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 ...
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 ...
Fabrication techniques developed for integrated circuit (IC) production have been refined to the extent of supporting a multi-billion-dollar industry. Chip manufacturing relies on silicon-based processing where micron-sized features are routinely used in production. Microtechnology-Based Energy and Chemical Systems do not require the extremely small ‘‘line widths’’ needed for IC fabrication. Furthermore, in many energy applications, silicon is not the favored material, as discussed previously. Other fabrication techniques, such as LIGA, have been specifically developed for MEMS (Micro Electro Mechanical Systems). (more…)
Silicon is the material of choice for most Micro Electro Mechanical Systems due to (1) the feature size often being in the rang ...
Many small-scale energy systems require effective miniaturized pumps and expanders. These devices are responsible for conveying ...
Microvalves have been developed for a variety of applications suitable for Microtechnology-Based Energy and Chemical Systems. Valve ...
Microtechnology-Based Energy and Chemical Systems will most likely employ combustion for driving processes such as vapor generation ...
Heat-actuated heat pumps are cooling systems requiring no electricity for operation. Rather, a heat source is used, avoiding the ne ...
Microvalves have been developed for a variety of applications suitable for Microtechnology-Based Energy and Chemical Systems. Valve classification can be divided into passive and active categories. The passive type is the most fundamental and is configured as a basic check valve where a thin flapper plate covers an orifice. Microvalves of this type have been fabricated using a variety of techniques, including lithography and etching, laser micromachining, and electro-discharge machining. Materials have included metal on metal, metal on polymers, and silicon with photoresists such as PMMA and polyimides. (more…)
The pressure relief valves protect against the devastating effects of the overpressure. Unfortunately there are so careful with ...
Many small-scale energy systems require effective miniaturized pumps and expanders. These devices are responsible for conveying ...
Many characteristics of traditional engines make them attractive for use in power generation and propulsion technology. They tend t ...
Micro technology can be employed to produce miniaturized refrigeration and cryocooling systems. Although process intensificat ...
Fabrication techniques developed for integrated circuit (IC) production have been refined to the extent of supporting a multi-b ...
Many small-scale energy systems require effective miniaturized pumps and expanders. These devices are responsible for conveying a working fluid through various components to execute a cycle that may result in power production, heat pumping, or refrigeration. As an example, a pump is required for pressurizing the working fluid in Rankine power cycles. Miniaturized pumps could also cycle a heat transfer fluid through a cooling loop for heat rejection purposes. On the other hand, expanders are necessary for any cycle employing a working fluid to generate power. Specific examples include microturbines, miniaturized piston-based machines, and roots-type expanders. (more…)
Heat-actuated heat pumps are cooling systems requiring no electricity for operation. Rather, a heat source is used, avoiding the ne ...
Micro technology can be employed to produce miniaturized refrigeration and cryocooling systems. Although process intensificat ...
Separation is a unit operation used in absorption heat pumps and chemical processing applications such as solvent extraction and pr ...
Many characteristics of traditional engines make them attractive for use in power generation and propulsion technology. They tend t ...
Microvalves have been developed for a variety of applications suitable for Microtechnology-Based Energy and Chemical Systems. Valve ...
Hydrogen has many applications when it comes to fuel. It can be used both in internal combustion engines and hydrogen fuel cells. Hydrogen engines are using the same principle the same way as gasoline fuels or hydrogen natural gas burned combustion, while the chemical energy of hydrogen used to generate electricity and heat transmission. Since the electrochemical reactions produced more efficient energy compare to the combustion energy, fuel cells are created more efficient fuel compare to internal combustion engines. In the long term it will benefit to the more efficient hydrogen conversion process. (more…)
All of today’s hydrogen conversion products, demonstration models, and prototypes possess some deficiencies; they cannot yet pr ...
Most production systems try to become first full-scale production begins as small toys and devices of concept. The Horizon hydr ...
A fuel cell is an electrochemical device that combines hydrogen with oxygen to generate electricity, heat and water to produce. ...
There are different types of vehicle propulsion systems and the transportation fuels that have been studied for their potential ...
The issues of hydrogen storage run through the hydrogen production, hydrogen transport, supply and demand for end use of hydrog ...
The hydrogen can come from various sources including fossil fuels, wind, solar, biomass, nuclear, solar thermo-chemical reactions, and solar photolysis. (more…)
Researchers at the Institute of Chemical Technology have developed a new catalyst that allows to obtain, from bioethanol, hydrogen ...
Hydrogen has many applications when it comes to fuel. It can be used both in internal combustion engines and hydrogen fuel cells. ...
The issues of hydrogen storage run through the hydrogen production, hydrogen transport, supply and demand for end use of hydrog ...
Most production systems try to become first full-scale production begins as small toys and devices of concept. The Horizon hydr ...
With ethanol’s future uncertain, many commentators see the transportation debate evolving into a war between two other technologies ...