The basic processes that occur in such a system are well understood. The semiconductor electrode efficiently absorbs light, producing an excited electronic state. In this excited state, the electron and the electron vacancy (the ‘‘hole’’) are both more energetic than they were in their respective ground states. The photo-excited electrons and holes are generally not tightly bound to an individual atom or set of atoms in the solid. (more…)

Several molecular systems have been constructed that mimic various aspects of photosynthesis. Two of these utilize molecular systems that are derived from natural photosynthesis but that incorporate chemically based modifications to produce artificial photosynthetic devices. These devices use artificial photosynthetic pigments to drive chemical reactions across lipid bilayers or use noble metal catalysts to change the function of the photosynthetic process to produce hydrogen and oxygen instead of sugars ethanol and oxygen. Neither of these systems are sufficiently robust to be operated for extended periods of time as energy unit conversion devices, but they have shown that it is possible to produce artificial photosynthetic assemblies that function well in a laboratory setting. (more…)

Because transportation is such a large contributor to global warming, both globally and in the United States, climate and energy experts say finding clean alternatives to gasoline is also key to replacing fossil fuels and slowing global warming. Just as there is debate and competing research about which type of alternative transportation fuel should be developed to produce electricity, however, there is also competition among possible new transportation fuels. So far, in the United States, significant funding has been put into two transportation technologies—ethanol and hydrogen fuel cells. Many energy commentators say cars powered by electric batteries are the technology closest to mass production capability, however. (more…)

With ethanol’s future uncertain, many commentators see the transportation debate evolving into a war between two other technologies—hydrogen-powered fuel cells and battery powered electric vehicles. Some alternative fuel advocates are putting their support behind hydrogen, the most abundant element on Earth. Water, for example, is composed of hydrogen and oxygen molecules. Hydrogen can be produced from water by electrolysis, which separates the oxygen from the hydrogen. It can be used to power hydrogen fuel cells for vehicles (or to provide heat and electricity for buildings). Hydrogen fuel cells work by recombining hydrogen and oxygen—a process that produces electricity, heat, and water. Hydrogen-powered cars, therefore, could be an ideal transportation solution—nonpolluting, zero-emission vehicles that release only water, a natural and completely safe waste product. Also, fuel cells are highly efficient and powerful, and unlike typical batteries, fuel cells will never lose their charge as long as hydrogen fuel is supplied.

Hydrogen fuel cell technologies, however, must overcome many stubborn challenges before they can become a practical source of energy. Perhaps the biggest obstacle is cost; it currently takes more energy to make hydrogen than is produced, and production relies on expensive catalysts made from platinum, a scarce metal. And like biofuels, hydrogen is currently made using fossil fuels, so it is not emissions-free. In addition, liquid hydrogen fuel is highly flammable and must be stored at very low temperatures or under very high pressure, making transport and storage difficult. Switching vehicles to hydrogen fuel cell power also would require building a whole new infrastructure similar to the chain of gas stations that currently dot the landscape. Researchers are hoping to find answers to these problems by searching for other types of catalysts, studying other ways to improve production, and developing better hydrogen storage options.

Hydrogen researchers, however, have been promising breakthroughs since the 1990s with little progress to show for their efforts. Many observers are thus coming to the conclusion that the hydrogen fuel cell is a technology that will not be perfected in the near future. As physicist and climate expert Joe Romm explains, “Neither government policy nor business investment should be based on the assumption that these technologies will have a significant impact in the near or medium-term.” The Obama administration apparently agrees; it submitted a budget for 2010 that sharply cut back on government support for hydrogen projects. U.S. Energy Secretary Steven Chu explained the administration’s problems with hydrogen technology:

Right now, the way we get hydrogen primarily is from reforming [natural] gas. That’s not an ideal source of hydrogen. . . . The other problem is, if it’s for transportation, we don’t have a good storage mechanism yet. Compressed hydrogen is the best mechanism [but it requires] a large volume. We haven’t figured out how to store it with high density. What else? The fuel cells aren’t there yet, and the distribution infrastructure isn’t there yet. So . . . to get significant deployment, you need four significant technological breakthroughs. That makes it unlikely

Congress promptly reversed President Obama’s decision, however, restoring more than $200 million to 190 hydrogen projects around the country.

Approximately 40% of Earth’s population is ‘‘off the grid,’’ mainly in developing countries. Wireless power transmission envisioned by Nikola Tesla a century ago is feasible today. Microwave beams can propagate power efficiently along lines-of-sight over long distances. Orbiting microwave reflectors could form the basis of a global electric grid.

An advanced technology path to electrification is the solar power satellite (SPS) proposed by Peter Glaser. Solar flux is about 10 times higher in space outside Earth’s shadow cone than the long- term average at the surface of spinning, cloudy Earth, and power from space can be beamed by microwave efficiently through cloudy skies to the surface where it is needed. (more…)

The total installed geothermal power generating capacity in the world is approximately 9000 MWe from 21 countries, with the United States leading at nearly 3000 MWe and The Philippines with nearly 2000 MWe (Table II). Other major countries are Italy, Mexico, Indonesia, Japan, and New Zealand, with between 400 and 800 MWe each. (more…)

Microtechnology-Based Energy and Chemical Systems will most likely employ combustion for driving processes such as vapor generation and vapor barrier, endothermic chemical reactions, and (most notably) fuel reforming. Both fuel reformers and combustors will be of a miniature design relying on embedded catalysts for promoting chemical reactions at moderate temperatures (350–7501C). Many potential configurations exist depending on the application and constraints on the design. Microchannel arrays are a potential configuration; mesh and post architecture is another to achieve the desired surface area and small diffusional lengths necessary. (more…)

A fuel cell is an electrochemical device that combines hydrogen with oxygen to generate electricity, heat and water to produce. In many ways, the fuel cell is similar to an electrochemical cell. Instead of a regular charge, a continuous supply of oxygen and hydrogen is supplied from outside. Oxygen is produced in the control of air and hydrogen as a fuel made from a pressure instrumentation container. Alternatively, methanol, propane, butane, natural gas supply and diesel are used. (more…)

Gasification is a thermo chemical process that has been exploited for more than a century for converting solid feedstocks to gaseous energy carriers. The first gasifier patent was issued in England at the end of the 18th century and producer gas from coal gasification was mainly used as lighting fuel throughout the 19th century. At the turn of the 20th century, the main use of producer gas, obtained essentially from coal, switched to electricity generation and automotive applications via internal combustion engines. The use of producer gas was gradually supplanted by the use of higher energy density liquid fuels and as a result confined to areas with expensive or unreliable supplies of petroleum fuels. (more…)

Alkaline fuel cell, often known as the Bacon fuel cell following the British inventor’ name. It has become the most created fuel cell systems and is the cell which traveled Man to the Moon. NASA has utilized alkaline fuel cells since beginning of-1960s, in Apollo-series tasks and on the Space Shuttle. The alkaline fuel cell has a long history in the space program. It is still used in the space shuttle in an expensive guise, producing power for the onboard systems by combining the pure hydrogen and oxygen stored in the rocket-fuelling system. (more…)