IEO2007: Liquid Fuels

The International Energy Outlook 2007 (IEO2007) presents an assessment by the Energy Information Administration (EIA) of the outlook for international energy markets through 2030. Selected excerpt's regarding total energy consumption and liquids are given in the remainder of this post. Other topics will be reviewed later.

In its reference case World marketed energy consumption is projected to increase by 57 percent from 2004 to 2030. Total energy demand in the non-OECD countries increases by 95 percent, compared with an increase of 24 percent in the OECD countries.

The IEO2007 reference case projects increased world consumption of marketed energy from all sources over the 2004 to 2030 projection period (left). Fossil fuels (petroleum and other liquid fuels, natural gas, and coal)

Liquids remain the dominant energy source, given their importance in the transportation and industrial end-use sectors; however, their share of the world energy market in this year’s outlook is lessened in the projection, as other fuels replace liquids where possible outside those sectors.

World consumption of petroleum and other liquid fuels, grows from 83 million barrels oil equivalent per day in 2004 to 97 million in 2015 and 118 million in 2030. liquids production is projected to increase by 14 million barrels per day from 2004 to 2015 and by an additional 20 million barrels per day from 2015 to 2030. OPEC producers are expected to provide more than one-half of the additional production in 2015 (8 million barrels per day) and more than two-thirds in 2030 (23 million barrels per day). Non-OPEC production in 2030 is projected to be 12 million barrels per day higher than in 2004, representing 35 percent of the increase in total world production over the 2004 total. The estimates of production increases are based on current proved reserves and a country-by-country assessment of ultimately recoverable petroleum, as well as the potential for unconventional liquids production.

In IEO2007, the projected increase in OPEC production (excluding Angola) is about 22 million barrels per day over the same period. There are several regions where production is restrained through 2015 in the reference case. For instance, in the key resource-rich countries of Mexico and Venezuela, expected investment levels are lower than those assumed in the IEO2006 reference case. In both countries, liquids production is projected not to expand (and, in Mexico, to decline) until after 2015, when economic decisions on investment allow production to improve. Also, North Sea production is projected to decline more rapidly than in last year’s outlook.

World production of unconventional liquids (including biofuels, coal-to-liquids, and gas-to-liquids), (left) which totaled only 2.6 million barrels per day in 2004, is projected to increase to 10.5 million barrels per day and account for 9 percent of total world liquids supply in 2030, on an oil equivalent basis, in the IEO2007 reference case.

The world oil prices in the IEO2007 reference case—and in the high world oil price case—also are projected to make previously uneconomical, unconventional resources available.

Reserve estimates for oil, natural gas, and coal are difficult to develop. EIA develops estimates of reserves for the United States but not for foreign countries. As a convenience to the public, EIA makes available global reserve estimates from the Oil & Gas Journal, World Oil, and BP’s Statistical Review of World Energy, shown below.

Since 2000, the largest net increase in estimated proved oil reserves has been made in Canada, with the addition of 174 billion barrels of Canadian oil sands as a conventional reserve. Iranian oil reserves have increased by 46.6 billion barrels, or 52 percent, since 2000. Kazakhstan has had the third-largest increase, 24.6 billion barrels, since 2000.

You may be disapointed in some of these projections, but I believe that they are as good as any available and if you wish to alter the course of energy consumption you must take steps such as energy conservation by using less energy and switching to energy sources that are more environmentally friendly.

Southern California Edison Proposes Clean Hydrogen Power Generation to Reduce GHG Emissions

According to a press release dated May 17, Edison International’s (NYSE:EIX) electricity utility, Southern California Edison (SCE), has requested approval to build and test a commercial 600 MW power plant to determine the feasibility of a new combination of several advanced “clean” coal technologies in an effort to advance these emerging approaches to low-carbon generation.

Their proposal consist of:

• A gasifier that combines coal and steam with a controlled amount of oxygen under high pressures to produce hydrogen and carbon monoxide.
• Converting the carbon monoxide to additional hydrogen and carbon dioxide in the shift conversion.
• Further processing the gasses to remove sulfur, mercury, and carbon dioxide.
• Sequestering the carbon in a depleted oil formation, enabling enhanced oil recovery, or in a deep saline formation.
• Producing a mostly hydrogen fuel, emitting only 10 percent of the carbon released by an integrated gasification combined-cycle coal project without carbon capture.
• The hydrogen is fed to gas turbines where electricity is generated.
• Exhaust heat from the gas turbines is used to create steam and drive additional turbines.
• The use of these technologies in a full-scale, 600-megawatt (MW) commercial generating facility.

The advanced technologies in SCE’s proposed study, an approach the utility calls Clean Hydrogen Power Generation (CHPG), are being considered or tested in clean coal projects elsewhere. The SCE plan would be the first assessment of a full-scale, 600-MW facility using all of them. One of the main differences between this process and others is that the carbon monoxide is converted to additional hydrogen enabling the gas turbines to only burn hydrogen.

SCE is seeking authorization to commit $52 million of revenues it collects from customer rates during a two-year period to an advanced technology feasibility study. If approved, this would represent less than a quarter of one percent of current customer rates.

SCE also is the nation’s leading purchaser of renewable energy, buying and delivering approximately 13 billion kWh in 2006 from wind, solar, biomass, biogas, geothermal, and small hydro suppliers – 16.7% of the power it delivered to customers. An equivalent amount of generation using fossil fuels would produce 7 million tons of GHG emissions. SCE purchases one-sixth of all U.S. renewable energy used to generate electricity for retail sale, including more than 90% of all the U.S. solar generation.

The above article was adapted from the press release referred to in the first paragraph.

Chevron, Fuel Cell Energy to Turn Wasetewater Sludge and Kitchen Grease into Renewable Power

Chevron Energy Solutions, a Chevron (NYSE: CVX) subsidiary, today announced that it has begun engineering and construction of a system at the City of Rialto’s (California) wastewater treatment facility that will transform wastewater sludge and kitchen grease from local restaurants into clean, renewable power.

The new system will provide a beneficial use for the thousands of gallons of fats, oils and grease (FOG) that are washed daily from restaurant grills and pans, which is collected by grease hauling companies. At the Rialto facility, a FOG-receiving station will provide an effective disposal alternative to landfills, where FOG is often disposed, creating methane - a greenhouse gas - as it decomposes, releasing it directly into the atmosphere. It also will provide a revenue stream to the city through “tipping fees” paid by grease haulers for each disposal.

The system includes a 900-kilowatt fuel cell power plant, manufactured by FuelCell Energy (NasdaqNM: FCEL), that will generate electricity without combustion using methane, a biogas produced on site from the digesters that treat the wastewater sludge and FOG. Three 300-kilowatt Direct FuelCell® units will convert the methane into hydrogen and then use the hydrogen to generate power electrochemically, without combustion. The residual waste heat from the fuel cells will be used to warm the digesters to stimulate further methane production.

The environmentally friendly system will increase municipal revenues, reduce landfill wastes and lower greenhouse emissions by nearly 5.5 million tons annually, while decreasing the city’s energy costs by about $800,000 a year.

The project, which will cost $15.1 million, is eligible for a $4.05 million rebate on the fuel cell plant cost from California’s Self-Generation Incentive Program. The remaining cost will be self-funded through energy cost savings and FOG station revenues, without any impact on local taxpayers.

New Japanese Company Formed to Manufacture Lithium-Ion Batteries

GS Yuasa Corporation, Mitsubishi Corporation (MC), and Mitsubishi Motors Corporation (MMC) have begun collaboration on establishing a joint venture to manufacture large capacity and high performance Lithium-ion batteries that can be used in electric vehicles (EV). The three partners aim to complete the details and set up the new company sometime within half a year.

The batteries that will be produced by the new company are based on the "LIM series" of Large Lithium-ion batteries manufactured by GS Yuasa (currently the only mass producer of Large Lithium-ion batteries in Japan) with improved cell-structure and electrode materials to improve the energy density and power density of the new batteries. These batteries will have ten times the capacity of those for hybrid electric vehicles, and are the perfect choice for EVs. MMC plans to install the batteries to its next generation EV "i MiEV" (i Mitsubishi innovative Electric Vehicle), which it aims to introduce to the market by 2010. The batteries can also be supplied to EVs manufactured by other auto-makers and to industrial applications for energy storage use.

The new batteries are capable of high-speed energy input and output to meet the needs of high-speed charge specifications under consideration by electrical power companies and potentially for plug-in hybrid electric vehicles (PHEV). They hope that their product will become the de facto standard for large lithium-ion batteries; the new company plans on increasing their production capacity and line-up of products in response to the expanding market.

GS Yuasa possesses advanced technologies for large lithium-ion batteries and is planning on widening their applications; MC intends to enter the battery manufacturing business and create other related businesses; and MMC is working to increase the use of electric vehicles.

GS Yuasa is expected to own a 51% share of the new company, with MC and MMC owing 34% and 15% respectively. During the first stage of development, 3 billion yen (US$3.3 million) will be invested to install automated mass production lines within a 7000m² facility at GS Yuasa's Kyoto's head office plant, capable of manufacturing 200,000 cells per year. Operations are slated to commence by 2009.

Supplying the World's Energy Needs with Light and Water

A leading chemist says that a better understanding of photosynthesis could lead to cheap ways to store solar energy as chemical fuel.

By Kevin Bullis

Unleashing energy: Daniel Nocera, professor of chemistry at MIT, says that basic research into the chemical processes of photosynthesis could lead to a society powered by water and sunlight.

While researchers and technologists around the world scramble to find cleaner sources of energy, some chemists are turning to nature's own elegant solution: photosynthesis. In photosynthesis, green plants use the energy in sunlight to break down water and carbon dioxide. By manipulating electrons and hydrogen, oxygen, and carbon atoms in a series of complex chemical reactions, the process ultimately produces the cellulose and lignin that form the structure of the plant, as well as stored energy in the form of sugar. Understanding how this process works, thinks Daniel Nocera, professor of chemistry at MIT, could lead to ways to produce and store solar energy in forms that are practical for powering cars and providing electricity even when the sun isn't shining.

What's needed are breakthroughs in our understanding of the fundamental chemical processes that make photosynthesis possible, according to Nocera, a recognized photosynthesis expert. He is studying the principles behind photosynthesis and applying what he learns to making catalysts that use solar energy to create hydrogen gas for fuel cells. Nocera's goal: a world powered by light and water.

Technology Review: What's the biggest challenge related to energy right now?

Daniel Nocera: The real challenge with energy is the scaling problem. We're going to have this huge energy need, and when you start looking at all the numbers, there's only one supply that has scale, and it's the sun. But it's still a research problem. Technologies all follow lines; then there's a discovery and a new line that's better. We're on a very predictable line now in solar. Most things you hear about are incremental advances.

TR: You're studying photosynthesis to get ideas for how to convert sunlight into a chemical fuel--hydrogen--for use when the sun isn't shining or in powering fuel-cell vehicles.

DN: You can use the electricity directly when the sun is out, in places that have sun. [But] you need storage. There's absolutely no way around it. I am distilling the essence of photosynthesis down to be able to use it.

TR: Why is photosynthesis attractive in finding a source of clean energy?

DN: [Photosynthesis] does three things. It captures sunlight, and [second,] it converts it into a wireless current--leaves are buzzing with electricity. And third, it does storage. It stores the converted light energy in chemical energy. And it uses that chemical energy for its life process, and then it stores a little.

It turns out [that] photosynthesis is one of the most efficient machines in the world for energy conversion. But it's not great for storing energy because that's not what [a plant] was built to do. It was built to live and grow and reproduce.

And so that's the approach we take. Can we now do what the leaf is doing artificially, which is the capture, conversion, and storage in chemical bonds? But my device doesn't have to live: it can take a lot more of that energy and put it into chemical bonds.

Nuclear for Oil Sands?

It appears that Canada may be going to nuclear power to replace natural gas for oil-sands projects, as is indicated in this item from World Nuclear News:

Energy Alberta is searching for communities to host the province's largest power station to provide emission-free power for oil sands projects. The company plans to build a C$6.2 billion ($5.6 billion) 2200 MWe twin Candu reactor plant in northern Alberta, and is looking at the town of Whitecourt among others. ...

The costs of natural gas can account for up to 60% of operating costs at an oil sands facility, and the associated greenhouse gas emissions are a further barrier to economic oil extraction. Nuclear could be a way of providing the necessary power. ...

The company is planning to submit an application to the Canadian Nuclear Safety Commission on 15 June, according to reports. A decision on the location of the plant is expected by 15 September.

Short-Term Energy Outlook

The May 8 Short-Term Energy Outlook, by the EIA, had some points that help explain the high prices of gasoline, the major point being that gasoline inventories are down now and it will take until the end of summer for inventories to catch-up creating a situation where supply is very tight causing high prices.

• Continuing problems for refineries in the United States and abroad, combined with strong global gasoline demand, have raised our projected average summer gasoline price by 14 cents per gallon from our last Outlook. Retail regular grade motor gasoline prices are now projected to average $2.95 per gallon this summer compared with the $2.84 per gallon average of last summer. During the summer season, the average monthly gasoline pump price is projected to peak at $3.01 per gallon in May and again in August, compared with $2.98 per gallon last July. ...
• World oil markets are projected to tighten this summer due to continued growth in oil demand and production restraint by members of the Organization of Petroleum Exporting Countries (OPEC). Despite the recent increases in world oil prices, global oil consumption is projected to grow by 1.4 million barrels per day (bbl/d) in 2007 and by 1.6 million bbl/d in 2008. About one-half of the projected growth will come from China and the United States ....
• For 2007, U.S. crude oil production is projected to average 5.15 million bbl/d ... With the startup of new deepwater production from the Atlantis platform later this year and from the Thunderhorse platform late next year total domestic crude oil production is projected to average 5.34 million bbl/d in 2008.

Better Catalysts for Fuel Cells

Nanoparticles with a completely new shape may lead to cheaper catalysts that could make many experimental-energy technologies more practical.

By Kevin Bullis

Nano geometry: This 24-sided platinum nanoparticle could lead to cheaper alternative energy.

New nanoparticles with a totally original shape, made by researchers at Georgia Tech, in Atlanta, and Xiamen University, in China, and described in the current issue of Science, could lead to cheaper catalysts for making and using alternative fuels. The 24-sided platinum nanoparticles have surfaces that show up to four times greater catalytic activity compared with commercial catalysts.

If researchers can make even smaller nanoparticles with this same efficient shape, it could significantly reduce the amount of platinum used. Reducing the amount of this expensive metal--it currently sells for about $1,300 per ounce--would make applications such as fuel cells more affordable. Reducing the cost of platinum catalysts could also be critical in other applications, such as synthesizing alternative fuels and converting waste materials like carbon dioxide into useful products. (See "Making Gasoline from Carbon Dioxide.")

The new work is important, says Francesco Stellacci, professor of materials science and engineering at MIT, because it involves platinum, which he says is "by far the most interesting metal" for catalysis. The work could also advance the basic understanding of how changing the shape of particles affects catalysis, he says.

To make the nanoparticles, the Georgia Tech and Xiamen researchers began with relatively large platinum particles scattered on a carbon surface. They then applied an oscillating voltage, which induces alternating chemical reactions that determine where platinum atoms will accumulate and where they won't. For example, at positive voltages, oxygen atoms can infiltrate some areas of these nanoparticles, dislodging platinum atoms. At the same time, a layer of platinum oxide forms on other parts of the nanoparticle, protecting them. The resulting 24-sided shapes, called tetrahexahedra, were the first such shapes formed artificially in metals, says Zhong Lin Wang, professor of materials science and engineering at Georgia Tech.

The multifaceted shape made by the researchers has many high-energy areas in which more atoms are unstable and reactive than in conventional platinum nanoparticles. The researchers showed that these surfaces, compared with the surfaces of commercial platinum nanoparticles, catalyzed reactions at a much higher rate.

The current work is only a step toward the goal of making cheaper catalysts. Alexis Bell, professor of chemical engineering at the University of California, Berkeley, says that while the work is interesting because it addresses one of the particular challenges of creating catalysts--controlling the surface structure--the new nanoparticles are in fact not small enough. Existing commercial platinum catalysts can be less than five nanometers wide. The Georgia Tech and Xiamen researchers made particles between 50 and 200 nanometers. Being larger, the new type of nanoparticles have a larger proportion of the expensive platinum locked beneath the surface, where it can't serve to catalyze reactions. As a result, for now, the new nanoparticles are actually worse catalysts than are commercial catalysts available today.

According to Wang, the goal is ultimately to use the new nanoparticles and the methods for making them to help find ways of transforming much cheaper materials into useful catalysts. If that can be done, some technologies limited to the lab bench today could be applied to meeting growing worldwide energy needs.

Indeed, notes Daniel Feldheim, professor of chemistry and biochemistry at the University of Colorado at Boulder, in a commentary accompanying the Science article, researchers have long known that changing particle shape and size can make even seemingly inert materials such as gold into valuable catalysts. The methods used by the Georgia Tech and Xiamen researchers, Feldheim says, provide a new level of control that could lead to improved mixed-metal and metal-oxide catalysts, which are cheaper than precious metals such as platinum.

A Spark of Hope for Fusion

A new device clears an obstacle to a type of fusion power plant.

By Kevin Bullis

Fusion future? Sandia researcher Bill Fowler tests circuits on a device designed to produce large electrical impulses rapidly and repeatedly. Groups of such devices could be used to initiate nuclear fusion. Each element of the system features a pair of large capacitors and a switch arranged in a configuration that minimizes current-slowing magnetic fields.

A new device could bring high-yield nuclear fusion for generating electricity a step closer to reality, according to researchers at Sandia National Laboratories, in Albuquerque, NM. The technology, developed by Sandia researchers in collaboration with the Institute of High Current Electronics, in Tomsk, Russia, can deliver very brief bursts of extremely large amounts of electricity and do it every 10 seconds thousands of times in a row. The researchers still need to use the device to produce a continuous series of miniature nuclear explosions that could heat water and drive turbines in a fusion power plant.

The Sandia device stores energy in a group of large capacitors and releases it very quickly, in just 100 nanoseconds. A new kind of physical arrangement of these capacitors prevents magnetic fields from forming and slowing electrical current, a major problem with previous devices. But while acknowledging that the technology is an important advance for delivering pulses of power, several experts say a power plant based on such technology faces significant hurdles, not the least of which is building the plant sturdy enough to withstand the strong explosions going off every 10 seconds.

While scientists have long known how to produce fusion--it's the heart of the hydrogen bomb--they've yet to find a way to harness that power in a power plant. Currently, the favored path to high-yield fusion that produces more energy than it consumes involves creating an ultrahot plasma and containing it within a magnetic field. An experimental machine designed to demonstrate such a concept is being built by a large international consortium in the south of France, and it's scheduled to be completed in about 10 years. (See "International Fusion Research.") But even if the project is successful, commercial-scale fusion power plants will still be decades away, as researchers will need to find ways to economically harvest the energy released by the fusion reactions.

Meanwhile, researchers have been routinely creating small amounts of fusion in the lab using a different technique, called inertial confinement. Here fusion starts when a small pellet of fuel is compressed by a burst of energy, which can be from different sources, including lasers. At Sandia, inertial confinement is now done with the Z machine, which uses electricity to create a burst of x-rays that compress the pellet. While such machines are good for helping to simulate nuclear weapons, they produce only a modest amount of fusion, releasing only a small part of the energy in the fuel.

Method for Cheaper Quantum Dots

Research by Michael Wong (left) and Rice University scientists at Rice's Center for Biological and Environmental Nanotechnology (CBEN), today revealed a breakthrough method for producing molecular specks of semiconductors called quantum dots, a discovery that could clear the way for better, cheaper solar energy panels.

Quantum dots interact with light in unique ways, to give off different-colored light or to create electrons and holes, due partly to their tiny size, partly to their shape and partly to the material they're made of. Rice scientists have developed a new chemical method for making four-legged cadmium selenide quantum dots, which previous research has shown to be particularly effective at converting sunlight into electrical energy.

Quantum dots are "megamolecules" of semiconducting materials that are smaller than living cells. Prior research by others has shown that four-legged quantum dots, which are called tetrapods, are many times more efficient at converting sunlight into electricity than regular quantum dots. But, principal investigator Michael Wong, assistant professor of chemical and biomolecular engineering said the problem is that there is still no good way of producing tetrapods. Current methods lead to a lot of particles with uneven-length arms, crooked arms, and even missing arms. Even in the best recipe, 30 percent of the prepared particles are not tetrapods, he said.

CBEN's formula produces same-sized particles, in which more than 90 percent are tetrapods. The essence of the new recipe is to use cetyltrimethylammonium bromide instead of the standard alkylphosphonic acid compounds. Cetyltrimethylammonium bromide happens to be safer – it's used in some shampoos, for example – and it's much cheaper than alkylphosphonic acids. For producers looking to eventually ramp up tetrapod production, this means cheaper raw materials and less purification steps, Wong said.

The research, by Wong and his graduate student Subashini Asokan with CBEN Director Vicki Colvin and graduate student Karl Krueger appears this week in the journal Small.

Energy and Water from Beer Waste

On a somewhat lighter note, from Physorg.com, Australian beer maker Foster's is going to generate clean energy and clean water from brewery waste water by using a fuel cell in which bacteria consume the sugar, starch and alcohol in the waste.

The fuel cell is expected to produce 2 kilowatts of power — enough to power a household — and the technology would eventually be applied in other breweries and wineries owned by Foster's. The cell should be operating at the brewery by September."Brewery waste water is a particularly good source because it is very biodegradable ... and is highly concentrated, which does help in improving the performance of the cell," said Prof. Jurg Keller, the university's wastewater expert. .

The 660-gallon fuel cell will be 250 times bigger than a prototype that has been operating at Australia's University of Queensland laboratory for three months.

The experimental technology was unveiled Wednesday by scientists at the university, which was given a $115,000 state government grant to install the microbial fuel cell at the brewery.

The Case for Burying Charcoal

Research shows that pyrolysis is the most climate-friendly way to consume biomass.

By Tyler Hamilton

Carbon capture: Heating biomass such as wood pellets (right) in an oxygen-free environment produces char (left) and byproducts such as methane that can be burned. Research shows that turning biomass into char and burying the char is a good way to avoid releasing greenhouse gases into the atmosphere.

Several states in this country and a number of Scandinavian countries are trying to supplant some coal-burning by burning biomass such as wood pellets and agricultural residue. Unlike coal, biomass is carbon-neutral, releasing only the carbon dioxide that the plants had absorbed in the first place.

But a new research paper published online in the journal Biomass and Bioenergy argues that the battle against global warming may be better served by instead heating the biomass in an oxygen-starved process called pyrolysis, extracting methane, hydrogen, and other byproducts for combustion, and burying the resulting carbon-rich char.

Even if this approach would mean burning more coal--which emits more carbon dioxide than other fossil-fuel sources--it would yield a net reduction in carbon emissions, according to the analysis by Malcolm Fowles, a professor of technology management at the Open University, in the United Kingdom. Burning one ton of wood pellets emits 357 kilograms less carbon than burning coal with the same energy content. But turning those wood pellets into char would save 372 kilograms of carbon emissions. That is because 300 kilograms of carbon could be buried as char, and the burning of byproducts would produce 72 kilograms less carbon emissions than burning an equivalent amount of coal.

Such an approach could carry an extra benefit. Burying char--known as black-carbon sequestration--enhances soils, helping future crops and trees grow even faster, thus absorbing more carbon dioxide in the future. Researchers believe that the char, an inert and highly porous material, plays a key role in helping soil retain water and nutrients, and in sustaining microorganisms that maintain soil fertility.

Johannes Lehmann, an associate professor of crops and soil sciences at Cornell University and an expert on char sequestration, agrees in principle with Fowles's analysis but believes that much more research in this relatively new area of study is needed. "It heads in the right direction," he says.

Interest in the approach is gathering momentum. On April 29, more than 100 corporate and academic researchers will gather in New South Wales, Australia, to attend the first international conference on black-carbon sequestration and the role pyrolysis can play to offset greenhouse-gas emissions.

Lehmann estimates that as much as 9.5 billion tons of carbon--more than currently emitted globally through the burning of fossil fuels--could be sequestered annually by the end of this century through the sequestration of char. "Bioenergy through pyrolysis in combination with biochar sequestration is a technology to obtain energy and improve the environment in multiple ways at the same time," writes Lehmann in a research paper to be published soon in Frontiers in Ecology and the Environment.

Making Gasoline from Carbon Dioxide

A solar-powered reaction turns a greenhouse gas into a valuable raw material.

By Kevin Bullis

Solar splitter: An amber-colored semiconductor (gallium phosphide), together with metal contacts, is part of a new device that uses solar energy to split carbon dioxide to make carbon monoxide.

Chemists have shown that it is possible to use solar energy, paired with the right catalyst, to convert carbon dioxide into a raw material for making a wide range of products, including plastics and gasoline.

Researchers at the University of California, San Diego (UCSD), recently demonstrated that light absorbed and converted into electricity by a silicon electrode can help drive a reaction that converts carbon dioxide into carbon monoxide and oxygen. Carbon monoxide is a valuable commodity chemical that is widely used to make plastics and other products, says Clifford Kubiak, professor of chemistry at UCSD. It is also a key ingredient in a process for making synthetic fuels, including syngas (a mixture largely of carbon monoxide and hydrogen), methanol, and gasoline.

The work is part of a growing effort to find practical uses for carbon dioxide, a leading greenhouse gas, says Philip Jessop, professor of chemistry at Queen's University, in Ontario, Canada. Converting carbon dioxide into carbon monoxide is difficult to do, which Jessop says makes the UCSD work impressive and exciting.

At least at first, such a process will not make a significant impact on reducing greenhouse gases in the atmosphere--that would take quite large-scale operations, Kubiak says. But "any chemical process that you can develop that uses CO₂ as a feedstock, rather than having it be an end product, is probably worth doing." He adds that "if chemical manufacturers are going to make millions of pounds of plastics anyway, why not make them from greenhouse gases rather than making tons of greenhouse gases in the process?"

The system may also be part of a solution to a continuing problem with solar energy. For solar panels to be useful when the sun isn't shining, the electricity they produce has to be stored. A potentially practical way of doing that is by converting the electrical energy into chemical energy. One popular approach is to use solar cells to produce hydrogen, which could then be used in fuel cells. But hydrogen gas is much more difficult to transport and store than are liquid fuels, such as gasoline, which contain far more energy by volume than hydrogen does. The UCSD system shows that it is possible to use solar energy to make carbon monoxide that then, together with hydrogen, can be converted into gasoline. Currently, carbon monoxide is made from natural gas and coal. But carbon dioxide is a more attractive raw material in part because it's very cheap--indeed, it's something industrial companies will pay to get off their hands, Jessop says. "There are very few chemicals which are cheaper than free, and carbon dioxide is one of them," he says.