1. Blue arrow: IPCC projection
B1 scenario: to stabilize CO2 concentrations, we need to reduce the rate of CO2 emissions
Blue arrow: IPCC projection

2. How do we get from 13% renewables to 80% within 4 decades?
Invest ~1% of global GDP
Boost existing growth: of 300 gigawatts of new electrical generation capacity added between , ~140 GW from renewable sources
Renewable production rate increase by 20x
Science in Special Report on Renewable Energy Sources and Climate Change Mitigation agreed to by all nations
Policy on renewable energy set at next major climate conference, COP17, in South Africa in December.

3. Where does this line go next?
Historical Emissions
Billions of Tons Carbon Emitted per Year 16
Historical
emissions 8
Where does this line go next?
1950
2000
2050
2100 3

4. Developed countries have emitted the most, but the growth is fastest in developing world

5. Cut out the future growth as a “Stabilization Triangle”
Billions of Tons Carbon Emitted per Year 16
Current path = “ramp”
Stabilization Triangle
Interim Goal
Historical
emissions 8
Flat path
1.6
1950
2000
2050
2100 5

6. Stabilization Triangle
Harmful climate impacts at “easy” target Still experience change at “tough” target
Billions of Tons Carbon Emitted per Year
Easier CO2 target 16
Current path = “ramp”
~850 ppm
Stabilization Triangle
Interim Goal 8
Historical
emissions
Flat path
Tougher CO2 target
~500 ppm
1.6
1950
2000
2050
2100 6

7. Slice up the stabilization triangle into “wedges”
Billions of Tons Carbon Emitted per Year 16
Current path = “ramp”
16 GtC/y
Eight “wedges”
Goal: In 50 years, same
global emissions as today
Historical
emissions 8
Flat path
1.6
1950
2000
2050
2100 7

8. What is a “Wedge”?
A “wedge” is a strategy to reduce carbon emissions that grows in 50 years from zero to 1.0 GtC/yr. The technology is here: these strategies have already been scaled up viably somewhere.
1 GtC/yr
Total = 25 Gigatons carbon
50 years
Cumulatively, a wedge redirects the flow of 25 GtC in its first 50 years. If there is a price on carbon of $100/tC this is $2.5 trillion.

9. Socolow & Pacala describe 15 existing wedges each to reduce carbon by 1 Gt/yr by 2050
Energy Efficiency &
Conservation (4)
16 GtC/y
Fuel Switching
(1)
Renewable Fuels
& Electricity (4)
Stabilization
Stabilization
Triangle
Triangle
CO2 Capture
& Storage (3)
8 GtC/y
Forest and Soil Storage (2)
2007
2057
Nuclear Fission (1)
What does a wedge look like? 9

10. Efficiency Coal: 25% global emissions
Double the fuel efficiency of the world’s cars or halve miles traveled
Double efficiency of coal-based electricity (better turbines, fuel cells)
Use best practices in all residential and commercial buildings
E, T, H / $
“E,T, H” = can be applied to electric, transport, or heating sectors, $=rough indication of cost (on a scale of $ to $$$)
Sector s affected:
E = Electricity, T = Transport, H = Heat
Cost based on scale of $ to $$$
Replace all incandescent bulbs with CFLs = 1/4 of a wedge

11. Fuel Switching
Substitute 1400 natural gas electric plants for an equal number of coal-fired facilities
Photo by J.C. Willett (U.S. Geological Survey).
“E,H” = can be applied to electric or heating sectors, $=rough indication of cost (on a scale of $ to $$$)
Effort needed for 1 wedge:
Build 1400 GW of capacity powered by natural gas instead of coal (60% of current fossil fuel electric capacity)
Requires an amount of natural gas equal to that used for all purposes today
So a slice is 50 LNG tanker discharges/day by m3/tanker, or
one new “Alaska” 4 Bscfd.
Detailed Description: NATURAL GAS TURBINES ARE BEING DEVELOPED TO PRODUCE ELECTRICITY IN A SIMPLE, LOW COST ENVIRONMENTALLY FRIENDLY WAY. DOE'S NATIONAL ENERGY TECHNOLOGY LABORATORY (NETL) INITIATED THE ADVANCED TURBINE SYSTEMS (ATS) PROGRAM AND HAS PARTNERED WITH INDUSTRY TO PRODUCE A NEW GENERATION OF HIGH EFFICIENCY GAS TURBINES FOR CENTRAL STATION ELECTRICITY PRODUCTION, USING CLEAN BURNING NATURAL GAS.
700 1-GW baseload coal plants (5400 TWh/y) emit 1 GtC/y.
Natural gas: 1 GtC/y = 190 Bscfd
Yr 2000 electricity:
Coal : TWh/y; Natural gas: 2700 TWh/y.
A wedge requires an amount of natural gas equal to that used for all purposes today
E, H / $
E = Electricity, T = Transport, H = Heat
Cost based on scale of $ to $$$

12. Carbon Capture & Storage (CCS)
Implement CCS at
800 GW coal electric plants or
1600 GW natural gas electric plants or
180 coal synfuels plants or
10 times today’s capacity of hydrogen plants
“E,T, H” = can be applied to electric, transport, or heating sectors, $=rough indication of cost (on a scale of $ to $$$)
Graphic courtesy of Alberta Geological Survey
There are currently three storage projects that each inject 1 million tons of CO2 per year – by 2055 need 3500.
E, T, H / $$
E = Electricity, T = Transport, H = Heat Cost scale of $ to $$$

13. Fertilization?
Atmocean commercial proposol to pump nutrients to the surface, where the sunlight is.
“As with any human manipulation of the environment, ocean iron fertilization carries potential risks, as well as potential benefits; moving forward on (iron fertilization) should only be done if society is willing to acknowledge explicitly that it will result in alteration of ocean ecosystems and that some of the consequences may be unforeseen.” - Buesseler et al., 2008, Science

14. CCS requires carbon audits to verify
Permanence
Does carbon removed stay out of the atmosphere for years?
Does project reduce CO2 beyond what would have happened any way?
Additionality
Monitoring
Can regulators really measure how effective carbon storage is?
Leakage
Does storage cause no harm?

15. Nuclear Electricity
Triple the world’s nuclear electricity capacity by 2055
Graphic courtesy of NRC
“E” = can be applied to electric sector, $$=rough indication of cost (on a scale of $ to $$$)
Plutonium (Pu) production by 2054, if fuel cycles are unchanged: 4000 t Pu (and another 4000 t Pu if current capacity is continued).
Compare with ~ 1000 t Pu in all current spent fuel, ~ 100 t Pu in all U.S. weapons.
5 kg ~ Pu critical mass.
The rate of installation required for a wedge from electricity is equal to the global rate of nuclear expansion from
E/ $$

16. Wind Electricity
Install 1 million 2 MW windmills to replace coal-based electricity,
Combined area ~ size of Germany (land could be dual purpose: agriculture?)
“E,T, H” = can be applied to electric, transport, or heating sectors, $-$$=rough indication of cost (on a scale of $ to $$$)
Photo courtesy of DOE
A wedge worth of wind electricity will require increasing current capacity by 30x
E, T, H / $-$$

17. Photos courtesy of DOE Photovoltaics Program
Solar Electricity
Install 20,000 square km (size of New Jersey) by 2054
Photos courtesy of DOE Photovoltaics Program
“E” = can be applied to electric sector, $$$=rough indication of cost (on a scale of $ to $$$)
A wedge of solar electricity = increasing current capacity 700x
E / $$$

18. Biofuels: “Borrowed Carbon”
Scale up current global ethanol production 30x
Photo courtesy of NREL
“T, H” = can be applied to transport or heating sectors, $$=rough indication of cost (on a scale of $ to $$$)
Using current practices, one wedge requires planting an area the size of India with biofuels crops
T, H / $$

19. Natural Sinks Eliminate tropical deforestation OR
Plant new forests over an area the size of the continental U.S.
Use conservation tillage on all cropland (1600 Mha)
Natural Sinks
“B” = biostorage sector, $=rough indication of cost (on a scale of $ to $$$)
B / $
Conservation tillage is currently practiced on less than 10% of global cropland
Photos courtesy of NREL, SUNY Stonybrook, United Nations FAO

20. If we can do it, should we? If so, how?
In order to avoid a doubling of atmospheric CO2, we need to rapidly deploy low-carbon energy technologies and/or enhance natural sinks
We already have an adequate portfolio of technologies to make large cuts in emissions
No one technology can do the whole job – a variety of strategies will need to be used to stay on a path that avoids a CO2 doubling
Every “wedge” has associated impacts and costs

21. We may have to.. Peak oil? IEA World Energy Outlook - Nov 2008
1999
2004
IEA World Energy Outlook - Nov 2008
“The world’s energy system is at a crossroads. Current global trends in energy supply and consumption are patently unsustainable — environmentally, economically, socially. What is needed is nothing short of an energy revolution.” 21