Energy is Essential for Society
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Adequate energy supplies are crucial for modern life.
Coupling between energy and the economy has been reduced, but it is still a
reality.
The rest of the world has justifiable aspirations that will entail greater energy
use. (5.3% per year in Asia).
Fossil fuels constitute the largest energy sector (84%).
US has large coal reserves, declining domestic crude oil, and surging
production of natural gas through “fracking.”
Reliance on oil imports creates problems for the U.S. and other nations.
Dependence on oil from the Middle East entails military and economic risks.
Fossil fuel combustion harms air quality and contributes to climate change.
Energy production and use can adversely affect the environment.
Gains in building and appliance energy efficiency are desirable.
Transportation alternatives are an extremely important challenge.
Non-fossil fuel energy sources could be the key, but they cost too much now.
Renewable energy sources are not widely replacing fossil energy sources.
Nuclear fission's role will diminish without new initiatives.
Fusion energy, at best, will not be available for several decades
U.S. Energy Consumption by Energy Source, 2002–2008
(Quadrillion Btu)
“Hard Path” and “Soft Path”
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Hard Path Technologies.
Associated with the “big 5” non-renewables.
Oil, Coal, Natural Gas, Hydro, and Nuclear.
Large Scale (Dams, Reactors, Power plants, Oil fields).
Capital Intensive (Expensive to Build and Maintain).
Extensive Infrastructure (Power grids and pipelines).
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Soft Path (appropriate) technologies.
Associated with renewable, local energy sources.
Solar, windmills, biomass, efficiency, conservation.
Relatively inexpensive and very flexible.
Generates energy locally and of the appropriate grade.
Solar
• The Thermonuclear Sun is our maternal star. It is responsible for
photosynthesis and life. All the food we eat is yesterday's sunshine!
The universe is cold. If it weren't for solar energy, the earth would be
a frozen, dark rock. The wind from the sun powered Christopher
Columbus' ship. All buildings use passive solar energy on a sunny
winter day.
• The hot Sun gives light and life. It is an inexhaustible supply of
pollution-free power.
• Nuclear fusion at the core of the sun converts 107 tons of matter into
energy each second. Equivalent of 50 cubic meters of solid rock per
second! (12'x12'x12').
Historical Aspects of Solar Power
• Solar energy is not new and is well-proven!
• Ancient Egypt: Pharaohs heated their palaces by capturing solar
energy in black pools of water by day and draining the hot water
into pipes in the floor of the palaces at night.
• Ancient Greeks designed their homes orientated to the sun to
use winter sunlight for heating.
• 1874: 1/2 hp solar powered steam engine.
• 1912: 60 hp engine for irrigation in Egypt.
• 1939: model solar home built at MIT.
• Sir George Porter: "If sunbeams were weapons of war, we would
have had solar energy centuries ago."
Solar (cont.)
• Passive solar - no moving parts, south facing windows, thermal
mass, 65% of Israel’s domestic hot water supply.
• Active solar - flat plate collectors (black) with water pump to
circulate warm water.
• Photovoltaics - solar cells use semiconductor technology to
convert sunlight directly into electricity. Simple and quiet; requires
no moving parts. Batteries store energy for use when the sun is
not shining. Applications: solar-powered calculators to gigantic
power plants.
• But cost is $.25/kwh (3-5 times the cost of conventional)
Advantages of Solar Power.
Free and nonpolluting.
Only need to capture and store it.
Can be integrated onto existing structures.
Especially useful at remote sites.
Disadvantages of Solar Power.
Solar cells are costly and fragile.
Power production is intermittent between night and day.
Power production is interrupted by bad weather.
Large plants are efficient in only certain areas.
Research opportunities
Better and cheaper solar cells.
Efficient energy storage systems needed.
Low loss transmission lines.
WIND
Winds are driven by solar heating.
Windmills can drive generators to produce electricity.
Enormous potential (20% of national needs).
Advantages of Wind Power.
Clean, produces no air pollution or waste products.
Multiple use possible (e.g. pasture and wind farm).
Wind farms can be gradually expanded as needed.
Disadvantages of Wind Power.
Suitable steady winds are found only at limited locations.
Storage and transport problems are similar to solar power.
Damaging to birds, aesthetically unattractive.
Generating electricity from solar or wind does not significantly reduce
the need for transportation fuels.
Research opportunities
Greater turbine efficiency, clean storage batteries, and resistance to
wind damage.
BIOMASS
BIOMASS is formed by photosynthesis in plants.
Consists of wood and wood waste, crop residues, grass clippings and
leaves, manure, and municipal wastes, including sewage.
Some may be burned directly, others converted into alcohol or
methane -- gasohol.
We may see fuel farms in the future .
A major domestic energy source in the developing world.
Entire U.S. corn crop could supply total U.S. energy needs!
EXAMPLE: Brazil has limited oil reserves.
Uses ethanol (from sugarcane) as a transportation fuel.
1/3 of their 10 million cars run on 192 proof ethanol.
Petroleum imports would end if 2% of Brazilian land area were devoted
to growing sugarcane for ethanol.
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Advantages of Biomass.
Does not release fossil carbon to the atmosphere.
A good way to recycle organic wastes.
Helps landfills generate energy and produce a salable product
(methane).
Large potential (15-20% of future US energy).
Disadvantages of Biomass
More bulky than fossil fuels (lower energy to mass ratio).
Can compete with food crops for growing space.
Fertilizer use can produce considerable pollution.
Conversion of biomass into fuel is inefficient and costly.
Research needs
Development of more effective crops.
More efficient conversion of the biomass to useful energy with less
pollution.
Other -- High Tech
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Tidal energy
Clean and produces no CO2 or other pollution.
Available at only a few limited sites.
Requires huge capital investments.
Equipment has to be immersed in corrosive seawater.
Nuclear Fusion
Uses Deuterium and Tritium isotopes (heavy water).
Tries to generate P and T within the sun.
Expensive and speculative, generates nuclear waste water.
Hydrogen
Break water into H2 and O2, then burn it, producing H2O and energy.
Requires energy to do this.
Or burn propane in a fuel cell producing some CO2 but less than gas, oil,
or coal.
• No existing technology can economically store electricity on an industrial
scale.
A Solar-Hydrogen Economy?
• Problems: Fossil fuels are polluting & in limited supply.
• Solar / wind power peak production and peak demand do not
match.
• Solar / wind power are not directly applicable to transportation.
• Solutions (?): Switch temporarily to natural gas which is less
polluting, then convert eventually to H2.
• Use solar and wind power to extract H2 from H2O.
• Use fuel cells to “burn” H2 in autos / homes ---> H2O.
• Would eliminate electric transmission lines and big “hard path”
power plants.
Conservation and Efficiency
• Basic principles:
• Reduce unnecessary energy conversion steps
(coal--> heat--> electricity--> heat).
• Increase the conversion efficiency at each step.
• Generate energy locally if possible.
• Increase the efficiency by which energy is transported.
• Reduce energy demand and energy losses.
• Reuse “waste” heat.
• Recycle materials to conserve energy in mfg.
• Conservation and Efficiency are not energy sources, but, in
many ways are equivalent and even superior.
• Generate “Negawatts” instead of Megawatts (Demand-side
management).
• This saves fuel resources.
• This avoids extractive pollution.
• This avoids combustion pollution.
• Costs less than building new power plants.
• Improved insulation, smaller cars, increased vehicle mileage,
recycling, less packaging and processing, energy cogeneration.
Examples
• Buildings
• As much energy leaks from American windows every year as flows
through the Alaskan pipeline.
• Build efficiently, superinsulate (25% savings).
• Appliances
• Replace old refrigerator (87% savings), air conditioner (75%), water
heater (75%), range (50%).
• Light bulbs
• 18 w fluorescent = 75 w incandescent, lasts 10X longer.
• Automobiles
• U.S. cars went from 14 MPG average in 1973 to 25 MPG in 1985 (a
92% increase). Prototype vehicles get 100 MPG.
A Sustainable Energy Future
1. Taxes on non-renewable (fossil) fuels.
2. Economic incentives to reduce fossil fuel wastes.
3. Fines and penalties for polluters.
4. Legislation to mandate reduced emissions.
5. Conservation and efficiency
6. Research
– On renewable energy sources.
– Batteries for storage and for electric autos.
– Long-distance, low-loss power transmission.
7. International Agreements -- U.S. should join and lead.
8. Lifestyle choices and changes
– Mass transit and national transportation planning.
– Bicycles and walking.
Energy-Income Inequity
A Consumer’s Prayer
And may we continue to be worthy of consuming
an inordinate amount of this planet’s resources
Mumford’s Periodization of the History of Technology
Eo-technic
• Agricultural
• Wind/ Water
• Wood
• Sailing Ship
Paleo-technic
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Industrial
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Steam/ Coal
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Iron
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Locomotive
Neo-technic
• High-tech
• Electricity/ Oil
• Aluminum/ Plastic
• Airplane
Going beyond Mumford:
Eco-Technic* Era?
*The term “Eco-technic” implies that humans will always engage in technological
innovation, yet we must always live within an ecosystem.
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Eco-technic?
Bio-technic?
Nano-technic?
Cyber-technic?
Geo-technic?
Geotechnic ?