Using Less and Getting More
Conservation vs. Efficiency
While often used interchangeably, these concepts are distinct:
Energy Conservation: The act of reducing or going without a service to save energy. It is a behavioral change.
Example: Turning off lights when you leave a room, taking shorter showers, or driving less.
Energy Efficiency: The use of technology that requires less energy to perform the same function. It is a technological change.
Example: Replacing an incandescent light bulb with an LED bulb, which produces the same amount of light for a fraction of the energy.
Conservation Strategies
In Buildings:
Insulation: Reducing heat transfer through walls, ceilings, and floors.
Weatherization: Sealing air leaks around windows and doors.
Thermostat Management: Lowering the thermostat in winter and raising it in summer.
Using Natural Light: Designing buildings to maximize daylighting.
In Transportation:
Reducing Vehicle Miles: Using public transportation, carpooling, walking, and biking.
Efficient Driving: Avoiding rapid acceleration and braking, maintaining proper tire pressure.
Reducing Idling: Turning off the engine when parked for more than a minute.
Energy Return on Investment (EROI)
EROI is a critical metric for evaluating the viability of an energy source. It is the ratio of the amount of usable energy delivered from a particular energy resource to the amount of energy used to obtain that energy resource.
EROI = (Usable Energy Acquired) / (Energy Expended)
An EROI of 1.0 means you only get back as much energy as you put in.
A sustainable energy source must have an EROI significantly greater than 1.
Examples (approximate):
Early conventional oil had a very high EROI (>100:1).
Modern oil sands may have an EROI of 5:1.
Solar PV has an EROI that varies but is often in the 10:1 to 20:1 range.
EROI helps to compare different energy sources on a 'net energy' basis.