Hydrogen s

Hydrogen s

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  Hydrogen What is Hydrogen? Electricity is a secondary source of energy. Secondary sources of energy —energy carriers—are used to store, move, and deliver energy in easily Hydrogen is the simplest element known to exist. An atom of hydrogen usable form. We convert energy to electricity because it is easier for us to has one proton and one electron. Hydrogen has the highest energy transport and use. Try splitting an atom, building a dam, or burning coal content of any common fuel by weight, but the lowest energy content to run your television. Energy carriers make life easier. by volume. It is the lightest element and a gas at normal temperature Hydrogen is one of the most promising energy carriers for the future. It is and pressure. a high efficiency, low polluting fuel that can be used for transportation, Hydrogen is also the most abundant gas in the universe, and the source heating, and power generation in places where it is difficult to use of all the energy we receive from the sun. The sun is basically a giant ball electricity. Since hydrogen gas is not found on Earth, it must be of hydrogen and helium gases. In a process called fusion, four hydrogen manufactured. There are several ways to do this. atoms combine to form one helium atom, releasing energy as radiation. This radiant energy is our most abundant energy source. It gives us light How is Hydrogen Made? and heat and makes plants grow. It causes the wind to blow and the rain to fall. It is stored as chemical energy in fossil fuels. Most of the energy we Industry produces the hydrogen it needs by a process called steam use originally came from the sun. reforming. High-temperature steam separates hydrogen from the carbon atoms in methane (CH4). The hydrogen produced by this method Hydrogen as a gas (H2), however, doesn’t exist naturally on Earth. It is isn’t used as a fuel, but for industrial processes. This is the most cost- found only in compound form. Combined with oxygen, it is water (H2O). effective way to produce hydrogen today, but it uses fossil fuels both in Combined with carbon, it forms organic compounds such as methane the manufacturing process and as the heat source. (CH4), coal, and petroleum. It is found in all growing things—biomass. Hydrogen is also one of the most abundant elements in the Earth’s crust. Another way to make hydrogen is by electrolysis—splitting water into its basic elements—hydrogen and oxygen. Electrolysis involves Most of the energy we use today comes from fossil fuels. Only seven passing an electric current through water to separate the atoms percent comes from renewable energy sources. Usually renewable (2H2O + electricity = 2H2 + O2). Hydrogen collects at the cathode and sources are cleaner, and can be replenished in a short period of time. We oxygen at the anode. won’t run out of hydrogen either. Hydrogen produced by electrolysis is extremely pure, and electricity Every day we use more fuel, principally coal, to produce electricity. from renewable sources can power the process, but it is very expensive at this time. Today, hydrogen from electrolysis is ten times more costly than natural gas and three times more costly than gasoline per Btu. On the other hand, water is abundant and renewable, and technological Hydrogen Life Cycle advances in renewable electricity could make electrolysis a more attractive way to produce hydrogen in the future. Primary Renewable Energy Source There are also several experimental methods of producing hydrogen. Photoelectrolysis uses sunlight to split water molecules into its Hydrogen Production components. A semiconductor absorbs the energy from the sun and Hydrogen acts as an electrode to separate the water molecules. Water In biomass gasification, wood chips and agricultural wastes are super- Oxygen heated until they turn into hydrogen and other gases. Biomass can also Storage and be used to provide the heat. Environment Transport Scientists have also discovered that some algae and bacteria produce Oxygen hydrogen under certain conditions, using sunlight as their energy Water source. Experiments are underway to find ways to induce these microbes Hydrogen to produce hydrogen efficiently. Hydrogen Utilization Nearly every region of the country (and the world) has one or more resources that can be used to produce hydrogen. It can be produced at Useful Energy large central facilities or at small distributed facilities for local use. One of its main advantages is its flexibility. 54 Secondary Energy Infobook
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  Hydrogen Uses SPACE SHUTTLE The U.S. hydrogen industry currently produces about nine million metric tons of hydrogen a year. Most of this hydrogen is used for industrial applications such as refining, treating metals, and food processing. At the present time, hydrogen’s main use as a fuel is in the NASA space program. Liquid hydrogen is the fuel that has propelled the space shuttle and other rockets since the 1970s. Hydrogen fuel cells power the shuttle’s electrical systems, producing pure water, which is used by the crew as drinking water. In the future, however, hydrogen will join electricity as an important energy carrier, since it can be made safely from renewable energy sources and is virtually non-polluting. It will also be used as a fuel for zero-emissions vehicles, to heat homes and offices, to produce electricity, and to fuel aircraft. Cost is the major obstacle. The first widespread use of hydrogen will probably be as an additive to transportation fuels. Hydrogen can be combined with gasoline, ethanol, methanol, and natural gas to increase performance and reduce NASA uses hydrogen as a fuel source in the space shuttles. pollution. Adding just five percent hydrogen to gasoline can reduce nitrogen oxide (NOX) emissions by 30 to 40 percent in today’s engines. An engine converted to burn pure hydrogen produces only water and Hydrogen Fuel Cell minor amounts of NOX as exhaust. A fuel cell consists of an electrolyte A few hydrogen-powered vehicles are on the road today, but it will be membrane sandwiched between two catalyst–coated electrodes ELECTRICITY OUT awhile before you can walk into your local car dealer and drive away in (anode and cathode). Oxygen (air) one. Today about 58 hydrogen fuel stations are operating in 20 states, passes through one electrode and but not all are open to the public. hydrogen through the other, Can you imagine how huge the task would be to quickly change the generating electricity, water, and heat gasoline-powered transportation system we have today? (Just think of the thousands of filling stations across the country and the production and distribution systems that serve them.) Change will come slowly to MEMBRANE C AT H O D E this industry, but hydrogen is a versatile fuel; it can be used in many ANODE HYDROGEN IN AIR IN ways. The space shuttle uses hydrogen fuel cells (batteries) to run its computer systems. The fuel cells basically reverse electrolysis— hydrogen and oxygen are combined to produce electricity. Hydrogen fuel cells are very efficient and produce only water as a by-product, but they are expensive to build. With technological advances, small fuel cells could someday power WATER AND HEAT OUT electric vehicles and larger fuel cells could provide electricity in remote areas. Because of the cost, hydrogen will not produce electricity on a wide scale in the near future. It may, though, be added to natural gas to Future of Hydrogen reduce emissions from existing power plants. Before hydrogen can make a significant contribution to the U.S. energy As the production of electricity from renewables increases, so will the picture, many new systems must be designed and built. There must be need for energy storage and transportation. Many of these sources— large production and storage facilities and a distribution system. And especially solar and wind—are located far from population centers consumers must have the technology to use it. and produce electricity only part of the time. Hydrogen may be the The use of hydrogen raises concerns about safety. Hydrogen is a volatile perfect carrier for this energy. It can store the energy and distribute gas with high energy content. Early skeptics had similar concerns about it to wherever it is needed. It is estimated that transmitting electricity natural gas and gasoline—even about electricity. People were afraid to long distances is four times more expensive than shipping hydrogen let their children too near the first light bulbs. As hydrogen technologies by pipeline. develop, safety issues will be addressed. Hydrogen can be produced, stored, and used as safely as other fuels. The goal of the U.S. Department of Energy’s Hydrogen Program is for hydrogen to produce ten percent of our total energy demand by the year 2030. Hydrogen can reduce our dependence on foreign oil and provide clean, renewable energy for the future. © 2011 The NEED Project P.O. Box 10101, Manassas, VA 20108 1.800.875.5029 www.NEED.org 55