Summer Session, Week 5
Tuesday, July 9, 2013
The NRG Cheswick Power Plant is 1 of the NRG's 800 power plants nation-wide. It is coal-fired, like many of the power plants in Pennsylvania and the surrounding states. However, in states like Pennsylvania, which have deregulated energy industries, the consumer is free to choose which company provides their electricity. [If you are a PA resident interested in researching what this means for you, visit PAPowerSwitch.com]
Our guide, Kevin, explained that when it comes to coal-fired electricity generation, there is not a high rate of job growth, and that the Cheswick site only employs 103 people. However, because of certain laws and regulations placed on the energy industry, the company utilizes third-party consulting firms to prevent fines and penalties, and the market has been growing for these firms.
This particular plant supplies about 570 MW of electricity in a year. The coal used is delivered from the West Virginia pan handle via river barge on the Allegheny River, and the plant burns 5-6 of these barges daily. Those 5-6 barges produce 500-600 tons of ash a day. Burying it in a landfill owned by the company is a last resort. Instead, the ash is often given to concrete companies as additive.
To generate electricity, only a few materials are required: conductive wire, magnets, and relative motion between the two. With coal-fired electricity generation, coal is burned as a fuel to heat water into steam, then the steam is used to turn a turbine which creates a fast-spinning relative motion between the two. This causes electrons to move from + to - , one way, creating electricity.
All forms of fuel work in basically this same way, from coal, oil and natural gas to nuclear, wind and hydroelectric. All rely on the burning of a fuel to turn water into steam in order to turn a turbine. (The main exception is photovoltaic cells, which directly convert the sun's energy into the movement of electrons = electricity in a usable form.)
Back to our big focus in this summer's session: water. The Cheswick power plant purifies the water it uses to boil into steam beforehand. It was estimated that about 20,000 gallons of this water is lost in a day via leaks, cracks or otherwise. It takes 35 to 40 million gallons of this water to operate the power plant a day, but this includes steam that is reused by condensation before being boiled again.
The Cheswick power plant relies on the nearby Allegheny River to supply it with enough water to cool its machines, as well as to provide the temperature change necessary to convert its purified steam back into purified water. The purified and the river water never mix, but pass in parallel tubes by one another in order to provide cooling. It is estimated that the plant uses 249,000 gallons of river water for this purpose EVERY MINUTE.
In list form, the Cheswick Power Plant uses water for:
- Purified water for creating steam to turn a turbine
- River water to cool steam back into purified water for reuse
- River water to cool machines
- River water for firefighting
- Well water to replace steam water lost in turbine system
Pictures from our visit can be viewed here.