Chapter 13: Energy

Renewable Energy

• Types- Solar energy directly from

the sun or indirectly from:- Wind- Moving water- Biomass

- Geothermal Energy

• Renewable energy provides, only 8% of the worlds energy

• If subsidies and tax breaks were removed from non-renewable energy today, then by, 2050, 50% of the earth’s energy could come form renewable sources.

Using Solar Energy to Heat Water and Houses

Passive solar heating system

• Heat is allowed in through large ‘superwindows’ facing the direction of the sun, then stored in the structure’s masonry.

Active solar heating system

• Uses heat absorbing liquids pumped to solar collectors outside, then pumped back though the house.

Cooling Buildings Naturally

• Living roofs

• Lightly colored roofs that can reflect up to 80% of light

• High-efficiency windows

Solar Thermal Systems

• These systems concentrate and transform energy from the sun into high temperature thermal energy

Examples:- Central Receiver System: computer controlled heliostats

concentrate sunlight on a heat collecting tower to produce steam to drive a turbine.

- Solar cooker: used to concentrate heat to cook food and purify water.

Solar Cells

Advantages• Safe/quiet• Little maintenance• No pollution when

operating• Works on cloudy days

Disadvantages • Currently expensive• Contains toxic material.• Fossil fuels used in

production• High land use

-Photovoltaic (PV) cells made of thin slates of silicon with traces of metals, emit electrons when sunlight passes through them.

Hydropower

• Uses kinetic energy of flowing and falling water to produce electricity.

• Most common method is the use of large dams to create reservoirs, whose water is then slowly released though the dam turning a turbine and creating energy.

Wind

• Turbines located on land or at sea convert wind into electricity

• It has been estimated that only 1/5 of the wind energy from the world’s best sites could create 7 times more electricity than the world currently consumes.

Wind

Advantages• Mostly pollution free• Low cost compared to

other energy producers.

• Little land use

Disadvantages• Needs steady winds • Noise pollution • Unsightly• Disrupts bird

migration if not placed correctly

• Some pollution in construction

Biomass

• Plant material and animal waste that can be burned directly as solid biofuel or converted into liquid Biofuels

• 95% of energy use in the poorest countries• Destroys biodiversity when forests are destroyed for

biofuels and biomass plantations can deplete nutrient- rich soil with overuse.

• The burning of biofuels releases CO2 and destroying forests reduces vegetation that could capture CO2.

Liquid Biofuels Created From Plants

• Unlike gasoline and diesel fuel, Biofuels are not concentrated in a few countries, eliminating reliance on foreign fuel sources.

• Biofuels can be used in pre-existing vehicles with only small alterations.

• Examples; Biodiesel, Ethanol

Biodiesel

Advantages • Reduced CO2 emissions• Better gas mileage• High net energy yield for

oil palm crops

Disadvantages • Increase NOx emissions

and smog• Higher cost than diesel• Low net energy yield for

soybean crops• Loss of biodiversity

Biodiesel is produced from the oil and fats of vegetables.

Ethanol

Advantages• High octane• Reduce in CO2

(sugarcane)• High net energy yield

(sugarcane)• Can be mixed with

gasoline or ethanol

Disadvantages• Low net energy yield

(corn)• Higher CO2 emissions

(corn)• Higher cost• May increase food prices

Created by converting starch in plants into sugars which are then processed into Ethanol

Geothermal Energy

Geothermal Heat Pump:During the winter a closed loop of buried pipes filled with fluids circulates heat from the ground into a building. The system does the opposite during the summer storing heat below ground.

Tapping into Hydrothermal Reservoir:

Hot water underground is pumped to the surface where it is used to heat houses or to spin turbines

Heat stored in soil, underground rocks and liquids in the earth’s mantle

Geothermal Energy Advantages• Very high efficiency• Lower CO2 emissions

than fossil fuels• Low cost at favorable

sights• Low land use and

disturbances

Disadvantages • Scarcity of suitable

sights • Can be depleted if

used too rapidly • CO2 emissions • Noise and ordor

Hydrogen• Currently hydrogen fuel

cells combine oxygen with hydrogen to produce electricity and water vapor.

• Produces more energy per gram than does any other fuel and does not produce CO2

• Hydrogen effects on the environment depends on the chemical system used to split it from water.

• Current fuel cells are too expensive for commercial use

How Can We Make a Transition to a More Sustainable Energy Future?

• Step 1 Switch from large centralized macropower systems to smaller decentralized micropower system.

• Step 2 The temporary use of natural gas to transition to locally available energy resources.

• Step 3 Continue to use fossil fuels in large quantities but do so more efficiently.

How the Government Can Help

• Step 1 Keep prices on renewable resources artificially low.

• Step 2 Keep prices of non-renewable resources artificially high.

• Step 3 Emphasize consumer education

Nuclear Energy

• Task: Boil water to produce steam that spins a turbine and generate electricity.

• Uses nuclear fission reaction to provide heat– Takes place in reactor– Highly inefficient

• Fuel for reactor is made from uranium ore mined from earth’s crust.

Nuclear Fuel Cycle

• Three steps– Mining of uranium– Using uranium in reactor– Safely storing the resulting highly radioactive

waste for thousands of years until radioactivity falls to safe levels.

Advantages of Nuclear Fuel Cycle

• Large fuel supply

• Low environmental impact—without accidents.

• Emits 1/6 as much CO2 as coal

• Not a lot of land accidents or water pollution.

• Low risk of accidents with safety systems.

Disadvantages of Nuclear Fuel Cycle

• Can’t compete economically without huge government subsidies.

• Low net energy yield

• Risk of catastrophic accidents

• No acceptable solution for long-term storage of radioactive waste

• Subject to terrorist attacks/spreads knowledge for building nuclear weapons.

Dealing with Radioactive Waste

• 10 years after being removed from a reactor, a spent-fuel assembly would still emit enough radiation to kill a person standing 1 meter away in less than 3 mins.

• Consensus that burial is the safest and cheapest method.

• Shoot wastes into space or the sun?

• Bottom Line: No agreement whatsoever

Nuclear Fusion

• Two isotopes of light elements are forced together at high temperatures until fused together releasing energy in the process.

• Advantages– No risk of meltdown, or large release of

radioactive materials from terrorist attack, and supplies electricity.

• Still in laboratory stage.

Energy Efficiency

• Important energy resource

• US could save as much as 43% of all energy it uses by improving the energy efficiency of industrial operations, motor vehicles, and buildings.

• Roughly 84% of all commercial energy is US is wasted.

Solutions to Reducing Energy Waste

• Prolongs fossil fuel supplies

• Reduces oil imports—improves energy security

• Very high net energy yield

• Low cost

• Reduces pollution

• Creates local jobs

We can Save Energy and Money in Industry

• Cogeneration: two useful forms of energy (such as steam and electricity) are produced from the same fuel source.

• Replacing energy-wasting electric motors would help (it consumes ¼ of the electricity produced in the US)

• Switch from low-efficiency incandescent lighting to high-efficiency fluorescent lighting.

We can Save Energy and Money in Transportation

• Accounts for 2/3 of US oil consumption– Low fuel efficiency standards

• Government can give consumers tax breaks or other economic incentives for more fuel-efficient vehicles.

We Can Design Buildings that Save Energy and Money

• Better architecture and energy savings in buildings could save 30-40% of the energy used globally.

• Green building certification standards in 21 countries.

We can Save Energy and Money in Existing Buildings

• Insulate the building and plug leaks

• Use energy efficient windows

• Heat houses more efficiently

• Heat water more efficiently

• User energy-efficient appliances

• Use energy-efficient lighting.

Sources of Energy

• Fossil fuels supply most of our commercial energy• Almost all of the energy that heats the earth and

our buildings comes from the sun at no cost to us.• The three indirect solar energy is wind,

hydropower and biomass

Commercial Energy

• Comes from extraction and burning nonrenewable resources obtained from the earths crust

• 92% of the worlds energy comes from these sources

• 86% from carbon containing fossil fuels• 6% from nuclear power• The remaining 8% comes from renewable

resources

Fossil Fuels

• We depend heavily on oil• Petroleum or crude oil is

a black, gooey liquid that consists for different combustible hydrocarbons

• The petroleum is then sent to a refinery to be separated into different components with different boiling points and this is called refining

How Long Will Crude Oil Last?• The amount of barrels crude oil used each

day would stretch from end to end circling the equator twice

• Crude oil reserves will be 80% depleted between 2050 and 2100

Three Options

1. Look for more oil

2. Use and waste less oil

3. Find other energy sources

OPEC

• Organization of Petroleum Exporting Countries

• They control most of the worlds crude oil supply at about 78% of it

• Members: Algeria, Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates, and Venezuela.

• Saudi Arabia has most of it at 20%• Canada is second with 16%

United States

• We use much more oil than we produce

• We produce about 9% of the world Crude oil and use about 25% of it

• We also only have 2% of the worlds oil reserves

• This results in a massive annual transfer of wealth from the United States to oil-producing countries

Tar Sand and Oil Shale

• Tar sand is a mixture of clay, sand, water, and a combustible organic material with a high sulfur content.

• Oil shale are products from oily rocks

• Both of these are potential supply's of heavy oil

Clean Oil Campaign

• The U.S. coal industry is rich and politically powerful.

• For decades it has fought to preserve its profits by opposing measures such as stricter air pollution standards for coal burning

• In reality there is no such thing as clean coal

Convert Coal into Gaseous and Liquid Fuels

Solid coal can be converted into synthetic natural gas process called coal gasification