area v: energy resources, consumption vf: energy efficiency

Area V: Energy Resources, Consumption

VF: Energy Efficiency

18-1 Improving Energy Efficiency energy efficiency: measure of useful

energy produced compared to energy converted to low-quality heat energy

energy efficiency can be improved through technology

example: fluorescent bulbs (20% efficient) vs. incandescent bulbs (5% efficient)

about 84% of all commercial energy used in the U.S. is wasted

41% due to degradation imposed by the 2nd law of thermodynamics

18-1 Improving Energy Efficiency energy efficiency, cont.

commercial energy, cont. 43% of the energy is unnecessarily wasted

by such things as motor vehicles, furnaces, and living and working in leaky, poorly designed buildings

that’s as much energy as two-thirds of the world’s population consumes!

cycle cost (initial cost plus lifetime operating costs) is an important factor in making a buying decision

Fig 18-3 Flow of energy in U.S. economy

18-1 Improving Energy Efficiency energy efficiency, cont.

between 1970 and 2003, the U.S. has reduced the amount of energy used per person and has cut U.S. energy bills by $275 billion a year; unnecessary energy waste still costs the U.S. about $300 billion a year

4 commonly used energy devices’ waste: incandescent light bulb (95% waste) nuclear power plant (86–92% waste) internal combustion engine (75–80%

waste), coal-burning power plant (66% waste)

Fig 18-4 Energy use per person in U.S.

Fig 18-5 Energy efficiencies

18-1 Improving Energy Efficiency net energy efficiency: measure of the

useful energy we get from a resource after subtracting the energy used and wasted to make energy available

includes efficiency of each step in the process of making energy available for use

nuclear power plant: 14% of initial energy produced is useful

passive solar heating: 90%

Fig 18-6 Net energy efficiency

18-1 Improving Energy Efficiency net energy efficiency, cont.

two general principles for saving energy are: keep the number of steps in an energy

conversion process as low as possible strive to have the highest possible energy

efficiency for each step in an energy conversion process

18-2 Ways to Improve Energy Efficiency

industry cogeneration, a combination of heat and

power systems, saves energy and money same fuel source produces both steam and

electricity; 9% of U.S. electricity production replace energy-wasting electric motors with

adjustable speed drive motors switch from incandescent to fluorescent

lighting


transportation increase fuel efficiency of motor vehicles

between 1973 and 1985, fuel efficiency rose sharply for new cars sold in the U.S. due to government-mandated standards

between 1985 and 2004, the average fuel efficiency for new cars sold in the U.S. leveled off or declined slightly

fuel-efficient cars are available, but gasoline prices in the U.S. are low; preference for larger vehicles, no new standards

Fig 18-7 Average fuel economy


transportation, cont. increase fuel efficiency, cont.

if the average car got 40 miles/gallon within 10 years:

gasoline consumption would be cut in half save three times the oil in the U.S. current

proven oil reserves eliminate all current oil imports to the U.S.

from the Middle East

Fig 18-8 Real price of gasoline


transportation, cont. hybrid-electric vehicles have a battery and

a small internal combustion engine to recharge the battery

this vehicle runs on gas, diesel fuel, or natural gas PLUS a small battery

such cars have been available from Toyota since 1997, and Honda and Nissan since 2000

sales projected to grow rapidly between 2010 and 2030

trucks and SUVs are not safer (?)

Fig 18-9 Hybrid gas-electric vehicle


transportation, cont. fuel-cell vehicles burn hydrogen fuel; H fuel

combines with oxygen in the air to produce electrical energy and water vapor

fuel cells are at least twice as efficient as internal combustion engines

they have no moving parts and require little maintenance

they produce little or no pollution affordable fuel-cell vehicles should be on the

market by 2020

Fig 18-10a Fuel cell car

Fig 18-10b Fuel cell


transportation, cont. fuel-cell vehicles, cont.

the fuel-cell car is expected to have a fuel efficiency equivalent to more than 100 mpg

hydrogen gas stations will need to be built or perhaps a fuel-cell system may be available for home use

one problem is how to get the hydrogen efficiently

Fig 18-11 Prototype Hy-Wire car


new buildings get heat from the sun, super insulate, and

initiate plant-covered ecoroofs Atlanta’s Georgia Power Company building

uses 60% less energy than conventional office buildings of the same size

each floor extends out over the floor below it to block out the summer sun and let in the winter sun

lights focus on desks, not the entire room

Georgia Power building


new buildings, cont. green buildings, cont.

ING Bank in the Netherlands built a headquarters that uses 92% less energy than conventional buildings

the U.S. Green Building Council has certified 89 office or apartment buildings, etc. since 2001 as meeting strict environmental design standards

ING headquarters in Netherlands



Green Councils LEED program established building standards used by more and more architects, developers, and elected officials in the U.S.

a super insulated house is another energy efficient design

cost savings in 5 years in Sweden, these homes use 90% less

energy than a typical American home

Fig 18-12 Superinsulated house



strawbale houses use walls made of compacted straw covered with plaster or adobe

ecoroofs or green roofs are covered with plants, provide good insulation, absorb storm water, outlast conventional roofs, and make a building more energy efficient

Fig 18-13a Strawbale house during

Fig 18-13b Strawbale house after


existing buildings insulating, plugging leaks, using energy-

efficient heating and cooling systems, appliances, and lighting

about one-third of heated air escapes through closed windows, holes, and cracks

energy-efficient windows with low-E (low-emissivity) cut heat losses by two-thirds and reduce CO2 emissions

wrapping ducts in attics and basements

Fig 18-14 Heat loss


existing buildings, cont. improving existing buildings, cont.

in order, these are the most energy-efficient methods to heat space:

superinsulation a geothermal heat pump passive solar heating a conventional heat pump (in warm climates

only) a high efficiency natural gas furnace

Fig 18-15 Heating a house



microturbines are cogeneration units about the size of a refrigerator that run on natural gas or liquified petroleum gas (LPG) to produce heat and electricity; save fuel and electricity

heat water more efficiently by use of a tankless instant water heater fired by natural gas or LPG – NOT electricity; last 3–4 times longer and cost less to operate

Fig 18-16 Passive and active solar heating



use energy-efficient appliances the Department of Energy (DOE) has set

federal energy-efficiency standards for more than 20 appliances; environmental benefits are conservatively estimated at $60–80 billion

use energy-efficient lighting; it could cut electricity cost by 30–60%



use more efficient white-light LEDs (light-emitting diodes) and organic LEDs; these bulbs last 80 times longer than incandescent ones

cut off electrical devices when not using them, and cut off the instant-on features in TVs, cable boxes, DVDs, computers, etc.

set strict energy-efficiency standards for new buildings; could reduce energy usage per home by about two-thirds


pricing a glut of low-cost oil and gasoline are part

of the reason for energy wastage; the price does not include the harmful costs

government tax breaks and other economic incentives for consumers and businesses would help promote improving energy efficiency

invest in improving the energy efficiency of one’s home

area v: energy resources, consumption vf: energy efficiency

Documents

initial energy

commercial energy

energy resources

energy use

energy efficiencies18

energy bills

flow of energy

measure of useful energy