Section 2GENERATION

• Capacity• Process• Methods• Fuel Diversity• New Technology

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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”

• 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

Sec 2-Generation-Process

• Generation plants have two types of circuits• MAIN – Carry power from generator to step-

up 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 loadsCircuit 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 categoriesFossil Fuel 70% USA generation Nuclear 20% “ “Renewable 9% “ “

Sec 2-Generation-Methods• FOSSIL FUELS Major Coal

PetroleumNatural Gas

OtherPetroleum 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 rodsWater is commonly used to transfer the heat to drive the turbine - “light water reactor”

Sec 2-Generation-MethodsNUCLEAR 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-MethodsCOMBINED 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-MethodsDISTRIBUTED GENERATION

Until recently regulatory and technology issues meant customer generated power could not be easily or safely coupled with incoming grid supplied electricityThe advent of improved electronic control devices allow for cogenerators to sell back their surplus generated power to the utilitiesThe proliferation of distributed generators will challenge the grid networks ability to manage the flows

Sec 2-Generation-MethodsMICROTURBINES

Newer technology..usually smaller in relative size to other types of generatorCan be used in “distributed generation” schemesWhen used in CHP systems efficiencies of over 90% can be achieved

Sec 2-Generation-Fuel DiversityFUEL DIVERSITYThe variety and proportions of energy sources

used to produce electric powerPrimary 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 DiversityRENEWABLE 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• HYDROPOWERTurbine turned by kinetic energy of waterThree 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 energyMechanical from tides and by waves

Sec 2-Generation-Fuel Diversity• GEOTHERMALUses 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 SystemSunlight 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 TechNUCLEAR REVIVAL– Newer Safer Smaller Designs

• PEBBLED MODULAR REACTORS (PBMR)

– fuel pebbles encapsulated in carbon– reactor cooled by Helium gas

•Sec 2- Generation-New TechCLEAN COAL TECHNOLOGY (CCT)

Reduction of SO2,NOx,CO2 and Heavy metal emissionsCombustion - combine coal with other substances to make it burn cleanerPost combustion-use scrubber technology to clean emissions before they leave the plantConversion- 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 TechWIND– NTWC (National Wind Technology Center

Capacity for generation of all US demandLimited 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 TechRENEWABLE 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