Energy

Chapter 13

WHAT IS NET ENERGY AND WHY IS IT IMPORTANT?

Section 13-1

Basic science: Net energy is the only energy that really counts

• The usable amount of high-quality energy available from a given quantity of an energy resource is its net energy yield: the total amount of useful energy available from an energy resource minus the energy needed to make it available to consumers.

• We can express net energy as the ratio of energy produced to the energy used to produce it. As the ratio increases, the net energy also rises. When the ratio is less than 1, there is a net energy loss.

Net energy ratios for various energy systems over their estimated lifetimes differ widely

Fig. 13-2a, p. 301

Fig. 13-2b, p. 301

Fig. 13-2c, p. 301

Fig. 13-2d, p. 301

Energy resources with low or negative net energy need help to compete in the marketplace

• Any energy resource with a low or negative net energy ratio cannot compete in the open marketplace with other energy alternatives with higher net energy ratios unless it receives financial support from the government (taxpayers) or other outside sources of funding.– For example, the low net energy yield for the nuclear

power fuel cycle is one reason why many governments throughout the world must heavily support nuclear power financially to make it available to consumers at an affordable price.

Fossil fuels supply most of our commercial energy

• The direct input of solar energy produces several other forms of renewable energy resources that: wind, flowing water, and biomass.

• Most commercial energy comes from extracting and burning nonrenewable energy resources obtained from the earth’s crust. – 87% from carbon-containing fossil fuels (oil, natural gas, and

coal). – 6% from nuclear power. – 8% from renewable energy resources—biomass,

hydropower, geothermal, wind, and solar energy.

Energy use by source throughout the world and US in 2009

NONRENEWABLE RESOURCES

Petroleum

Natural Gas

Use of fracking to extract natural gas is controversial

• Hydraulic fracturing, or fracking, pumps water mixed with sand and some toxic chemicals underground to fracture deep rock and free up natural gas stored there. – The gas flows out, along with a toxic slurry of water, salts,

toxic heavy metals, and naturally occurring radioactive materials that is stored in tanks and holding ponds.

– Drillers maintain that fracking is necessary for exploiting this reserve at a reasonably low cost, and they argue that no groundwater contamination directly due to fracking has ever been recorded.

Coal has advantages and disadvantages

Oil Shale and Tar Sands

Keystone Pipeline

Keystone Pipeline

• Jobs?• Environment?

Nuclear power cycle to produce energy has advantages and disadvantages

Chernobyl

• April 26 1986 • extensive parts of the

western Soviet Union, Eastern Europe, Western Europe, Northern Europe, and eastern North America

• Nearly thirty to forty times more fallout was released than had been by the atomic bombings of Hiroshima and Nagasaki

• Direct Deaths: 56

Three Mile Island

• March 28 1979 • partial core meltdown in

Unit 2 of the nuclear power plant

• release of a significant amount of radioactivity, an estimated 43,000 curies of radioactive krypton (1.59 PBq), but under 20 curies (740 GBq) of the particularly hazardous iodine-131, to the environment.

• no deaths or injuries

Hershey

Fukushima Daiichi Nuclear Power Plant

• March 11, 2011

• Triggered by 8.9 earthquake

• Evacuation of 6 mile area at first

• U.S urged 50 mile area

RENEWABLE RESOURCES

We waste huge amounts of energy

• Energy efficiency is the measure of how much work we can get from each unit of energy we use.

• Roughly 84% of all commercial energy used in the U.S. is wasted.– About 41% of this energy is unavoidably lost because of the

degradation of energy quality imposed by the second law of thermodynamics.

– The other 43% is wasted unnecessarily, mostly due to the inefficiency of incandescent light bulbs, industrial motors, most motor vehicles, coal and nuclear power plants, and numerous other energy-consuming devices.

– Poorly insulation and building design also contribute.

Benefits of reducing energy waste

You can takes steps to save energy and money

Homes can be heated with passive or active solar systems

Heating a house with passive or active solar energy systems has advantages and disadvantages

Using solar energy to generate high-temperature heat and electricity has advantages and disadvantages

Using solar cells has advantages and disadvantages

Large-scale hydropower has advantages and disadvantages

Wind power has advantages and disadvantages

Solid biomass has advantages and disadvantages

Advantages and disadvantages of liquid biofuels

Using geothermal energy has advantages and disadvantages

Using hydrogen has advantages and disadvantages

HOW CAN WE MAKE THE TRANSITION TO A MORE SUSTAINABLE ENERGY FUTURE?

Section 13-6

Choosing energy paths• Energy policies need to consider the future.

– Usually takes at least 50 years and huge investments to phase in new energy alternatives.

• Creating energy policy involves trying to answer the following questions for each alternative:– How much of the energy resource is likely to be available in the

near future (the next 25 years) and in the long term (the next 50 years)?

– What is the estimated net energy yield (p. 000) for the resource?

– What are the estimated costs for developing, phasing in, and using the resource?

Suggestions for transitioning to a more sustainable future

Economics, politics, and education can help us shift to more sustainable energy resources

• Governments can use three strategies to help stimulate or reduce the short-term and long-term use of a particular energy resource.– Keep the prices of selected energy resources

artificially low to encourage their use.– Keep the prices of selected energy resources

artificially high to discourage their use.– Governments can emphasize consumer

education.

Three big ideas• We should evaluate energy resources on the basis of their

potential supplies, how much net energy they provide, and the environmental impacts of using them.

• Using a mix of renewable energy sources—especially solar, wind, flowing water, sustainable biofuels, and geothermal energy—can drastically reduce pollution, greenhouse gas emissions, and biodiversity losses.

• Making the transition to a more sustainable energy future will require sharply reducing energy waste, using a mix of environmentally friendly renewable energy resources, and including the harmful environmental costs of energy resources in their market prices.

Principles

P 78 # 7P 118 # 4P 122 # 11P 124 # 12P 80 # 10P 106 # 17P 110 # 23