Transcript Slide 1 - climateknowledge.org

CO2 and Energy #2
Jasper Kok
Applied Physics Program
Climate science & policy enthusiast
Lecture for AOSS 480, Ricky Rood
Outline and review lecture 1
– Historic CO2 emissions
and energy use
– Current sources of
energy
– Energy use and CO2
emissions of economic
sectors
– Energy use and CO2
emissions by end use
US energy use by sector
Carbon Emissions (GtC/yr)
 Lecture 1: Current and
past energy use
10
cement and
gas flaring
8
gas
6
oil
4
coal
2
deforestation
0
1850
1900
1950
2000
World CO2 emissions by
fuel and end use
Outline Lecture 2
 Lecture 2: Future energy use and climate change
mitigation
– ‘Business as usual’
 Do we need to act to prevent ‘dangerous anthropogenic
interference’ in the climate system?
– ‘Wedges’ to mitigate climate change
– Energy supply decarbonization ‘tools’




Energy efficiency
Renewable energies
Carbon capture and sequestration
Biofuels
– Specific ‘wedges’ of mitigation
– Externality: energy and water
Key reference
 The ‘wedge’ paper: “A plan to keep carbon in
check” by Socolow and Pacala, Scientific
American, 2006.
– This is an influential policy-oriented paper on how
to reform energy sector while still achieving
economic growth
– Accessible through http://mirlyn.lib.umich.edu
 On local server: Socolow and Pacala:
Keeping Carbon in Check (Scientific
American, 2006)
Future energy policy: What are we
trying to achieve?
 The 1992 UN Framework
Convention on Climate
Change was signed by most
countries. Stated objective:
“to achieve stabilization of GHG
concentrations in the atmosphere
at a low enough level to prevent
dangerous anthropogenic
The green countries have signed UNFCCC!
interference with the climate
system”
 This should be done in a time frame sufficient:
– to allow ecosystems to adapt naturally to climate change
– to ensure that food production is not threatened
– to enable economic development to proceed in a sustainable manner
 Does ‘business as usual’ allow this? If not, then what energy
policies should we introduce (as a world community)?
Outline Lecture 2
 Lecture 2: Future energy use and climate change mitigation
– ‘Business
as usual’
 Do we need to act to prevent ‘dangerous
anthropogenic interference’ in the climate
system?
– ‘Wedges’ to mitigate climate change
– Energy supply decarbonization ‘tools’




Energy efficiency
Renewable energies
Carbon sequestration
Biofuels
– Specific ‘wedges’ of mitigation
– Externality: energy and water
‘Business as usual’
CO2-trajectory path
≈ business as usual
 ‘Business as usual’ has CO2 emissions growing
at current rate (1.5%/year)
– Likely end-of-century warming: ~2.3 – 3.4 ºC
‘Business as usual’
End-of-century temperature change
 “Business as usual” (2090-2099) scenario
– Global mean warming 2.8 ºC;
– Much of land area warms by ~3.5 ºC
– Arctic warms by ~7 ºC
Will ‘business as usual’ lead to
‘dangerous’ climate change?
 At > 2ºC
– Ecosystems become
threatened
– Food supply
jeopardized
– Abrupt / irreversible
changes (could lead to
large-scale economic
damage)
 Many scientists think
should prevent >2ºC
warming
 EU policy aimed at
< 2ºC warming
 So what is a ‘safe’ CO2
trajectory and how do
we achieve it?
Likely range of ‘business
as usual’ by 2100
CO2 stabilization trajectory
 Need to stay below ~2 ºC
to avoid ‘dangerous’
climate change.
 Stabilize at < 550 ppm.
Pre-industrial: 275 ppm,
current: 385 ppm.
 Need 7 ‘wedges’ of
prevented CO2 emissions.
Outline Lecture 2
 Lecture 2: Future energy use and climate change mitigation
– ‘Business as usual’
 Why we need to act to prevent ‘dangerous anthropogenic interference’ in
the climate system
–‘Wedges’ to mitigate climate change
– Energy supply decarbonization ‘tools’




Energy efficiency
Renewable energies
Carbon sequestration
Biofuels
– Specific ‘wedges’ of mitigation
– Externality: energy and water
What is a ‘wedge’?
 A ‘wedge’ is a strategy to
reduce carbon emissions
that grows from zero to 1
GtC/year in 50 years
 The world needs to
implement 7 of these
wedges to prevent
‘dangerous’ climate
change
 Examples:
– Expand wind energy
– Make cars more efficient
– Reduce deforestation rates
Developing Vs. developed world
 Implementation of
wedges would lead
to large emission
reductions in
developed world
 Developing world
would increase
emissions, but less
than without carbon
constraints
How and where to get the wedges
 Need 7 wedges for
2xCO2 stabilization
 Where and how is
most cost-effective to
cut CO2?
 Tools wedges use:
– Improved energy
efficiency
– Renewable energies
(wind, solar)
– Carbon capture and
sequestration
– Biofuels
Outline Lecture 2
 Lecture 2: Future energy use and climate change
mitigation
– ‘Business as usual’
 Why we need to act to prevent ‘dangerous anthropogenic
interference’ in the climate system
– ‘Wedges’ to mitigate climate change
– Energy supply decarbonization tools
 Energy efficiency
 Renewable energies
 Carbon capture and sequestration
 Biofuels
– Specific ‘wedges’ of mitigation
– Externality: energy and water
Efficiency Gains
 The low-hanging fruit!
 Essentially three kinds:
– End-use electricity efficiency (fluorescent bulbs instead of
incandescent bulbs)
– Energy generation efficiency (coal plant operating at 60 %
efficiency instead of current 40 %)
– Transportation efficiency (60 mpg instead of 30 mpg)
 Efficiency gains are generally cheap mitigation options
 But will only get so far before cutting into primary energy
used for economic activity
Kinds of renewable energy
 Hydro-power
– Already widely
used - not much
potential for
expansion
 Wind
– Abundant and
competitive
 Solar
– Photovoltaic (PV)
– Concentrating solar
Renewable energy: Wind
 Probably most promising
renewable energy source
Wind energy cost in $/kWh
$0.40
$0.30
$0.20
 Supplies ~1 % of world
electricity, ~0.3 % in US
 Is cost-effective against coal
and natural gas
 Is undergoing very rapid
growth (5-fold increase 20002007)
$0.10
$0.00
1980
1984
1988
1991
1995
2000
2005
Renewable energy: Wind
 Advantages:
– Wind energy is relatively
mature technology and is cost
effective
– Can be utilized at all scales
 Large wind farms
 On small agricultural farms
– Total theoretical potential of
wind energy on land/near
shore is 5x current energy
consumption
Large potential for
expansion
Renewable energy: Wind
 Disadvantages:
– Horizon pollution and NIMBY
siting problems
– Birds…(though this is often overstated – about 1-2 birds per
turbine per year)
– Wind is intermittent! It can
therefore not make up a large
fraction of base load (unless
effective energy storage)
Renewable energy: Solar
 Essentially three kinds:
1. Solar heat
–
–
Water is heated directly by
sunlight
Used cost-effectively on
small scale in houses
2. Solar photovoltaic (PV)
–
–
Uses photo-electric effect
(Einstein!) to produce
electricity
Supplies ~0.04 % of world
energy use
3. Solar concentrated
–
–
Use large mirrors to focus
sunlight on steam turbine or
very efficient PV panels
More cost-effective than just
PV
Renewable energy: Solar
 Advantages:
–
–
–
–
Enormous theoretical potential!
Applicable at various scales
(individual houses to solar plants)
Solar heating can be cost effective
Economy of scale and/or
breakthroughs might reduce costs of
PV and solar concentrated
 Disadvantages
–
–
PV and solar concentrated are
expensive! Currently only costeffective with government subsidies
Intermittent – can not make up large
portion of base load (except with
storage capability)
Outline Lecture 2
 Lecture 2: Future energy use and climate change mitigation
– ‘Business as usual’
 Why we need to act to prevent ‘dangerous anthropogenic interference’
in the climate system
– ‘Wedges’ to mitigate climate change
– Energy supply decarbonization tools
 Energy efficiency
 Renewable energies
 Carbon capture and sequestration
 Biofuels
– Specific ‘wedges’ of mitigation
– Externality: energy and water
Carbon Capture and Sequestration (CCS)
 Main idea:
– Burn fossil fuels for
electricity/hydrogen production
– Capture CO2
– ‘Sequester’ it in geological formation,
oil/gas field, or ocean floor
 This principle is immensely
important for future CO2 mitigation!
– Fossil fuels are abundant and cheap
– Renewable energy generally not
mature enough to replace fossil fuels
– Coal-fired power plants with CCS
could provide low-carbon energy at
competitive costs
 Currently successfully employed in
‘pilot’ projects
CCS: Carbon Capture
 Both conventional and modern types of
coal-fired power plants can be adapted for
CCS
 Conventional coal-fired power plant:
– Burn coal in air (much like the old days)
– Exhaust gas is ~15 % CO2 (rest is mostly
nitrogen and water vapor)
– Exhaust gas flows over chemicals that
selectively absorb CO2 (‘amines’)
– The amines are heated to ~150 ºC to give up
the CO2 and produce a (nearly) pure CO2
gas that can be sequestered.
 Modern coal-fired power plant:
– Coal is burned with pure oxygen in a
gasification chamber to produce hydrogen
and CO2
– The CO2 is filtered out and the hydrogen is
burned for electricity
CCS: Sequestration
 CO2 can be sequestered at ~1 km underground, here pressure
is high enough to liquify CO2, which helps prevent it from leaking
 Several options for sequestering CO2:
1.
2.
3.
4.
Depleted oil/gas reservoirs
(can be even be used to
enhance oil/gas recovery –
reduces costs)
Deep saline (brine)
formations – these are
porous media in which
CO2 can be stored and
dissolve in the salty water
Use for coal-bed methane
recovery (one of those
‘unconventional’ fossil
fuels)
Ocean floor (very
controversial!)
CCS: economics
 CCS could become cost-effective with
future carbon legislation
Biofuels
 Initially hailed as a sustainable
substitute for oil
 Can help reduce oil imports and
improve national security
– In US, this is probably main motivation
for recent push (“addicted to oil”,
Bush’s 2006 State of the Union)
 Two main kinds of biofuels:
1. First generation:
Produced by converting sugar in corn,
sugar beets, etc., into ethanol (alcohol)
2. Second generation:
Produced through “cellulosic
conversion” of biomass into sugar, then
sugar into ethanol
 Climate change impact of different
biofuels is very different!
Biofuels – First Generation
 In US, mainly corn-based ethanol
– Heavily subsidized by federal government to reduce oil dependence
(~$1.90/gallon)
 Effect on climate change is negative:
– Energy used in production is comparable to energy content
– Significant amounts of N2O (a potent GHG) can be produced through fertilizer
use
– More carbon would be sequestered by letting crop land lie fallow
– Raises food prices  Tropical deforestation, which releases more carbon
than saved from fuel production over > 30-year period
Source:
Fargione et
al., Science,
2008
Biofuels – Second Generation
 Produced from plants containing cellulose
– Cellulosic conversion to sugar is very difficult and expensive! (cows
have 4 stomach compartments for a reason…)
 Second generation biofuels are better for climate change:
– Similar amount of carbon sequestered as fallow cropland
– But, competition with food still leads to tropical deforestation and net
release of carbon!
US 1st
generation
biofuel
US 2nd
generation
biofuel
Biofuels – do they help or hurt?
 In general, biofuels that compete with food will not contribute to
mitigating climate change
– Direct link between food demand/prices and tropical deforestation
 Production of first generation biofuels (directly from food such as corn)
is not a solution to climate change and should be avoided!
 Production of second generation biofuels (from biomass) is only helpful
if it doesn’t compete with food production (so not grown on cropland)
– Second generation biofuels from agricultural waste could play important
role, but is currently not cost-effective
 In light of these recent results (2007/2008), EU is reconsidering past
biofuel mandates and subsidies
Outline Lecture 2
 Lecture 2: Future energy use and climate change
mitigation
– ‘Business as usual’
 Why we need to act to prevent ‘dangerous anthropogenic
interference’ in the climate system
– ‘Wedges’ to mitigate climate change
– Energy supply decarbonization ‘tools’




Energy efficiency
Renewable energies
Carbon sequestration
Biofuels
–Specific ‘wedges’ of mitigation
– Externality: energy and water
Where can we create ‘wedges’
in the energy system?
 Power generation (40 %)
– This is the ‘easy’ target because
of availability of cost effective
low-carbon options (wind, CCS)
 Direct fuel use (36 %)
– This can be ‘switched’ to lowcarbon electricity
 Transportation (24 %)
– This is the tough nut to crack!
– Currently no real feasible low
carbon alternatives
 Lot of infrastructure in place for
fossil fuel-based transportation!
???
???
How to create ‘wedges’:
Power Generation
 Several options, each one
wedge:
– Increase efficiency of coal-fired
power plants from 40 to 60 % ($)
– Replace coal-fired to natural gasfired power plants ($)
– Double nuclear electricity to
replace coal-fired power plants ($$)
– Use CCS for low-carbon coal-fired
power plants ($$)
– Expand wind energy 30x to replace
coal-fired power plants ($$)
– Expand solar energy 700x to
replace coal-fired power plants
($$$)
How to create ‘wedges’:
Direct Fuel Use
 Several options, each
one wedge:
– Improve building
insulation ($)
– Replace natural gas
heat with low-carbon
hydrogen from
wind/coal with CCS
($$$)
– (and general switch to
electricity heat instead
of fuel heat)
How to create ‘wedges’:
Transportation
 Several options, each one
wedge:
– Increase car efficiency from 30
to 60 mpg ($)
– More compact world with less
travel  5,000 instead of 10,000
miles/vehicle ($)
– Switch to low-carbon hydrogen
($$$)
– Switch to sustainable biofuels 
unlike corn ethanol, these must
not compete with food
production! ($$$)
Outline Lecture 2
 Lecture 2: Future energy use and climate change
mitigation
– ‘Business as usual’
 Why we need to act to prevent ‘dangerous anthropogenic
interference’ in the climate system
– ‘Wedges’ to mitigate climate change
– Energy supply decarbonization ‘tools’




Energy efficiency
Renewable energies
Carbon sequestration
Biofuels
– Specific ‘wedges’ of mitigation
–Externality: energy and water
Must address climate change without
exacerbating freshwater shortage
 Both energy and water are
critical resources
 Many areas already suffer
water stress
– note Africa, India, China, where
greatest population growth is
projected to occur
 Projected to become worse with
increasing population, pollution,
and climate change
– Dry areas are generally projected
to become drier.
 Must address energy challenge
without exacerbating water
scarcity
So where is our fresh water used?
 You can take many,
many, very long showers
for a pound of steak…
 Greatly expanding
biofuels from ethanol to
substitute oil would
probably be bad idea…
Class on Thursday
 Ben Santer will be lecturing on Thursday
– He’s a well-known climate scientist!
– Few contemporary scientists get their own
Wikipedia page…
(http://en.wikipedia.org/wiki/Benjamin_D._Santer)