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93-534: Planning for the Connecticut Science Center began in 2001. The Science Center's goals are to promote the study of science by the state's youth and to encourage urban revitalization in Hartford. The state of Connecticut provided more than $ 100 million of support for the $ 165 million museum, and the balance was donated by businesses, foundations and individuals. The Connecticut Science Center is

186-403: A cathode , and an electrolyte that allows ions, often positively charged hydrogen ions (protons), to move between the two sides of the fuel cell. At the anode, a catalyst causes the fuel to undergo oxidation reactions that generate ions (often positively charged hydrogen ions) and electrons. The ions move from the anode to the cathode through the electrolyte. At the same time, electrons flow from

279-499: A cogeneration power plant in hospitals, universities and large office buildings. In recognition of the fuel cell industry and America's role in fuel cell development, the United States Senate recognized October 8, 2015 as National Hydrogen and Fuel Cell Day , passing S. RES 217. The date was chosen in recognition of the atomic weight of hydrogen (1.008). Fuel cells come in many varieties; however, they all work in

372-652: A metal hydride storage electrode into a reversible proton exchange membrane (PEM) fuel cell . During charging, PFB combines hydrogen ions produced from splitting water with electrons and metal particles in one electrode of a fuel cell. The energy is stored in the form of a metal hydride solid. Discharge produces electricity and water when the process is reversed and the protons are combined with ambient oxygen. Metals less expensive than lithium can be used and provide greater energy density than lithium cells. Compared to inorganic redox flow batteries, such as vanadium and Zn-Br 2 batteries. Organic redox flow batteries advantage

465-828: A 400 MWh, 100 MW vanadium flow battery, then the largest of its type. Sumitomo Electric has built flow batteries for use in Taiwan, Belgium, Australia, Morocco and California. Hokkaido’s flow battery farm was the biggest in the world when it opened in April 2022 — until China deployed one eight times larger that can match the output of a natural gas plant. A flow battery is a rechargeable fuel cell in which an electrolyte containing one or more dissolved electroactive elements flows through an electrochemical cell that reversibly converts chemical energy to electrical energy . Electroactive elements are "elements in solution that can take part in an electrode reaction or that can be adsorbed on

558-727: A SOFC system are less than those from a fossil fuel combustion plant. The chemical reactions for the SOFC system can be expressed as follows: SOFC systems can run on fuels other than pure hydrogen gas. However, since hydrogen is necessary for the reactions listed above, the fuel selected must contain hydrogen atoms. For the fuel cell to operate, the fuel must be converted into pure hydrogen gas. SOFCs are capable of internally reforming light hydrocarbons such as methane (natural gas), propane, and butane. These fuel cells are at an early stage of development. Challenges exist in SOFC systems due to their high operating temperatures. One such challenge

651-471: A battery, except as hydrogen, but in some applications, such as stand-alone power plants based on discontinuous sources such as solar or wind power , they are combined with electrolyzers and storage systems to form an energy storage system. As of 2019, 90% of hydrogen was used for oil refining, chemicals and fertilizer production (where hydrogen is required for the Haber–Bosch process ), and 98% of hydrogen

744-662: A complete, closed-loop system: Solar panels power an electrolyzer, which makes hydrogen. The hydrogen is stored in a 500-U.S.-gallon (1,900 L) tank at 200 pounds per square inch (1,400 kPa), and runs a ReliOn fuel cell to provide full electric back-up to the off-the-grid residence. Another closed system loop was unveiled in late 2011 in Hempstead, NY. Fuel cells can be used with low-quality gas from landfills or waste-water treatment plants to generate power and lower methane emissions . A 2.8 MW fuel cell plant in California

837-449: A concentrated solution of KOH or NaOH which serves as an electrolyte. H 2 gas and O 2 gas are bubbled into the electrolyte through the porous carbon electrodes. Thus the overall reaction involves the combination of hydrogen gas and oxygen gas to form water. The cell runs continuously until the reactant's supply is exhausted. This type of cell operates efficiently in the temperature range 343–413   K (70 -140 °C) and provides

930-565: A durability of over 120,000 km (75,000 miles) with less than 10% degradation. In a 2017 Well-to-Wheels simulation analysis that "did not address the economics and market constraints", General Motors and its partners estimated that, for an equivalent journey, a fuel cell electric vehicle running on compressed gaseous hydrogen produced from natural gas could use about 40% less energy and emit 45% less greenhouse gasses than an internal combustion vehicle. Flow battery A flow battery , or redox flow battery (after reduction–oxidation ),

1023-408: A fluctuating simulated power input tested the viability toward kWh scale storage. In 2016, a high energy density Mn(VI)/Mn(VII)-Zn hybrid flow battery was proposed. A prototype zinc – polyiodide flow battery demonstrated an energy density of 167 Wh/L. Older zinc–bromide cells reach 70 Wh/L. For comparison, lithium iron phosphate batteries store 325 Wh/L. The zinc–polyiodide battery

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1116-597: A fuel-to-electricity efficiency of 50%, considerably higher than the 37–42% efficiency of a phosphoric acid fuel cell plant. Efficiencies can be as high as 65% when the fuel cell is paired with a turbine, and 85% if heat is captured and used in a combined heat and power (CHP) system. FuelCell Energy, a Connecticut-based fuel cell manufacturer, develops and sells MCFC fuel cells. The company says that their MCFC products range from 300 kW to 2.8 MW systems that achieve 47% electrical efficiency and can utilize CHP technology to obtain higher overall efficiencies. One product,

1209-564: A graphite felt positive electrode operating in a mixed solution of VOSO 4 and H 2 SO 4 , and a metal hydride negative electrode in KOH aqueous solution. The two electrolytes of different pH are separated by a bipolar membrane. The system demonstrated good reversibility and high efficiencies in coulomb (95%), energy (84%), and voltage (88%). They reported improvements with increased current density, inclusion of larger 100 cm electrodes, and series operation. Preliminary data using

1302-461: A high operating temperature provides an advantage by removing the need for a precious metal catalyst like platinum, thereby reducing cost. Additionally, waste heat from SOFC systems may be captured and reused, increasing the theoretical overall efficiency to as high as 80–85%. The high operating temperature is largely due to the physical properties of the YSZ electrolyte. As temperature decreases, so does

1395-403: A higher current to be supplied. Such a design is called a fuel cell stack . The cell surface area can also be increased, to allow higher current from each cell. In the archetypical hydrogen–oxide proton-exchange membrane fuel cell (PEMFC) design, a proton-conducting polymer membrane (typically nafion ) contains the electrolyte solution that separates the anode and cathode sides. This

1488-432: A hot water storage tank to smooth out the thermal heat production was a serious disadvantage in the domestic market place where space in domestic properties is at a great premium. Delta-ee consultants stated in 2013 that with 64% of global sales the fuel cell micro-combined heat and power passed the conventional systems in sales in 2012. The Japanese ENE FARM project stated that 34.213 PEMFC and 2.224 SOFC were installed in

1581-589: A hydrogen source would create less than one ounce of pollution (other than CO 2 ) for every 1,000 kW·h produced, compared to 25 pounds of pollutants generated by conventional combustion systems. Fuel Cells also produce 97% less nitrogen oxide emissions than conventional coal-fired power plants. One such pilot program is operating on Stuart Island in Washington State. There the Stuart Island Energy Initiative has built

1674-455: A hydrogen-rich gas in the anode, eliminating the need to produce hydrogen externally. The reforming process creates CO 2 emissions. MCFC-compatible fuels include natural gas, biogas and gas produced from coal. The hydrogen in the gas reacts with carbonate ions from the electrolyte to produce water, carbon dioxide, electrons and small amounts of other chemicals. The electrons travel through an external circuit, creating electricity, and return to

1767-499: A low-cost anion exchange membrane. This MV/TEMPO system has the highest cell voltage, 1.25   V, and, possibly, lowest capital cost ($ 180/kWh) reported for AORFBs as of 2015. The aqueous liquid electrolytes were designed as a drop-in replacement without replacing infrastructure. A 600-milliwatt test battery was stable for 100 cycles with nearly 100 percent efficiency at current densities ranging from 20 to 100 mA/cm , with optimal performance rated at 40–50   mA, at which about 70% of

1860-459: A potential of about 0.9   V. Alkaline anion exchange membrane fuel cell (AAEMFC) is a type of AFC which employs a solid polymer electrolyte instead of aqueous potassium hydroxide (KOH) and it is superior to aqueous AFC. Solid oxide fuel cells (SOFCs) use a solid material, most commonly a ceramic material called yttria-stabilized zirconia (YSZ), as the electrolyte . Because SOFCs are made entirely of solid materials, they are not limited to

1953-770: A power-plant-to-wheel efficiency of 22% if the hydrogen is stored as high-pressure gas, and 17% if it is stored as liquid hydrogen . Stationary fuel cells are used for commercial, industrial and residential primary and backup power generation. Fuel cells are very useful as power sources in remote locations, such as spacecraft, remote weather stations, large parks, communications centers, rural locations including research stations, and in certain military applications. A fuel cell system running on hydrogen can be compact and lightweight, and have no major moving parts. Because fuel cells have no moving parts and do not involve combustion, in ideal conditions they can achieve up to 99.9999% reliability. This equates to less than one minute of downtime in

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2046-425: A requirement, as in enclosed spaces such as warehouses, and where hydrogen is considered an acceptable reactant, a [PEM fuel cell] is becoming an increasingly attractive choice [if exchanging batteries is inconvenient]". In 2013 military organizations were evaluating fuel cells to determine if they could significantly reduce the battery weight carried by soldiers. In a fuel cell vehicle the tank-to-wheel efficiency

2139-401: A six-year period. Since fuel cell electrolyzer systems do not store fuel in themselves, but rather rely on external storage units, they can be successfully applied in large-scale energy storage, rural areas being one example. There are many different types of stationary fuel cells so efficiencies vary, but most are between 40% and 60% energy efficient. However, when the fuel cell's waste heat

2232-494: A solid layer. The major disadvantage is that this reduces decoupled energy and power. The cell contains one battery electrode and one fuel cell electrode. This type is limited in energy by the electrode surface area. HFBs include zinc–bromine , zinc–cerium , soluble lead–acid , and all-iron flow batteries. Weng et al. reported a vanadium– metal hydride hybrid flow battery with an experimental OCV of 1.93 V and operating voltage of 1.70 V, relatively high values. It consists of

2325-569: A subclass of regenerative fuel cell (H01M8/18), even though it is more appropriate to consider fuel cells as a subclass of flow batteries. 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 . The zinc–bromine flow battery (Zn-Br2)

2418-492: A supporting electrolyte. At pH neutral conditions, organic and organometallic molecules are more stable than at corrosive acidic and alkaline conditions. For example, K4[Fe(CN)], a common catholyte used in AORFBs, is not stable in alkaline solutions but is at pH neutral conditions. AORFBs used methyl viologen as an anolyte and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl as a catholyte at pH neutral conditions, plus NaCL and

2511-411: A system or device that converts energy is measured by the ratio of the amount of useful energy put out by the system ("output energy") to the total amount of energy that is put in ("input energy") or by useful output energy as a percentage of the total input energy. In the case of fuel cells, useful output energy is measured in electrical energy produced by the system. Input energy is the energy stored in

2604-437: A welding machine. In the 1960s, Pratt & Whitney licensed Bacon's U.S. patents for use in the U.S. space program to supply electricity and drinking water (hydrogen and oxygen being readily available from the spacecraft tanks). In 1991, the first hydrogen fuel cell automobile was developed by Roger E. Billings. UTC Power was the first company to manufacture and commercialize a large, stationary fuel cell system for use as

2697-572: Is flow batteries , in which the fuel can be regenerated by recharging. Individual fuel cells produce relatively small electrical potentials, about 0.7 volts, so cells are "stacked", or placed in series, to create sufficient voltage to meet an application's requirements. In addition to electricity, fuel cells produce water vapor, heat and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions. PEMFC cells generally produce fewer nitrogen oxides than SOFC cells: they operate at lower temperatures, use hydrogen as fuel, and limit

2790-613: 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 current flow through an external circuit) occurs across the membrane while the liquids circulate in their respective spaces. Various flow batteries have been demonstrated, including inorganic and organic forms. Flow battery design can be further classified into full flow, semi-flow, and membraneless. The fundamental difference between conventional and flow batteries

2883-440: Is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen ) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most batteries in requiring a continuous source of fuel and oxygen (usually from air) to sustain the chemical reaction, whereas in a battery the chemical energy usually comes from substances that are already present in

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2976-476: Is because originally (in the 1800s) fuel cells emerged as a means to produce electricity directly from fuels (and air) via a non-combustion electrochemical process. Later, particularly in the 1960s and 1990s, rechargeable fuel cells (i.e. H 2 / O 2 , such as unitized regenerative fuel cells in NASA 's Helios Prototype ) were developed. Cr–Fe chemistry has disadvantages, including hydrate isomerism (i.e.

3069-597: Is claimed to be safer than other flow batteries given its absence of acidic electrolytes, nonflammability and operating range of −4 to 122 °F (−20 to 50 °C) that does not require extensive cooling circuitry, which would add weight and occupy space. One unresolved issue is zinc buildup on the negative electrode that can permeate the membrane, reducing efficiency. Because of the Zn dendrite formation, Zn-halide batteries cannot operate at high current density (> 20 mA/cm ) and thus have limited power density. Adding alcohol to

3162-625: Is fueled with natural gas , and does not use combustion. Instead, the fuel gas undergoes an electrochemical process that produces direct current electricity, heat, and water. Carbon dioxide gas is also released, as an undesirable byproduct of the fuel cell operation. A stadium-seating-style theater that houses over 200 people, it has a 30-by-40-foot (9.1 m × 12.2 m) screen, an 18,000-watt Dolby sound system, and utilizes Dolby 3D technology and glasses. 41°45′52″N 72°40′11″W  /  41.7644°N 72.6697°W  / 41.7644; -72.6697 Fuel cell A fuel cell

3255-651: Is greater than 45% at low loads and shows average values of about 36% when a driving cycle like the NEDC ( New European Driving Cycle ) is used as test procedure. The comparable NEDC value for a Diesel vehicle is 22%. In 2008 Honda released a demonstration fuel cell electric vehicle (the Honda FCX Clarity ) with fuel stack claiming a 60% tank-to-wheel efficiency. It is also important to take losses due to fuel production, transportation, and storage into account. Fuel cell vehicles running on compressed hydrogen may have

3348-482: Is produced by steam methane reforming , which emits carbon dioxide. The overall efficiency (electricity to hydrogen and back to electricity) of such plants (known as round-trip efficiency ), using pure hydrogen and pure oxygen can be "from 35 up to 50 percent", depending on gas density and other conditions. The electrolyzer/fuel cell system can store indefinite quantities of hydrogen, and is therefore suited for long-term storage. Solid-oxide fuel cells produce heat from

3441-589: Is referred to as the heart of the PEMFC and is usually made of a proton-exchange membrane sandwiched between two catalyst -coated carbon papers . Platinum and/or similar types of noble metals are usually used as the catalyst for PEMFC, and these can be contaminated by carbon monoxide , necessitating a relatively pure hydrogen fuel. The electrolyte could be a polymer membrane . Phosphoric acid fuel cells (PAFCs) were first designed and introduced in 1961 by G. V. Elmore and H. A. Tanner . In these cells, phosphoric acid

3534-438: Is said to be the largest of the type. Small-scale (sub-5kWhr) fuel cells are being developed for use in residential off-grid deployment. Combined heat and power (CHP) fuel cell systems, including micro combined heat and power (MicroCHP) systems are used to generate both electricity and heat for homes (see home fuel cell ), office building and factories. The system generates constant electric power (selling excess power back to

3627-596: Is that energy is stored in the electrode material in conventional batteries, while in flow batteries it is stored in the electrolyte . A flow battery may be used like a fuel cell (where new charged negolyte (a.k.a. reducer or fuel) and charged posolyte (a.k.a. oxidant) are added to the system) or like a rechargeable battery (where an electric power source drives regeneration of the reducer and oxidant). Flow batteries have certain technical advantages over conventional rechargeable batteries with solid electroactive materials, such as independent scaling of power (determined by

3720-594: Is the cells' short life span. The high-temperature and carbonate electrolyte lead to corrosion of the anode and cathode. These factors accelerate the degradation of MCFC components, decreasing the durability and cell life. Researchers are addressing this problem by exploring corrosion-resistant materials for components as well as fuel cell designs that may increase cell life without decreasing performance. MCFCs hold several advantages over other fuel cell technologies, including their resistance to impurities. They are not prone to "carbon coking", which refers to carbon build-up on

3813-498: Is the near-perfect match of the voltage window of carbon/aqueous acid interface with that of vanadium redox-couples. This extends the life of the low-cost carbon electrodes and reduces the impact of side reactions, such as H2 and O2 evolutions, resulting in many year durability and many cycle (15,000–20,000) lives, which in turn results in a record low levelized cost of energy (LCOE, system cost divided by usable energy, cycle life, and round-trip efficiency). These long lifetimes allow for

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3906-534: Is the potential for carbon dust to build up on the anode, which slows down the internal reforming process. Research to address this "carbon coking" issue at the University of Pennsylvania has shown that the use of copper-based cermet (heat-resistant materials made of ceramic and metal) can reduce coking and the loss of performance. Another disadvantage of SOFC systems is the long start-up, making SOFCs less useful for mobile applications. Despite these disadvantages,

3999-531: Is the tunable redox properties of its active components. As of 2021, organic RFB experienced low durability (i.e. calendar or cycle life, or both) and have not been demonstrated on a commercial scale. Organic redox flow batteries can be further classified into aqueous (AORFBs) and non-aqueous (NAORFBs). AORFBs use water as solvent for electrolyte materials while NAORFBs employ organic solvents. AORFBs and NAORFBs can be further divided into total and hybrid systems. The former use only organic electrode materials, while

4092-506: Is used as a non-conductive electrolyte to pass protons from the anode to the cathode and to force electrons to travel from anode to cathode through an external electrical circuit. These cells commonly work in temperatures of 150 to 200 °C. This high temperature will cause heat and energy loss if the heat is not removed and used properly. This heat can be used to produce steam for air conditioning systems or any other thermal energy-consuming system. Using this heat in cogeneration can enhance

4185-436: Is used to heat a building in a cogeneration system this efficiency can increase to 85%. This is significantly more efficient than traditional coal power plants, which are only about one third energy efficient. Assuming production at scale, fuel cells could save 20–40% on energy costs when used in cogeneration systems. Fuel cells are also much cleaner than traditional power generation; a fuel cell power plant using natural gas as

4278-693: Is used, the CO 2 is released when methane from natural gas is combined with steam, in a process called steam methane reforming , to produce the hydrogen. This can take place in a different location to the fuel cell, potentially allowing the hydrogen fuel cell to be used indoors—for example, in forklifts. The different components of a PEMFC are The materials used for different parts of the fuel cells differ by type. The bipolar plates may be made of different types of materials, such as, metal, coated metal, graphite , flexible graphite, C–C composite , carbon – polymer composites etc. The membrane electrode assembly (MEA)

4371-623: The Electrochemical Society journal Interface in 2008, wrote, "While fuel cells are efficient relative to combustion engines, they are not as efficient as batteries, primarily due to the inefficiency of the oxygen reduction reaction (and ... the oxygen evolution reaction, should the hydrogen be formed by electrolysis of water). ... [T]hey make the most sense for operation disconnected from the grid, or when fuel can be provided continuously. For applications that require frequent and relatively rapid start-ups ... where zero emissions are

4464-511: The ionic conductivity of YSZ. Therefore, to obtain the optimum performance of the fuel cell, a high operating temperature is required. According to their website, Ceres Power , a UK SOFC fuel cell manufacturer, has developed a method of reducing the operating temperature of their SOFC system to 500–600 degrees Celsius. They replaced the commonly used YSZ electrolyte with a CGO (cerium gadolinium oxide) electrolyte. The lower operating temperature allows them to use stainless steel instead of ceramic as

4557-428: The waste heat produced by the primary power cycle - whether fuel cell, nuclear fission or combustion - is captured and put to use, increasing the efficiency of the system to up to 85–90%. The theoretical maximum efficiency of any type of power generation system is never reached in practice, and it does not consider other steps in power generation, such as production, transportation and storage of fuel and conversion of

4650-494: The DFC-ERG, is combined with a gas turbine and, according to the company, it achieves an electrical efficiency of 65%. The electric storage fuel cell is a conventional battery chargeable by electric power input, using the conventional electro-chemical effect. However, the battery further includes hydrogen (and oxygen) inputs for alternatively charging the battery chemically. Glossary of terms in table: The energy efficiency of

4743-576: The amortization of their relatively high capital cost (driven by vanadium, carbon felts, bipolar plates, and membranes). The LCOE is on the order of a few tens cents per kWh, much lower than of solid-state batteries and near the targets of 5 cents stated by US and EC government agencies. Major challenges include: low abundance and high costs of V 2 O 5 (> $ 30 / Kg); parasitic reactions including hydrogen and oxygen evolution; and precipitation of V 2 O 5 during cycling. The hybrid flow battery (HFB) uses one or more electroactive components deposited as

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4836-493: The anode that results in reduced performance by slowing down the internal fuel reforming process. Therefore, carbon-rich fuels like gases made from coal are compatible with the system. The United States Department of Energy claims that coal, itself, might even be a fuel option in the future, assuming the system can be made resistant to impurities such as sulfur and particulates that result from converting coal into hydrogen. MCFCs also have relatively high efficiencies. They can reach

4929-478: The anode to the cathode through an external circuit, producing direct current electricity. At the cathode, another catalyst causes ions, electrons, and oxygen to react, forming water and possibly other products. Fuel cells are classified by the type of electrolyte they use and by the difference in start-up time ranging from 1 second for proton-exchange membrane fuel cells (PEM fuel cells, or PEMFC) to 10 minutes for solid oxide fuel cells (SOFC). A related technology

5022-423: The anode to the cathode), as is the case in all other types of fuel cells. Oxygen gas is fed through the cathode, where it absorbs electrons to create oxygen ions. The oxygen ions then travel through the electrolyte to react with hydrogen gas at the anode. The reaction at the anode produces electricity and water as by-products. Carbon dioxide may also be a by-product depending on the fuel, but the carbon emissions from

5115-534: The battery's original voltage was retained. Neutral AORFBs can be more environmentally friendly than acid or alkaline alternatives, while showing electrochemical performance comparable to corrosive RFBs. The MV/TEMPO AORFB has an energy density of 8.4   Wh/L with the limitation on the TEMPO side. In 2019 Viologen -based flow batteries using an ultralight sulfonate –viologen/ ferrocyanide AORFB were reported to be stable for 1000 cycles at an energy density of 10 Wh/L,

5208-511: The battery. Fuel cells can produce electricity continuously for as long as fuel and oxygen are supplied. The first fuel cells were invented by Sir William Grove in 1838. The first commercial use of fuel cells came almost a century later following the invention of the hydrogen–oxygen fuel cell by Francis Thomas Bacon in 1932. The alkaline fuel cell , also known as the Bacon fuel cell after its inventor, has been used in NASA space programs since

5301-548: The cathode. There, oxygen from the air and carbon dioxide recycled from the anode react with the electrons to form carbonate ions that replenish the electrolyte, completing the circuit. The chemical reactions for an MCFC system can be expressed as follows: As with SOFCs, MCFC disadvantages include slow start-up times because of their high operating temperature. This makes MCFC systems not suitable for mobile applications, and this technology will most likely be used for stationary fuel cell purposes. The main challenge of MCFC technology

5394-462: The cell substrate, which reduces cost and start-up time of the system. Molten carbonate fuel cells (MCFCs) require a high operating temperature, 650 °C (1,200 °F), similar to SOFCs . MCFCs use lithium potassium carbonate salt as an electrolyte, and this salt liquefies at high temperatures, allowing for the movement of charge within the cell – in this case, negative carbonate ions. Like SOFCs, MCFCs are capable of converting fossil fuel to

5487-500: The commercial leaders. They use vanadium at both electrodes, so they do not suffer cross-contamination. The limited solubility of vanadium salts, however, offsets this advantage in practice. This chemistry's advantages include four oxidation states within the electrochemical voltage window of the graphite-aqueous acid interface, and thus the elimination of the mixing dilution, detrimental in Cr–Fe RFBs. More importantly for commercial success

5580-478: The cost of power (size of stacks). Also, most flow batteries (Zn-Cl 2 , Zn-Br 2 and H 2 -LiBrO 3 are exceptions) have lower specific energy (heavier weight) than lithium-ion batteries . The heavier weight results mostly from the need to use a solvent (usually water) to maintain the redox active species in the liquid phase. Patent Classifications for flow batteries had not been fully developed as of 2021. Cooperative Patent Classification considers RFBs as

5673-606: The development of his first crude fuel cells. He used a combination of sheet iron, copper, and porcelain plates, and a solution of sulphate of copper and dilute acid. In a letter to the same publication written in December 1838 but published in June 1839, German physicist Christian Friedrich Schönbein discussed the first crude fuel cell that he had invented. His letter discussed the current generated from hydrogen and oxygen dissolved in water. Grove later sketched his design, in 1842, in

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5766-549: The diffusion of nitrogen into the anode via the proton exchange membrane, which forms NOx. The energy efficiency of a fuel cell is generally between 40 and 60%; however, if waste heat is captured in a cogeneration scheme, efficiencies of up to 85% can be obtained. The first references to hydrogen fuel cells appeared in 1838. In a letter dated October 1838 but published in the December 1838 edition of The London and Edinburgh Philosophical Magazine and Journal of Science , Welsh physicist and barrister Sir William Grove wrote about

5859-404: The efficiency of phosphoric acid fuel cells from 40 to 50% to about 80%. Since the proton production rate on the anode is small, platinum is used as a catalyst to increase this ionization rate. A key disadvantage of these cells is the use of an acidic electrolyte. This increases the corrosion or oxidation of components exposed to phosphoric acid. Solid acid fuel cells (SAFCs) are characterized by

5952-447: The electricity into mechanical power. However, this calculation allows the comparison of different types of power generation. The theoretical maximum efficiency of a fuel cell approaches 100%, while the theoretical maximum efficiency of internal combustion engines is approximately 58%. Values are given from 40% for acidic, 50% for molten carbonate, to 60% for alkaline, solid oxide and PEM fuel cells. Fuel cells cannot store energy like

6045-640: The electrode." Electrolyte is stored externally, generally in tanks, and is typically pumped through the cell (or cells) of the reactor. Flow batteries can be rapidly "recharged" by replacing discharged electrolyte liquid (analogous to refueling internal combustion engines ) while recovering the spent material for recharging. They can also be recharged in situ . Many flow batteries use carbon felt electrodes due to its low cost and adequate electrical conductivity, despite their limited power density due to their low inherent activity toward many redox couples. The amount of electricity that can be generated depends on

6138-608: The electrolyte of the ZnI battery can help. The drawbacks of Zn/I RFB lie are the high cost of Iodide salts (> $ 20 / Kg); limited area capacity of Zn deposition, reducing the decoupled energy and power; and Zn dendrite formation. When the battery is fully discharged, both tanks hold the same electrolyte solution: a mixture of positively charged zinc ions ( Zn ) and negatively charged iodide ion, ( I ). When charged, one tank holds another negative ion, polyiodide, ( I 3 ). The battery produces power by pumping liquid across

6231-619: The equilibrium between electrochemically active Cr3+ chloro-complexes and inactive hexa-aqua complex and hydrogen evolution on the negode. Hydrate isomerism can be alleviated by adding chelating amino-ligands, while hydrogen evolution can be mitigated by adding Pb salts to increase the H 2 overvoltage and Au salts for catalyzing the chromium electrode reaction. Traditional redox flow battery chemistries include iron-chromium, vanadium , polysulfide–bromide (Regenesys), and uranium . Redox fuel cells are less common commercially although many have been proposed. Vanadium redox flow batteries are

6324-553: The first science center to generate most of its needed power from an on-site fuel cell . This step was a major one for the Connecticut Science Center and its steps towards being a Gold Level LEED Certified green building. The 200-kilowatt fuel cell, built by UTC Power (a United Technologies Corp business based in South Windsor), generates 100 percent of the electricity the Science Center uses. The PureCell System

6417-442: The flat plane configuration of other types of fuel cells and are often designed as rolled tubes. They require high operating temperatures (800–1000 °C) and can be run on a variety of fuels including natural gas. SOFCs are unique because negatively charged oxygen ions travel from the cathode (positive side of the fuel cell) to the anode (negative side of the fuel cell) instead of protons travelling vice versa (i.e., from

6510-463: The fuel. According to the U.S. Department of Energy, fuel cells are generally between 40 and 60% energy efficient. This is higher than some other systems for energy generation. For example, the internal combustion engine of a car can be about 43% energy efficient. Steam power plants usually achieve efficiencies of 30-40% while combined cycle gas turbine and steam plants can achieve efficiencies above 60%. In combined heat and power (CHP) systems,

6603-506: The grid when it is not consumed), and at the same time produces hot air and water from the waste heat . As the result CHP systems have the potential to save primary energy as they can make use of waste heat which is generally rejected by thermal energy conversion systems. A typical capacity range of home fuel cell is 1–3 kW el , 4–8 kW th . CHP systems linked to absorption chillers use their waste heat for refrigeration . The waste heat from fuel cells can be diverted during

6696-462: The ions are reunited with the electrons and the two react with a third chemical, usually oxygen, to create water or carbon dioxide. Design features in a fuel cell include: A typical fuel cell produces a voltage from 0.6 to 0.7 V at a full-rated load. Voltage decreases as current increases, due to several factors: To deliver the desired amount of energy, the fuel cells can be combined in series to yield higher voltage , and in parallel to allow

6789-406: The latter use inorganic materials for either anode or cathode. In larger-scale energy storage, lower solvent cost and higher conductivity give AORFBs greater commercial potential, as well as offering the safety advantages of water-based electrolytes. NAORFBs instead provide a much larger voltage window and occupy less space. pH neutral AORFBs are operated at pH 7 conditions, typically using NaCl as

6882-400: The load. At the anode a catalyst ionizes the fuel, turning the fuel into a positively charged ion and a negatively charged electron. The electrolyte is a substance specifically designed so ions can pass through it, but the electrons cannot. The freed electrons travel through a wire creating an electric current. The ions travel through the electrolyte to the cathode. Once reaching the cathode,

6975-609: The membrane to the cathode, but the electrons are forced to travel in an external circuit (supplying power) because the membrane is electrically insulating. On the cathode catalyst, oxygen molecules react with the electrons (which have traveled through the external circuit) and protons to form water. In addition to this pure hydrogen type, there are hydrocarbon fuels for fuel cells, including diesel , methanol ( see: direct-methanol fuel cells and indirect methanol fuel cells ) and chemical hydrides. The waste products with these types of fuel are carbon dioxide and water. When hydrogen

7068-485: The mid-1960s to generate power for satellites and space capsules . Since then, fuel cells have been used in many other applications. Fuel cells are used for primary and backup power for commercial, industrial and residential buildings and in remote or inaccessible areas. They are also used to power fuel cell vehicles , including forklifts, automobiles, buses, trains, boats, motorcycles, and submarines. There are many types of fuel cells, but they all consist of an anode ,

7161-663: The negolyte and in the posolyte) were used in order to reduce the effect of time-varying concentration during cycling. In the late 1980s, Sum, Rychcik and Skyllas-Kazacos at the University of New South Wales (UNSW) in Australia demonstrated vanadium RFB chemistry UNSW filed several patents related to VRFBs, that were later licensed to Japanese, Thai and Canadian companies, which tried to commercialize this technology with varying success. Organic redox flow batteries emerged in 2009. In 2022, Dalian , China began operating

7254-490: The original fuel cell design by using a sulphonated polystyrene ion-exchange membrane as the electrolyte. Three years later another GE chemist, Leonard Niedrach, devised a way of depositing platinum onto the membrane, which served as a catalyst for the necessary hydrogen oxidation and oxygen reduction reactions. This became known as the "Grubb-Niedrach fuel cell". GE went on to develop this technology with NASA and McDonnell Aircraft, leading to its use during Project Gemini . This

7347-769: The period 2012–2014, 30,000 units on LNG and 6,000 on LPG . Four fuel cell electric vehicles have been introduced for commercial lease and sale: the Honda Clarity , Toyota Mirai , Hyundai ix35 FCEV , and the Hyundai Nexo . By year-end 2019, about 18,000 FCEVs had been leased or sold worldwide. Fuel cell electric vehicles feature an average range of 505 km (314 mi) between refuelings and can be refueled in about 5 minutes. The U.S. Department of Energy's Fuel Cell Technology Program states that, as of 2011, fuel cells achieved 53–59% efficiency at one-quarter power and 42–53% vehicle efficiency at full power, and

7440-414: The power stack. The main disadvantages are: Flow batteries typically have a higher energy efficiency than fuel cells , but lower than lithium-ion batteries . Traditional flow battery chemistries have both low specific energy (which makes them too heavy for fully electric vehicles) and low specific power (which makes them too expensive for stationary energy storage ). However a high power of 1.4 W/cm

7533-498: The recombination of the oxygen and hydrogen. The ceramic can run as hot as 800 °C (1,470 °F). This heat can be captured and used to heat water in a micro combined heat and power (m-CHP) application. When the heat is captured, total efficiency can reach 80–90% at the unit, but does not consider production and distribution losses. CHP units are being developed today for the European home market. Professor Jeremy P. Meyers, in

7626-405: The same general manner. They are made up of three adjacent segments: the anode , the electrolyte , and the cathode . Two chemical reactions occur at the interfaces of the three different segments. The net result of the two reactions is that fuel is consumed, water or carbon dioxide is created, and an electric current is created, which can be used to power electrical devices, normally referred to as

7719-514: The same journal. The fuel cell he made used similar materials to today's phosphoric acid fuel cell . In 1932, English engineer Francis Thomas Bacon successfully developed a 5 kW stationary fuel cell. NASA used the alkaline fuel cell (AFC), also known as the Bacon fuel cell after its inventor, from the mid-1960s. In 1955, W. Thomas Grubb, a chemist working for the General Electric Company (GE), further modified

7812-427: The size of the stack) and of energy (determined by the size of the tanks), long cycle and calendar life, and potentially lower total cost of ownership ,. However, flow batteries suffer from low cycle energy efficiency (50–80%). This drawback stems from the need to operate flow batteries at high (>= 100 mA/cm2) current densities to reduce the effect of internal crossover (through the membrane/separator) and to reduce

7905-423: The stack where the liquids mix. Inside the stack, zinc ions pass through a selective membrane and change into metallic zinc on the stack's negative side. To increase energy density, bromide ions ( Br – ) are used as the complexing agent to stabilize the free iodine, forming iodine–bromide ions ( I 2 Br ) as a means to free up iodide ions for charge storage. Proton flow batteries (PFB) integrate

7998-764: The summer directly into the ground providing further cooling while the waste heat during winter can be pumped directly into the building. The University of Minnesota owns the patent rights to this type of system. Co-generation systems can reach 85% efficiency (40–60% electric and the remainder as thermal). Phosphoric-acid fuel cells (PAFC) comprise the largest segment of existing CHP products worldwide and can provide combined efficiencies close to 90%. Molten carbonate (MCFC) and solid-oxide fuel cells (SOFC) are also used for combined heat and power generation and have electrical energy efficiencies around 60%. Disadvantages of co-generation systems include slow ramping up and down rates, high cost and short lifetime. Also their need to have

8091-463: The thousands of hours. The alkaline fuel cell (AFC) or hydrogen-oxygen fuel cell was designed and first demonstrated publicly by Francis Thomas Bacon in 1959. It was used as a primary source of electrical energy in the Apollo space program. The cell consists of two porous carbon electrodes impregnated with a suitable catalyst such as Pt, Ag, CoO, etc. The space between the two electrodes is filled with

8184-579: The use of a solid acid material as the electrolyte. At low temperatures, solid acids have an ordered molecular structure like most salts. At warmer temperatures (between 140 and 150   °C for CsHSO 4 ), some solid acids undergo a phase transition to become highly disordered "superprotonic" structures, which increases conductivity by several orders of magnitude. The first proof-of-concept SAFCs were developed in 2000 using cesium hydrogen sulfate (CsHSO 4 ). Current SAFC systems use cesium dihydrogen phosphate (CsH 2 PO 4 ) and have demonstrated lifetimes in

8277-482: The volume of electrolyte. Flow batteries are governed by the design principles of electrochemical engineering . Redox flow batteries, and to a lesser extent hybrid flow batteries, have the advantages of: Some types offer easy state-of-charge determination (through voltage dependence on charge), low maintenance and tolerance to overcharge/overdischarge. They are safe because they typically do not contain flammable electrolytes, and electrolytes can be stored away from

8370-540: Was called a solid polymer electrolyte fuel cell ( SPEFC ) in the early 1970s, before the proton-exchange mechanism was well understood. (Notice that the synonyms polymer electrolyte membrane and proton-exchange mechanism result in the same acronym .) On the anode side, hydrogen diffuses to the anode catalyst where it later dissociates into protons and electrons. These protons often react with oxidants causing them to become what are commonly referred to as multi-facilitated proton membranes. The protons are conducted through

8463-543: Was demonstrated for hydrogen–bromine flow batteries, and a high specific energy (530 Wh/kg at the tank level) was shown for hydrogen–bromate flow batteries The redox cell uses redox-active species in fluid (liquid or gas) media. Redox flow batteries are rechargeable ( secondary ) cells. Because they employ heterogeneous electron transfer rather than solid-state diffusion or intercalation they are more similar to fuel cells than to conventional batteries. The main reason fuel cells are not considered to be batteries,

8556-408: Was the first commercial use of a fuel cell. In 1959, a team led by Harry Ihrig built a 15 kW fuel cell tractor for Allis-Chalmers , which was demonstrated across the U.S. at state fairs. This system used potassium hydroxide as the electrolyte and compressed hydrogen and oxygen as the reactants. Later in 1959, Bacon and his colleagues demonstrated a practical five-kilowatt unit capable of powering

8649-728: Was the original flow battery. John Doyle file patent US 224404   on September 29, 1879. Zn-Br2 batteries have relatively high specific energy, and were demonstrated in electric cars in the 1970s. Walther Kangro, an Estonian chemist working in Germany in the 1950s, was the first to demonstrate flow batteries based on dissolved transition metal ions: Ti–Fe and Cr–Fe. After initial experimentations with Ti–Fe redox flow battery (RFB) chemistry, NASA and groups in Japan and elsewhere selected Cr–Fe chemistry for further development. Mixed solutions (i.e. comprising both chromium and iron species in

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