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Section 2 GENERATION • • • • • Capacity Process Methods Fuel Diversity New Technology This product was funded by a grant awarded under the President’s Community-Based Job Training Grants as implemented by the U.S. department of labor’s Employment and Training Administration. The information contained in this product was created by a grantee organization and does not necessarily reflect the official position of the U.S. Department of labor. All references to nongovernmental companies or organizations, their services, products, or resources are offered for informational purposes and should not be construed as an endorsement by the Department of Labor. This product is copyrighted by the institution that created it and is intended for individual, organizational, non-commercial use only. Sec 2- Generation Capacity • Generation units use a variety of technologies convert energy from falling water, coal, natural gas , oil , nuclear and other sources to produce electricity • The majority of electric generators are driven by hydraulic (water/steam) turbines • The electric capacity a generator can produce is usually measured in……… MEGAWATTS Sec 2-Generation- Capacity • Customer need for electricity is called demand • Constant consumer demand is referred to as BASE LOAD – Base load is usually served by coal, natural gas or constant hydro • Temporary or short term demand is called PEAK LOAD – Peak load often served by gas/oil combustion turbines ….or pumped –storage hydros Sec 2-Generation- Capacity • In 2003 total USA nameplate capacity was 1,031,692 MW • Industry forecasts a need for new generation 428,000 MW by 2025 • Planned generation additions by 2008 115.5 MW……… 88% of which will be Natural Gas Sec 2-Generation-Capacity • Net “availability” of system generation varies as generators and transmission equipment is brought on and off line and is always less than “nameplate” capacity • Utilities maintain surplus generating standby generating capacity known as “Capacity Margins” Sec 2-Generation-Process • • • • Fuel is converted to heat Heat process moves turbines Turbines turn generators Generators convert motion/magnetic fields to create currents of Electricity Sec 2-Generation-Process • Generation plants have two types of circuits • MAIN – Carry power from generator to stepup transformers and to station high voltage terminals • ACCESSORY or AUXILIARY- Carry power to motors used to drive pumps etc. needed for the particular generating process SEC 2-Generation- Process • AUXILIARY CIRCUITS are also needed for – Control circuits (circuit breakers etc.) – Lighting circuits – Excitation circuits to create magnetic fields necessary for generation – Instrument and Relay circuits – Communication circuits Sec 2-Generation-Process • RELAY CONTROLLED CIRCUIT BREAKERS Are used to turn on and off circuits carrying high voltage and large loads Circuit Breakers are devices designed to interrupt power in a manner to reduce the “arc” of the flow of electricity across the switching device as the switch opens Relays are low voltage devices to control breakers Sec 2-Generation-Methods • Steam turbines are the most common method to generate power • Steam turbines- three categories Fossil Fuel 70% USA generation Nuclear 20% “ “ Renewable 9% “ “ Sec 2-Generation-Methods • FOSSIL FUELS Major Coal Petroleum Natural Gas Other Petroleum coke, coke oven gas, liquefied petroleum, peat, oil shale, various industry wastes Sec 2-Generation-Methods • NUCLEAR Heat is produced by controlled nuclear reaction in a “containment vessel” This is done by controlling the reaction between nuclear fuel (uranium)- fuel tubes and control mediums (elements that absorb neutrons)- control rods Water is commonly used to transfer the heat to drive the turbine - “light water reactor” Sec 2-Generation-Methods NUCLEAR LIGHT WATER REACTORS use the water to slow down or moderate the neutrons in the reaction process and as a medium to transfer heat energy to turn the turbines • TWO TYPES of Light Water Reactors -Pressurized Water Reactor- PWR (closed loop/heat exchanger) -Boiling Water Reactor-BWR (direct to turbine) Sec 2-Generation-Methods • GAS TURBINE -Works with compressed gas which is ignited and hot gases then turn the turbine -Often used for peak, emergency, and reserve power because of their quick startup -less cost efficient than steam turbines -generally 100 MW or less - can be turned on and off within minutes Sec 2-Generation-Methods COMBINED CYCLE UNITS Hybrid Plants combine both steam and gas turbines to utilize excess heat byproduct to increase net plant efficiency COGENERATION ….aka Combined Heat and Power (CHP) Use a generating plant to provide both steam(for heat or manufacturing process) and electricity Sec 2-Generation-Methods DISTRIBUTED GENERATION Until recently regulatory and technology issues meant customer generated power could not be easily or safely coupled with incoming grid supplied electricity The advent of improved electronic control devices allow for cogenerators to sell back their surplus generated power to the utilities The proliferation of distributed generators will challenge the grid networks ability to manage the flows Sec 2-Generation-Methods MICROTURBINES Newer technology..usually smaller in relative size to other types of generator Can be used in “distributed generation” schemes When used in CHP systems efficiencies of over 90% can be achieved Sec 2-Generation-Fuel Diversity FUEL DIVERSITY The variety and proportions of energy sources used to produce electric power Primary Sources- Fossil, Nuclear and Renewables “A sound national energy policy should encourage a clean and diverse portfolio of domestic energy supplies. Such diversity helps to ensure future generations ….will have access to the energy they need” ……….NEPDG 2001 Sec 2-Generation-Fuel Diversity The Edison Electric Institute (EEI), a trade group representing IOU’s, has statistically shown Electric use in the USA will increase by 54% by 2025 Sec 2- Generation-Fuel Diversity RENEWABLE ENERGY SOURCES -Biomass -Hydropower -Geothermal -Wind -Solar Currently the total of above sources is 9% of the USA fuel mix Sec 2 –Generation- Fuel Diversity • BIOMASS —burned to turn steam turbines -Residues from wood and paper industry -Residues from food production/processing -Trees and grasses grown for energy crops -Gaseous fuels from solid biomass, animal wastes , and landfills • BIOFUELS from Biomass -Ethanol…fermented biomass carbos (corn) -Biodiesel..oils, fats, algae..cooking greases Sec 2-Generation-Fuel Diversity • HYDROPOWER Turbine turned by kinetic energy of water Three types -falling water (dam, reservoir, water conduit) -run of river (current turns turbines, no reservoir) -pumped storage (pump water to reservoirs during off peak with cheap power for use to hydro generate during peaks Sec 2-Generation-Fuel Diversity • HYDROPOWER -OCEAN ENERGY Thermal from solar heating- Sun heats surface and technology uses difference in water temperature at different depths to supply energy Mechanical from tides and by waves Sec 2-Generation-Fuel Diversity • GEOTHERMAL Uses the heat from the earth – various technologies -Heat exchanger types from shallow depths -Direct heat/steam from geologically active areas -Inject water to deep depths to dry/rock heat at core and retrieve heat via the circulated water Sec 2-Generation-Fuel Diversity • WIND – turns Wind Turbines to generate power, charge batteries or pump waters – Usually needs towers over 100 ft tall • Wind farms of multiple towers supply grid • Individual tower units for local use Sec 2-Generation-Fuel Diversity • SOLAR Photovoltaic (PV) Technology -Semiconductor PV cells (sunlight knocks loose electrons from semiconducting material and electrons produce a charge captured for electrical use -Cells combined into Modules -Modules combined into Arrays Sec 2-Generation-Fuel Diversity • SOLAR(cont) Concentrated Solar System Sunlight collected and focused by mirrors to concentrate heat to create steam of mechanical energy to generate Sec 2- Generation-New Tech • • • • • Nuclear revival Clean Coal Technology (CCT) Fuel Cells/Develop Hydrogen Economy Develop Wind Technology Enact renewable Energy Standards (RES) Laws to mandate use by utilities of alternative fuel mix technologies Sec 2- Generation-New Tech NUCLEAR REVIVAL – Newer Safer Smaller Designs • PEBBLED MODULAR REACTORS (PBMR) – fuel pebbles encapsulated in carbon – reactor cooled by Helium gas •Sec 2- Generation-New Tech CLEAN COAL TECHNOLOGY (CCT) Reduction of SO2,NOx,CO2 and Heavy metal emissions Combustion - combine coal with other substances to make it burn cleaner Post combustion-use scrubber technology to clean emissions before they leave the plant Conversion- convert to a gas or liquid to be further refined so as to burn cleaner Sec 2- Generation-New Tech FUEL CELLS – Use chemical energy of hydrogen to generate electricity with waste products of pure H2O and heat – DOE (Department of Energy) program is focused on Polymer Electrolyte Membrane type of fuel cells primarily for transportation Sec 2- Generation-New Tech FUEL CELLS- Hydrogen Economy • Research ongoing to develop hydrogen fuel production and distribution in conjunction with fuel cell improvements – Purpose to reduce fossil fuel dependence in internal combustion engines and motors thus reducing the overall dependence on fossil fuels into the next century Sec 2- Generation-New Tech WIND – NTWC (National Wind Technology Center Capacity for generation of all US demand Limited by Transmission Grid – Industry growth dependant on development of “deep water”, offshore facilities • • • • • Higher wind quality- less turbulence Load proximity Increased Transmission options Reduced land use and landbased aesthetics Relaxed size constraints (transportation/installation Sec 2- Generation-New Tech RENEWABLE ENERGY STANDARDS (RES) Legislative mandates (State) • Primary driver of new renewable energy generation in the USA • Existing RES as of 2003 will result in CO2 reductions of 64.3 million metric tons equivalent to – 9.6 million cars off the road – Planting 15.4 acres of trees • National RES legislation is inevitable