Chapter 5: Energy Efficiency and Renewable Energy

Making Transportation More Efficient

-Fuel efficiency standards raised -Fules should have "true costs" would would encourage being of electric and hybrid cars -tax break on fuel efficient cars -mass transit systems -ship freight by more efficient means

Example of net energy yield: To produce wind power

-burn coal to produce steel -consume energy in a factory to make turbines -burn diesel fuel to transport turbine to site

Geothermal Drawback

-costly -requires a lot of land -could possibly deplete the source

Hydrogen Drawback

-currently requires more energy to make H than recovered in the fuel (negative net energy yield so has to be heavily subsidized) -fuel cells used to burn H are very expensive -burns cleanly, but producing it requires some other energy source that would pollute

Wind power limitations

-disadvantages include bird and bat mortality, noise/vibrations and looks

Hydropower shortcomings

-environmental cost can be high: wild life killed and people forced to leave -sometimes unreliable due to droughts or sediment buildup

wind power issues

-good sites are limited -aesthetics is often an issue -future development may be concentrated offshore

Promise of Wind Power

-has grown 20 fold -continues to grow -as demand increases, price falls -needs smart electrical grid to constantly balance load as wind varies with time and connect with other solar and thermal -saves money for companies and govt -could supply all of US demand if enough installed

Dependence on Fossil Fuels Problems

1. Outdoor air pollution 2. Climate disruption 3. increasing ocean acidification

Save Energy in Homes

1. add new high quality insulation and plug up air leaks 2. use programmable thermostats 3. insulate hot water heaters 4. seal and wrap heating and AC ductwork 5. energy efficient heating and cooling systems 6. energy efficient lighting and electrical devices and appliances (lightbulbs, light areas not whole rooms, motion detectors)

What we have to do to combat energy waste

1. cut our energy waste 2. shift to renewable energy 3. reduce environmental harm

Issues with Current Energy Use

16% is used for work and 84% is wasted price of fossil fuels does not reflect full cost ex: oil and gas receives subsidies and waste costs are not included

Drawbacks of Solar

Direct solar limitations -has medium net energy yield -not possible to use in all locations Solar cells can be costly -in some areas low sunlight limits their usefulness

Energy Efficiency as an Energy Resource

Energy Efficient Machines: drive high mph cars, use low watt bulbs, energy saver applicator, etc. Cogeneration: uses 1 fuel source to generate 2 forms of useful electricity Recycling: make steel from scrap iron

Drawbacks of Biomass

Renewable only when it grows back -growing populations threaten biomass source areas -soil depletion due to lack of crop variation -reduces biodiversity due to monoculture -biomass production diverts food to energy which increases the price -sometimes not energy positive ex: corn and sugar cane

hydrogen

abundant high-quality energy but is is not found in useful form on earth. It must be processed to a useful potential energy form in a process that uses a lot of energy. -clean bc only output is water -negative net energy yield -explosive in air so must be careful

energy conservation

aims to reduce energy use or energy waste (or both), increase work done per unit of energy

Photovoltaic cells (solar cells)

captures direct solar energy and converts directly to electric

passive solar heating system

captures heat during the day, stores for the night

Biofuels

converting biomass into liquid ex: ethanol and biodiesel

solar thermal system

converts solar heat to hot water or electricity generated from heat

Renewable examples

geothermal, hydropower, biomass total of 13%

Biomass

green plants that convert direct energy from the sun into chemical energy stored in their tissues -ancient source of cooking and heating -95% of energy in poor countries -mostly makes electricity

biggest problem of solar energy

how to store it

wind power

makes use of the movement of air by solar heating, so it is an indirect form of solar energy

Decentralized energy system

more control over resources, more use of local resources, more physical security from a terrorist attack or disaster, more economic stability from making more jobs

active solar heating

moves heat from solar source to place where heat is needed

Hidden cost

not incorporating subsidies and environmental costs into energy products. ex: gas would be $12 a gallon

nonrenewable examples

nuclear, natural gas, coal, oil total of 87% of energy

Renewable Energy Resource

one that natural processes can replenish within a relatively short time ex: solar energy, firewood from trees, energy from water, heat from earth

geothermal energy

recover energy from the heat stored beneath the surface of the earth -rock temperature increases with depth -volcanic regions have highest potential energy -can supplement other energy systems -costly and efficient in limited areas

Nonrenewable Energy Resource

resource that can used up and not replenished on a human time scale ex: fossil fuels- oil, coal natural gas uranium

net energy yield

the difference between the energy used for energy production and the useful energy that is produced

hydropower

the electricity produced by harnessing flowing water to generate electricity -usually consist of a dam and reservoir for storage -turns potential into kinetic, only 13% of global is developed

energy efficiency

the measure of how much work we can get from each unit of energy we use, lower the efficiency the more we waste

Degree of net energy yield

the more steps we have to take to find, process and use the resource, the lower the net energy will be

use of subsidies

when an energy product has a low or negative net energy it needs to be discounted to be sold