Today, I present a guest post from my student Hope W., who described her experiences visiting the Chalk Point Generating Station in Maryland on our Environmental Geology field trip the weekend before last. The essay is posted here with her permission. Enjoy! -CBThe Chalk Point Generating Station is a coal burning power plant owned by the Mirant Corporation. Our guide during our tour was Greg Staggers, the plant manager. There were three main subject areas that Mr. Staggers talked to us about: power generation, the economic supply and demand, and environmental regulations and precautions.
Power Generation:Mr. Staggers explained how the station has two different types of units. They have steam units and combustion units. Mr. Staggers described how the two different types of units are designed. He said that the steam units are like giant boilers, and that the combustion units are like jet engines. The plant has four steam units and seven combustion units, both types use fossil fuels to produce energy. Mr. Staggers explained how when power is first generated it is at too high of a voltage to be safely used by the public in homes or offices; and how the current has to be run through various lines to transformers and substations in order to be brought down from 20,000 volts (the level generated) to 110-220 volts (the level used in homes and offices.) Mr. Staggers pointed out the transformer field we drove past on the way in on the aerial photograph of the plant explaining that that’s where the process of conversion begins.
In response to Sophia's question about why the plant was built next to the water, Mr. Staggers explained the complex system for using water from the river to cool the equipment in the plant. As he talked in depth about this system he described how ideas improved through time and experience, as well as environmental regulations which lead the plant to finding more efficient and ecological ways of utilizing the river water. Later on when we took our tour through the plant we had the opportunity to see the some pipelines that the river water runs through. The water runs through the pipe-lines to cool the steam that is emitted during the power generation process. When the river water is released back into the river from the plant it has picked up no chemicals, and has only increased in temperature by approximately 20°F.
Mr. Staggers told us about four of the units that get run; units 1 and 2 which are combustion units and units 3 and 4 which are steam units. When running at full capacity units 1 and 2 operate at 90% efficiency, burn 2.5 million pounds of coal per hour, and use 14 megaWatts of the energy produced to operate; and when units 3 and 4 are running at full capacity the burn 650 gallons of oil per minute. Mr. Staggers informed us that the enormous pile of coal we saw on our way in would last for 45 days if the plant were running at full capacity.
Economic Supply and Demand:In the 1990's the system was deregulated, which basically means that the power generation, wholesaling of the utility, and the supply distribution were all split up. So when the Chalk Point station produces energy they sell it to PJM a 'middleman' who will then sell it to the suppliers like Dominion Power etc. who then sell and distribute the supply to the public. I mentioned the transformer field earlier in this paper in reference to the generation process, but the transformer field has economic implications as well. The transformer field is also where the producers pass of the ownership of the energy to the middleman.
Mr. Staggers explained the bidding system for establishing the market value for each day. In the bidding system if you are over producing you get paid the difference in price from your morning bid in real time. During the tour we got to see the control rooms where the market price rates were being adjusted in real time. In response to Dustin's question about how they know when to produce Mr. Staggers explained how the middle men suppliers make that call based on the morning bids and the actual demand by the public, when the suppliers make the decision about production levels they call the plant to inform them of how much they need to be producing.
In terms of the national economy coal is the cheapest in explicit costs, in equivalent quantities the price for coal is 1/3 that of oil and natural gas prices, which is why more than 50% of the U.S.'s power is generated by coal. In terms of the local economy the Chalk Point station produces a 500 thousand volt ring around D.C. It is estimated that in the next five years 1 million homes will be added to the market that the Chalk Point station caters to.
The demand for coal is influenced by seasonal changes which gives it a cyclical demand. Callan asked if the increased attention on alternative methods of energy has affected the demand for coal in terms of reduction. Mr. Staggers said that no such change has been apparent and that the cyclical trend has followed a predictable pattern.
Environmental Regulations and Precautions:Mr. Staggers told us about the regulations the plant has been mandated to conform to, as well as what the plant has done of their own accord for the sake of the environment. Some of the changes that the plant made in the past include setting up new stack facilities in 1982 because of environmental regulations. When the clean air act was passed in 1992 brought down their level of pollutants they were releasing into the atmosphere from 1.4 to .7 Further regulations such as; the separated overfire air controls in 2000, selective auto-catalystic reduction in 2007, and selective catalystic reduction in 2008 brought the pollutant rate down to .06. All of the methods above have dropped total output capacity by some amount.
The plant has also put up two boundary nets to protect fish from the areas where hot water is released and two more boundary nets as well as a fine mesh screen to prevent the fish from getting sucked up into the pumps for the cooling system. The plant has many systems in place to reclaim energy where they can to avoid waste, such as how they use residual heat from the coal burning process to heat the incoming air from its current temperature to be closer to the temperature required for being used as an infuser in the combustion process. The plant is in the process of building a "scrubber" which will reduce the sulfur emissions by 98%. The method this "scrubber" will use will allow the plant produce and collect gypsum which the plant will sell for its use in drywall. The plant also has a system set up to collect ash by a precipitation method; the ash collected is also sold for its use in drywall.
The plant has continuous emissions monitors which monitor emission levels of CO
2, SO
2, and NO
x. The data from the monitors is sent quarterly to the State and the E.P.A. In the control room Callan asked a question about the plant's ppm output of CO
2. Mr. Staggers said that measure by percentage and he did not know the output in ppm . This discussion lead to a very clear statement by Mr. Staggers that he wasn't convinced that it really made a difference. Mr. Staggers informed us that the plant's output of CO
2 is 12% of flue gas volume, which Callan calculated to be 120,000 ppm. From Mr. Staggers' point of view as a producer of a commodity it is hard to see much else besides bottom line explicit costs. This was not his position out of greed, but out of responsibility to keep the company running so he has a job to provide for his family, and his employees as well. On the other hand, scientists cannot escape the implicit costs of CO
2 emissions.
There needs to be a level headed discussion in a neutral setting were the two groups can learn to understand each other and start to cooperate. We as individuals and a nation must step up and set the example. When we start working together we will create the safe harbor necessary for understanding and cooperation to grow and flourish.
Labels: coal, energy, environmental, maryland, nova, oil, teaching