2006 over the previous year. Worldwide PV installations totaled 1,744 megawatts (MW) in 2006, a new record and a growth of 19 percent over 2005. The United States contributed just 8 percent of those installations, or about 140 MW, while Germany led the world market with 960 MW of PV installations, comprising 55 percent of the world's total PV installations for 2006. To supply that market, the global production of solar cells reached 2,204 MW in 2006, a growth of 33 percent over PV production in 2005, while the production of polysilicon a critical ingredient for silicon solar cells increased by 16 percent.

The Photovoltaic Service Program at Navigant Consulting has published a “Pre-Release” of its quarterly PV industry newsletter, Solar Outlook. The feature article in the release is an analysis of 2006 PV technology shipments. The PV industry grew by 41%, the same rate as the CAGR from 2000 to 2006. In 2005, thin film technologies were 6% of total shipments. Thin films increased their share of total to 7% in 2006, and are on track to increase by another percentage point, to 8% in 2007. Many more facts are included in the referenced pdf.

Notice that the Solarbuzz numbers are for global production, while the Navigant numbers are for shipments, perhaps explaining the difference in numbers or it may simply be a matter of discrepencies in data collection.

TOP TEN SOLAR MANUFACTURERS

RANKING	2004	2005	2006
1	Sharp Solar	Sharp Solar	Sharp Solar, 22%
2	Kyocera	Kyocera	Q-Cells, 12%
3	BP Solar	Q-Cells	Kyocera, 9%
4	Shell Solar	Shott Solar	Suntech, 8%
5	Q-Cells	BP Solar	Sanyo, 6%
6	Shott Solar	Mitsubishi Electric	Mitsubishi Electric, 6%
7	Sanyo	Sanyo	Shott Solar, 5%
8	Mitsubishi Electric	Shell Solar	Motech, 5%
9	Isofoton	Motech	BP Solar, 4%
10	Motech	Isofoton	SunPower, 3%
Total Shipments	1049.8	1407.7	1982.4

DOE Selects 13 Projects for Solar Technology Development

U.S. Department of Energy (DOE) Secretary Samuel W. Bodman on February 8 announced the selection of 13 industry-led solar technology development projects for negotiation for up to $168 million (FY’07-’09) in funding, subject to appropriation from Congress.  These projects will help significantly reduce the cost of producing and distributing solar energy.  As part of the cost-shared agreements, the industry-led teams will contribute more than 50 percent of the funding for these projects for a total value of up to $357 million over three years. These cooperative agreements, to be negotiated, will be the first made available as part of President Bush’s Solar America Initiative (SAI), a component of his Advanced Energy Initiative (AEI), announced in his 2006 State of the Union Address. 

These projects enable the projected expansion of the annual U.S. manufacturing capacity of PV systems from 240 MW in 2005 to as much as 2,850 MW by 2010, representing more than a ten-fold increase.  Such capacity would also put the U.S. industry on track to reduce the cost of electricity produced by PV from current levels of $0.18-$0.23 per kWh to $0.05 - $0.10 per kWh by 2015 – a price that is competitive in markets nationwide.

Santa Monica Aims to be "Net Zero" City

John Addison writes in his blog about the city of Santa Monica, CA and its plans to be the nation's first "Net Zero" city. Through energy efficiency, solar and other renewable energy, the city hopes to generate enough clean energy to match its total energy consumption. Two paragraphs from the post and you can read the rest at Cleantech blog.

Solar Santa Monica formally launches a two year program on January 1, 2007. The voluntary program will start with 50 residential and commercial buildings. With the benefit of what is learned from these 50 projects, the program will be made available to all. The 50 buildings will include 30 to 35 residences, 5 to10 business and 5 municipal buildings.

Susan Munves estimated that over 20 years, $1.4 billion is the probable investment required to achieve being a “Net Zero” city. This is likely to offset a utility electric charges which would be higher than the $1.4 billion.

Solar Energy Tax Credit Extended One Year

From the Solar Energy Industries Association via Neal Dikeman in the Cleantech Blog:

"In its waning hours, the 109th Congress today passed legislation that would extend the 30% solar energy investment tax credit (ITC) for homeowners and businesses for one additional year, through the end of 2008."

Neal has some good, bad and ugly comments on this legislation.

Rand: 25% of Energy from Renewables by 2025

The Wall Street Journal reports that a Rand Corp. study shows that if the the falling costs of ethanol, wind power and other forms of renewable energy continue to fall, as they have historically, such sources could supply as much as 25% of the U.S.'s conventional energy by 2025 at little or no additional expense.

This is certainly good news if costs continue to drop as they forecast, the problem they didn't mention is whether the manufacturing infrastructure can expand that rapidly.

The Rand study concludes that because prices for gasoline, natural gas and coal are likely to remain high, their cost advantage over renewables will erode, furthered by the hope that ethanol from farm wastes will be available by 2020.

I would agree that fossil fuel costs will remain high and that would allow cellulosic ethanol to be, not only competitive, but lower in cost than fossil fuels.

Houston, MS High School Wins Dell-Winston School Wins Solar Car Challenge

The Houston, Mississippi (population 4,079) Sundancer solar car team won the Dell-Winston School Solar Car Challenge open division championship trophy at Texas Motor Speedway for the sixth consecutive year. During the challenge’s four days and seven racing periods of three hours each, the Sundancer solar car traveled more than 619 miles (413 laps), at an averaged a speed of almost 30 mph, reached a top speed of approximately 60 mph and completed more laps than any of the 13 other cars competing in the race.

Heating and Cooling from the Sun

Harnessing the heating - and cooling - powers of the sun from PhysOrg.com
Imagine heat radiating from the walls of your home on a cold winter night, or the glass in your home's windows emitting cool temperatures on a scorching summer afternoon. Now imagine these systems operating on an endless supply of affordable energy – the sun. Three years ago a team of Rensselaer Polytechnic Institute researchers began developing an "intelligent" heating and cooling system that made these seemingly too-good-to-be-true scenarios a possibility.

Developed by Steven Van Dessel, assistant professor of architecture at Rensselaer, the patented Active Building Envelope (ABE) system uses a photovoltaic (PV) system to collect and convert sunlight into electricity. That power is then delivered to a series of thermoelectric (TE) heat-pumps that are integrated into a building envelope (the walls,windows, and roof). Depending on the direction of the electric current supplied to the TE heat-pump system, the sun's energy can actively be used to make the inside space warmer or cooler. An energy storage mechanism is also integrated to collect extra energy for use when little or no sunlight is available.

Energy Usage Forecast

The June issue of Popular Science features an article on energy technologies that they say will cut our oil consumption in half and reduce our dependence on fossil fuels to produce electricity almost entirely by 2025.

They forecast that ultralight parts and plug-in hybrids could reduce fossil fuel consumption by 19% and that use of biofuels could reduce fossil fuel consumption by 30%.

Electricity needs could be reduced by the following technologies and conservation.

Home Electricity Conservation - 36%
Wind - 20%
Biopower - 17% (biomass gasification and methane generation)
Distributed Generation - 10%
Solar Power - 10% (PV and thermal solar power)
Geothermal Power - 5%
Ocean Power - 2% (wave power and tidal power)

While I don't think that I would have come up with the same numbers, the numbers give some idea of what mix of technologies could be used to reduce our dependence on fossil fuels.  My two concerns are that, while that degree of conservation proposed is possible, electricity costs would have to be extremely high before sufficient motivation for this degree of conservation would be possible.  After reducing consumption as much as forecast by conservation the percentage of electricity produced by wind, solar, and ocean power is higher than could easily be integrated into a grid, without massive energy storage or a much stronger grid, because of the intermittency of these generation methods.  Economical energy storage on a large scale is unlikely by 2025.  Geographical separation of these methods in an area as large as the U.S. reduces the effects of intermittency, but a much stronger grid is required to transport the energy from one area to another which would mean a very costly investment in the electrical infrastructure.  The area between the great plains and the east coast is not especially suitable for these methods and the grid would have to be reinforced significantly in this area. Superconducting power transmission would be especially useful, but development of economical systems is progressing rather slowly, although some usage could be expected by 2025.

I would hope that plug-in vehicles would be in wider use by this time, but that is very dependent on the acceptance of the technology by manufacturers. Their forecast for use of biofuels, although possible someday, is very unlikely by 2025.

The articles (without statistics) can be viewed at http://www.popsci.com/popsci/energy/

Solar Energy’s Bright Future

A very rosy picture is painted for the solar industry in this article in Red Herring. A good read.  Some short excerpts:

During the last year, solar power got more buzz with each oil and natural gas spike ... Some solar stocks doubled in just the last three months ... The worldwide solar market grew from $8.3 billion in 2004 to more than $12 billion in 2005 ... expects the market to top $16 billion this year and $40 billion in 2010 ... That still leaves a peanut-sized industry compared to fossil fuel—a trillion-dollar-plus market ... It’s not a matter of if solar will play a big part in electricity generation, but when. ... That’s one reason why plenty of venture capitalists are happy to bet on these companies. Energy is one of the greatest problems facing the world ... Peak times, 8 a.m. to 6 p.m., roughly correspond to when the sun shines. In some parts of California, solar prices now match peak power prices, even when incentives are excluded.

Technorati tags: solar, solar power, energy, technology

The Energy Blog: Solar Energy’s Bright Future

Solar Powered UAV

QinetiQ, Europe's largest science and technology organization, has completed the first flight trials of Zephyr - a High-Altitude, Long-Endurance Unmanned Aerial Vehicle (UAV) that has a 12 meter (39 ft) wingspan but weighs just 27 kilograms (59 pounds).

The trials took place at the White Sands Missile Range, New Mexico, USA. Two aircraft were flown for four and a half and six hours respectively, the maximum flight times permitted under range restrictions. The maximum altitude attained was 27,000 feet above sea level.

Solar Energy from Space

The following press release reports on an article that appeared in the March issue of Time Warner's Business 2.0 magazine that included plans for Space Island Group (SIG) to supply energy from space to any point on earth beginning in the next decade.  According to SIG's website, "... solar satellites (will be) launched, assembled and operated cheaply enough to profitably sell their power for ten cents per kilowatt-hour. Conversion of 90% of Earth’s power needs to solar power generators could be completed by 2050, giving companies and employees several decades to adjust to this new technology."  This company has the appearance of a very serious company committed to their plan. Take a look at their extensive description of what they plan to do at their website. What do you think?

WEST COVINA, CA, Mar 16, 2006 (MARKET WIRE via COMTEX) .... According to B2.0, early in the next decade SIG will begin placing huge, mile-wide sheets of solar cells in earth orbit. These NASA-designed structures, called solar power satellites, will convert sunlight into electricity, then use weak, pollution-free, environmentally safe microwave beams to send that energy down to simple antennas anywhere on Earth. The antennas will convert the beams back into electricity and feed it into standard existing power grids at an extremely low cost. The system will operate 24/7 overcoming the drawback of rooftop solar cells and windmills.

Solar Overview on CNET

An overview of the solar industry on CNET's News.com courtesy of Clean Break gives a review of the some of the companies involved in the various solar technologies that regular readers of The Energy Blog will recognize. The article is worth a read. The article is written from the perspective that if so many venture capitalists are putting money into these technologies it must be a sign that it is the real thing. It adds a few more names that I will have to investigate and perhaps be the subject of a future post.  Surprisingly it does not mention some of the companies that are leading the charge.  There are so many new companies in the solar arena that we are going to have a period of significant drop-outs or consolidation in the years to come.

Please note that I have subdivided the solar category for my posts into four categories because one category was becoming too unwieldly. Solar-PV is still rather large and may have to be broken down into silicon and non-silicon categories.

Technorati tags: solar, solar power, energy, technology

The Energy Blog: Solar Overview on CNET

More Proof of Global Warming

Dr Michael Coughlin, head of the National Climate Centre was reported as saying that the world is now hotter than any time since prehistoric times.  He is supported by research using gas trapped in Antarctic ice going back 650,000 years that found that current levels of carbon dioxide in the air are 27% higher than at any tiny time during that period.  This goes along with NASA's report that says that 2005 is the hottest year on record.

Effects that have been attributed to the warming include that the Artic sea ice dropped to its lowest level ever, the record hurricane season and an unprecedented drought that reduced the flow of the Amazon river to its lowest ever rate.  Canada and Australia had their hottest ever weather this year, while India, Pakistan, Bangladesh and Algeria suffered heatwaves reaching 50C.

If this isn't strong enough proof that global warming is real, what do you need Mr President?  It certainly should be enough to convince you to take all possible measures to reduce global warming, which should include as its main point the reduction of burning of fossil fuels. The time required for any mitigating measures to have any impact is so great, that all stops have to be pulled out now.  Items that have been repeatedly indicated as being necessary include:

How GE Captures New Energy Markets

An article from Fortune magazine via the World Business Council for Sustainable Development, gives a comprehensive review of General Electrics activities in the energy market. In perhaps the broadest and largest corporate effort anywhere, GE spent $700 million in 2004 on clean-energy R&D--ranging from hydrogen production to solar cells, cleaner coal plants, and biofuels. Their wide variety of activities include:

• Their very successful wind turbine business has sold 5,500 turbines since 2002, with 1,600 to be installed this year.  They hope wind power will eventually supply 20% of U.S.'s total energy.
• They are developing hybrid electric locomotives that they have running on an eight mile long test track, which they will start selling in 2007.
• They have many hydrogen related projects including solid oxide fuel cells for stationary applications, ICE engines modified to run on hydrogen, gas stations that use electrolysis to generate hydrogen, methods of storing hydrogen in man-made nanoparticles or in metal hydrides and thermochemical methods of producing hydrogen.
• GE has been building new high temperature nuclear reactors in Europe and Asia.
• They have teamed with Exxon Mobil and Schlumberger to study how to sequester carbon dioxide.
• They are developing IGCC technology for producing electricity and hydrogen.
• GE is pursuing three ways of using solar cells: developing more efficient solar cells, developing electrochemical cells that produce hydrogen, reducing the size of thermal solar farms from hundreds of acres to tens of acres by improving concentrating solar system efficiency.  An example of their research in solar is the development of nanodiodes--whiskers 1/80,000th the thickness of a human hair--displaying a photovoltaic effect that converts sunlight into electricity.

John K. Reinker, who runs a team of about 60 scientists on hydrogen related subjects, is excited about the sheer scope of GE's energy R&D. "I don't think there is any other company in the world that is looking at so many energy technologies and as a result is able to understand which have the most probability of success." Thomas Edison, GE's original research scientist, would be proud.

More blogs about wind power, hydrogen, fuel cells, solar, nuclear, sequestration, hybrids, coal, alternative energy, renewable, renewable energy, energy

BP Alternitive Energy Unit Details

Today BP announced a website that gives greater details about its Alternative Energy business, a new unit that consolidates its low-carbon activities in the power industries, that was announced yesterday.  The website gives an insite into their current activities in each of these areas and a clue as to what they will be doing in the future.

They have formed this unit because they believe that solar, wind, hydrogen power and gas-fired technologies have reached the a tipping point where they think they can create a profitable, high growth, global business in the course of the next decade. 

More blogs about solar, hydrogen, natural gas, wind power, electrical generation, alternative energy, renewable, renewable energy, energy

Solar Tower Used to Test Space Materials

For the last two years, tests have been conducted at Sandia National Laboratories' National Solar Thermal Test Facility to apply heat equivalent to 1,500 suns to spacecraft shields called Advanced Charring Ablators. The ablators protect spacecraft entering atmospheres at hypersonic speeds. The test facility includes a "solar tower" surrounded by by a field of hundreds of sun-tracking mirror arrays called heliostats.  The heliostats direct sunlight to the top of the tower where the test objects are located.

The National Solar Thermal Test Facility is located on an eight-acre field of 220 solar-collection heliostats and a 200-ft.-tall tower that receives the collected energy at one of several test bays. A single heliostat includes 25 mirrors that are each four feet square. The total collection area is 88,000-square feet. Because the heliostats are individually computer controlled, test radiation can be a shaped pulse as well as a square wave in terms of intensity vs. time.

Test samples are mounted high in the receiver tower, and the heliostats direct the sunlight upward to irradiate the sample surface. The samples are mounted in a water-cooled copper plate inside the tower's wind tunnel with a quartz window that allows entry of the concentrated radiation.

Resource: Sandia Conducts Tests at Solar Tower to Benefit Future NASA Space Explorations, Sandia press release, September 7, 2005

More blogs about solar, solar tower, energy

About Solar Towers

Solar towers use many large, computer controlled, sun tracking mirrors (heliostats) to focus the suns energy on a receiver located at the top of a tower.  A heat transfer fluid, usually molten nitrate salt, is heated in the receiver and used either to drive a turbine/generator to produce electricity or to provide high temperature thermal heat.  The molten salt can be used to store the thermal energy for producing electricity at night or during cloudy weather. Commercial power plants would be sized from 50 MW to 200 MW each.

A ten MW plant, Solar One, located near Barstow CA operated for six years demonstrating the viability of solar towers.  It used a heat transfer fluid to transfer the heat to the generator.  Solar Two, shown left, was a retrofit of solar one, built to demonstrate the advantages of molten salt for heat transfer and solar storage.  At one point it delivered power to the grid for seven days, 24 hours a day during cloudy weather.  Molten salt solar towers are well suited to peaking power applications, being able to generate power when most needed, day or night, cloudy or sunny.

11 MW Solar Tower Project in Spain Announced

Building of the first solar tower that will generate electricity commercially was announced by Solucar Energia, SA in Spain.  The 11 MW power tower, called PS-10, under construction near Seville will be Europe's largest solar plant.  The field surrounding the tower will consist of 624 large mirrors built on computer controlled pedestals to focus the sunlight on the top of a 330 foot tower, generating steam to make electricity.  The control system will synchronize the movement of all the mirrors relative to the sun's position in order to maximize the plants performance. The plant will benefit greatly from last year's royal decree that will allow it to sell power for up to three times the normal rate. The plant is scheduled to be operational by July 2006.

Further information on solar towers can be found in this previous post.

Resource:  "Spain to Build an 11-Megawatt Solar Power Tower", EERE News, 8/24/05

Technocrati tags: solar power, solar tower, renewable energy

The US Energy Bill of 2005

The US energy bill of 2005 has received a mixed bag of reviews depending on your interests.  The folowing are the portions of the energy bill that appear to be most relevant to the topics I discuss:

A two-year extension of a tax credit to companies that produce power from renewable sources — an allocation worth $2.7 billion. The bulk of those funds will promote the construction of new wind farms, a boon to utilities and wind turbine manufacturers, while the remainder will assist biomass, geothermal and hydroelectric companies.

Biofuels : A 7.5 billion gallon Renewable Fuels Standard (RFS) which would add billions of gallons of ethanol, biodiesel and other renewables to the nations fuel supply by 2012.  In addition to the RFS, the bill updates the small ethanol producer definition to 60 million gallons, extends the biodiesel tax credit through 2008, and establishes a 30% tax credit up to $30,000 for the cost of installing clean fuel refueling equipment, such as an E85 fuel pump.

Solar : Increases the permanent 10 percent business energy credit for solar to 30% for two years.   Eligible technologies include photovoltaics, solar water heaters, concentrating solar power, and solar hybrid lighting. The credit reverts back to the permanent 10 percent level after two years. The bill establishes a 30 percent residential energy credit for solar for two years.   For residential systems, the tax credit is capped at $2,000.

Geothermal, Wind: The bill continues to include geothermal energy in the Section 45 Production Tax Credit (PTC) for the full 1.9 cent/kwhr credit amount, but expands the credit period from five to the full ten years. As a result, geothermal and wind will now receive equal tax treatment -- the full ten-year, 1.9 cent production tax amount. Other technologies, such as open loop biomass, receive the full ten-year credit but for half the credit amount, or 0.95 cents/kwhr. The biggest clean energy perk in the bill was a two-year extension of a tax credit critical to companies that produce power from renewable sources -- an allocation worth $2.7 billion. The bulk of those funds will promote the construction of new wind farms, a boon to utilities and wind turbine manufacturers, while the remainder will assist biomass, geothermal and hydroelectric companies.

Direct users of geothermal energy may use a simpler procedure for leasing, or establishing a fee schedule instead of royalties payments. State and local governments are allowed to use geothermal resources for public purposes at a nominal charge.

Hybrid, fuel efficient vehicles: Close to $875 million in tax credits could be given to those who buy hybrid gas-electric vehicles before 2010.  The bill favors companies that are just getting into the hybrid business. Each manufacturer can apply the tax credit to just 60,000 vehicles.  Toyota sells roughly 150,000 hybrids per year and Honda 50,000 which means that a only a portion of their vehicles will be eligible for credits. The bill fails to include any provision for new fuel efficiency standards.

A new category of tax credits known as clean renewable energy bonds, or CREBs, that have an estimated value of $400 million. These tax-exempt bonds can be issued by local governments or electricity cooperatives to help pay for wind, solar, biomass and other specified projects.  An additional $194 million will go toward the two-year extension of excise- and income-tax credits for manufacturers of biodiesel, a soybean derivative that is blended with regular diesel.

About Solar Chimneys

Solar chimneys, are one of the least publicized forms of solar power plants.  The power plant consists of a very large glazed solar collector with a chimney in the center through which the hot air generated in the collector rises.  The hot air wind drives turbo-generators located at the base of the chimney.  The floor of the collector, is lined with heat absorbing media, which absorb heat during the daytime and release the heat during the night, so that the power is produced on a continuous basis.  Cold air enters the collector, with an upward sloping ceiling, from its outer perimeter, is heated and rises through the tower at 50 feet per second (15 meters per second).  The solar tower works on the principle that the higher temperature of the air in the collector compared to the outside temperature causes a density difference, which causes the air, heated to about 100 ^oF (38^oC) hotter than the outside air, to rise, creating a solar wind that drives the turbines. 

Recent improvements in the conceptual design, specifically, potential improvements in the performance of the roof area of the collector and a new method of storing heat have enabled modularization to units as small as 25  megawatts (MW).  The smaller units are said to greatly reduce development costs, while still providing much lower capital costs for larger installations. Having a shorter chimny (still very tall) will reduce the profile of the plant which should reduce permiting and regulatory problems.  Solar tower power plant modules, unlike most forms of renewable energy, produce a very significant quantity of electricity, 25 to 200 MW or more.  The two disadvantages of the system are that they requires a large land area and are quite expensive.

Diversity in Renewables Smooths Output

Renewable sources of power, wind, solar, wave and tidal power have been criticized because they do not produce power at a consistent or predictable rate. "By mixing between sites and mixing technologies you can markedly reduce the variability of electricity produced by renewables, Graham Sinden, of Oxford's Environmental Change Institute was quoted as saying in the May 12th edition of The Guardian.  Sinden went on to say, "And if you plan the right mix, renewable and intermittent technologies can even be made to match real-time electricity demand patterns. This reduces the need for backup, and makes renewables a serious alternative to conventional power sources."  He found that by combining a diversity of geographical locations and a diversity of technologies, renewables combined with domestic combined heat and power could ultimately make the the following contributions to Britain's total energy supply: wind 35%, wave and tidal 15%, combined heat and power 15%, and solar 5-10%. 

A more detailed report can be found at the University of Oxford's Environmental Change Institute's web site.  The Cambridge-MIT Institute has a related paper "Diversity and Security In UK Electricity Generation: The Influence of Low Carbon Objectives"

The conclusion that diversity reduces variability is rather intuitive.  These studies put some numbers on the required mix. I would assume that similar findings would apply to other regions of the world.  If eventually more than 50% of our electricity could be produced from renewables that would be an enormous contribution.  Add another 10% for hydro and 40% from a combination of bidiesel made from algae and syngas made from biomass and we have total independence from fossil fuels.

Proven Technology for the Next 20 Years

With oil probably peaking in less than 20 years, if not five years, the more I think we need an alternative to the emphasis being placed on the hydrogen economy.  Demonstrated and emerging technology as listed below likely to be the dominant technologies in the next thirty years.  None of these technologies alone can get us there but together but in some combination they make sense.

• The hybrid is here and can be ramped up as fast as anything.
• Diesel technology can be used now, and should be, as lower sulfur fuels are brought to market in 2005-2006. They will reduce the environmental impact of diesels significantly.  What we need is more models to choose from as there are very few.
• Electric cars and plug-in hybrids for commuting and shopping will be more attractive, with greater range, as gasoline prices go up and battery technology gets better as it is starting to.
• Unconventional oil is already starting to ramp up and will continue as oil companies cannot meet the demand.
• Ethanol production is already significant with 3.4 billion gallons produced in the US in 2004.
• Production costs for biodiesel can be reduced by using newer technologies.
• The Fischer-Tropsh process can be used to produce both ethanol and diesel in larger quantities, at lower cost, than current biofuel producers.  It can handle a much wider variety of feedstocks, like switchgrass, corn stover, wood chips, willows and poplars which are less costly.
• Coal liquefaction is a proven technology and could supply all of our needs, but not in the required time period.
• We can increase our electrical production from renewables like wind and solar systems.
• More rapid development of unconventional oil in Canada and Venezula.