Geothermal Energy

AP ES students listen to Dennis Rice explain how the geothermal HVAC system works at the recently renovated Whitin Mill complex. 100% of HVAC demand comes from 5 geothermal wells dug down 1500 feet to 52 degree F water, saving $60,000/year in heating/cooling costs.

The Nuclear Option

Worcester Academy gets approximately 27% – as compared to a 20% national average- of its electricity from nuclear energy: fission of 2-3% enriched Uranium-235.

The benefits of nuclear are the enormous amount of energy that fissionable U-235 releases. One gram of U-235 (depending on enrichment level) produce the same amount of heat energy as burning 6,000 pounds of coal when used to heat water into steam which in turn spins a turbine to generate electricity. Further, there are no greenhouse gas emissions, electricity can be produced cheaply (though this could be argued against given special insurance policies for nuclear and unsettled costs for nuclear waste management), and in theory nuclear fuel can be reprocessed many times over. Capacity of New England nuclear reactor plants (see photo) is as follows:

Location- Name- Capacity
Maine- Wiscasett Maine Yankee (closed) 850 MW
CT- Haddam Neck Plant (closed) 590 MW
Millstone Nuclear Niantic Bay, Waterford (unit
closed) 652 MW
Unit 2 900MW
Unit 3 1200 MW
VT- Vermont Yankee, Vernon, VT 540 MW
NH- Seabrook Nuclear Station, Seabrook, NH 1200 MW*
MA- Yankee Nuclear, Rowe, MA (closed) 185 MW*
Plymouth Station, Plymouth, MA 655MW
Approximate Total: 4,500 MW (operating)

However, reprocessing fuel is dangerous (particularly if spent plutonium is involved, which can be isolated easily using chemical means to make a bomb but is rare in the US for energy production) and there are currently no operating reprocessing plants in the United States. Complications with nuclear energy also include managing nuclear waste which contains lethal and carcinogenic radioactive materials with half lives ranging from a few dats to 10’s of 1,000’s of years [Pu-239:1/2 life=24,360 years: alpha emissions, cocentrates in bones/lings, Sr-90: 1/2 life= 28.8 years: beta emissions: concentrates in bone and teeth, I-131: 1/2 life=8days: beta and gamma: thyroid, Cs-137:1/2life=30 years: beta and gamma: whole body] The many waste products of nuclear fission, such as these, must be handled without mistake and need to be stored securely for 100,000’s of years. Current solutions have included underground storage in geological stable caves. Currently there are over 50,000 metric tons of nuclear waste in the U.S., ( click for details: us-nuclear-waste.pdf ) most of which is stored in water pools on-site of the power plants (see Yankee Rowe photo). Over 3,000 tons of waste is stored in New England Power Nuclear Power Plants (see photos).

Some point out the security issues of transporting the waste through highway, water, and railway to waste collection sites such as the proposed Yucca Mountain, Nevada. Studies have, also, shown and critics point out ways that nuclear plants are not secure form terrorist attacks.

For further explanation and more information on nuclear science click on MITcourse nuclear info.jpg

Many scientists studying energy supply and climate change remediation insist that nuclear power needs to be part of the solution.

Essential questions:

1) How many nuclear power plants would need to be built to meet increasing world energy demands and after the end of oil?

2. What is the risk analysis for nuclear fuel procurement and waste production management, transportation, as well as attacks on nuclear facilities? What are the realities and complexities of storing nuclear waste?

3. What is the economic structure and conditions for past, current, and future nuclear power plants?

4. What are the numbers for the world’s current nuclear fuel sources? What will they be in the future?

5. What impact does uranium mining and reprocessing have on the environment, workers, etc.?

6. What % of efficiency as a resource unto itself would be needed to replace the use of nuclear, how could this number be achieved?

WA Fossil Fuel Heating System

Up until the 1970’s WA heated its campus by burning coal in a 1940 model boiler (middle photo above) located underneath the Megaron. Water was boiled into steam and pumped through large pipes (top right) throughout all of campus. This centralized heating system lost vast amounts of heat energy during transfer through contact with the cold earth, and by burning coal, the dirtiest of the three major fossil fuels, emitted carbon dioxide, sulfur dioxide, carcinogenic hydrocarbons and particulate matter, mercury, and arsenic.

WA used the same boiler when it switched over to heating oil #6, a thick high sulfur content fuel.
At some point in the 1990’s WA began decentralizing its heating system, placing gas boilers (below middle) in each building. Cleaner less polluting natural gas is burned to heat up water which is then pumped (photo of motors, below right) in pipes throughout the building in the form of hot water rather than steam. In 2003, WA installed oil #2 (lower sulfur content) boilers (below left) to replace the old Megaron boiler, the only campus system burning oil.

WA typically burns up to 35,000 gallons of oil #2 to heat Walker, Megaron and Adams Hall, and 176,000 therms of gas for all buildings on campus.