CO2 and Energy #2 Jasper Kok Applied Physics Program Climate science & policy enthusiast Lecture for AOSS 480, Ricky Rood

Outline and review lecture 1 Lecture 1: Current and past energy use 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 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 interference with the climate system” The green countries have signed UNFCCC! 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 IPPC 4AR executive summary; Pacala and Socolow, Science, 2004 ‘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. Roberta Hotinski (CMI), Stabilization Wedges: A Concept & Game, 2007

Outline Lecture 2 ‘Wedges’ to mitigate climate change 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 Source: Pacala and Socolow, Scientific American, 2006

Source Rosina Bierbaum’s 2007 guest lecture

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 Energy supply decarbonization tools 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 Wind energy cost in $/kWh Probably most promising renewable energy source 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 2000-2007) Sources: http://en.wikipedia.org/wiki/Image:Wind_2006andprediction_en.png and “wind energy” lecture by Stephen R. Lawrence, CU

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 Sources: http://en.wikipedia.org/wiki/Image:Wind_2006andprediction_en.png and “wind energy” lecture by Stephen R. Lawrence, CU

Renewable energy: Wind Disadvantages: Horizon pollution and NIMBY siting problems Birds…(though this is often over-stated – 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) Sources: http://en.wikipedia.org/wiki/Image:Wind_2006andprediction_en.png and “wind energy” lecture by Stephen R. Lawrence, CU; http://www.acsu.buffalo.edu/~insrisg/nature/nw04/0509Windmills.htm

Renewable energy: Solar Essentially three kinds: Solar heat Water is heated directly by sunlight Used cost-effectively on small scale in houses Solar photovoltaic (PV) Uses photo-electric effect (Einstein!) to produce electricity Supplies ~0.04 % of world energy use Solar concentrated Use large mirrors to focus sunlight on steam turbine or very efficient PV panels More cost-effective than just PV Source: http://en.wikipedia.org/wiki/Solar_energy, http://www.iea.org/textbase/papers/2006/renewable_factsheet.pdf and http://www.nytimes.com/2008/03/06/business/06solar.html?_r=1&oref=slogin and http://www.eere.energy.gov/

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 cost-effective with government subsidies Intermittent – can not make up large portion of base load (except with storage capability) Source: http://en.wikipedia.org/wiki/Solar_energy, http://www.iea.org/textbase/papers/2006/renewable_factsheet.pdf and http://www.nytimes.com/2008/03/06/business/06solar.html?_r=1&oref=slogin and http://www.eere.energy.gov/

Outline Lecture 2 Carbon capture and sequestration Biofuels 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 Source: Socolow, 2005, Scientific American; http://en.wikipedia.org/wiki/Carbon_capture_and_storage

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: 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 Source: Socolow, 2005, Scientific American 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: First generation: Produced by converting sugar in corn, sugar beets, etc., into ethanol (alcohol) Second generation: Produced through “cellulosic conversion” of biomass into sugar, then sugar into ethanol Climate change impact of different biofuels is very different! Sources: http://en.wikipedia.org/wiki/Biofuels; Scharlemasnn and Laurance, How green are biofuels, Science, 2008; Fargione et al., Land clearing and the biofuel carbon debt, Science, 2008; Searchinger et al., Use of US croplands for biofuels increases GHG…, Science, 2008

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 Sources: http://en.wikipedia.org/wiki/Biofuels; Scharlemasnn and Laurance, How green are biofuels, Science, 2008; Fargione et al., Land clearing and the biofuel carbon debt, Science, 2008; Searchinger et al., Use of US croplands for biofuels increases GHG…, Science, 2008 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 Sources: http://en.wikipedia.org/wiki/Biofuels, Scharlemasnn and Laurance, How green are biofuels, Science, 2008,

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 Sources: http://en.wikipedia.org/wiki/Biofuels, Scharlemasnn and Laurance, How green are biofuels, Science, 2008,

Outline Lecture 2 Specific ‘wedges’ of mitigation 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 low-carbon 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! ??? ??? Source: Pacala and Socolow, 2004, Science (supplemental material)

How to create ‘wedges’: Power Generation Several options, each one wedge: Increase efficiency of coal-fired power plants from 40 to 60 % ($) Replace coal-fired to natural gas-fired power plants ($) 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 ($$$) Switch to sustainable biofuels  unlike corn ethanol, these must not compete with food production! ($$$)

Source Rosina Bierbaum’s 2007 guest lecture

Outline Lecture 2 Externality: energy and water 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 Sources: 2nd UN World Water Development Report, 2006; UN 2007 world water day brochure; Energy demands on water resources, Report to congress on the interdependency of energy and water, 2006

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… Sources: 2nd UN World Water Development Report, 2006; UN 2007 world water day brochure; Energy demands on water resources, Report to congress on the interdependency of energy and water, 2006

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)