Energy 101:Hanson Boyd

Basics of Traditional Power Generation

What is Energy? Energy - Capacity for doing work

Common units: British Thermal Unit (Btu) or Kilowatt hour (kWh)

Standard glazed doughnut

900 Btu

1 ton of water 100ft in the air

260 Btu

1 lb of molten lava

4,000 Btu

1 gallon of gasoline

125,000 Btu

Watt is Power? Power - Rate of doing work

Common units: Watt (W, kW, MW)

Boeing 747

90 MW57,000 Btu/minute

(5,700 glazed dougnughts per minute)

Incandescent light bulb

60 W3.4 Btu/minute

Air-conditioner

5 kW280 Btu/minute

Turning Energy into Power There are many machines that do this

Rockets, engines, dams, windmills How about electric motors?

For this discussion we will only talk about heat energy into electricity Can we turn all the heat energy in a pound of lava into

power?

Thermal Efficiency

Second Law of Thermodynamics

1 lb of molten lava

@ 2,200 F

Sage Hall B08@ -20 F

At best we can only turn 83% of 4,000 Btu into useful power

Thermal Efficiency Large steam turbine plant

TH ~ 1,100 F

TC ~ 100 F Efficiency: 55% – 60%

Small gas turbine power plant TH ~ 2,300 F

TC ~ 1,000 F Efficiency: 35% – 40%

Automobile TH ~ 2,300 F

TC ~ 1,400 F Efficiency: 25% – 35%

The Power Plant

What is a Turbine?

Power Demand

Energy cannot be effectively stored at grid levels

How do we deal with varying demand? Baseload plant

Large and efficient Natural gas / Coal / Nuclear Slow startup and shutdown

Intermediate load plant Medium size and efficient Coal / Natural Gas Follows load, spinning reserve, runs daily

Peaking Plant Small and inefficient Runs only for a few hours when needed

Thermal Efficiency Large steam turbine plant

TH ~ 1,100 F

TC ~ 100 F Efficiency: 55% – 60%

Small gas turbine power plant TH ~ 2,300 F

TC ~ 1,000 F Efficiency: 35% – 40%

Automobile TH ~ 2,300 F

TC ~ 1,400 F Efficiency: 25% – 35%

Combined Cycle

Combined Cycle

GE FlexEfficiency* 50 Combined Cycle Power Plant

Connecting this power to the grid All power plants on a grid are “synchronized”

Electric power is distributed as AC (60Hz for the US)

Generators on a grid share the electrical demand Once synced they are electrically joined like a car clutch Generators share electrical demand

Summary Basic ideas:

Energy - ability to do work Power - rate of doing work

Power plants turn energy into useful power Only a fraction of energy can be turned into power (thermal

efficiency) Bigger power plants tend to be more efficient but take longer to

start and stop than small ones

Electric demand is irregular We need a combination of Baseload, Intermediate and peaking

plants Generators and linked together and need careful management

to avoid blackouts