Combined Heating and Power (CHP)

    Combined Heat and Power (CHP) is another name for co-generation, a type of electrical facility that uses the heat produced in the generation of electricity to heat and cool buildings near the facility. The result is a thermal efficiency rate of 50-70% compared with traditional coal power plant efficiency which averages around 33% (EPA). High thermal efficiency is desirable because it means that more energy is produced for each pound of coal used, and thus less CO2 is emitted.

    In Chapel Hill, there is already one CHP system used to fuel the University of North Carolina at Chapel Hill.  This co-generation plant was built in 1992, generating steam and electricity for the University in order to meet a growing demand for energy using a cost-effective fuel.

    The basic idea behind co-generation is that the system produces steam and electricity simultaneously, greatly reducing CO2 output compared to traditional coal plants. In fact, the UNC facility can generate twice as much energy per pound of coal because of its 69% efficiency.

Statistics for UNC’s Co-Generation Facility:

• Electric Capacity: 28 MW
• Heating Capacity: 900,000 lbs/hr
• Cooling Capacity: 33,100 tons
• Cut CO2 by: 10,620 tons/yr

Combined Cycle Generators

    Combined Cycle Generators could also improve the efficiency of coal plants and reduce CO2 emission in Chapel Hill.  There are two main technologies identified as Combined-Cycle Generators that improve the thermal efficiencies of coal-fired plants:

Pressurized Fluid Bed Combustion (PFBC): A PFBC system creates a gas stream under high pressures that drives a gas turbine, while steam created in the combustion process drives a steam turbine. The first of these PFBC systems had a net system efficiency of 40%. However, estimates predict that new versions of this technology will achieve over 50% efficiency by 2015. UNC’s Co-generation facility uses a Circulating Fluid Bed Combustion system in combination with the other CHP technologies.

Integrated Gasification Combined Cycle (IGCC): In an IGCC "Cool Water" system, coal is turned into a gas than drives a gas and a steam turbine. The gas turbine is driven by a syngas while the steam turbine is driven by steam generated from exhaust heat. Some researchers predict that IGCC system could increase efficiency enough to reduce CO2 emissions by 30-40 percent.

Book Source: Moore, Curtis and Alan Miller. Green Gold: Japan, Germany, the United States, and the Race for Environmental Technology. Beacon Press, Boston: 1994.

For more about Clean Coal Systems see: www.iea-coal.com

NC GREEN POWER

    NC Green Power is a nonprofit organization through that allows citizens in North Carolina to buy “blocks” of renewable energy through Duke Power when they pay their electricity bill.  NC Green Power uses this money to support renewable energies such as solar, wind, water, landfill methane, and biomass burning in North Carolina.  Individual consumers of electricity have the option of paying $4 per month to support one block of 100 kWh, while large organizations can buy 100 or more blocks for $2.50 per block. This process is less direct than building a windmill or solar panels and hooking them directly to the building they power. However, the renewable energy sources that Green Power supports produce negligible amounts of CO2 with emissions coming more from their construction than the daily use of these energies.  NC Green Power is an easy way to support energy consumption from efficient technology, reducing Chapel Hill carbon emissions.

Source: NC Green Power