Fossil fuels and nuclear energy, the resources used to meet most of our energy needs today, are expected to be widely used in the near future. However, fossil and nuclear energy resources are nonrenewable and will someday be exhausted, while their continued use poses environmental risks related to air pollution, global warming, land use, and waste disposal. These challenges have stimulated the search for alternative means of producing and using energy. New resources that are being researched or developed include hydrogen, nuclear fusion, ocean thermal energy conservation, and tidal and wave energy.
Solar
The sun is expected is remain much as it is today for another five billion years. Because we can anticipate harvesting the sun's energy for the foreseeable future, the outlook for solar energy is optimistic.
Solar Electricity is flexible and the environmental benefits make it an attractive alternative to fossil and nuclear fuels. Continued growth in utility-scale solar power generation is expected. The flexibility and environmental benefits of solar electricity make it an attractive alternative to fossil and nuclear fuels. The cost of solar panels has dropped significantly. Other solar installations (such as CSP) are relatively expensive when compared to the amount of electricity they generate. Incentives are increasingly offered at the utility, county, state, and federal levels. The U.S.Department of Energy's SunShot Initiative has launched an effort to make solar energy more cost-competitive with other types of energy. Incentives such as these will ultimately assist in the continued growth of solar energy.
In the United States, there is enough installed solar power to power more than 3,000,000 homes and many more are planned. In the near future, the use of solar electric systems will likely continue to increase in the southern and western parts of the United States where sunshine is plentiful. Solar energy growth in Wisconsin has been slower than that of Southern and Western states but currently has 26 MW of solar energy installed, equivalent to what is needed to power 3,800 homes. A number of homeowners and businesses in Wisconsin have already demonstrated that solar electric systems can meet their needs, and it is reasonable to expect growth of solar power in Wisconsin as well. Over the next five years, Wisconsin is expected to install 157 MW of solar electric capacity, ranking the state 34th over that time span. This amount is more than 10 times the amount of solar installed over the last five years.
Solar Heating also benefits the environment and its ability to meet the heating needs of most homes and buildings make it an attractive alternative to using nonrenewable fossil fuels. The high cost of solar heating systems is the main obstacle. Reducing costs by mass-producing equipment, designing buildings that include passive solar energy features, and improving energy efficiency may help make solar heating systems more acceptable to consumers. Price increases in fossil fuels may also make solar heating systems more attractive. In the near future, it is more likely that increased use of solar heating systems will occur in the southern and western parts of the United States where solar energy is plentiful. On the other hand, a number of homeowners and businesses in Wisconsin have already demonstrated that active and passive solar heating systems can adequately meet their needs. These systems may become more common in Wisconsin as fossil fuel supplies decline and the environmental advantages of solar heating become increasingly important.
Wind
Although growth in wind energy has stalled in recent years, utilities have been taking a second look at wind farms. Continued growth through 2016 and beyond is expected and likely. Texas continues to lead the nation in wind energy production, but other states such as Minnesota have implemented large-scale wind systems. Europe has aggressively developed wind power, and it has taken over hydropower as the third largest source of power generation in the EU. India, Brazil, China, Mexico, and Egypt also have sizable wind power projects underway.
Experts predict that by the year 2020 wind power could supply the U.S. with about 10 percent of the total electricity produced. No offshore wind energy plants are currently operating in the U.S. but progress is being made toward an offshore project in Rhode Island. The cost of wind-generated electricity has fallen and is becoming competitive with other ways of generating electricity. While wind energy is not expected to completely replace fossil- and nuclear-fueled electric power plants, its environmental advantages make it an attractive choice for the future.
Biomass
Biomass fuels are versatile, which allows nations with different levels of technical development to meet their energy needs without having to import energy resources. The use of biomass fuels is increasing, but these fuels are not likely to replace the use of fossil fuels in the near future unless gasoline prices rise substantially. Environmental impacts, competing land uses, the need for food, and the energy required to harvest biomass material are limiting factors. Harvesting biomass sustainably and burning biomass fuels efficiently will help ensure that they are widely used in the future. Wood will continue to play a role in providing energy for heating, cooking, and generating electricity in the United States and the world. However, there is not enough wood to completely replace fossil fuels for these purposes due to limited availability, restrictions on harvesting wood in protected areas, and competing uses for making various products. Although the use of wood as an energy resource is expected to increase, it will be limited. In developing countries, the use of fuel wood is essential to the survival of many people, yet the problem of wood shortages is becoming more acute. The environment may also be harmed if proper precautions are not taken to harvest wood sustainably and burn it efficiently.
Hydropower
Hydropower will continue to be an important energy resource in the United States and the world. However, it is unlikely that enough new hydroelectric plants will take the place of fossil- and nuclear-fueled electric power plants. Most available sites for large-scale hydroelectric power production in the United States have already been developed. On the other hand, the potential for further development of hydropower on smaller rivers and streams still exists. However, water shortages have decreased electricity produced by hydropower by 14 percent over the past two decades globally.
Geothermal
Low-temperature geothermal heating and cooling systems are becoming increasingly popular in new construction for the long-term energy savings associated with these systems. Even though the installation price of a geothermal heat pump system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs are returned to you in energy savings in 5 to 10 years. System life is estimated at 25 years for the inside components and 50+ years for the ground loop. There are approximately 50,000 geothermal heat pumps installed in the United States each year.
The United States has hundreds of locations in at least 15 states that have been identified as having potential to support high temperature geothermal electric power production. Thousands more megawatts of power could be developed from already-identified geothermal resources. As of February 2015, there was 3,522 MW of geothermal resources developed in the U.S. with an additional 1,275 MW planned. With improvements in technology, much more power will become available. The outlook for geothermal energy use depends on several factors including: the demand for energy in general; the inventory of available geothermal resources; and the competitive position of geothermal among other energy sources. The inventory of accessible high temperature geothermal energy is sizable. Using current technology, geothermal energy from already-identified reservoirs can contribute as much as 10 percent of the United States' energy supply, or about 39,000 MW of geothermal energy. With more exploration, the inventory can become larger.
Enhanced Geothermal Systems, or EGS, could be used to reach geothermal energy that is not easily accessed by a form of engineering. An EGS is a man-made reservoir created where there is hot rock but insufficient permeability or fluid saturation. A fluid is injected into the subsurface to cause pre-existing fractures to re-open, creating permeability and allowing fluid to circulate throughout the rock, transporting heat to the surface. While this technology could lead to more geothermal electricity production, many risks are associated with it including increased seismic activities, especially dangerous in urban areas where it would be ideal to place. The geothermal resource base becomes more available as methods and technologies for accessing it are improved through research and experience.
Hydrogen
One fuel that has the potential of being widely used in the future is hydrogen gas (H2). Like natural gas, hydrogen can be burned to heat buildings, cook food, and produce electricity in power plants. Should hydrogen replace natural gas, the existing natural gas pipeline network could be modified to transport hydrogen. Hydrogen gas can also be compressed in a fuel tank and used to power cars and buses, although difficulties in storing enough hydrogen for motor vehicles to run long distances need to be overcome. Another problem is building the infrastructure to refuel these vehicles.
Fuel cells have high efficiencies (up to 60 percent), or two to three times more efficient than an internal combustion engine running on gasoline. Hydrogen can be used in fuel cells. The electrons in hydrogen atoms generate electricity in the fuel cell. The combination of hydrogen and oxygen creates water and heat from the reaction. The heat may be used to produce electricity, but can be used simply to heat things. At the anode, hydrogen is split into protons and electrons. The electrons move down a separate channel generating electricity. The U.S. space program has used them since the 1960s; the space shuttle uses fuel cells to generate electricity. Electrical power plants could be built using large banks of fuel cells, while small groups of cells could provide electricity for individual home and commercial buildings. Experimental cars and buses powered by fuel cells have already been built and tested and in recent years have been coming onto the market.
Hydrogen is used to store energy produced in other ways. Plentiful hydrogen is available from water (H2O), which can be split into gaseous hydrogen and oxygen using an electrical process called electrolysis. This process, however, is very energy instensive. Hydrogen can also be produced from natural gas and biomass resources. Hydrogen is cleaner than other fuels, although it is necessary to take into consideration from where the hydrogen is derived. When burned, because it is reacting with oxygen and nitrogen in the air, it produces only water vapor and, in some cases, small amounts of nitrogen oxides. Hydrogen is often considered a renewable fuel because the water vapor produced by burning hydrogen cycles back into the environment. But, Earth's supply of water is finite, so we are limited to what we have on Earth and the locations of these water sources may change over time. Hydrogen fuel, when produced by renewable sources of energy like wind or solar power, can be considered a renewable fuel. Although hydrogen's explosiveness has given it a reputation for being unsafe, studies have shown that hydrogen is no more hazardous than gasoline and natural gas.
Choosing a renewable source of electricity to produce hydrogen is important. Using electricity from coal- or nuclear-fueled power plants can erase hydrogen's advantage as a clean fuel. Using solar cells, hydroelectric dams, or wind turbines maintains this advantage. A number of experts foresee the expanded use of hydrogen going hand in hand with the increased development of renewable energy resources.
Before hydrogen is widely developed, three goals must be met: cheaper renewable electricity, improved fuel cells, and better ways to store hydrogen for vehicles. When these problems are solved, there is a good chance that hydrogen fuel and fuel cells will be common in the future. Since hydrogen can be produced from water and transported by pipeline, there would be few geographic restrictions to its use, making the future use of hydrogen possible in Wisconsin, the United States, and the rest of the World.
Ocean Thermal Energy Conversion (OTEC)
The large temperature difference between the warm surface waters of tropical oceans and the cold, deep waters lying beneath them provides a potential energy source. A device that works like a refrigerator in reverse can use this difference in temperature to drive a turbine that generates electricity. This process, called ocean thermal energy conversion (OTEC), could provide electricity for tropical islands and coastal nations. OTEC power plants can be placed offshore on floating platforms; they do not need to be built on land.
Since the sun produces the temperature difference between surface and deep ocean waters, the energy source for OTEC plants is inexhaustible for the foreseeable future. On the other hand, OTEC plants are more expensive to build than other types of electrical power plants, and the technology is still young. The best sites for OTEC are often located far from the nations and population centers that most need electricity. The temperature differences in bodies of water outside of tropical latitudes are too small to operate an OTEC power plant. For this reason, OTEC power plants on Wisconsin's Great Lakes are not feasible.
Tidal and Wave Energy
Changes in tide levels can be harnessed as a source of energy by building a barrier similar to a dam across a bay and allowing the incoming and outgoing tides to spin turbines that produce electricity. A large tidal energy site has been built in Canada's Bay of Fundy, near Maine. The tide changes in Alaska's Cook Inlet are also large enough to be harnessed for energy.
Ocean waves can also be used as an energy source. Ocean waves oscillate, moving in a curcular motion. Terminator devices capture an oscillating water column and cause it to move up and down. Scientists and inventors have designed and tested experimental devices that harness the kinetic energy in a wave to generate electricity through turbines. Some of the more promising designs are undergoing demonstration testing at commercial scales.
Tidal and wave energy are renewable resources that produce little or no pollution. Despite these advantages,the potential for developing tidal or wave energy is limited to a few coastal areas. Tidal and wave energy systems may also affect aquatic life. The equipment must also be able to withstand storms and saltwater corrosion.
Because of these limitations, many experts do not foresee tidal and wave energy making a major contribution toward meeting the energy needs of the United States or the world. The Great Lakes do not experience large tides, so tidal energy is not an option for meeting Wisconsin's energy needs. Harnessing wave energy from the Great Lakes may be technically feasible, but it is not likely to be pursued because of limited energy output and high costs.
Outlook
Hydrogen has the best chance of being widely used in the future. Sources of hydrogen are plentiful, it has many uses, and most of the needed technology has already been developed. However, hydrogen is not a primary energy source like solar or wind power; it is used to store energy produced by other means and an input of external energy is needed to power hyrdogen fuel cells. Nuclear fusion continues to pose formidable engineering problems and waste disposal and storage obstacles. Limited sites, high costs, and the need for technological development will also likely restrict the growth of OTEC, tidal, and wave energy systems. However, technical breakthroughs combined with the proper economic and environmental incentives may result in the successful development of these energy resources, despite their limitations. In addition, development of energy resources unknown to today's society may also occur.
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