A Primer on Energy
Understanding energy alternatives, and the opportunities they represent for the Three Rivers Region (southwestern Pennsylvania and northern West Virginia), requires an understanding of the key components of energy production and distribution.
Many different fuels can be used to generate energy. Coal serves as the fuel for more than half of the total U.S. electricity use (nearly 4 TWh). Nuclear power supplies 22.5% of U.S. electricity, while natural gas provides about 10%. Hydroelectricity supplies 10% of U.S. electricity, representing the bulk of the "renewable" source production, while geothermal, biomass, wind, and solar energy comprise another 2%.
In addition to electricity, natural gas, oil, and biomass can be burned to create steam heat. The sun can heat water for home and business use. Microbes can convert biomass to liquid fuels. Coal can also be converted to liquid fuels.
Other Inputs to Energy Production
Water is a critical component of combustion processes. Nearly 20 billion gallons are lost through evaporation due to power generation annually in Pennsylvania alone. Nuclear energy consumes the most water, using 0.62 gallons/kWh, followed by coal and oil. Many regions are not able to support utility scale power generation because of limited water supplies.
Energy can take the form of electricity, heat, or liquid fuels and can be derived from many different sources. Liquid fuels comprise gasoline and diesel (from both fossil and biomass sources), ethanol, butanol, and others. Gasoline is the most widely used liquid fuel and is derived almost exclusively from petroleum sources.
Electrical power is delivered to the transmission grid from two types of generators.
A "base load" generator provides a steady flow of power to the grid regardless of user demand. Baseload plants are typically efficient, large, low cost facilities, but are difficult to ramp up and down to follow a customer demand profile. They are typically fueled by coal, nuclear, geothermal, or biomass and provide most of the power to the transmission grid.
"Peaking" power plants typically run only when demand is high, such as late afternoon in the summer. They are typically gas-, oil-, or diesel-fired, and as such they are relatively easy to ramp up and down in response to changes in demand. They may run only a few hours each day or not at all. They are more expensive to operate than base load plants.
The National Energy Technology Laboratories estimate that in the U.S. alone, 100 million tons of coal combustion byproducts are generated each year - 70 million tons of which end up in impoundments and landfills. Much of the remainder, which comes in the form of fly ash, can be used in the manufacturing of gypsum board and cinder blocks as a replacement for Portland cement.
The next generation of clean coal-fired plants (FutureGen) have a goal of zero emissions. That means every gas, liquid, or solid product of the combustion process will find a valuable use. These Integrated Gasification Combined Cycle (IGCC) plants will burn coal for electricity generation, but will also produce hydrogen that can then be used for electricity production with steam turbines and fuel cells, or after refining, as transportation fuel. The carbon dioxide generated during burning will be captured and injected into underproducing oil and gas wells to enhance recovery of those fuels or sequestered in geologic formations for later use. Other products will serve as feedstock for the chemical industry.
Heat is another byproduct of the combustion process. Some generating facilities, called combined heat and power systems (CHP) have particular applicability in industrial settings and provide both electricity and process steam heat. These systems operated at a fuel efficiency of as much as 90%.
Transmission and Distribution
For electricity, "transmission" refers to the transportation of electricity through wires over long distances. Once the electricity is carried to its destination, the high voltage must be stepped down to a useable voltage and then "distributed" to the customer. This overall network is referred to as the electricity grid.In Pennsylvania, even though electricity production and sale are becoming deregulated, the "wires" companies - the transmission and distribution companies like Duquesne Light - are still regulated.
Natural gas is transported through a network of pipelines. As with electricity, there are large capacity pipelines which transport natural gas between regions, and a network of smaller capacity pipelines which distribute natural gas to consumers.
Every form of energy generation has some sort of environmental impact.
The environmental impact of energy production from fossil fuels, such as coal, begins with the problems caused by mining (e.g., abandoned mine drainage, mine subsidence, and scarring of the landscape) and continues through the greenhouse gas emissions from generation and other combustion waste products.
Wind generation has viewshed impacts and is responsible for the deaths of bats and birds. The steel and other materials that are used to build the wind turbines also come with some level of environmental impact.
Solar cells based on silicon require significant amounts of energy for their manufacture.
Hydroelectric dams flood valleys and kill fish in their turbines.
Nuclear power generation brings with it centuries of radioactive waste.
The burning of gasoline and diesel from petroleum sources makes vehicles the largest contributor to greenhouse gas emissions in the U.S.
Users include businesses, homeowners, institutions, and others. The first and most important constraint on energy production is the need to satisfy the demands of customers, which include cost, reliability, and quality.
In certain states users can also be generators, through a process known as net metering, where users who are generating their own heat or electricity from solar panels, wind turbines, microgeneration stations, etc., send surplus electricity back to the grid or share energy through a distributed heating grid.
Distributed generation will be the grid architecture of the future. Sometimes referred to as "distributed power," "distributed energy resources," "embedded generation," and "decentralized power," the concept is based on the use of small-scale power generation technologies located close to the customer being served. This approach has the potential to enable businesses and homeowners to lower their costs, improve the reliability of energy delivery, and increase the security of transmission.
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