1. Cogeneration. Is the simultaneous production of electrical and thermal energy from a single fuel source

2. Typical Cogeneration Fuels  Natural Gas  Coal  Diesel oil  Bio mass [e.g. methane, from digesters or municipal landfills]

3. Example

4.  Overall Thermodynamic Efficiency Often called Utilization Factor  Conventional Efficiency Power Plant Boiler  Improvement

5.  Fuel Savings if conventional System Output is 50 MW  Fuel cogen  Fuel conven  Fuel Savings

6. Economics  Plant operates 68% of time or 6000 hrs/year (conservative estimate). Fuel Savings If we use natural gas, $8/MMBtu, the monetary savings ~$7,000,000/year.  How much could you invest economically?  How much CO2 reductions per year?

7. Operating cycles  Topping Cycle  Bottoming Cycle

8. Gas Turbine Topping Cycle Installed at Rice University

9. Prime movers  Reciprocating engines efficient compact easy to install suitable for small applications  Gas Turbines Intermediate power applications Relatively compact Reliable Easy to install “combined cycles”, but only for large industrial applications

10. Prime Movers (cont.)  Steam Turbines Good efficiency only for units larger that 10mW Can use a variety of fuels including solid waste and biomass “extraction” turbines; a portion of the steam flow removed during the expansion process “back pressure” entire steam flow used after last stage of expansion

11. Characteristics Of Prime Movers

12. Typical Cogeneration Performance Parameters

13. Economic Criteria  Payback Period Is the length of time required for the cumulative net savings to equal the initial installed capital cost. Divide the initial investment by the annual net savings.  Discounted Cash-Flow Method Analyses the cash-flows over the full life of the project and accounts for the time value of money, including interest rate and rate of inflation.