Transcript Slide 1

Stabilization Wedges:
Mitigation Tools for the Next Half-Century
Robert Socolow
Princeton University
[email protected]
Future of Energy Series
Center for the Environment
Harvard University
April 5, 2006
This talk is based on a paper by Stephen Pacala and Robert Socolow,
published in the August 13, 2004, issue of Science, 305 (5686), pp. 968-972,
and its Supporting Online Material, available at www.princeton.edu/~cmi
What if the fossil fuel future is robust, but
the Greenhouse problem is severe?
Will the fossil fuel system wither away?
Will the case
for
Greenhouse
damage
wither away?
YES
NO
YES
A nuclear or
renewables world
unmotivated by
climate.
Most people in the
fuel industries and
most of the public
have been here
NO
Environmentalists,
nuclear advocates
are often here.
OUR WORKING
ASSUMPTIONS
Outline of Talk
1. The Wedges Model: A simple quantification of carbon
mitigation
2. Some specific wedges, with special attention to CO2 capture
and storage
3. Two underlying issues worthy of a Harvard program on
energy
Past Emissions
Billion of Tons of
Carbon Emitted
per Year
14
Historical
emissions
7
1.9 
0
1955
2005
2055
2105
The Stabilization Triangle
Billion of Tons of
Carbon Emitted
per Year
14
Stabilization
Triangle
Historical
emissions
7
Flat path
Interim Goal
O
1.9 
0
1955
2005
2055
2105
The Stabilization Triangle:
Beat doubling or accept tripling
21
GtC/yr
(530)
14
7
(750)
Stabilization
triangle
(470)
Historical (380)
emissions
Flat = Act Now
(320)
(500)
1.9
1955
2005
2055
2105
(850)
(500)
2155
Values in parentheses are ppm. Note the identity (a fact about
the size of the Earth’s atmosphere): 1 ppm = 2.1 GtC.
(850)
(500)
2205
The Interim Goal is Within Reach
Reasons for optimism that global emissions in 2055 need not
exceed today’s emissions:
•The world today has a terribly inefficient energy system.
•Carbon emissions have just begun to be priced.
•Most of the 2055 physical plant is not yet built
Wedges
Billion of Tons of
Carbon Emitted per
Year
14
14 GtC/y
Seven “wedges”
Historical
emissions
7
Flat path
O
7 GtC/y
1.9 
0
1955
2005
2055
2105
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 strategy
has already been commercialized at scale somewhere.
1 GtC/yr
Total = 25 Gigatons carbon
50 years
Cumulatively, a wedge redirects the flow of 25 GtC in its first 50
years. This is 2.5 trillion dollars at $100/tC.
A “solution” to the CO2 problem should provide at least one wedge.
Outline of Talk
1. The Wedges Model: A simple quantification of carbon
mitigation
2. Some specific wedges, with special attention to CO2
capture and storage
3. Two underlying issues worthy of a Harvard program on
energy
Allocation of 6.2 GtC/yr
Electricity: 40%
Fuels used directly: 60%
Transportation
Electricity
Heating
Fill the Stabilization Triangle with Seven Wedges
Energy Efficiency
Methane
Management
14 GtC/y
Stabilization
Triangle
Forests & Soils
2004
7 GtC/y
2054
Fuel Displacement by
Low-Carbon Electricity
Decarbonized
Electricity
Decarbonized
Fuels
Nuclear
Electricity
Effort needed by 2055 for 1 wedge:
700 GW (twice current capacity) displacing
coal power.
Phase out of nuclear power creates
the need for another half wedge.
Graphic courtesy of NRC
Wind Electricity
Effort needed by 2055 for
1 wedge:
One million 2-MW windmills
displacing coal power.
Today: 50,000 MW (1/40)
Prototype of 80 m tall Nordex 2,5 MW wind turbine located in Grevenbroich, Germany
(Danish Wind Industry Association)
Pholtovoltaic
Power
Effort Needed by 2055 for
one wedge:
2000 GWpeak (700 times
current capacity)
2 million hectares
Solar thermal power via concentrators (troughs and
dishes) is produced at high efficiency, like PV.
Graphics courtesy of DOE Photovoltaics Program
Power with Carbon Capture and Storage
Effort needed by
2055 for 1 wedge:
Carbon capture and
storage at 800 GW
coal power plants.
Graphics courtesy of DOE Office of Fossil Energy
Efficient Use of Electricity
buildings
industry
Effort needed by 2055 for 1 wedge:
.
25% - 50% reduction in expected 2055
electricity use in commercial and
residential buildings
power
Efficient Use of Fuel
Effort needed by 2055 for 1 wedge:
2 billion cars driven 10,000 miles per year at 60 mpg instead of 30 mpg.
1 billion cars driven, at 30 mpg, 5,000 instead of 10,000 miles per year.
Coal-based Synfuels with CCS*
*Carbon capture and storage
Effort needed for 1 wedge by 2055
Capture and storage of the CO2 byproduct at
plants producing 30 million barrels per day of
coal-based synfuels
Assumption: half of C originally in the coal
is available for capture, half goes into
synfuels.
Graphics courtesy of DOE
Office of Fossil Energy
Result: Coal-based synfuels have no worse CO2 emissions
than petroleum fuels, instead of doubled emissions.
Biofuels
Effort needed by 2055 for
1 wedge:
2 billion 60 mpge cars running
on biofuels instead of gasoline
and diesel.
To produce these biofuels: 250
million hectares of high-yield
(15 t/ha) crops, one sixth of
world cropland.
Challenge: To find ecologically responsible
ways to grow biomass for power and fuel on
hundreds of millions of hectares.
Usina Santa Elisa mill in Sertaozinho, Brazil
(http://www.nrel.gov/data/pix/searchpix.cgi?getrec=5691971&display_type=verbose&search_reverse=1_
Emission Commitments from Capital Investments
Historic
emissions,
all uses
2003-2030 power-plant lifetime CO2 commitments
WEO-2004 Reference Scenario.
Lifetime in years: coal 60, gas 40, oil 20.
Deter investments in new long-lived high-carbon stock: (e.g., power plants,
buildings). Coordinate “green-field” (new) and “brown-field” (replacement).
Needed: “Commitment accounting.”
Credit for comparison: David Hawkins, NRDC
$100/tC
Carbon emission charges in the neighborhood of $100/tC can enable
scale-up of most of the wedges. (PV is an exception.)
Form of Energy
Equivalent to $100/tC
Natural gas
$1.50/1000 scf
Crude oil
$12/barrel
Coal
$65/U.S. ton
Gasoline
25¢/gallon (ethanol subsidy: 50¢/gallon)
Electricity from coal
2.2¢/kWh (wind and nuclear subsidies: 1.8 ¢/kWh)
Electricity from natural gas
1.0¢/kWh
Today’s global energy system
$700 billion/year (2% of GWP)
$100/tC is approximately the EU trading price for the past six months.
$100/tC ≈ 2¢/kWh induces CCS. Three views.
Transmission and
distribution
}
Wholesale power
w/o CCS: 4 ¢/kWh
6
Plant
capital
Coal at the
power plant
6
A coal-gasification power plant
can capture CO2 for an added
2¢/kWh ($100/tC). This:
3
1
triples the price of delivered
coal;
adds 50% to the busbar price
of electricity from coal;
CCS 2
Retail power
w/o CCS: 10 ¢/kWh
adds 20% to the household
price of electricity from coal.
Do wedge strategies get used up?
For any strategy, is the second wedge easier or harder to achieve than the
first? Are the first million two-megawatt wind turbines more expensive or
cheaper than the second million two-megawatt wind turbines?
The first million will be built at the more favorable sites.
But the second million will benefit from the learning acquired building the
first million.
The question generalizes to almost all the wedge strategies: Geological
storage capacity for CO2, land for biomass, river valleys for hydropower,
uranium ore for nuclear power, semiconductor materials for photovoltaic
collectors.
All present the same question: Will saturation or learning dominate?
Summary: What’s appealing
stabilization wedges?
The stabilization triangle:
Does not concede doubling is inevitable.
Shortens the time frame to within business horizons.
The wedge:
Decomposes a heroic challenge (the Stabilization
Triangle) into a limited set of monumental tasks.
Establishes a unit of action that permits quantitative
discussion of cost, pace, risk.
Establishes a unit of action that facilitates quantitative
comparisons and trade-offs.
Outline of Talk
1. The Wedges Model: A simple quantification of carbon
mitigation
2. Some specific wedges, with special attention to CO2
capture and storage
3. Two underlying issues worthy of a Harvard program on
energy:
A. Redistribution – ethics and technology in a world
with limits
B. Prospicience (“the art of looking forward”) –
principles and practices in a world with limits
“60% reduction by 2050” (Blair) + “constant
global emissions” leaves room for others
5.37  2.15/(US pop. growth)
1.13  1.13/(World pop. growth)
CO2 emissions (tC/yr) per capita, 1997, from the 10 largest-emitting countries
Under a constant global emissions cap, if emissions from countries responsible
for top half (3.5 GtC/y) of per capita emissions are reduced by 60% (Blair),
emissions from the rest can increase by 160%: 50-50 becomes 20-80.
2002: OECD 54%, Transition economies 11%, Developing countries 35%.
Source: Marland et al., 1999, as presented in Rubin, Fig 12.25(b).
Consensus Building via Wedges?
Advocates of particular wedges agree:
1. It is already time to act.
2. It is too soon to pick “winners.”
3. Subsidy of early stages is often desirable.
4. At later stages, markets help to choose the best wedges.
5. The best wedges for one country may not be the best for another.
6. The environmental and social costs of scale-up need attention.
Can a consensus for early action be built on stabilization wedges?
Leapfrogging and Wedges
“To leapfrog”: To introduce advanced technology in developing
countries first, industrialized countries later.
Some developing countries can leapfrog to the deployment of
advanced concepts, e.g., for city planning, buildings,
transport, coal, or biofuels.
The world learns faster, reducing everyone’s costs.
The world compensates those who move first.
Leapfrogging is a path to globally coordinated mitigation.
Carbon and Basic Human Needs
Basic Human
Need
People without
Sufficiency
access (billions) (per capita-yr)
Carbon
required
(GtC/yr)
Electricity
1.6
0.15*
600 kWh
*using global average
C-intensity of power in
2002: 160 gC/kWh
Clean cooking
fuel
Total
2.6
35 kg propane
0.07
†
0.22
†
current global carbon
emissions: 7 GtC/yr
Instantly meeting Basic Human Needs for electricity and clean cooking fuel
would produce only a three percent increase in global CO2 emissions.
Including coal and kerosene not burned, net might be a decrease.
-0.15 wedges: Faster provision of
electricity for 1.6 billion people
0.15 GtC/yr
3.75 GtC
‘
2005
‘
2030
‘
2055
1.6 Billion people get access to 600 kWh/yr of electricity by 2030 in AA, but
only by 2055 in BAU. Electricity is provided at the current world average carbon
intensity: 160 gC/kWh. With linear ramps, AA adds 3.75 GtC of CO2 emissions to
the atmosphere. One “stabilization wedge” is 25 GtC of avoided emissions, so
following AA instead of BAU is -0.15 wedges.
-0.07 wedges: Faster provision of clean
cooking fuels for 2.6 billion people
0.07 GtC/yr
1.75 GtC
‘
2005
‘
2030
‘
2055
2.6 Billion people get access to 35 kg/yr of LPG (propane) or equivalent
clean cooking fuel by 2030 in AA, but only by 2055 in BAU. With linear ramps,
AA adds 1.75 GtC of CO2 emissions to the atmosphere. One “stabilization wedge”
is 25 GtC of avoided emissions, so following AA instead of BAU is -0.07 wedges.
Wedges
Billion of Tons of
Carbon Emitted per
Year
14
14 GtC/y
Basic Human Needs for
cooking and electricity
Historical
emissions
7
Seven “wedges”
Flat path
O
7 GtC/y
1.9 
0
1955
2005
2055
2105
Prospicience
Prospicience: “The art [and science] of looking ahead.” We
need a new word to describe a new intellectual domain.
In the past 50 years we have become aware of our deep
history: the history of our Universe, our Earth, and life. All
this is quantitative for the first time.
Can we achieve a comparable quantitative understanding of
human civilization at various future times: 50 years ahead
vs. 500 vs. 5000 vs. longer?
We have scarcely begun to ask: What are we on this planet
to do? What are our goals? What are our responsibilities?
Imagine spending as much effort on our collective destiny on
Earth as we spend on our personal destiny in the afterlife!
Where might a discipline of looking
ahead be helpful?
Currently, we are unable to think clearly in areas of technology policy
where distinctions among future time frames (10, 100, 1000, 10,000
years) are critical.
We are making a mess of nuclear waste policy, We have been
distracted by a set of irrelevant time scales, the long half-lives of
particular isotopes.
We are finding it difficult to think coherently about the geological
storage of CO2. How long should CO2 stay down!
We are in a muddle about Hubbert's peak and other resource
issues. Yes, we are using up our best stuff (spending our
spectacular endowment), but, yes, there is lots of less good stuff.
Details matter.
We are dismayed by the tyranny of the discount rate in much
analysis.
Earth Engineering
How should we perform our new role of Earth engineers?
As we learn how the world works as a physical and biological
system, we will learn how to manipulate it.
We will struggle over goals: levels of risk, intergenerational and
intragenerational equity, responsibility for ecosystems and other
species.
We will struggle over processes: Who decides?
“Stabilization”
Do we desire stabilization? When we imagine our destiny, we often
imagine a future without change. Won’t our descendants be restless as
we are?
Many UN population projections assume stationary populations
forever, after some near date (2050). Might we prefer the global
population to return by 2200 to two billion, without war or
pestilence?
The Framework Convention on Climate Change calls for
stabilization of the CO2 concentration. “Stabilization” is a word from
control theory. Will we negotiate an optimal CO2 concentration once,
and intervene thereafter to keep it constant?
There are no plateaus.
A world transformed
by deliberate attention to carbon
A world with the same total CO2 emissions in 2055 as in 2005 will also
have:
1. Institutions for carbon management that reliably communicate the
price of carbon.
2. If wedges of nuclear power are achieved, strong international
enforcement mechanisms to control nuclear proliferation.
3. If wedges of CO2 capture and storage are achieved, widespread
permitting of geological storage.
4. If wedges of renewable energy and enhanced storage in forests and
soils are achieved, extensive land reclamation and rural development.
5. A planetary consciousness.
Not an unhappy prospect!
Can We Do It?
People are becoming increasingly anxious about our limited
understanding of the experiments we are performing on the
only Earth we have…
…and are learning that there are ways to live more
cautiously.
We should anticipate a discontinuity:
What has seemed too hard becomes what simply must
be done.
Precedents include abolishing child labor, addressing the
needs of the disabled, and mitigating air pollution.