Fri. Nov 5, 2004 Sustainable Energy
Outline
1. Nuclear Power
fission (splitting) of U235
1950 – “Atoms for Peace”
power “too cheap to meter”
1957 – Price Anderson Act – liability limit for nuclear industry – equivalent subsidy of roughly $30 million/yr/plant
Issues
Economics (rising costs)
Safety
3
Mile
Radioactive Waste disposal
No
new
High level
waste – proposed burial site –
radioactive 500,000 yrs
controversy – geological faults
native American sacred landscape
safety of transporting that much waste
Currently: 103 nuclear plants in US = 1/5 of electricity
waste disposal; cost of decommissioning, etc.
industry not likely to revive
II. Energy conservation and efficiency
Energy efficiency
Thermal conversion machines- < 40% of energy in primary fuel
rest is waste heat
Energy conservation measures
more efficient technologies –eg CFLs
load reduction
insulation
passive strategies
Energy management
automation
behavioral
Lifestyle, consumption patterns
Conservation as modifying individual behavior –
neglected today
compare WW2
Examples of potential savings with efficiency measures
100 million in US
14 TWh total
could save 9.7 TWh with LEDs
efficiency increased since mid 1970s
but size also larger
compare efficiency gains with other sources of energy
Examples in transportation
most energy lost as waste heat
raising average
fuel efficiency of the
1970s oil shock: 13.3 mpg in 1973 -> 25.9 mgp in 1988
1990s falling efficiency
2002 = 20.4 mpg, lowest since 1980, mostly due to SUVs
Ex: 1991 vs 1992 Honda Civic
56% more fuel efficient, no change in safety or size
achieved at cost of 77cents/conserved gallon of gas
If energy efficiency is such a good idea, why don’t people do it?
some assumptions not rue
(1) markets perfectly reflect consumer desires
(2) consumers have perfect info
(3) consumer desires exist outside advertisements, information, etc
Transaction costs eg uncertainty over new products, hidden subsidies in current technologies
need policy tools
Tools: standards, taxes, Energy guide label
Problem with focus on EE technologies
- idea that energy use ok as long as technologies “efficient”
- eg Consumer reports
over-reliance on technical “solutions”
EE now overshadows all other conservation
EE has increased but so has energy consumption per capita
Efficiency and conservation by utilities
1. Cogeneration – 30% à 80-90%
2. Negawatts (managing demand) invests in conservation rather than new capacity
eg conservation: $350 /kw vs. coal - $1000 /kw
III. Wind energy
fastest growing
Worldwide > 35,000 MW, 3.5 million average American homes;
Total potential = 20 million MW of wind power = 10 times the total current global electrical generating capacity.
Wind energy resources
Installed
wind capacity – US second after
Advantages
1. Declining costs. now as low as 3 cents/ kwh (compare coal, 4-5 c/kwh)
2. modular
3 dual land-use capacity
4 one 750 kw turbine = 3 million lb CO2 (= 2 million SUV miles)
Barriers
1. wildlife – birds – improvement
2. transmission connections ( policy issue)
3. intermittent source – less of an issue than previously believed)
IV. Solar energy
source of all life on earth
10,000 times more than commercial energy use annually
too diffuse until recently
Two things: (1) heat (2) electricity
Heating
passive solar heat – eg greenhouse, brick walls to absorb heat and release at night
active solar heat – pump heat-absorbing medium through a collector, used for space
heating or pump water through to heat water (water heating = 15% of US domestic
energy budget)
Solar cookers – boil water
Electricity
Solar thermal
- long, curved mirrors focused on a central tube containing a heat-absorbing fluid
- mirrors in concentric rings around a tall central tower – molten salt/other fluid heated
to drive a steam-turbine electric generator
Photovoltaic panels
convert solar energy into DC current
Silicon with impurities. When sunlight hits – separates electrons from parent atoms – causes current to flow
falling costs, now $5 /watt. cost-competitive if remote
continue to fall; doubling of shipment – drop in cost of about 28%
isolated, stand-alone uses
building-integrated uses
storage – lead-acid batteries are expensive, heavy, can only store moderate amounts of energy
V. Fuel Cells
hydrogen + oxygen –> water, heat, electricity
positive and a negative electrode, separated by electrolyte
Hydrogen – electrons stripped away . Protons migrate across electrolyte. Electrons flow outside -> current
No waste – only water, heat
problem; how to make the H
different types (different electrolytes)
performance good
cost and durability still need improvement
automakers all working on them right now for electric vehicles
VI. Biomass