Certain materials, generally metal oxides, can sustain the unassisted photo-electrolysis of water into H2 and O2. The energy contained in the photons that are absorbed by these materials can in many cases be efficiently converted into energy stored into the chemical fuels produced by the photo-electrolysis system. However, these materials have optical absorption thresholds (band gaps) that are too large to permit effective absorption of the visible and infrared portions of the solar spectrum, thereby wasting a large fraction of the incident solar energy and yielding overall energy conversion efficiencies of o 1%. Modification of metal oxide materials has been claimed to be much more promising, with a modified TiO 2 photo-anode yielding 8% efficiency in the photo-assisted splitting of water into H2 and O2 . (more…)
Several molecular systems have been constructed that mimic various aspects of photosynthesis. Two of these utilize molecular system ...
The basic processes that occur in such a system are well understood. The semiconductor electrode efficiently absorbs light, produci ...
The issues of hydrogen storage run through the hydrogen production, hydrogen transport, supply and demand for end use of hydrog ...
Hydrogen has many applications when it comes to fuel. It can be used both in internal combustion engines and hydrogen fuel cells. ...
All of today’s hydrogen conversion products, demonstration models, and prototypes possess some deficiencies; they cannot yet pr ...
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 system ...
Today, photovoltaic cells only contribute a small proportion (approximately 0.04 percent) of total electricity in the United St ...
Certain materials, generally metal oxides, can sustain the unassisted photo-electrolysis of water into H2 and O2. The energy co ...
The fuel cell can trace its roots back to the 1800s when a Welsh-born, Oxford-educated barrister, Sir William Robert Grove, realize ...
A fuel cell is an electrochemical device that combines hydrogen with oxygen to generate electricity, heat and water to produce. ...
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…)
The basic processes that occur in such a system are well understood. The semiconductor electrode efficiently absorbs light, produci ...
Certain materials, generally metal oxides, can sustain the unassisted photo-electrolysis of water into H2 and O2. The energy co ...
A fuel cell is an electrochemical device that combines hydrogen with oxygen to generate electricity, heat and water to produce. ...
A fuel cell is an electrochemical device that directly converts a fuel to electricity by means of reactions on the surfaces of ...
The fuel cell can trace its roots back to the 1800s when a Welsh-born, Oxford-educated barrister, Sir William Robert Grove, realize ...
Fiber optic systems have many advantages on the basis of the communication systems technology compare to metallic media communication. These advantages include lower interference, small signal attenuation and bandwidth characteristics. In addition, relatively small cross-section of the fiber optic cable from a substantial growth in capacity in the existing lines is replaced. Properties of optical fibers can be classified as linear and nonlinear. Non-linear properties are influenced by parameters such as bit rate, channel spacing, and the level of performance. (more…)
There are literally thousands of uses for lasers. One of the largest applications is telecommunications—sending a signal throug ...
Several passive heating systems, if provided with proper ventilation, can ensure to provide cooling. Passive heating and cooling fo ...
Most discussions of energy use in paper production and papermaking are confusing because of a failure to define exactly what is mea ...
More than 48% of the raw material fiber used for paper production (chemical pulp or mechanical pulp) in the United States in 2002 w ...
Different lasers use different materials as the active medium. The medium can be either solid, liquid, or gas, and there are ad ...
Different lasers use different materials as the active medium. The medium can be either solid, liquid, or gas, and there are advantages for each in the amount of energy that can be stored, ease of handling and storage, secondary safety hazards, cooling properties, and physical characteristics of the laser output. (more…)
There are literally thousands of uses for lasers. One of the largest applications is telecommunications—sending a signal throug ...
The word “laser” is an acronym for “light amplification by the stimulated emission of radiation.” Lasers of all kinds consist o ...
The first known laser was made by Theodore Maiman at Hughes Research Laboratories in Malibu, California, in 1960, but the seeds ...
Several molecular systems have been constructed that mimic various aspects of photosynthesis. Two of these utilize molecular system ...
It is known that laser printers print faster, but swallow a large amount of energy, even if the printer is in the energy saving ...
The word “laser” is an acronym for “light amplification by the stimulated emission of radiation.” Lasers of all kinds consist of several basic components: an active medium, an outside energy source, and an optical cavity with carefully designed mirrors on both ends. One of the mirrors is 100 percent reflective while the other is somewhat less reflective, so a beam can be emitted. The active medium is inside the optical cavity and is excited with an external energy source (typically electricity). For the cavity to emit laser radiation, the active medium has to achieve an unusual energy state called “population inversion.” (more…)
The first known laser was made by Theodore Maiman at Hughes Research Laboratories in Malibu, California, in 1960, but the seeds ...
Different lasers use different materials as the active medium. The medium can be either solid, liquid, or gas, and there are ad ...
There are literally thousands of uses for lasers. One of the largest applications is telecommunications—sending a signal throug ...
It is known that laser printers print faster, but swallow a large amount of energy, even if the printer is in the energy saving ...
Fabrication techniques developed for integrated circuit (IC) production have been refined to the extent of supporting a multi-b ...
There are literally thousands of uses for lasers. One of the largest applications is telecommunications—sending a signal through fiber optic cables, for example. This application grew rapidly in the 1990s with the phenomenal increase in traffic on the Internet. Optical data storage, such as on compact disks, CD-ROMs, and DVDs, is another important use for lasers. The information age was obviously a boon to this application, and as researchers obtained smaller wavelengths with diode lasers, they were able to fit more information on smaller storage devices. (more…)
Different lasers use different materials as the active medium. The medium can be either solid, liquid, or gas, and there are ad ...
The word “laser” is an acronym for “light amplification by the stimulated emission of radiation.” Lasers of all kinds consist o ...
The first known laser was made by Theodore Maiman at Hughes Research Laboratories in Malibu, California, in 1960, but the seeds ...
Several molecular systems have been constructed that mimic various aspects of photosynthesis. Two of these utilize molecular system ...
It is known that laser printers print faster, but swallow a large amount of energy, even if the printer is in the energy saving ...
Today, photovoltaic cells only contribute a small proportion (approximately 0.04 percent) of total electricity in the United States. At the same time the production of solar panels has growth rapidly per year by around 20% growth in the 1990s and photovoltaic panels prices decreases every year. Annual worldwide solar panel production (including solar panels with homemade solar power homes) is about 400 MW per year. Based on the total cumulative capacity figure, it is already reaching 2 GW. (more…)
So-called thin-film photovoltaic devices are usually based on mixtures of elements other than silicon — most notably copper ind ...
The broad range of home solar energy systems are mostly known as Photovoltaic Systems (PV) or Thin Film Solar Technology. The s ...
So you're finally tired of those exorbitant electricity bills, or, you're catching onto a "greener" way of life. Either way, solar ...
In the mid-1880s, Charles Fritts built the first solar cell formed by selenium coated with a thin layer of gold and with an ene ...
The basic processes that occur in such a system are well understood. The semiconductor electrode efficiently absorbs light, produci ...
The increased use of fossil energy since the industrial revolution, and especially since 1950, has been the major cause of increased emissions of air pollutants and, correspondingly, many environmental problems. Emissions due to the use of energy are major sources of sulfur dioxide, nitrogen oxides, carbon dioxide, and soot and constitute a large contribution of methane, non-methane volatile organic compounds, and heavy metals. (more…)
Almost all fossil fuels use is by burning them to create energy. Burning process then produces waste products due to impurities in ...
Acid deposition and the associated particulate nitrates and sulfates are implicated in the deterioration of certain sensitive e ...
Since the early 1960s, climate change and air quality have become major and often controversial issues in many countries and am ...
Smoke from biomass and coal combustion contains a large number of pollutants with known health hazards, including particulate matte ...