Chapter 16: Energy Efficiency and Renewable Energy –Evaluating Energy Resources

Chapter 16: Energy Efficiency and Renewable Energy

– Evaluating Energy Resources


– Evaluating Energy Resources– What Types of Energy Do We Use?



Some 99% of the energy used to heat the earth, and all of our buildings, comes directly from the sun.



Some 99% of the energy used to heat the earth, and all of our buildings, comes directly from the sun.

Solar energy also helps recycles the carbon, oxygen, water, and other chemicals we and other organisms need to stay alive and healthy.

This direct input of solar energy also produces several forms of renewable energy:

This direct input of solar energy also produces several forms of renewable energy:

• wind• falling/flowing water(hydropower) • biomass (solar energy converted to chemical energy stored in the chemical bonds of organic compounds in trees and other plants).

The remaining 1%, the portion we generate to supplement the solar input, is commercial energy sold in the marketplace.

The remaining 1%, the portion we generate to supplement the solar input, is commercial energy sold in the marketplace.

Most comes from extracting and burning mineral resources obtained from the earth’s crust, primarily nonrenewable fossil fuels.

How Should We Evaluate Energy Resources?


• Experience shows that it usually takes at least 50 years and huge investments to phase in new energy alternatives.



We must answer the following questions for each energy alternative:



We must answer the following questions for each energy alternative:

• How much of the energy source will be available in the near future (the next 15 years)


• intermediate future (the next 30 years)


• intermediate future (the next 30 years)

• and for the long term (the next 50 years)?

What is this source’s net - energy yield?

• What is this source’s net energy yield?

• How much will it cost to develop, phase in, and use this energy resource?



• Example ... Hydrogen



• How will extracting, transporting, and using the energy resource affect the environment?



• How will extracting, transporting, and using the energy resource affect the environment?

• What will using this energy source do to help sustain the earth for us, for the future generations, and for the other species living on this planet?

What is Net Energy?

What is Net Energy?

The Only Energy That Really Counts

• It takes energy to get energy

• It takes energy to get energy

• First Law of Thermodynamics...

• It takes energy to get energy• (second law of energy – when we use energy some of it is always wasted and is degraded to low-quality energy).

Net Energy

Net Energy• the total useful energy available from the resource over its lifetime, minus the amount of energy used.

Net Energy• the total useful energy available from the resource over its lifetime, minus the amount of energy used. (the first law of energy)


• automatically wasted


• automatically wasted (the second law of energy)


• automatically wasted (the second law of energy)

• and unnecessarily wasted in finding, processing, concentrating, and transporting it to users.

Net Energy Ratio

Net Energy Ratio• the ratio of useful energy produced to the useful energy used to produce it.


• The higher the ratio-


• The higher the ratio-the greater the net energy yield.


• The higher the ratio-the greater the net energy yield.

• When the ratio is less than 1, there is a net energy loss.

The Importance of Improving Energy Efficiency

What is Energy Efficiency?


What is Energy Efficiency? Doing More with Less



• 84% of all commercial energy used in the U.S. is wasted.




• People in the U.S. unnecessarily waste as much energy as 2/3 of the world’s population consumes.




• People in the U.S. unnecessarily waste as much energy as 2/3 of the world’s population consumes.

• THERFORE...

• The easiest, fastest, and cheapest way to get more energy with the least environmental impact is to eliminate mush of this energy waste by making lifestyle changes that reduce energy consumption:

• The easiest, fastest, and cheapest way to get more energy with the least environmental impact is to eliminate mush of this energy waste by making lifestyle changes that reduce energy consumption: HOW???

• The easiest, fastest, and cheapest way to get more energy with the least environmental impact is to eliminate mush of this energy waste by making lifestyle changes that reduce energy consumption: HOW???

• walking or biking for short trips, using mass transit, putting on a sweater instead of turning up the thermostat, and turning off unneeded lights.

Another important way is to increase the efficiency of the energy conversion devices we use.


• Energy Efficiency


• Energy Efficiency:

the percentage of total energy input that does useful work (is not converted to low-quality, essentially useless heat)

• Life Cycle Cost

• Life Cycle Cost:initial cost plus lifetime operating costs

• Life Cycle Cost:initial cost plus lifetime operating costs

(some energy-efficient models may cost more initially but in the long run they usually save money by having a lower life cycle cost)

Why Is Reducing Energy Waste So Important?


• Makes nonrenewable fossil fuels last longer.



• Gives us more time to phase in renewable energy resources.




• Decreases dependence on oil imports.





• Lessens the need for military intervention in the oil-rich but politically unstable Middle East.





• Lessens the need for military intervention in the oil-rich but politically unstable Middle East.

• Reduces local and global environmental damage.

• Is the cheapest and quickest way to slow projected global warming.


• Saves more money, provides more jobs, improves productivity, and promotes more economic growth per unit of energy than other alternatives.


• Saves more money, provides more jobs, improves productivity, and promotes more economic growth per unit of energy than other alternatives.

• Improves competitiveness in the international marketplace.

Ways to Improve Energy Efficiency

Ways to Improve Energy Efficiency

How Can We Use Waste Heat?• For a house, insulate thoroughly, eliminate air leaks, and equip it with an air-to-air heat exchanger to prevent buildup of indoor air pollutants.

• In office buildings and stores, waste heat from lights, computers, and other machines can be collected and distributed to reduce heating bills during cold weather; during hot weather, this heat can be collected and vented out doors to reduce cooling bills.

• Waste heat from industrial plants and electrical power plants can be used to produce electricity (cogeneration)

• Waste heat from industrial plants and electrical power plants can be used to produce electricity (cogeneration)

• it can also be distributed through insulated pipes to heat nearby buildings, greenhouses, and fist ponds, as is done in some parts of Europe.

How Can We Save Energy in Industry?


• Cogeneration


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



• Replacing energy-wasting electric motors.



• Replacing energy-wasting electric motors.

• Switching to high-efficiency lighting.

How Can We Save Energy in Producing Electricity?

The Negawatt Revolution


The Negawatt Revolution• Demand-Side Management or Negawatt Revolution


The Negawatt Revolution• Demand-Side Management or Negawatt Revolution

• To reduce demand, utilities give customers cash rebates for buying efficient lights and appliances, free home-energy audits, low-interest loans for home weatherization or industrial retrofits, and lower rates to households or industries meeting certain energy-efficiency standards.

• Direct Use of Solar Energy For Heat and Electricity

Direct Use of Solar Energy For Heat and Electricity• How Can Solar Energy Be Used to Heat Houses and Water?


• Passive Solar Heating System


• Passive Solar Heating System• Active Solar Heating System


• Passive Solar Heating System• Active Solar Heating System• Photovoltaic (PV) Cells or Solar Cells

http://www.uwsp.edu/cnr/WCEE/keep/Mod1/test/meter.asp

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Chapter 16: Energy Efficiency and Renewable Energy –Evaluating Energy Resources