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What is the most common source of energy in the United States? A) Oil A) Oil B) Natural Gas B) Natural Gas C) Coal C) Coal D) Nuclear D) Nuclear E) Hydroelectric E) Hydroelectric

What is the most common source of energy in the World? A) Oil A) Oil B) Natural Gas B) Natural Gas C) Coal C) Coal D) Nuclear D) Nuclear E) Hydroelectric E) Hydroelectric

Energy Sources United States: Nonrenewable 93% Nuclear Power 8% Natural gas 23% Coal 23% Oil 39% Renewable Energy 8% Biomass 4% Hydropower Geothermal, solar, wind 3% World: Nonrenewable 82% Nuclear Power 6% Natural Gas 21% Coal 22% Oil 33% Renewable Energy 18% Biomass 11% Hydropower Geothermal, solar, wind 7%

Powering the Planet Nathan S. Lewis, California Institute of Technology

Power Units: The Terawatt Challenge Power W 1 kW 1 MW 1 GW 1 TW Energy 1 J = 1 W for 1 s

Global Energy Consumption, 2001 Gas Hydro Renew Total: 13.2 TW U.S.: 3.2 TW (96 Quads)

Global Energy Sources

Image courtesy of Ren21 under public domain

(in the U.S. in 2002) 1-4 ¢ ¢ 6-8 ¢ 5-7 ¢ Today: Production Cost of Electricity 6-7 ¢ ¢ Cost, ¢/kW-hr

Energy Costs Brazil Europe $0.05/kW-hr

How long will it be before all the petroleum on earth is used up? A) 0-5 years A) 0-5 years B) 5-20 years B) 5-20 years C) years C) years D) years D) years E) more than 100 years E) more than 100 years

Petroleum US Reserves: years Global: years Trade-Offs Conventional Oil AdvantagesDisadvantages Ample supply for years Need to find substitute within 50 years Low cost (with huge subsidies Artificially low price encourages waste and discourages search for alternatives High net energy yieldAir pollution when burned Easily transported within and between countries Releases CO2 when burned Low land useModerate water pollution Technology is well developed Efficient distribution system Figure by UMB OpenCourseWare Image removed due to copyright restrictions.

Oil Resources Figure by UMB OpenCourseWare

36 Estimates of the Time of the Peak of World Oil Production (There are More) EIA’s short answer to “When will oil production peak?” is “Not soon, but within the present century.” The most probable scenarios put the peak at about mid century.

Fossil Fuel Reserves-to-Production (R/P) Ratios at End 2004  The world’s R/P ratio for coal is almost five times that for oil and almost three times that for gas. Coal’s dominance in R/P ratio is particularly pronounced in the OECD and the FSU.  R/P ratios for oil and gas have been approximately constant or slightly increasing during the past 20 years. Both reserves and production have increased during this period. See next chart YEARS OECDFSU Emerging Market Economies, excluding FSU World BP Statistical Review of World Energy 2005

Abundant, Inexpensive Resource Base of Fossil Fuels Renewables will not play a large role in primary power generation unless/until: –technological/cost breakthroughs are achieved, or –unpriced externalities are introduced (e.g., environmentally -driven carbon taxes) Conclusions

Projected World Energy Consumption in the Coming Century World Primary Energy Consumption (Quads) 826 1, Projections to 2025 are from the Energy Information Administration, International Energy Outlook, Projections for 2050 and 2100 are based on a scenario from the Intergovernmental Panel on Climate Change (IPCC), an organization jointly established in 1988 by the World Meteorological Organization and the United Nations Environment Programme. The IPCC provides comprehensive assessments of information relevant to human- induced climate change. The scenario chosen is based on “moderate” assumptions (Scenario B2) for population and economic growth and hence is neither overly conservative nor overly aggressive.

Projected World Energy Consumption by Region World Energy Consumption by Region (Quads) Overall, world energy consumption is predicted to increase faster than that of the U.S. and other industrialized countries, because between 2000 and 2025 energy demand in the developing countries nearly doubles. World Regions

Population Growth to Billion People in 2050 Per Capita GDP Growth at 1.6% yr -1 Energy consumption per Unit of GDP declines at 1.0% yr -1 *Image removed due to copyright restrictions.

U.S. Energy Flow, 2003 (Quads) U.S. Energy Flow, 2003 (Quads) 21 Production 70.5 Imports 31.0 Consumption 98.2 Adjustments 0.7 Exports 4.0  About 30% of primary energy is imported. Energy Sources Energy Consumption Sectors

U.S. Energy Flow, 2003 (Quads) U.S. Energy Flow, 2003 (Quads) 22  85% of primary energy is from fossil fuels; 8% is from nuclear; 6% is from renewables.  Most imported energy is petroleum, which is used for transportation.  The end-use sectors (residential, commercial, industrial, transportation) all use comparable amounts of energy.

Alternative Energy Sources Name as many alternative energy sources as you can think of… Name as many alternative energy sources as you can think of… What are the advantages and disadvantages of each? What are the advantages and disadvantages of each?

Resources oJ4http:// oJ html

Nuclear (fission and fusion) 10 TW = 10,000 new 1 GW reactors i.e., a new reactor every other day for the next 50 years 2.3 million tonnes proven reserves; 1 TW-hr requires 22 tonnes of U Hence at 10 TW provides 1 year of energy Terrestrial resource base provides 10 years of energy Would need to mine U from seawater (700 x terrestrial resource base; so needs 3000 Niagra Falls or breeders) Carbon sequestration Renewables Sources of Carbon-Free Power

Nuclear power 235 U readily absorbs neutrons to become 236 U 236 U then decays into lighter fission products 235 U + neutron  fragments neutrons MeV (remember 300K = 1/40 eV) 27 *Image removed due to copyright restrictions.

130 Gt total U.S. sequestration potential Global emissions 6 Gt/yr in 2002 Test sequestration projects CO 2 Burial: Saline Reservoirs Study Areas One Formation Studied Two Formations Studied Power Plants (dot size proportional to 1996 carbon emissions) DOE Vision & Goal: 1 Gt storage by 2025, 4 Gt by 2050 Near sources (power plants, refineries, coal fields) Distribute only H 2 or electricity Must not leak At 2 Gt/yr sequestration rate, surface of U.S. would rise 10 cm by 2100

What is the most promising form of renewable energy? A) Wind A) Wind B) Solar B) Solar C) Geothermal D) Biofuels C) Geothermal D) Biofuels E) Tidal E) Tidal

Renewable Energy Consumption by Major Sources

Hydroelectric Geothermal Ocean/Tides Wind Biomass Solar Potential of Renewable Energy

Hydro-electric power Gravity drives the whole process! 32 Image courtesy of U.S. Geological Survey

Globally Gross theoretical potential 4.6 TW Technically feasible potential 1.5 TW Economically feasible potential 0.9 TW Installed capacity in TW Production in TW (can get to 80% capacity in some cases) Source: WEA 2000 Hydroelectric Energy Potential

Three Gorges Dam Yangtze River 100 m high, 100 m thick 100 m high, 100 m thick 2.3 km long 2.3 km long 22,000 MW 22,000 MW $32 Billion $32 Billion 10 Year payback 10 Year payback Image courtesy of roberthuffstutter, flikr under Creative Common Licenseroberthuffstutter

Geothermal Energy Hydrothermal systems Hot dry rock (igneous systems) Normal geothermal heat (200 C at 10 km depth) 1.3 GW capacity in 1985 *Image removed due to copyright restrictions.

Geothermal Energy Potential

Mean terrestrial geothermal flux at earth’s surface W/m 2 Mean terrestrial geothermal flux at earth’s surface W/m 2 Total continental geothermal energy potential 11.6 TW Total continental geothermal energy potential 11.6 TW Oceanic geothermal energy potential 30 TW Oceanic geothermal energy potential 30 TW Wells “run out of steam” in 5 years Wells “run out of steam” in 5 years Power from a good geothermal well (pair) 5 MW Power from a good geothermal well (pair) 5 MW Power from typical Saudi oil well500 MW Power from typical Saudi oil well500 MW Needs drilling technology breakthrough Needs drilling technology breakthrough (from exponential $/m to linear $/m) to become economical) (from exponential $/m to linear $/m) to become economical)

Wind Power Megawatts of energy 420 Megawatts of energy 75% of Cape and Islands electricity needs 75% of Cape and Islands electricity needs Equivalent to removing 162,000 cars Equivalent to removing 162,000 cars 113 million gallons of oil 113 million gallons of oil Birds, views, sealife, navigation, noise Birds, views, sealife, navigation, noise Image courtesy of EPA

Electric Potential of Wind Image courtesy of US Department of Energy In 1999, U.S consumed 3.45 trillion kW-hr of Electricity = 0.39 TW

Top-down: Downward kinetic energy flux: 2 W/m 2 Total land area: 1.5x10 14 m 2 Hence total available energy = 300 TW Extract <10%, 30% of land, 30% generation efficiency: 2-4 TW electrical generation potential Bottom-Up: Theoretical: 27% of earth’s land surface is class 3 ( W/m 2 at 50 m) or greater If use entire area, electricity generation potential of 50 TW Practical: 2 TW electrical generation potential (4% utilization of ≥class 3 land area, IPCC 2001) Off-shore potential is larger but must be close to grid to be interesting; (no installation > 20 km offshore now) Global Potential of Terrestrial Wind

Global: Top Down Requires Large Areas Because Inefficient (0.3%) 3 TW requires ≈ 600 million hectares = 6x10 12 m 2 20 TW requires ≈ 4x10 13 m 2 Total land area of earth: 1.3x10 14 m 2 Hence requires 4/13 = 31% of total land area Biomass Energy Potential

Land with Crop Production Potential, 1990: 2.45x10 13 m 2 Cultivated Land, 1990: x10 13 m 2 Additional Land needed to support 9 billion people in 2050: 0.416x10 13 m 2 Perhaps 5-7 TW by 2050 through biomass (recall: $1.5- 4/GJ) Possible/likely that this is water resource limited Biomass Energy Potential Global: Bottom Up

Theoretical: 1.2x10 5 TW solar energy potential (1.76 x10 5 TW striking Earth; 0.30 Global mean albedo) Energy in 1 hr of sunlight  14 TW for a year Practical: ≈ 600 TW solar energy potential (50 TW TW depending on land fraction etc.; WEA 2000) Onshore electricity generation potential of ≈60 TW (10% conversion efficiency): Photosynthesis: 90 TW Solar Energy Potential

Roughly equal global energy use in each major sector: transportation, residential, transformation, industrial World market: 1.6 TW space heating; 0.3 TW hot water; 1.3 TW process heat (solar crop drying: ≈ 0.05 TW) Temporal mismatch between source and demand requires storage (  S) yields high heat production costs: ($0.03-$0.20)/kW-hr High-T solar thermal: currently lowest cost solar electric source ($ /kW-hr); potential to be competitive with fossil energy in long term, but needs large areas in sunbelt Solar-to-electric efficiency 18-20% (research in thermochemical fuels: hydrogen, syn gas, metals) Solar Thermal, 2001

Solar Land Area Requirements 6 Boxes at 3.3 TW Each

U.S. Land Area: 9.1x10 12 m 2 (incl. Alaska) Average Insolation: 200 W/m U.S. Primary Power Consumption: 99 Quads=3.3 TW 1999 U.S. Electricity Consumption = 0.4 TW Hence: 3.3x10 12 W/(2x10 2 W/m 2 x 10% Efficiency) = 1.6x10 11 m 2 Requires 1.6x10 11 m 2 / 9.1x10 12 m 2 = 1.7% of Land Solar Land Area Requirements

Artificial Photosynthesis soffice/2008/oxygen html soffice/2008/oxygen html soffice/2008/oxygen html soffice/2008/oxygen html Nathan Lewis (Cal Tech)-creates electricity from sunlight Nathan Lewis (Cal Tech)-creates electricity from sunlight Daniel Nocera (MIT)- catalyst to split water Daniel Nocera (MIT)- catalyst to split water Fuel cell burns H 2 + O 2 Fuel cell burns H 2 + O 2 *Image removed due to copyright restrictions.

The Need to Produce Fuel “Power Park Concept” Fuel Production Distribution Storage

Need for Additional Primary Energy is Apparent Case for Significant (Daunting?) Carbon-Free Energy Seems Plausible (Imperative?) Scientific/Technological Challenges Energy efficiency: energy security and environmental security Coal/sequestration; nuclear/breeders; Cheap Solar Fuel Inexpensive conversion systems, effective storage systems Policy Challenges Is Failure an Option? Will there be the needed commitment? In the remaining time? Summary

Light Fuel Electricity Photosynthesis Fuels Electricity Photovoltaics sc e SC CO Sugar H O O Energy Conversion Strategies Semiconductor/Liquid Junctions H 2 O O H 2 2 SC

O2O2 A H2H2 e-e- cathode anode Fuel Cell vs Photoelectrolysis Cell H2H2 anode cathode O2O2 Fuel Cell MEA Photoelectrolysis Cell MEA membrane MO x MS x e-e- H+H+ H+H+

Solar-Powered Catalysts for Fuel Formation hydrogenase 2H + + 2e -  H 2 10 µ chlamydomonas moewusii 2 H 2 O O2O2 4e - 4H + CO 2 HCOOH CH 3 OH H 2, CH 4 Cat oxidationreduction photosystem II 2 H 2 O  O e - + 4H +

Photovoltaic + Electrolyzer System

Global Energy Consumption

Efficiency (%) Year crystalline Si amorphous Si nano TiO 2 CIS/CIGS CdTe Efficiency of Photovoltaic Devices

US Energy Flow Net Primary Resource Consumption 102 Exajoules

Tropospheric Circulation Cross Section Source: John Brandon

Powering the Planet Solar  Electric Extreme efficiency at moderate cost Solar paint: grain boundary passivation Solar  Chemical Chemical  Electric Inorganic electrolytes: bare proton transport O H S 100 nm Catalysis: ultra high surface area, nanoporous materials Photoelectrolysis: integrated energy conversion and fuel generation h = 2.5 eV H 3 O + ½H 2 + H 2 O ½O 2 + H 2 O OH  __S* __S + S__ TiO 2 VB CB Pt Bio-inspired fuel generation ee Synergies: Catalysis, materials discovery, materials processing

By essentially all measures, H 2 is an inferior transportation fuel relative to liquid hydrocarbons So, why? Local air quality: 90% of the benefits can be obtained from clean diesel without a gross change in distribution and end-use infrastructure; no compelling need for H 2 Large scale CO 2 sequestration: Must distribute either electrons or protons; compels H 2 be the distributed fuel-based energy carrier Renewable (sustainable) power: no compelling need for H 2 to end user, e.g.: CO 2 + H 2 CH 3 OH DME other liquids Hydrogen vs Hydrocarbons

1.2x10 5 TW of solar energy potential globally Generating 2x10 1 TW with 10% efficient solar farms requires 2x10 2 /1.2x10 5 = 0.16% of Globe = 8x10 11 m 2 (i.e., 8.8 % of U.S.A) Generating 1.2x10 1 TW (1998 Global Primary Power) requires 1.2x10 2 /1.2x10 5 = 0.10% of Globe = 5x10 11 m 2 (i.e., 5.5% of U.S.A.) Solar Land Area Requirements

Need for Additional Primary Energy is Apparent Case for Significant (Daunting?) Carbon-Free Energy Seems Plausible (Imperative?) Scientific/Technological Challenges Coal/sequestration; nuclear/breeders; Cheap Solar Fuel Inexpensive conversion systems, effective storage systems Policy Challenges Energy Security, National Security, Environmental Security, Economic Security Is Failure an Option? Will there be the needed commitment? Summary