Test 5_E efficiency and Renewable E Flashcards
___% of all energy used in the US is wasted.
84%
How much of that waste is unnecessary?
43%
What is the life-cycle cost of an energy using devise?
Initial costs + lifetime operating costs.
What three devices are perhaps the least efficient devices in widespread use?
- Incandescent light bulb
- Internal combustion engine
- Nuclear power plant
How much energy do the following waste: Incandescent light bulb
Internal combustion motor vehicles
Nuclear power plants when energy is used for heating
95%; 86-90%; 86-92%
What is cogeneration?
Using steam to generate electricity and then to warm/cool buildings.
Why are most of the electric motors used today inefficient?
Run at full speed – could use adjustable speed drives
What is “the best way” to save energy and money in transportation?
Increase fuel efficiency
What are other ways to save energy and money in transportation?
Mass transit, bike, barges etc.
From 1973 to 1985 average fuel efficiency of cars rose by 37%. Why have they fallen since then?
Popularity of SUVs
What is CAFÉ?
Corporate average fuel economy – government mandated
Why is the auto industry trying to eliminate CAFÉ?
–
What mpg can the new hybrid cars obtain?
up to 150 MPG VW small car gets 235.
Why is there little public interest in fuel efficient vehicles
Cheap gas in US (but there are hidden costs)
Who is the largest energy user in the US?
Military
How much extra does it cost to super-insulate a house?
5% more
How long does it take to pay back that cost at today’s energy prices?
within 5 years
How much does super-insulation save a homeowner over a 40 year period?
$50,000-100,000
How can the energy efficiency of an existing house be improved?
Plug leaks, add insulation, energy saving windows and lighting.
What is a strawbale house?
House made from strawbales – straw has a very high insulation value
What is the most energy efficient way commonly used to heat water for washing and bathing?
Tankless water heaters.
What is the Energy Star program?
Major household appliance ranked according to their energy efficiency. Only those that are the most efficient can carry the ES label.
How much does a fluorescent bulb save over an incandescent over a 10 year time period?
$48-70
What are the energy savings of the use of a microwave for cooking?
25-50%
Why doesn’t the average person in the US not doing more to reduce energy waste? Or any other waste for that matter!!
Cheap energy, lack of incentives, lack of information especially on life cycle costs.
What is the difference between a passive and an active solar heating system?
Active requires energy input to operate fans and pumps
What is the typical pay-back time for a passive solar system?
3-7 years
What are some energy efficient ways to cool a house?
Earth tubes, appropriate design, evaporative colors in arid regions.
An acre of lawn is equivalent to how much air-conditioning?
1 ton
What is a photovoltaic cell? What are they commonly called?
Solar cells— of semiconductor material where light causes electrons to flow.
What are the advantages of solar cells?
Fairly high net energy Work on cloudy days Quick installation Easily expanded or moved No CO2 emissions Low environmental impact Last 20–40 years Low land use (if on roof)
What are the disadvantages of solar cells?
Light not 24 hours/day – need some sort of back up.
Other buildings/ structures may block light.
Expensive – but costs are coming down with new technologies.
What different types of hydropower are there?
small, large scale, pumped.
What country gets 99% of its electricity from hydropower?
Norway
What are the pros of hydropower?
Moderate to high net energy High efficiency (80%) Low-cost electricity Long life span No CO2 emissions during operation May provide flood control below dam Provides water for year-round irrigation
What are the cons of hydropower?
High construction costs High environmental impact High CO2 Emissions from Biomass decay in Shallow tropical reservoirs Floods natural areas Converts land habitat to lake habitat Danger of collapse Uproots people Decreases fish harvest below dam Decreases flow of natural fertilizer (silt) to land below dam
Where are two large tidal energy facilities?
Rance estuary in France, Bay of Fundy in Canada
What are the pros and cons of tidal energy?
Works well but good sites are limited.
What is the world’s fastest growing energy resource?
Wind power.
What has the Bush administation done re wind power?
Cut funds for research and development.
What country is the world’s largest producer of wind power and manufacturer of wind turbines?
Denmark
What are the advantages of wind power?
Moderate to high net energy High efficiency Moderate capital cost Low electricity cost (and falling) Very low environmental impact No CO2 emissions Quick construction Easily expanded
What are the disadvantages of wind power?
Steady winds needed Backup systems when needed winds are low High land use for wind farm Visual pollution Noise when located near populated areas May interfere in flights of migratory birds and kill birds of prey
What % of people in developing countries heat and cook with wood or charcoal?
70%
What is biogas?
60% methane, 40% CO2 produce from biomass by bacteria
How much does it cost to make a biogas generator?
@$50 including labor
What is ethanol made form?
sugar and grain crops
What is methanol made form?
natural gas, oraganic wasted
What are the pros of using biofuels?
Large potential supply
Moderate costs
No net CO2 increase if harvested and burned sustainably
Plantation can be located on semiarid land not needed for crops
Plantation can help restore degraded lands
Can reduce water pollution
Recycles waste products
What are the cons of using biofuels?
Nonrenewable if harvested unsustainably
Moderate to high environmental impact
CO2 emissions if harvested and burned unsustainably
Soil erosion, water pollution, and loss of wildlife habitat
Plantations could compete with cropland
Often burned in inefficient and polluting open-fires and stoves
What is considered the “fuel of the future”?
hydrogen
What is geothermal energy?
using high temperatures from the earths interior
Where is it currently being used?
22 countries – Iceland, Japan, California, Chile
What are the pros of the use of geothermal energy?
Very high efficiency Moderate net energy at accessible sites Lower CO2 emissions than fossil fuels Low cost at favorable sites Low land use Low land disturbance Moderate environmental impact
What are the cons of the use of geothermal energy?
Scarcity of suitable sites Depleted if used too rapidly CO2 emissions Moderate to high local air pollution Noise and odor (H2S)
What is micropower?
Small generating facilities
What are the advantages of decentralization?
more local control, less problems with terrorism.
We have the technology why aren’t we using more energy alternatives to nonrenewable fuels?
Economics and politics.
