Transcript Renewable Energy; Rationale and Vision Emanuel Sachs Mechanical Engineering MIT U.S. Historical Energy Use 100% Wood 80% Wood Coal Coal 60% OilOil 40% Gas Gas 20% Hydro Hydro 0% elec. Nuclear Nuclear.

Renewable Energy;
Rationale and Vision
Emanuel Sachs
Mechanical Engineering
MIT
U.S. Historical Energy Use
100%
Wood
80%
Wood
Coal
Coal
60%
OilOil
40%
Gas
Gas
20%
Hydro
Hydro
0%
1800
1850
1900
elec.
1950
Nuclear
Nuclear
2000
Oil
• Domestic Oil
• Imported Oil
– OPEC Hubbert’s peak is 10-30
years away
– Non-OPEC imported Hubbert’s
peak is 5-15 years away
Hubbert’s Peak
The Other Players
• Coal
– Lots of it
– Twice as much CO2 per kW-h as Gas, 50% more than oil; can only rely
on it if sequestration is practical and stable
• Gas
– Candidate “transition” fuel, but will have same supply issues as oil (just
delayed).
• Nuclear
– Extraordinary challenges in disposal, proliferation, and defense against
terrorist action.
Hydrogen to the Rescue?
• Hydrogen is NOT a
naturally occurring source
of energy
• Hydrogen must be MADE
from a fossil fuel (natural
gas) or by electrolysis of
water using electricity.
• Hydrogen MAY be useful
as a medium for energy
storage.
Identifying a
New Primary Energy Source
is one of the
Grand Challenges
that Civilization Faces Today
Current Energy Use: United States
• The U.S. uses approx. 100 Quads of energy per year. ( 1 Quad =
1015 BTU). 100 Quads ~ 100 Exajoules (1 Exajoule = 1018 Joule).
• The average power consumption of the U.S. is 3.3 x 1012 W.
• The average per capita power consumption in the U.S. is 13 kW.
– We don’t get to use all of this. For example, the 1.6 kW of electricity
that each of us uses required 5 kW of heat energy (5 of 13).
Renewable Energy Sources
•
•
•
•
Hydroelectricity
Biomass
Photovoltaics (PV) Solar to electricity
Wind
Photovoltaics and Wind are complimentary in availability
Wind is more economical today, PV has the larger potential
Magnitude of Solar Resource
• At our latitude, the solar flux at mid-day on a clear day is 1000 W/m2.
– The average Including night and clouds is 200 W/m2.
• The average solar power incident on Continental US is 1.6 x 1015 W.
– This is 500X the average power consumption in the U.S. (3.3 x 10
12
W).
• If we cover 2% of the Continental US with 10% efficient PV systems,
we will make all the energy we need*.
• For perspective:
– 1.5% of the Continental US is covered with roads.
– 40% is used to make food (20% crops, 20% grazing)
What Determines the Temperature of the Earth?
Radiative balance determines temp of Earth (to first order)
Rural electrification
• Drivers:
– 2 billion people without electricity
world-wide
• Applications:
–
–
–
–
Solar home systems
Village power
Water pumping
Telecommunications
Wireless power
• Drivers:
– Lowest cost for remote requirements
– Power line extension cost $10,000 to
$30,000 per mile
• Applications:
–
–
–
–
–
Telecommunications
Vacation homes
Irrigation
Billboard and street lighting
Instrumentation, traffic signals
On-grid Market
•
Drivers:
–
–
–
Reduce Peaking Loads
Government subsidies
Environmental orientation
•
Applications:
– Residential
– Commercial / industrial
– Cover the land
Declining Prices Build Markets
Price NOT adjusted for inflation
Shipments CAGR 1981 - 2002 = 22%
1996 - 2002 = 35%
Electricity Cost [cent/kWH]
Cost Model
50
•Assumptions
40
–20 year system life
–6% interest rate
–No subsidies
New Jersey
30
20
California
10
2004
0
0
2
4
6
8
System Cost [$/W]
Must improve performance/cost by between and factor of 3 and 6
Detail of Solar Panel
Tempered
Glass
Clear
laminate
Solar cells
Clear
laminate
Plastic backing
Junction box
Aluminum
frame
Wafers: Same as Used for Micro-electronics
String Ribbon
Think soap bubble, but continuous and with the bubble hardening
• No grinding sawing or etching
•
120 Furnaces in operation.
•
15 MW annual production in
Marlboro, MA
•
30 MW factory to be built in
Germany
No grinding, no slicing, no etching
• Ribbon is laser cut into
wafers
• Wafers go DIRECTLY onto
belt furnace for p-n junction
diffusion
Finished cells emerging from firing of metallization
Vision
• MIT plays a lead role in moving from the Epoch of Fossil Fuel to
the Epoch of Renewable Energy.
–
–
–
–
–
15-20 years of work on crystalline silicon PV
30-70 years of work on alternative materials systems for PV
20-25 years work on off-shore wind
20-70 years of work on storage
Policy work throughout
• MIT Contributes to “re-setting” global geo-politics.
– Move from finite, poorly distributed resources to “universally
available” distributed resources.
– Allow the U.S. to attain energy independence.
• Satisfy student’s desire to do well by doing good.