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Hydrogen: Pros & Cons
Pros GHG Reduction - A hydrogen powered vehicle can immensely cut down GHG and particulate matter emissions if the hydrogen was produced through electrolysis using renewable energy to power the hydrogen-oxygen bond split. The only emission from hydrogen usage in a fuel cell vehicle is water; if combusted in an internal combustion engine nitrous oxide can be produced. Excess Electricity Consumption - The electrolysis of water to produce hydrogen could be powered with excess electricity, whether it is excess supply from fossil fuel power plants or excess supply from renewable technologies, such as wind, wave or hydro power, during the night. This creates a way to store this extra electricity in a usable form. Distributed Electrolysis - To speed the production and infrastructure of a hydrogen economy, while lowering the initial capital costs, electrolyzers could be installed anywhere where hydrogen demand is. The electrolyzers could produce hydrogen using only water and electricity as inputs to meet demand. While this would reduce cost from building expensive pipelines, it would add demand to the already strained electric grid unless a majority of production was done during low demand periods (night time) and stored for usage during the next day. Available Globally - Nearly all countries have some form of renewable energy available, which could be used to either produce hydrogen on a full-time basis or with excess electricity produced in low demand periods. Price Competitive - A hydrogen economy powered by Biomass Gasification is price competitive to gasoline and diesel and falls below the U.S. DOE’s hydrogen price per gallon equivalent goal. The total investment to completely replace petroleum-based fuels is estimated to be $565 billion (this figure excludes transfer of hydrogen, be it by truck or pipeline). Home Generation - Firms are now producing electrolyzers to be used at home, where hydrogen can be produced and vehicles fueled with only water and electricity. Cons Land Usage - To use renewable energy sources to create a full hydrogen economy, solar would require installations larger than three times the size of Nevada or the use of the state of California for wind turbines. Biomass, the least expensive choice, would require the use of only 11% of U.S. farm acreage. See chart for land, cost, and CO2 emission comparisons from renewable and fossil fuel-powered hydrogen economy’s. Expensive Infrastructure - Hydrogen is predominantly transported via hydrogen pipelines or trucks to filling stations. This adds to cost of hydrogen from the continual fuel and labor cost of delivery or the high upfront cost of roughly $1.5 million per mile, but low ongoing cost, of special pipeline installation (hydrogen can crack unsealed steel pipes). This cost can be substantially reduced by installing small to medium size hydrogen generating systems at filling stations, which can produce to meet demand. On-board Storage Problems - Hydrogen has a low energy density by volume and must be pressurized or liquefied to be stored in a vehicle, otherwise the low density would require a much larger fuel tank. Pressurization requires additional energy to compress the hydrogen before usage. Liquefication requires even more energy as it pressurizes the hydrogen before cryogenically cooling it into liquid form. Depending on the type of hydrogen fuel used, adjustments need to be made to fuel tanks, which could add to the expense and weight of the vehicle, thus reducing fuel efficiency. Most hydrogen concept vehicles today use hydrogen pressurized at 700 bar. Lengthy Implementation - Current estimates call for a hydrogen fuel economy to take 40 years to have a meaningful impact on oil consumption and greenhouse gas emissions. Hydrogen Leaks - Molecular hydrogen leaks slowly from most containers at a rate of 1 to 2%, which creates potential environmental and explosive dangers. If enough hydrogen escaped it may form free radicals after exposure to ultraviolet radiation which could act as a catalyst for ozone depletion. Leaked hydrogen is also dangerous as it is colorless and flammable at room temperature. |
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