Scientists define energy as the ability to do work. Modern civilization is possible because we have learned how to change energy from one form to another and use it to do work for us and to live more comfortably.
Energy makes modern agriculture possible. It moves tractors and other farm machinery through the field and moves the trucks, trains and barges that carry agricultural products from the farm to the processing plant. It operates the machinery in the processing plant that turns agricultural products into the food we eat. It bakes bread in the oven and keeps meat frozen in the freezer until we are ready to eat it. It allows our bodies to grow and our minds to think.
All energy comes from the sun. It cannot be created or destroyed, but it can be converted from one form to another. The different forms of energy include light, heat, chemical energy, and motion. All forms of energy can be put into two categories: potential and kinetic.
Wind power is kinetic energy, the energy of motion. A spinning wheel (like a car wheel) or a projectile (like a thrown ball) are examples of kinetic energy. Potential energy is energy that is waiting to be used. It may be stored chemically, electrically or mechanically. Energy from oil and gas is potential energy.
The energy in your muscles is a form of chemical potential energy. (Think of a sprinter in the starting blocks). Potential energy can also be mechanical, as in a simple windmill. A roller coaster is an interaction between kinetic and potential energy. When the cart is at the top of a loop ready to fall, it has no kinetic energy but lots of potential energy (distance it can fall). At the bottom of the loop when the cart is going very fast it has lost all the potential energy and converted it to kinetic energy (speed). As the cart uses its momentum to go up the next "hill" it trades the kinetic energy back for potential energy. If it were not for things like air resistance and friction in the wheels, this process might go on forever.
Potential energy comes in forms that are stored. There are several forms of potential energy.
- Chemical energy is energy stored in the bonds of atoms and molecules. Batteries, biomass, petroleum, natural gas, and coal are examples of stored chemical energy. Chemical energy is converted to thermal energy when we burn wood in a fireplace or burn gasoline in a car's engine.
- Mechanical energy is energy stored in objects by tension. Compressed springs and stretched rubber bands are examples of stored mechanical energy.
- Nuclear energy is energy stored in the nucleus of an atom — the energy that holds the nucleus together. Very large amounts of energy can be released when the nuclei are combined or split apart. Nuclear power plants split the nuclei of uranium atoms in a process called fission. The sun combines the nuclei of hydrogen atoms in a process called fusion.
- Gravitational Energy is energy stored in an object's height. The higher and heavier the object, the more gravitational energy is stored. When you ride a bicycle down a steep hill and pick up speed, the gravitational energy is being converted to motion energy. Hydropower is another example of gravitational energy, where the dam "piles" up water from a river into a reservoir.
Kinetic energy is motion - of waves, electrons, atoms, molecules, substances, and objects. Electricity, heat, light, motion, and sound are forms of kinetic energy.
- Radiant energy is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays and radio waves. Light is one type of radiant energy. Sunshine is radiant energy, which provides the fuel and warmth needed by crops and makes life on Earth possible.
- Thermal energy, or heat, is the vibration and movement of the atoms and molecules within substances. As an object is heated up, its atoms and molecules move and collide faster. Geothermal energy is the thermal energy in the Earth.
- Motion energy is energy stored in the movement of objects. The faster they move, the more energy is stored. It takes energy to get an object moving, and energy is released when an object slows down. Wind is an example of motion energy. A dramatic example of motion is a car crash, when the car comes to a total stop and releases all its motion energy at once in an uncontrolled instant.
- Sound is the movement of energy through substances in longitudinal (compression/rarefaction) waves. Sound is produced when a force causes an object or substance to vibrate. The energy is transferred through the substance in a wave. Typically, the energy in sound is far less than other forms of energy.
- Electrical energy is delivered by tiny charged particles called electrons, typically moving through a wire. Lightning is an example of electrical energy in nature, so powerful that it is not confined to a wire.
Sources of Energy
We use many different energy sources to do work. Electrical power may be generated by burning coal or natural gas, by a nuclear reaction, or by a hydroelectric plant at a dam. When the farmer fills up a gas tank, the source might be petroleum or ethanol made by growing and processing corn or a combination of the two.
Energy sources are divided into two groups — renewable (an energy source that can be easily replenished) and nonrenewable (an energy source that we are using up and cannot recreate). Renewable and nonrenewable energy sources can be used to produce secondary energy sources including electricity and hydrogen.
In 2010 Oklahoma was number 11 in nation for per capita consumption of energy. In Oklahoma and in the US, most of our energy comes from nonrenewable energy sources like coal, petroleum, natural gas, propane, and uranium. They are called nonrenewable because the supplies are limited. Petroleum, for example, was formed millions of years ago from the remains of ancient sea plants and animals.
Renewable energy sources include biomass, geothermal energy, hydropower, solar energy, and wind energy. They are called renewable energy sources because they are naturally replenished. Day after day, the sun shines, the wind blows, and the rivers flow. We use renewable energy sources mainly to make electricity. Ethanol, a renewable energy source from biomass, can be used to fuel tractors, cars, trucks, etc.
Solar is the Latin word for sun—a powerful source of energy that can be used to heat, cool, and light our homes and businesses. That's because more energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. Oklahoma ranks seventh in the nation for solar energy potential because we have so many sunny days. On average we have 3,089 total hours of sunshine per year.
A variety of technologies convert sunlight to usable energy for buildings. The most commonly-used solar technologies for homes and businesses are solar water heating, passive solar design for space heating and cooling, and solar photovoltaics for electricity.
Solar photovoltaics solar cells, also called photovoltaic (PV) cells, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect. The PV effect was discovered in 1954, when scientists at Bell Telephone discovered that silicon (an element found in sand) created an electric charge when exposed to sunlight. Soon solar cells were being used to power space satellites and smaller items like calculators and watches. Today, thousands of people power their homes and businesses with individual solar PV systems. Some utility companies use PV technology for large power stations.
Solar panels use both direct and indirect sunlight to make electricity. Solar panels used to power homes and businesses are typically made from solar cells combined into modules that hold about 40 cells. A typical home will use about 10 to 20 solar panels to power the home. The panels are usually mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture more sunlight. Many solar panels combined together to create one system is called a solar array. For large electric utility or industrial applications, hundreds of solar arrays are interconnected to form a large utility-scale PV system. Traditional solar cells are made from silicon, are usually flat-plate, and generally are the most efficient.
Solar farms require five to seven acres of land per megawatt capacity. In Mustang, Oklahoma, Oklahoma Gas & Electric operates a farm that occupies over 16 acres of land and features 2,000 fixed and 8,000 sun-tracking solar panels. This farm generates enough electricity for over 1,000 homes.
When the winds of change blow, some people build walls and others build windmills.
Wind is air in motion, caused by the uneven heating of the earth's suface by the sun. Since the earth's surface is made up of land, desert, water and forest areas, the surface absorbs the sun's radiation differently in different locations.
During the day, air above the land heats more quickly than air above water. The hot air over the land expands and rises, and the heavier, cooler air over the body of water rushes in to take its place, creating local winds. At night, the winds are reversed because air cools more rapidly over land than over water. Similarly, the large atmospheric winds that circle the earth are created because land near the equator is heated more by the sun than land near the north and South Poles.
Wind power is the conversion of wind energy into a useful form of energy. The first use of wind power by humans was probably the use of sails for powering sailboats. Windmills were probably first used in Iran as long ago as 600 AD. Ancient windmills had small sails that caught the wind to turn an axis that produced mechanical power to grind grain. By the 1100s Europeans were using windmills for grinding grain and pumping water from lowlands.
The American windmill was developed for farmers during the 1800s and 1900s. The wheels of these windmills were made from curved blades of wood or steel. They were mounted at the end of a horizontal shaft. This shaft was connected to a pump by a vertical rod sunk deep into the ground. The windmill blades moved to face the wind, which blew on them and produced enough mechanical power to pump water up from the ground. The groundwater ran through a horizontal water pipe after it came up from the ground. The farmer placed a large tank at the end of that pipe and kept it filled with water for the farm animals to drink. Some farm families also had windmills near their homes to provide water for household use.
Today we use wind energy to produce electicity with an updated version of the windmill—a wind turbine. Wind turbines are mounted on towers. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Usually, three blades are mounted on a shaft to form a rotor. The wind flows over blades, causing lift, like the effect on airplane wings. The blades are connected to a drive shaft that turns an electric generator to produce electricity. The energy produced by large wind turbines must be used immediately, since storing it in batteries is not economically practical at this time.
Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their electric bills.
Wind power plants, or wind farms, are clusters of wind turbines used to produce electricity. A large wind farm usually has hundreds of wind machines in all shapes and sizes. One large wind machine needs about two acres of land, so a wind power plant can take up hundreds of acres. Wind farms work well on farm land because farmers can grow crops and graze cattle around the machines.
A standard two-megawatt (MW) wind turbine in the US generates enough electricity to power more than 550 average American homes, nearly twice the productivity of wind turbines in China and Germany. Today there are over 52,000 wind turbines in 41 states, producing enough electricity for 25 million average American homes.
Many farmers in Oklahoma have installed wind turbines on their farms to take advantage of a different kind of harvest. The western half of Oklahoma is in America's wind corridor, which stretches from Canada into North Dakota and Montana, south into west Texas, where the vast majority of the country's best on-shore wind resources are located. In 2015 Oklahoma ranked third in the nation in net electricity generation from wind. The total number of direct and indirect jobs in the state from wind power development is estimated to be between 1,000 and 2,000. In 2016 wind generation capacity in Oklahoma was more than 6,600 megawatts, supplying about a quarter of the state's generated electricity. Nationwide, an average 10 new wind turbines are built every day.
Geothermal energy uses the natural temperatures in the earth or water to heat and cool buildings. The word "geothermal" comes from the Greek words geo (earth) and therme (heat). Geothermal energy may be used directly for electricity generation or indirectly by heat pumps (also known as geoexchange systems or ground source heat pumps).
In agriculture, geothermal energy may be used for heating greenhouses, for fish farming and algae production (aquaculture) and for heating the soil in open-field plant root systems.
Most direct-use geothermal relies on high temperature ground water to either heat buildings directly or to generate electricity. Direct-use geothermal heating is limited to areas that have naturally occurring hot springs or easy access to high temperature ground water in the 100 – 250°F range. This water is good for use in spas, greenhouses, or building heating systems. In some cases it can be used to heat entire portions of cities.
Geo-exchange systems - or geothermal heat pumps - are the most commonly used form of geothermal energy used in homes and commercial buildings. These systems use the ambient temperature in the earth or water to heat or cool a building. Heat is removed from a substrate during the winter to heat a building and then during the summer the heat is removed from the building and put back into the substrate. The substrate is usually the earth but can also be water. A mix of water and antifreeze is used as the heat transfer fluid.
The Oklahoma Capitol uses more than 600 geothermal heat pumps to heat and cool the building. Oklahoma is a center of ground source heat pump research and development, although it is not a major consumer of geothermal energy. The International Ground Source Heat Pump Association was formed in Oklahoma and is based on the campus of Oklahoma State University.
The United States has significant geothermal resources but several factors have limited the growth of geothermal generating capacity:
New technology, referred to as enhanced geothermal systems (EGS), which may allow greater use of geothermal resources in other areas, is now in early development. Current cost estimates for EGS are generally higher than those for conventional geothermal plants and other more mature renewable technologies like wind power.
Geothermal plants can be very site-specific, and have generally been limited to areas with accessible deposits of high temperature ground water.
Lack of access to transmission lines limits growth.
Completion lead times
Completing a geothermal power generating project takes four to eight years, longer than completion timelines for solar or wind.
Even in well-characterized resource areas, there is significant exploration and production risk, which can result in high development costs.
Hydropower is the most widely-used renewable source of energy. People have used moving water to help them in their work throughout history. Flowing water creates energy that can be captured and turned into electricity. Hydroelectricity accounts for about 7% of total energy production in the US.
The most common type of hydroelectric power plant uses a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity. But hydroelectric power doesn't necessarily require a large dam. Some hydroelectric power plants just use a small canal to channel the river water through a turbine.
Another type of hydroelectric power plant - called a pumped storage plant - can even store power. The power is sent from a power grid into the electric generators. The generators then spin the turbines backward, which causes the turbines to pump water from a river or lower reservoir to an upper reservoir, where the power is stored. To use the power, the water is released from the upper reservoir back down into the river or lower reservoir. This spins the turbines forward, activating the generators to produce electricity.
Oklahoma has four hydroelectric power dams - Denison Dam, Eufaula Dam, Fort Gibson Dam,and Pensacola Dam- and one pumped storage plant - the Salina Pumped Storage Project.
Denison Dam, also known as Lake Texoma Dam, is located on the Red River between Texas and Oklahoma. The dam impounds Lake Texoma. The purpose of the dam is flood control, water supply, hydroelectric power production, river regulation, navigationa and recreation. It produces roughly 25,000 megawatt hours of electricity per year. The dam was completed in 1943.
Eufaula Dam is a dam across the Canadian River in southeastern Oklahoma. Completed in 1964, it impounds Eufaula Lake, one of the world's largest man-made lakes, covering 102,500 acres (41,500 hectares). The dam provides flood control, water supply, navigation and hydroelectric power generation. It supports a 90 MW power station. Three generators produce 30 MW each.
The Fort Gibson Dam is a gravity dam on the Grand (Neosho) River in northeastern Oklahoma. The purpose of the dam is flood control and hydroelectric power production. It was authorized by the Flood Control Act of 1941 and construction began the next year. During World War II construction was suspended and it contined in May 1946. In June 1949, the river was closed and the entire project was complete in September 1953. Four generators produce 208,482 Megawatts of electricity each year.
The Pensacola Dam, also known as the Grand River Dam, is located on the Grand River between Disney and Langley. The dam is operated by the Grand River Dam Authority and creates Grand Lake o' the Cherokees. It was constructed between 1938 and 1940 for the purposes of hydroelectric power generation, flood control and recreation. It is Oklahoma's first hydroelectric power plant and is the longest multiple-arch dam in the world. The idea to construct a dam on the Grand River originated in the late 1800s with Henry C. Holderman, a Cherokee Nationa citizen, who wanted to provide electric power to the Cherokee Nation. Holderman and a few colleagues conducted the first survey of the river in 1895 on their own handmade houseboat.
The Salina Pumped Storage Project is a 260-megawatt pumped-storage power station near Salina. Its construction was in response to growing power demands and a lack of dam sites on the Grand River. The first phase was completed in 1968 and the second in 1971. The upper reservoir for the power station is Lake W. R. Holway which was built on Saline Creek, and the lower reservoir is Lake Hudson on the Grand River. During periods of lower power demand, water is pumped from Lake Hudson to Lake Holway and released back down through the pump-generators during periods of high energy demand.
Unlike other renewable energy sources, biomass can be converted directly into liquid fuels, called "biofuels," to help meet transportation fuel needs. Biomass is organic (living or once-living) matter such as trees, grass, corn stalks, or even manure from humans or livestock. All living organisms get their energy from the sun, either directly or indirectly. They use the sun's energy to convert water and carbon dioxide into carbohydrates (sugars) and oxygen (and they also release water in the process). Because new plants can be grown, biomass is a renewable resource.
Most of the biomass used for energy production is products from wood—logs, bark, sawdust, etc. Wood products are used to generate electricity or heat ovens in wood-processing plants. This process alleviates disposal costs, saves landfill space, and cuts utility bills. Wood is also burned to heat homes in the form of logs or compressed wood pellets.
The two most common types of biofuels in use today are ethanol and biodiesel. Ethanol is an alcohol, the same as in beer and wine (although ethanol used as a fuel is modified to make it undrinkable). It is most commonly made by fermenting any biomass high in carbohydrates through a process similar to beer brewing. Today, ethanol is made from starches and sugars, but scientists are developing technology to allow it to be made from cellulose and hemicellulose, the fibrous material that makes up the bulk of most plant matter.
Ethanol is mostly used as blending agent with gasoline to increase octane and cut down carbon monoxide and other smog-causing emissions.
Biodiesel is a diesel fuel substitute that can be made from a variety of oils, fats, and greases. It is made by reacting vegetable oil or animal fat with an alcohol (usually methanol or ethanol) and a catalyst (usually sodium hydroxide or potassium hydroxide). The resulting product is thinner than the original oil or fat and thus works better in a diesel engine. Hundreds of governments, national parks, school districts and utility companies in the United States use biodiesel blends to run their fleets.
Biodiesel is of interest to farmers for a number of reasons:
- It can provide an additional market for vegetable oils and animal fats.
- It can allow farmers to grow the fuel they need for farm machinery.
Commonly-used crops for the production of biodiesel include soybean, rapeseed/canola, used (waste) vegetable oils, and tallow (animal fat).
Oklahoma State University, in cooperation with the Noble Foundation in Ardmore, is working on an alternative using switchgrass to make biofuels. Switchgrass is a native prairie grass that grows all over Oklahoma. Unlike corn and other crops, the current varieties of switchgrass grow without tillage and planting. Switchgrass is perennial and requires less water and fertilizer than crops such as corn. Switchgrass can produce between 300 and 700 gallons of ethanol per acre. In addition, more net energy is gained from switchgrass than from corn. Ethanol from corn yields 34 percent more energy than it takes to grow and process the corn into biofuel. Ethanol from switchgrass nets over five times more than that amount.