Chapter 16 - Energy Efficiency and Renewable Energy

Energy efficiency

is the percentage of total energy input that does useful work in an energy conversion system.

In the United States

84% of all commercial energy is wasted (about half of which is due to degradation of quality imposed by the second law of energy).

Why is reducing energy waste important?

• Makes nonrenewable fossil fuels last longer

• Decreases dependence on oil imports

• Increases competitiveness in international marketplace

• Reduces local and global environmental damage

• Slows global warming

• Saves money

Passive Solar Heating

is the heating of buildings directly by orienting energy-efficient windows toward the south (in the northern hemisphere)

Active Solar Heating

involves the use of solar collectors (converts solar energy into heat energy) or solar cells (converts solar energy into electrical energy)

Water can be

split by electricity to produce gaseous hydrogen and oxygen.

Hydrogen gas

is the simplest chemical fuel, and does not produce carbon dioxide like fossil fuels.

Hydroelectric Energy

uses the power of falling water to turn turbines, providing electricity.

Dams

provide the vertical distance for hydroelectric power, and disrupt the river ecosystem.

Other hydroelectric sources include

Tidal Energy, Wave Energy and Ocean Thermal Energy Conversion.

Wind Energy is an indirect form of

Solar energy.  The sun heats the Earth unevenly, creating atmospheric movements of air

windmills

convert the mechanical energy of the wind to spin the turbine connected to an electric generator.

Promising examples of biofuels

include ethanol (made from fermentation of plant sugars) and biodiesels (made from vegetable oil)

Solid biomass

(ex. wood, charcoal) is a renewable resource, but burning it faster than it is replenished produces a net gain in greenhouse gases.

Liquid biofuels

derived from biomass can be used in place of conventional fossil fuels.

While renewable, the locations where geothermal energy can be exploited are ___

limited

Geothermal energy

is harnessed by using heat from within the Earth to drive electrical generators

Three major goals are suggested to attain a sustainable energy future:

• Improve energy efficiency

• Use more renewable energy

• Reduce pollution and health risk

Improving Energy Efficiency

• Increase fuel efficiency standards for vehicles, buildings, and appliances

• Mandate government purchases of efficient products

• Provide tax credits for buying efficient products

• Reward utilities for reducing demand

• Increase efficiency research an\d development

• Cogeneration (using a fuel source to generate both electricity and useful heat)

Use More Renewable Energy

• Provide subsidies and tax credits for renewable energy

• Encourage government purchase of renewable energy products

• Increase renewable energy research and development

Reduce Pollution and Health Risk

• Cut coal use and phase out coal subsidies

• Levy taxes on coal and oil use

• Phase out nuclear power and nuclear power subsidies