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Hydrogen Technologies
Hydrogen technologies are technologies that relate to the production and use of hydrogen as a part hydrogen economy. Hydrogen technologies are applicable for many uses. Some hydrogen technologies are carbon neutral and could have a role in preventing climate change and a possible future hydrogen economy. Hydrogen is a chemical widely used in various applications including ammonia production, oil refining and energy. The most common methods for producing hydrogen on an industrial scale are: Steam reforming, oil reforming, coal gasification, water electrolysis. Hydrogen is not a primary energy source, because it is not naturally occurring as a fuel. It is, however, widely regarded as an ideal energy storage medium, due to the ease with which electricity can convert water into hydrogen and oxygen through electrolysis and can be converted back to electrical power using a fuel cell. There are a wide number of different types of fuel and electrolysis cells. The potential environme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technology
Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, science, industry, communication, transportation, and daily life. Technologies include physical objects like utensils or machines and intangible tools such as software. Many technological advancements have led to societal changes. The earliest known technology is the stone tool, used in the prehistoric era, followed by fire use, which contributed to the growth of the human brain and the development of language in the Ice Age. The invention of the wheel in the Bronze Age enabled wider travel and the creation of more complex machines. Recent technological developments, including the printing press, the telephone, and the Internet have lowered communication barriers and ushered in the knowledge economy. While technology contribu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others. The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field. When a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microbial Fuel Cell
Microbial fuel cell (MFC) is a type of bioelectrochemical fuel cell system that generates electric current by diverting electrons produced from the microbial oxidation of reduced compounds (also known as fuel or electron donor) on the anode to oxidized compounds such as oxygen (also known as oxidizing agent or electron acceptor) on the cathode through an external electrical circuit. MFCs can be grouped into two general categories: mediated and unmediated. The first MFCs, demonstrated in the early 20th century, used a mediator: a chemical that transfers electrons from the bacteria in the cell to the anode. Unmediated MFCs emerged in the 1970s; in this type of MFC the bacteria typically have electrochemically active redox proteins such as cytochromes on their outer membrane that can transfer electrons directly to the anode. In the 21st century MFCs have started to find commercial use in wastewater treatment. History The idea of using microbes to produce electricity was conceived in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Hydride Fuel Cell
Metal hydride fuel cells are a subclass of alkaline fuel cells that have been under research and development, as well as scaled up successfully in operating systems. A notable feature is their ability to chemically bond and store hydrogen within the fuel cell itself. Characteristics Metal hydride fuel cells have demonstrated the following characteristics: * The ability to be recharged with electrical energy (similar to NiMH batteries) * Operating at low temperatures (down to −20 °C) * Fast "cold start" properties * Ability to operate for limited periods of time with no external hydrogen fuel source, enabling "hot swapping" of fuel canisters Performance Electrode active areas of metal hydride fuel cells have been scaled up from 60 cm2 to 250 cm2, enabling systems to be scaled up to 500 Watts. The scaling up of electrode active areas also provided capabilities to develop higher power fuel cell stacks, each with 1500 Watts of power. Metal hydride fuel cells ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formic Acid Fuel Cell
Formic acid fuel cells (direct formic acid fuel cells or DFAFCs) are a subcategory of direct liquid-feed fuel cells (DLFCs), in which the liquid fuel is directly oxidized (electrochemically) at the anode instead of reforming to produce hydrogen. Formic acid-based fuel cells represent a promising energy supply system in terms of high volumetric energy density, theoretical energy efficiency, and theoretical open-circuit voltage. They are also able to overcome certain problems inherent to traditional hydrogen (H2) feed fuel cells such as safe handling, storage, and H2 transportation. There are 3 main types of DFAFCs: * Active DFAFCs, where a pump feeds the liquid fuel ito the anode and ogygen in compressed air to the cathode. * Active air-breathing DFAFCs, where the cathode is exposed to the oxygen present in ambient air. * Passive air-breathing DFAFCs, where there are no mechanical components injecting fuels and oxygen into the cell. The feeding of fuels and air into a cell increases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flow Battery
A flow battery, or redox flow battery (after reduction–oxidation), is a type of electrochemical cell where chemical energy is provided by two chemical components dissolved in liquids that are pumped through the system on separate sides of a membrane. Ion transfer inside the cell (accompanied by flow of electric current through an external circuit) occurs through the membrane while both liquids circulate in their own respective space. Cell voltage is chemically determined by the Nernst equation and ranges, in practical applications, from 1.0 to 2.43 volts. The energy capacity is a function of the electrolyte volume and the power is a function of the surface area of the electrodes. A flow battery may be used like a fuel cell (where the spent fuel is extracted and new fuel is added to the system) or like a rechargeable battery (where an electric power source drives regeneration of the fuel). While flow batteries have certain technical advantages over conventional rechargeable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Methanol Fuel Cell
Direct-methanol fuel cells or DMFCs are a subcategory of proton-exchange fuel cells in which methanol is used as the fuel. Their main advantage is the ease of transport of methanol, an energy-dense yet reasonably stable liquid at all environmental conditions. Whilst the thermodynamic theoretical energy conversion efficiency of a DMFC is 97%; the currently achievable energy conversion efficiency for operational cells attains 30% – 40%. There is intensive research on promising approaches to increase the operational efficiency. A more efficient version of a direct fuel cell would play a key role in the theoretical use of methanol as a general energy transport medium, in the hypothesized methanol economy. The cell In contrast to indirect methanol fuel cells, where methanol is reacted to hydrogen by steam reforming, DMFCs use a methanol solution (usually around 1 M, i.e. about 3% in mass) to carry the reactant into the cell; common operating temperatures are in the range , where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Ethanol Fuel Cell
Direct-ethanol fuel cells or DEFCs are a category of fuel cell in which ethanol is fed directly into the cell. They have been used as a model to investigate a range of fuel cell concepts including the use of PEM. Advantages DEFC uses Ethanol in the fuel cell instead of the more toxic methanol. Ethanol is an attractive alternative to methanol because it comes with a supply chain that's already in place. Ethanol also remains the easier fuel to work with for widespread use by consumers. Ethanol is a hydrogen-rich liquid and it has a high specific energy (8.0 kWh/kg) compared to methanol (6.1 kWh/kg). Ethanol can be obtained in great quantity from biomass through a fermentation process from renewable resources like from sugar cane, wheat, corn, or even straw. Bio-generated ethanol (or bio-ethanol) is thus attractive since growing crops for biofuels absorbs much of the carbon dioxide emitted into the atmosphere from fuel used to produce the biofuels, and from burning the biofuels the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Carbon Fuel Cell
A Direct Carbon Fuel Cell (DCFC) is a fuel cell that uses a carbon rich material as a fuel such as bio-mass or coal. The cell produces energy by combining carbon and oxygen, which releases carbon dioxide as a by-product. It is also called coal fuel cells (CFCs), carbon-air fuel cells (CAFCs), direct carbon/coal fuel cells (DCFCs), and DC-SOFC. The total reaction of the cell is C + O2 → CO2. The process in half cell notation: * Anode: C + 2O2− → CO2 + 4e− * Cathode: O2 + 4e− → 2O2− Despite this release of carbon dioxide, the direct carbon fuel cell is more environmentally friendly than traditional carbon burning techniques. Due to its higher efficiency, it requires less carbon to produce the same amount of energy. Also, because pure carbon dioxide is emitted, carbon capture techniques are much cheaper than for conventional power stations. Utilized carbon can be in the form of coal, coke, char, or a non-fossilized source of carbon. At least four types of DCFC exist. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Borohydride Fuel Cell
Direct borohydride fuel cells (DBFCs) are a subcategory of alkaline fuel cells which are directly fed by sodium borohydride or potassium borohydride as a fuel and either air/oxygen or hydrogen peroxide as the oxidant. DBFCs are relatively new types of fuel cells which are currently in the developmental stage and are attractive due to their high operating potential in relation to other type of fuel cells. Recently, DBFCs that rival proton-exchange membrane fuel cells (PEMFCs) in peak power but operating at double the voltage have been reported. Chemistry Sodium borohydride could potentially be used in more conventional hydrogen fuel cell systems as a means of storing hydrogen. The hydrogen can be regenerated for a fuel cell by catalytic decomposition of the borohydride: :NaBH4 + 2H2O → NaBO2 + 4H2 Direct borohydride fuel cells decompose and oxidize the borohydride directly, side-stepping hydrogen production and even producing slightly higher energy yields: :Cathode: 2O2 + 4H2O + ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkaline Fuel Cell
The alkaline fuel cell (AFC), also known as the Bacon fuel cell after its British inventor, Francis Thomas Bacon, is one of the most developed fuel cell technologies. Alkaline fuel cells consume hydrogen and pure oxygen, to produce potable water, heat, and electricity. They are among the most efficient fuel cells, having the potential to reach 70%. NASA has used alkaline fuel cells since the mid-1960s, in the Apollo-series missions and on the Space Shuttle. Half Reactions The fuel cell produces power through a redox reaction between hydrogen and oxygen. At the anode, hydrogen is oxidized according to the reaction: \mathrm_2 + \mathrm^- \longrightarrow \mathrm_2\mathrm + \mathrm^- producing water and releasing electrons. The electrons flow through an external circuit and return to the cathode, reducing oxygen in the reaction: \mathrm_2 + \mathrm_2\mathrm + \mathrm^- \longrightarrow \mathrm^- producing hydroxide ions. The net reaction consumes one oxygen molecule and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
