Google’s Proposal for reducing U.S. dependence on fossil fuels

Right now we have a real opportunity to transform our economy from one running on fossil fuels to one largely based on clean energy. Technologies and know-how to accomplish this are either available today or are under development. We can build whole new industries and create millions of new jobs. We can cut energy costs, both at the gas pump and at home. We can improve our national security. And we can put a big dent in climate change. With strong leadership we could be moving forward on an aggressive but realistic time-line and an approach that offsets costs with real economic gains.

The energy team at Google has been analyzing how we could greatly reduce fossil fuel use by 2030. Our proposal – “Clean Energy 2030” – provides a potential path to weaning the U.S. off of coal and oil for electricity generation by 2030 (with some remaining use of natural gas as well as nuclear), and cutting oil use for cars by 44%.

President-elect Obama announced his New Energy for America plan this past summer that is similar to ours in several ways, including a strong emphasis on efficiency, renewable electricity and plug-in vehicles. Similarly, the Natural Resources Defense Council, McKinsey and Company, and the Electric Power Research Institute have issued proposals that share all of these same elements. Al Gore has issued a challenge that is even more ambitious – getting us to carbon-free electricity by 2020 – and we hope the American public pushes our leaders to embrace it. T. Boone Pickens has weighed in with an interesting plan of his own to massively deploy wind energy, among other things. Other plans have also been developed in recent years that merit attention.

Google’s proposal will benefit the US by increasing energy security, protecting the environment, creating new jobs, and helping to create the conditions for long-term prosperity. Some of the necessary funds will be public, but much of it will come from the private sector — a typical approach for infrastructure and high technology investments.

Our goal in presenting this first iteration of the Clean Energy 2030 proposal is to stimulate debate and we invite you to take a look and comment – or offer an alternative approach if you disagree. With a new Administration and Congress – and multiple energy-related imperatives – this is an opportune, perhaps unprecedented, moment to move from plan to action.

This revised proposal was released on November 20, 2008. Check out Google CEO Eric Schmidt’s energy speech at the Commonwealth Club in San Francisco on October 1, and his energy speech at the Natural Resources Defense Council headquarters in New York on November 20.

Summary: What’s New in Version 2.0

Since Clean Energy 2030 was first published on October 1, 2008, we have made several changes based on comments from readers and internal feedback, most notably:

* an analysis of job creation in the electricity sector
* an improved vehicle model which results in higher average fleet fuel efficiency (and significantly increased savings)
* a decrease in the price of gasoline from $4 to $3 per gallon (doubling by 2030), in light of recent economic changes

Also included:

* a comment on why nuclear power was not expanded beyond the level in the baseline, and why coal with carbon capture and sequestration technology was not included
* an analysis of the precedent for rapid capacity build-outs in the natural gas and nuclear industries
* estimates of the required land area for wind and concentrating solar installations, and roof area for solar photovoltaics
* an analysis of the age of US coal and natural gas plants when retired under our proposal
* a more thorough analysis of the impact of accelerating the retirement of older vehicles
* a summary of the major activities Google is pursuing in the clean energy arena

Overall, we find a slight increase in vehicle fuel and economy-wide CO2 savings, and despite the decrease in fuel prices, a net economic savings almost as large as previously calculated, $820 billion over 22 years.

Summary: Reductions in Energy Use and Emissions

Our proposal will allow us to reduce from the Energy Information Administration’s (EIA) current baseline for energy use:

* Fossil fuel-based electricity generation by 88%
* Vehicle oil consumption by 44%
* Dependence on imported oil (currently 10 million barrels per day) by 37%
* Electricity-sector CO2 emissions by 95%
* Personal vehicle sector CO2 emissions by 44%
* US CO2 emissions overall by 49% (41% from today’s CO2 emission level)

We can achieve these results in 2030 by:

* Deploying aggressive end-use electrical energy efficiency measures to reduce demand 33%.

Baseline EIA demand is projected to increase 25% by 2030. In addition, the increase in plug-in vehicles (see below) increases electricity demand another 8%. Thus, our efficiency reductions keep demand flat at the 2008 level.

* Replacing all coal and oil electricity generation, and about half of that from natural gas, with renewable electricity:

380 gigawatts (GW) wind power: 300 GW onshore + 80 GW offshore
250 GW solar: 170 GW photovoltaic (PV) + 80 GW concentrating solar power (CSP)
80 GW geothermal: 15 GW conventional + 65 GW enhanced geothermal systems (EGS)

* Increasing plug-in electric vehicles (hybrids & pure electrics) to 90% of new car sales in 2030, reaching 41% of the total US fleet that year
* Increasing new conventional vehicle fuel efficiency from 31 to 45 mpg in 2030

Optionally,

* Accelerating the turnover of the vehicle fleet, resulting in maximum new vehicle sales of 21.5 million per year in 2020, a 30% increase over the baseline, and boosting fleet average fuel efficiency by 7.5 mpg.

Summary: Financial Bottom Line

The financial bottom line: Although the cost of the Clean Energy 2030 proposal is significant (about $3.86 trillion in undiscounted 2008 dollars), savings are even greater ($4.68 trillion), returning a net savings of $820 billion over the 22-year life of the plan.

Summary: Actions Required

A number of actions will be required to realize the Clean Energy 2030 proposal.

* Renewable electricity
A long-term national commitment to renewable electricity (e.g. national renewable portfolio standard, carbon price, long-term tax credits and incentives, etc.)

Adequate transmission capacity (to support about 450 GW targeting mostly Great Plains and coasts for wind, and desert southwest for concentrating solar power)

Adequate grid resources to manage large-scale intermittent generation

Public and private renewable energy R&D and investment to achieve cost parity with fossil generation in next several years

* Energy efficiency

Long-term commitment to energy efficiency by the federal government and states (e.g, national efficiency standard, aggressive appliance standards and building codes, “decoupling” of utility profits from sales, incentives for energy efficiency investments)

Deployment of a “smart” electricity grid that empowers consumers and businesses to manage their electricity use more effectively

* Personal vehicles

Public policies supporting the deployment of fuel-efficient vehicles, e.g. higher fuel efficiency standards for conventional vehicles, financial incentives to encourage efficient (especially plug-in) vehicle purchases, special electricity rates for “smart charging”, and greater R&D

Investment in infrastructure necessary to support massive deployment of plug-ins including charging stations and development of new power management hardware and software

All of the above will require a sufficient and well-trained work force and manufacturing capacity to meet projected growth.

Electricity Sector

Currently the US produces half of its electricity from coal, 20% each from natural gas and nuclear energy, with the remainder provided by hydro and other renewables. Very little oil is used to make electricity—only about 1.5%. Electricity generation produces about 2,400 million metric tons of CO2 per year (MMtCO2/yr), about 40% of total US emissions.

In Clean Energy 2030 we transform this sector by: 1) Keeping electricity demand FLAT at the 2008 level, rather than allowing it to grow 25% by 2030, and 2) Eliminating all coal and oil in electricity generation (and about half of natural gas) by 2030 and replacing that generation with renewable energy–primarily wind, solar and geothermal.

For energy efficiency, there is ample proof in several states and from research studies [1] that growth in electricity demand can be kept flat or even made to decline (nationally demand is otherwise projected to grow by about 1% per year). This can be done using a combination of strategies, including energy efficiency targets, appliance standards, building codes, R&D investment, financial incentives, “decoupling” of utility profits from sales, and voluntary programs (a list of simple things individuals can do was recently highlighted on Google’s home page). Providing detailed information about one’s energy use can also help consumers lower energy consumption, and Google PowerMeter is one proposed tool that aims to do just that.

Keeping demand flat would reduce fossil fuel-based generation by 30% in 2030, assuming no reduction in other generation. The question is how we would meet remaining electricity needs without fossil fuels. The “business-as-usual” scenario developed by the EIA has very modest growth projections for renewables: about the same hydropower capacity as today (7%), and an expansion from 2% to 7% for other renewables (mostly biomass). Under the EIA view most of our remaining electricity requirements would still be met by fossil fuels.

We propose something radically different. Onshore and offshore wind could grow from about 20 GW today to 380 GW, generating 29% of 2030 demand. Solar, both photovoltaic (PV) and concentrating solar power (CSP), could grow from about 1 GW today to 250 GW, generating 12% of demand. Geothermal, both conventional and enhanced geothermal systems (EGS; see below), could grow from 2.4 GW today to 80 GW, generating 15% of demand. Together with modest projected expansion of other non-fossil energy sources, including nuclear (115 GW), hydro (78 GW), and biomass and municipal waste (23 GW), about 90% of demand could be met.[2]

Such rapid build-ups of electric generating capacity are not without precedent in the US. Between 1998 and 2006, over 200 GW of natural gas capacity were added to the US grid, representing a 115% increase. At its peak in 2002, 60 GW of natural gas generating capacity was brought online in one year, a 24% annual increase. A similar story exists for nuclear energy, where 100 GW were built in the 1970s and 1980s from essentially zero capacity, with peak growth of almost 10 GW/yr and year-on-year growth after 1969 in excess of 60%.

The remaining demand would be supplied by natural gas (290 GW),[3] which is likely necessary for shoring up imbalances between generation and demand, particularly with large amounts of intermittent renewables on the grid. Some capacity would also be provided by hydro resources, while distributed demand management (scheduling of large devices such as washing machines, dryers and plug-in vehicles, and making loads such as air conditioning interruptible) and energy storage (both distributed and centralized) would help make optimal economic use of intermittent generation.

The projected increase in nuclear generation (about a 15% increase over today’s capacity) is unchanged from the EIA’s projection, which assumes about 20 GW of new capacity offset by 5 GW of retirements in 2030. We did not pursue a more aggressive expansion of nuclear because of our concerns over cost, waste disposal and proliferation risk. Going forward, however, we are keen to explore all types of cutting-edge renewable sources of electricity including, perhaps, clean nuclear technology.

Another technology that is conspicuously absent from our proposal is coal with CO2 capture and sequestration (CCS). This technology has the potential to allow coal to be burned with minimal greenhouse gas emissions (about 10% of conventional coal plants), but the technical and legal challenges of storing billions of tons of CO2 underground have yet to be solved. If these issues can be overcome at reasonable cost, CCS would be a welcomed additional low-carbon energy solution.

The US Department of Energy (DOE) just completed a study looking at deploying 300 GW of wind by 2030, and concluded that the wind resource was ample for the task, and the impact on manufacturing was measurable but not overwhelming. An earlier study by the National Renewable Energy Laboratory explored more rapid scale-ups of wind capacity, and found that up to about 600 GW by 2030 was feasible. Our target, 380 GW in 2030, is therefore not at all unrealistic. This level of wind energy deployment would occupy about 170 x 170 square miles, or 10% of the land area of Texas, but less than 2% of that area (24 x 24 square miles, less than a quarter of the land area of Delaware) would be occupied by towers, roads and other equipment; the rest of the land would still be available for farming, ranching, etc.

Solar photovoltaics (PV) have been growing very strongly in recent years, topping 50% per year, but this technology still has a very small market share because of its cost. Concentrating solar power (CSP) may break through this cost barrier faster, and could deliver massive amounts of power. Studies by Navigant Consulting and Clean Edge indicate that capacities at least as high as envisioned in our proposal are possible. Our proposal would require a 20 x 20 square mile area to be installed with CSP technology, 34 million home roofs (25% of total) to be installed with solar PV, and a similar PV capacity installed on commercial building rooftops.[4]

Geothermal energy is perhaps the sleeping giant. Conventional hydrothermal resources have been quietly growing in recent years, with 4 GW in the pipeline and likely 15 GW developed by 2030. Last month we announced a significant initiative in enhanced geothermal energy systems (EGS). This technology, which has the potential to provide significant baseload power on a broad-scale basis, promises extremely rapid growth if key technologies can be proven in the next few years.

For wind and solar, where the lion’s share of resources are located in the Great Plains and desert southwest – far from population centers – the biggest challenge is providing adequate transmission capacity to get the power to market. Extrapolating from the DOE study, about 20,000 miles of new transmission capacity would be required to support 300 GW of onshore wind and 80 GW of concentrating solar power generation in the Clean Energy 2030 proposal.

About 200,000 miles of high-voltage transmission now exist in the US. By contrast, offshore wind is located close to cities on both coasts, solar PV is typically highly distributed near where electricity is consumed, and there are significant potential EGS resources from border to border and coast to coast.

In summary, if we achieve the above electricity targets in the Clean Energy 2030 proposal, it would eliminate 88% of fossil fuel use and reduce CO2 emissions by 95% relative to the 2030 baseline, or about 2,800 MMtCO2/yr.

One might ask whether retiring all coal generation and one-half of natural gas generation (roughly one-third of standing capacity) would have an adverse financial impact, due to the premature retirement of undepreciated capital. The reality is that the the US fossil plant fleet is already fairly old, with half of coal capacity and a quarter of natural gas capacity built before 1973. Assuming the oldest plants are retired first, we calculate that a roughly linear progression of retired capacity would result in retiring 95% of coal and 100% of natural gas plants when they are at least 40 years old (see figure below). Forty years (or smaller) is the typical loan period for financing of fossil electric generation capital, so virtually all plants would be fully depreciated when they retire.

Personal Vehicle Sector

According to the Energy Information Administration, transportation-related energy use accounts for 70% of the 21 million barrels per day (mbd) of liquid fuels consumed in the US. By 2030, the sector will consume 17 mbd and emit 2,200 million metric tons of CO2 per year (MMtCO2/yr), about 1/3 of projected total US energy-related CO2 emissions.

Personal vehicles (also known as “light-duty” vehicles, e.g. cars, sport-utility vehicles, and light trucks), account for approximately 60% of transportation sector fuel consumption and CO2 emissions; the remainder comes primarily from freight trucks and airplanes, with appreciable contributions from other sources (buses, trains, ships, etc.). The Clean Energy 2030 proposal focuses on the personal vehicle subtotal, because we think this can be transformed by plug-in electric vehicles and higher efficiency conventional vehicles.

Although the average fuel efficiency of new conventional vehicles, currently 22 mpg, is projected to increase to 31 mpg by 2030,[5] plug-in vehicles can already achieve significantly higher fuel efficiency because they drive on electricity for a significant fraction of their yearly miles (see, for instance, Google’s recently-published RechargeIt driving experiment). A plug-in hybrid with a 40-mile electric range drives on electricity for about half of its yearly miles, so it consumes half the gasoline of its conventional cousin. And switching to an all-electric vehicle of course consumes no gasoline.

The Clean Energy 2030 plan rapidly ramps up sales of plug-in vehicles, starting with 100,000 in 2010 (annual US vehicle sales in 2007 were roughly 15 million), and increasing to 3.2 million annual vehicle sales in 2020 and 16.5 million in 2030. Seventy percent of these vehicles would be plug-in hybrids, with the remainder being all-electric vehicles.

In addition to rapidly deploying plug-in vehicles, the Clean Energy 2030 proposal assumes that conventional (e.g. non-plug-in) vehicle efficiency can increase as well. We have consulted with industry experts and determined that it is possible to push average conventional vehicle efficiency to 40-50 mpg in 2030, and assume 45 mpg in our proposal. In Europe, this average fuel efficiency target is mandated by 2012.

Finally, the average vehicle age in the US is about 8 years (and vehicles remain on the road for more than 20 years), meaning that many older, inefficient vehicles continue to consume large amounts of fuel with increasing maintenance cost. Our new model more accurately represents the turnover of vehicles by using a realistic survival function based on vehicle age (see figure below); the original model assumed a simple exponential decay irrespective of age. Also, the new model reduces the number of annual miles driven according to vehicle age. The result of these changes is a higher average fuel efficiency in 2030 (51 mpg) than in our original model (45 mpg), resulting in greater fuel savings, and an accurate depiction of the distribution of vehicle ages in the US fleet.

Accelerating the turnover of old vehicles would boost fuel efficiency even more, and increase the adoption of plug-in vehicles. There are a number of mechanisms that might be considered to accomplish this, such as “feebates,” consumer and manufacturer incentives for efficient vehicles, and cash incentives (or vouchers) for retiring old vehicles. The net effect of such a program by 2030 would be to reduce the future average vehicle age temporarily from 9 to 7 years, resulting in an additional 6% plug-in penetration, 7% fuel saved, and 7.5 mpg fleet average efficiency.

Taken together, these strategies (more plug-in vehicles and higher efficiency conventional vehicles) would reduce oil consumption (and CO2 emissions) by 44% relative to the baseline, or 63 billion gallons per year. With accelerated vehicle turnover included, savings would increase to 51% or 73 billion gallons per year.

Economics

We made the following economic assumptions in calculating the cost of the Clean Energy 2030 proposal:

Efficiency:

* Efficiency capital cost of 25 cents per kWh annual savings (one-time cost)
* Savings from efficiency of 10 cents per kWh (average electricity price)

Renewable energy:

* Renewable electricity capital costs:
Onshore wind: $2 per watt (W) falling to $1.5/W in 2030
Offshore wind: $3/W falling to $2/W in 2030
Solar PV: $6/W falling to $2/W in 2030
Solar CSP: $3.5/W falling to $2/W in 2030
Conventional geothermal: $3.5/W flat through 2030
Enhanced geothermal systems: $5/W falling to $3.5/W in 2030

* Intermittency cost of $20/MWh (applied to wind and solar)
* Avoided fossil capital costs (for plants planned in baseline but not built in our proposal because of efficiency and renewables):
Coal: $2/W constant
Natural gas and oil: $1/W constant

* Carrying charge for financing capital cost: 12%/yr for 20 years
* Saved fossil fuel cost (that is not already counted as efficiency savings):
Coal: $2/MBtu constant
Natural gas and oil: $10/MBtu constant

* No write-down cost for retiring coal plants (all plants assumed to be older than 40 years when retired), no decommissioning cost or salvage value for plants

* Transmission infrastructure cost: $0.30/W for wind (including offshore) and solar CSP

Vehicles:

* Plug-in vehicle premiums: $5000 per plug-in hybrid vehicle (PHEV), $10,000 per pure-electric vehicle (EV), plus $1000 per vehicle for charging infrastructure
* Higher-efficiency conventional vehicle premium $3000 for 45 mpg (pro-rated for lower mpg, down to zero cost for 22 mpg today)
* Fuel cost: $3/gallon gasoline today, doubling to $6/gallon by 2030
* Plug-in electricity cost: 7 cents per kWh (discounted due to flexible smart-charging price)
* Additional vehicle purchase cost (accelerated vehicle turnover scenario, not part of base case): $20,000 per vehicle (base cost; premiums for higher mpg vehicles covered separately above)

Carbon (not counted in net savings):

* Carbon credit for CO2 not emitted (relative to baseline): $20/ton CO2, doubling to $40/ton in 2030 (applied to both electricity and vehicles)

Some minor changes were made to the electricity sector model, including subtracting the cost of providing electricity for plug-in vehicles, since this is already counted in the vehicle sector. The other major change to the economic model was reducing the gasoline cost from $4 to $3 per gallon (doubling by 2030), and removing accelerated vehicle turnover from the base case.

Bottom line: undiscounted savings exceed costs by $820 billion over the 22 years of the scenario, or if carbon credits are included, $1,937 billion.

Economic variants:

*In our first release of Clean Energy 2030, we assumed gasoline cost $4/gallon and would double to $8/gallon by 2030. We noted at the time that making gasoline less expensive reduces the net savings by a significant amount. Recent economic conditions have now plunged gasoline prices below $3/gallon, so we have changed our baseline assumption to reflect this reality (we now assume prices will double to $6/gallon by 2030). However, because our improved model removes older, inefficient vehicles more quickly, the fleet average efficiency is now significantly higher. Therefore, making gasoline cheaper still results in a net savings of $820 billion. Increasing gasoline prices to $4/gallon again (doubling to $8/gallon in 2030) would increase savings to $1,613 billion.

*Accelerated vehicle turnover: including a program (discussed above in the vehicles section) to accelerate the removal of old, inefficient vehicles and replace them with higher-efficiency new conventional and plug-in vehicles would cost an additional $1,302 billion in extra vehicle purchases and save $666 billion in lower fuel costs. Including the additional carbon benefit (1,280 million metric tons CO2) saves an additional $42 billion. In the short term, such a program may be valuable to a US economy struggling to increase domestic spending.[6]

Jobs

Transforming our energy economy as laid out in this proposal will create large numbers of new jobs. By our estimates, Clean Energy 2030 will create 9 million net new jobs in the electrical efficiency and renewable energy sectors alone (the vehicles sector was not considered because of insufficient data–please help us obtain it!).

Note that the estimates include direct jobs (construction and operations of the power plants) as well as “indirect” jobs in associated industries (e.g., accountants, lawyers, steel workers, and electrical manufacturing) and “induced” jobs through economic expansion based on local spending. (However, for geothermal energy, only direct job estimates were available, so the contribution from this sector is disproportionately lower). The estimates are conservative in that they assume a declining job rate in future years due to productivity improvements which might not be realized (the scaling factor mentioned above). Also, some of the estimates are based on state-level scale-ups, which do not include additional jobs that might be created at the national level.

Carbon Dioxide Savings

The Clean Energy 2030 proposal only focuses on two sectors–electricity and personal vehicles–yet together, aggressive changes in these sectors can reduce overall US CO2 emissions by 49% in 2030 relative to the EIA baseline. Compared to today’s emission level of 6,000 MMtCO2/yr (about 20% of global energy-related CO2 emissions; see Marland), the proposal would reduce CO2 emissions by 41%, about halfway to the 80% reduction target by 2050 called for by the Intergovernmental Panel on Climate Change.

More reductions would be possible if other sectors were pursued similarly aggressively. We have chosen to focus on the electricity and personal vehicle sectors because these are areas where we currently are working. There are additional areas for fossil fuel and CO2 savings that are important to recognize, and may be added to our proposal in the future:

* Transport:

Reduced vehicle usage (mass transit, carpooling, telecommuting, per-mile vehicle fees, smart growth, etc.)
Low-carbon biofuels for transportation
Improved efficiency in freight trucks and airplanes

* Buildings and industry:

Improved efficiency of heating fuel use
Use of low-carbon biofuels or hydrogen as a heating fuel
Substitution of solar energy for fossil fuel combustion in heating water
Shift away from fuels and toward electricity (including use of combined heat and power systems)
Management of non-CO2 greenhouse gases including methane and halocarbon gases

* Agriculture and forestry:
Forest and grassland management
Methane management from animals and landfills

Google’s Role

Google is committed to implementing innovative and responsible environmental practices in every aspect of our business. To date, we’ve taken concrete steps to bolster the efficiency of our data centers and reduce the carbon footprint of our building and office operations. And we’re always looking for ways to create innovative products that help our users “go green.” Our philanthropic arm, Google.org, has made $50 million in renewable energy grants and investments to develop breakthrough technologies such as solar thermal, enhanced geothermal, and advanced wind. In 2007 we launched our Renewable Energy Cheaper than Coal (RE<C) initiative, flipped the switch on one of the largest corporate solar panel installations in the United States, and began our plug-in vehicle initiative, RechargeIT. This year we hired our first dedicated renewable energy engineers, announced a partnership with GE to advance renewable energy and build smart grid infrastructure, and continued to support public policies to combat climate change. It’s going to take the efforts of many to bring about a clean energy future, and we hope others will continue the hard work they’re already doing.

Acknowledgments

Authored by Jeffery Greenblatt, Ph.D., Climate and Energy Technology Manager, Google.org

We are indebted to many contributors from both inside and outside Google. These people include: Adhi Kesarla, Alec Brooks, Alec Proudfoot, Bill Weihl, Charles Baron, Chris Busselle, David Bercovich, Dan Reicher, Greg Miller, Hal Varian, Jacquelline Fuller, Jay Boren, John Fitch, Kevin Chen, Luis Arbulu, Megan Smith, Michael Terrell, Micheal Lopez, Rick Needham, Rolf Schreiber, Ross Koningstein, and Wilson Tsai. Outside experts include Mark Mehos, Maureen Hand and Nate Blair of the National Renewable Energy Laboratory, John “Skip” Laitner and Steve Nadel of the American Council for an Energy-Efficient Economy, Marshall Goldberg of MRG and Associates, and Luke Tonachel, Nathanael Greene, Rick Duke and Roland Hwang of the Natural Resources Defense Council.

Sources and Further Reading

Renewable Energy and Efficiency:

* American Wind Energy Association, AWEA 2nd Quarter 2008 Market Report, 2008: http://awea.org/publications/reports/2Q08.pdf.
* Clean Edge, Utility Solar Assessment Study: Reaching Ten Percent Solar by 2025, 2008: http://www.cleanedge.com/reports/reports-solarUSA2008.php.
* Energy Information Administration, Table 8.11a Electric Net Summer Capacity: Total (All Sectors), Selected Years, 1949-2007, Annual Energy Review, US Department of Energy, 2007: http://www.eia.doe.gov/emeu/aer/pdf/pages/sec8_42.pdf.
* Energy Information Administration, Table 9.2, Nuclear Power Plant Operations, 1957-2007, Annual Energy Review, US Department of Energy, 2007: http://www.eia.doe.gov/emeu/aer/txt/stb0902.xls.
* Energy Information Administration, Existing Electric Generating Units in the United States, 2005, US Department of Energy, 2007. http://www.eia.doe.gov/cneaf/electricity/page/capacity/existingunits2005.xls.
* Geothermal Energy Association, All About Geothermal Energy: Employment: http://www.geo-energy.org/aboutGE/employment.asp.
* Interlaboratory Working Group, Scenarios for a Clean Energy Future, Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory, ORNL/CON-476 and LBNL-44029, 2000: http://www.ornl.gov/sci/eere/cef/.
* Krupp, F. and M. Horn, Earth: The Sequel. The Race to Reinvent Energy and Stop Global Warming, New York: Norton, 2008: http://earththesequel.edf.org/.
* Laxson, A., M.M. Hand, and N. Blair., High Wind Penetration Impact on U.S. Wind Manufacturing Capacity and Critical Resources, National Renewable Energy Laboratory, NREL/TP-500-40482, 2006: http://www.nrel.gov/docs/fy07osti/40482.pdf.
* Massachusetts Institute of Technology, The Future of Geothermal Energy: Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century, DOE Contract DOE-AC07-05ID14517, 2007: http://geothermal.inel.gov/publications/future_of_geothermal_energy.pdf.
* Nadel, S., Energy Efficiency and Resource Standards: Experience and Recommendations, American Council for an Energy-Efficient Economy, Report E063, 2006: http://www.aceee.org/pubs/e063.htm.
* Navigant Consulting, Economic Impacts of Extending Federal Solar Tax Credits, Final Report Prepared for the Solar Energy Research and Education Foundation, 2008: http://www.seia.org/galleries/pdf/Navigant%20Consulting%20Report%209.15.08.pdf.
* National Renewable Energy Laboratory, Job and Economic Development Impact Models, 2008: http://www.nrel.gov/analysis/jedi/.
* Prindle, B., Eldridge, M., Laitner, J. A., Elliott, R. N., and S. Nadel, Assessment of the House Renewable Electricity Standard and Expanded Clean Energy Scenarios, American Council for an Energy-Efficient Economy, Report E079, 2007:
http://www.aceee.org/pubs/e079.htm.
* Simons, G. and J. McCabe, California Solar Resources in Support of the 2005 Integrated Energy Policy Report, Draft Staff Paper, CEC-500-2005-072-D, 2005: http://www.energy.ca.gov/2005publications/CEC-500-2005-072/CEC-500-2005-072-D.PDF.
* US Department of Energy, 20% Wind Energy by 2030: Increasing Wind Energy’s Contribution to U.S. Electricity Supply, DOE/GO-102008-2567, 2008: http://www.20percentwind.org/20percent_wind_energy_report_05-11-08_wk.pdf.

Vehicles:

* Blinder, Alan S., A Modest Proposal: Eco-Friendly Stimulus, The New York Times, July 27, 2008: http://www.nytimes.com/2008/07/27/business/27view.html.
* Godoy, M. CAFE standards: Gas-Sipping Etiquette for Cars, National Public Radio, 2007: http://www.npr.org/templates/story/story.php?storyId=5448289.
* Neff, J., Lutz says new CAFE standards will increase car price by $6k, Auto Blog Green, 2008:
http://www.autobloggreen.com/2008/01/13/lutz-says-new-cafe-standards-will-increase-car-price-by-6k/.
* Union of Concerned Scientists, Fuel economy basics:
http://www.ucsusa.org/clean_vehicles/solutions/cleaner_cars_pickups_and_suvs/fuel-economy-basics.html.

Carbon and General:

* Electric Power Research Institute, The Power to Reduce CO2 Emissions, 2007:
http://mydocs.epri.com/docs/public/DiscussionPaper2007.pdf
* Energy Information Administration, Annual Energy Outlook, US Department of Energy, 2008: http://www.eia.doe.gov/oiaf/aeo/.
* Gore, Al, The Climate for Change (op-ed), The New York Times, November 9, 2008:
http://www.nytimes.com/2008/11/09/opinion/09gore.html.
* Intergovernmental Panel on Climate Change, Fourth Assessment Report, 2007: http://www.ipcc.ch.
* Intergovernmental Panel on Climate Change, IPCC Special Report on Carbon Dioxide Capture and Storage. Prepared by Working Group III of the Intergovernmental Panel on Climate Change [Metz, B., O. Davidson, H. C. de Coninck, M. Loos, and L. A. Meyer (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 442 pp., 2005:
http://www.ipcc.ch/ipccreports/srccs.htm.
* Marland, G., T. Boden, and R. J. Andres, Global, Regional, and National Annual CO2 Emissions from Fossil-Fuel Burning, Cement Production, and Gas Flaring: 1751-2005, Carbon Dioxide Information Analysis Center Environmental Sciences Division, Oak Ridge National Laboratory, 2008: http://cdiac.ornl.gov/ftp/ndp030/global.1751_2005.ems.
* McKinsey & Company, Reducing US Greenhouse Gas Emissions: How Much at What Cost?, 2007:
http://www.mckinsey.com/clientservice/ccsi/pdf/US_ghg_final_report.pdf.
* Natural Resources Defense Council, A Responsible Energy Plan for America, 2005: http://www.nrdc.org/air/energy/rep/rep.pdf.
* Obama for America website, New Energy for America, 2008: http://my.barackobama.com/page/content/newenergy.
* Pacala, S. and R. Socolow, Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies, Science, 305, 968, 2004: http://www.princeton.edu/wedges/articles/ (other “wedges” articles also available via this link).
* Pickens Plan: http://www.pickensplan.com/.
* WeCanSolveIt.org.

Referencias

1. See also a study by McKinsey & Company:
http://www.mckinsey.com/clientservice/ccsi/pdf/US_ghg_final_report.pdf
2. Electricity generation technologies do not all generate the same amount of electricity over a year. The ratio of average output to maximum output is known as the “capacity factor,” and is around 20% for solar photovoltaics, 30% for concentrating solar, 35-40% for wind, 50% for hydroelectric, and 90% for geothermal, biomass, nuclear and coal. Natural gas, which is mostly used for “ramping” purposes (increasing or decreasing output quickly according to changing demand) can run up to 90% but is typically operated around 20%. Thus, 100 GW of geothermal (with 90% capacity factor) produces the same amount of electricity in a year as 300 GW of solar (with 30% capacity factor).
3. Attentive readers will note this capacity was 250 GW in the previous version of the proposal. We chose this higher amount to ensure that all plants would be at least 40 years old when retired; the same amount of generation is actually implied in the model, by reducing the number of hours per year these plants run from 20% to 17%.
4. Solar PV and CSP installations based on a California solar study by Simons and McCabe.
5. The Environmental Protection Agency (EPA) fuel efficiency estimates tend to be inflated by about 20%. This is because such estimates are done under ideal, rather than real-world, conditions. Therefore, although the current CAFE standard mandates that fleet average new vehicles must achieve 35 mpg in 2020 and beyond, the actual fuel efficiency is projected by EIA is lower.
6. See article by Blinder: http://www.nytimes.com/2008/07/27/business/27view.html

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