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Does Renewable Energy Reduce CO2?: The Case of Wind

Does Renewable Energy Reduce CO2?: The Case of Wind. Herbert Inhaber Risk Concepts Las Vegas, Nevada hinhaber@hotmail.com Presented at Third Santa Fe Conference on Global and Regional Climate Variability , October-November 2011.

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Does Renewable Energy Reduce CO2?: The Case of Wind

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  1. Does Renewable Energy Reduce CO2?: The Case of Wind Herbert Inhaber Risk Concepts Las Vegas, Nevada hinhaber@hotmail.com Presented at Third Santa Fe Conference on Global and Regional Climate Variability, October-November 2011

  2. What is seen and not seen (after Bastiat, French economist) Windmills – seen Backup fossil fuel plants when wind doesn’t blow - unseen

  3. CO2 Reductions with Intermittent (Variable) Energy Sources: How Much? • CO2 reduction is almost one-for-one for small number of windmills or solar collectors • BUT....

  4. What Happens when Fossil Fuel Backup is Turned on and Off? • An analogy: 2011 Toyota Camry mileage over highway and city (33 highway, 22 city) • Highway miles per gallon is always higher than city mpg • Stops and starts reduce efficiency, create greater pollution per mile driven

  5. Another Analogy Very few people have seen gas turbines turned on and off However, starting a lawn mower is similar to that action Even when the mover is later re-started, there is considerable pollution emitted, although perhaps less of a cloud

  6. In the same way, fossil fuel backup starts and stops create more CO2 than continuous operation • In some regions (e.g., Germany), there is so-called “feed-in” requirements • When windpower is generated, fossil fuel backups are turned off or down • This frequent cycling produces more CO2 than continuous operation • Thus CO2 savings from windpower is greatly reduced

  7. But won’t windpower average out; i.e., when wind stops in one area, it will blow in another region • Windpower production in the E.On Netz system, 2004 • This covers much of Germany, from Bavaria in the south to the German Bight in the north • There is very little averaging

  8. Will storage solve the frequent starts and stops of windpower backup? • Picture is of pumped storage in S. Carolina • There are 17 such systems in the U.S. • In principal, this type of storage could even out wind variability • But these systems are tiny in comparison to electricity demand

  9. Storage to solve windpower problems – continued • Chemical storage (molten salts) has been tried since 1974 (Univ. of Delaware) • Cost on large scale would be prohibitive • Lead-acid battery is still the cheapest (after 130 years) per unit energy stored – invented by Planté in France • Again, large-scale cost would be enormous. • Example: Cost of lithium batteries in a recent electric car is $18,000 – they store about $1.50 worth of electricity

  10. Nissan Leaf $18,000 worth of batteries holding about $1.50 of electric energy

  11. Results – cycling of backup substantially reduces CO2 saved • Data collected from around the world • Bentek (2010)– Colorado • Bentek (2010) – Texas • German study – 2005 • Ireland - 2004

  12. Results - continued • Estonia – 2007 • De Groot and Le Pair – “it is necessary to establish on the basis of data, rather than model predictions, the level of extra fuel...” • U.S. National Academy of Sciences: “the committee estimates that wind energy... [p]robably will contribute to offsets of approximately 4.5% in U.S. emissions of CO2...”

  13. Conclusions • Results have strong implications for plans to reduce CO2 emissions by deploying windpower • Results are applicable to other intermittent renewables such as solar photovoltaic and solar thermal • The only renewables exempt from this limitation of CO2 emission are hydroelectricity and geothermal, which have self-storage of energy • Results place in question President Obama’s goal of about 80% of American electricity supplied by renewables by 2035, presumably to reduce CO2 emissions substantially.

  14. Uncertainties • Type of fossil fuels • Some literature is polemic • Degree of intermittency • Open or closed cycle gas turbines • Some utilities don’t supply data • Types of fossil fuels used as back-up • How variable is the wind • Export of wind energy (Denmark) • Many others

  15. Action Plan to Reduce Uncertainties • In principle, regulatory agencies (public utility commissions [PUCs] in the U.S.) and electrical utilities should gather and analyze data on the “missing” CO2 reductions • They generally do not do so because any expenditures on wind and other renewables are passed on to the consumer. Both PUCs and utilities state they are reducing CO2 emissions, but do not calculate how much • Consumers should know what reduction of CO2 they are getting for their increased costs

  16. Summary The story of the tea bag label

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