CO 2 and Energy #2

1. CO2 and Energy #2 Jasper Kok Applied Physics Program Climate science & policy enthusiast Lecture for AOSS 605, Ricky Rood

2. US energy use by sector World CO2 emissions by fuel and end use 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

3. 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

4. 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

5. 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)?

6. 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

7. ≈ business as usual ‘Business as usual’ CO2-trajectory path • ‘Business as usual’ has CO2 emissions growing at current rate (1.5%/year) • Likely end-of-century warming: ~2.3 – 3.4 ºC

8. ‘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

9. 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

10. 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.

11. 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

12. 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

13. 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

15. 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

16. 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

17. Energy Decarbonization Tools:1. 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

18. Energy Decarbonization Tools: 2. Renewable energy • Hydro-power • Already widely used - not much potential for expansion • Wind • Abundant and competitive • Solar • Photovoltaic (PV) • Concentrating solar

19. Wind energy cost in $/kWh Energy Decarbonization Tools: 2a. Wind • 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)

20. Energy Decarbonization Tools: 2a. 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

21. Energy Decarbonization Tools: 2a. Wind • Disadvantages: • Dependent on Production Tax Credits provided by congress (~2 cents/kWh) to be competitive • President Obama’s stimulus package would extend these tax credits for 3 years. • 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)

22. Energy Decarbonization Tools: 2b. 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

23. Energy Decarbonization Tools: 2b. 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)

24. 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

25. Energy Decarbonization Tools:3. 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

26. 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

27. 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 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!)

28. CCS: economics • CCS could become cost-effective with future carbon legislation

29. Energy Decarbonization Tools:4. 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!

30. 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 • Often, 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

31. US 2nd generation biofuel US 1st generation biofuel 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 could still lead to tropical deforestation and net release of carbon!

32. 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 marginal farmland or agricultural waste could play important role, but is currently not cost-effective • Could play an important role in mitigating transportation emissions if breakthroughs in cellulosic conversion are made

33. 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

34. 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! ??? ???

35. How to create ‘wedges’: Power Generation • Several options, each one wedge: • Increase efficiency of coal-fired power plants from 40 to 60 % ($) • Replace coal-fired with natural gas-fired power plants ($) • 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 ($$) • Expand solar energy 700x to replace coal-fired power plants ($$$)

36. 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)

37. How to create ‘wedges’: Transportation • Several options, each one wedge: • Increase car efficiency from 30 to 60 mpg ($) • Compacter world with less travel  5,000 instead of 10,000 miles/vehicle ($) • Switch to low-carbon hydrogen ($$$) • Switch to sustainable biofuels  unlike corn ethanol, these must not compete with food production! ($$$)

39. 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

40. 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

41. 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…