Xi Lu, Michael B. McElroy, and Juha Kiviluoma. 2009. “
Global potential for wind generated electricity.” Proceedings of the National Academy of Sciences, 106, 27, Pp. 10933-10938s.
Publisher's VersionAbstractThe potential of wind power as a global source of electricity is assessed by using winds derived through assimilation of data from a variety of meteorological sources. The analysis indicates that a network of land-based 2.5-megawatt (MW) turbines restricted to nonforested, ice-free, nonurban areas operating at as little as 20% of their rated capacity could supply >40 times current worldwide consumption of electricity, >5 times total global use of energy in all forms. Resources in the contiguous United States, specifically in the central plain states, could accommodate as much as 16 times total current demand for electricity in the United States. Estimates are given also for quantities of electricity that could be obtained by using a network of 3.6-MW turbines deployed in ocean waters with depths <200 m within 50 nautical miles (92.6 km) of closest coastlines.
Wind power accounted for 42% of all new electrical capacity added to the United States electrical system in 2008 although wind continues to account for a relatively small fraction of the total electricity-generating capacity [25.4 gigawatts (GW) of a total of 1,075 GW] (ref. 1; www.awea.org/pubs/documents/Outlook_2009.pdf). The Global Wind Energy Council projected the possibility of a 17-fold increase in wind-powered generation of electricity globally by 2030 (ref. 2; www.gwec.net/fileadmin/documents/Publications/GWEO_2008_final.pdf). Short et al. (3), using the National Renewable Energy Laboratory's WinDs model, concluded that wind could account for as much as 25% of U.S. electricity by 2050 (corresponding to an installed wind capacity of ≈300 GW).
Archer and Jacobson (4) estimated that 20% of the global total wind power potential could account for as much as 123 petawatt-hours (PWh) of electricity annually [corresponding to annually averaged power production of 14 terawatts (TW)] equal to 7 times the total current global consumption of electricity (comparable to present global use of energy in all forms). Their study was based on an analysis of data for the year 2000 from 7,753 surface meteorological stations complemented by data from 446 stations for which vertical soundings were available. They restricted their attention to power that could be generated by using a network of 1.5-megawatt (MW) turbines tapping wind resources from regions with annually averaged wind speeds in excess of 6.9 m/s (wind class 3 or better) at an elevation of 80 m. The meteorological stations used in their analysis were heavily concentrated in the United States, Europe, and Southeastern Asia. Results inferred for other regions of the world are subject as a consequence to considerable uncertainty.
The present study is based on a simulation of global wind fields from version 5 of the Goddard Earth Observing System Data Assimilation System (GEOS-5 DAS). Winds included in this compilation were obtained by retrospective analysis of global meteorological data using a state-of-the-art weather/climate model incorporating inputs from a wide variety of observational sources (5), including not only surface and sounding measurements as used by Archer and Jacobson (4) but also results from a diverse suite of measurements and observations from a combination of aircraft, balloons, ships, buoys, dropsondes and satellites, in short the gamut of observational data used to provide the world with the best possible meteorological forecasts enhanced by application of these data in a retrospective analysis. The GEOS-5 wind field is currently available for the period 2004 to the present (March 20, 2009) with plans to extend the analysis 30 years back in time. The GEOS-5 assimilation was adopted in the present analysis to take advantage of the relatively high spatial resolution available with this product as compared with the lower spatial resolutions available with alternative products such as ERA-40, NECP II, and JRA-25. It is used here in a detailed study of the potential for globally distributed wind-generated electricity in 2006.
We begin with a description of the methodology adopted for the present study. The land-based turbines envisaged here are assumed to have a rated capacity of 2.5 MW with somewhat larger turbines, 3.6 MW, deployed offshore, reflecting the greater cost of construction and the economic incentive to deploy larger turbines to capture the higher wind speeds available in these regions. In siting turbines over land, we specifically excluded densely populated regions and areas occupied by forests and environments distinguished by permanent snow and ice cover (notably Greenland and Antarctica). Turbines located offshore were restricted to water depths <200 m and to distances within 92.6 km (50 nautical miles) of shore.
These constraints are then discussed, and results from the global analysis are presented followed by a more detailed discussion of results for the United States.
Yuxuan Wang, Jiming Hao, Michael B. McElroy, J. William Munger, Hong Ma, Dan Chen, and Chris P Nielsen. 2009. “
Ozone air quality during the 2008 Beijing Olympics: Effectiveness of emission restrictions.” Atmospheric Chemistry and Physics, 9, 14, Pp. 5237-5251.
Publisher's VersionAbstractA series of aggressive measures was launched by
the Chinese government to reduce pollutant emissions from
Beijing and surrounding areas during the Olympic Games.
Observations at Miyun, a rural site 100 km downwind of the
Beijing urban center, show significant decreases in concentrations
of O3, CO, NOy, and SO2 during August 2008, relative
to August 2006–2007. The mean daytime mixing ratio
of O3 was lower by about 15 ppbv, reduced to 50 ppbv, in
August 2008. The relative reductions in daytime SO2, CO,
and NOy were 61%, 25%, and 21%, respectively. Changes in
SO2 and in species correlations from 2007 to 2008 indicate
that emissions of SO2, CO, and NOx were reduced at least
by 60%, 32%, and 36%, respectively, during the Olympics.
Analysis of meteorological conditions and interpretation of
observations using a chemical transport model suggest that
although the day-to-day variability in ozone is driven mostly
by meteorology, the reduction in emissions of ozone precursors
associated with the Olympic Games had a significant
contribution to the observed decrease in O3 during August
2008, accounting for 80% of the O3 reduction for the
month as a whole and 45% during the Olympics Period (8–
24 August). The model predicts that emission restrictions
such as those implemented during the Olympics can affect
O3 far beyond the Beijing urban area, resulting in reductions
in boundary layer O3 of 2–10 ppbv over a large region of the
North China Plain and Northeastern China.
Michael B. McElroy, Xi Lu, Chris P Nielsen, and Yuxuan Wang. 2009. “
Potential for wind generated electricity in China.” Science, 325, 5946, Pp. 1378-1380.
Publisher's VersionAbstractWind offers an important alternative to coal as a source of energy for generation of electricity in China with the potential for substantial savings in carbon dioxide emissions. Wind fields derived from assimilated meteorological data are used to assess the potential for wind-generated electricity in China subject to the existing government-approved bidding process for new wind farms. Assuming a guaranteed price of 0.516 RMB (7.6 U.S. cents) per kilowatt-hour for delivery of electricity to the grid over an agreed initial average period of 10 years, it is concluded that wind could accommodate all of the demand for electricity projected for 2030, about twice current consumption. Electricity available at a concession price as low as 0.4 RMB per kilowatt-hour would be sufficient to displace 23% of electricity generated from coal.
Dan Chen, Yuxuan Wang, Michael B. McElroy, Kebin He, Robert M Yantosca, and Phillipe Le Sager. 2009. “
Regional CO pollution in China simulated by the high-resolution nested-grid GEOS-Chem model.” Atmospheric Chemistry and Physics, 9, 11, Pp. 3825-3839.
Publisher's VersionAbstractAn updated version of the nested-grid GEOSChem
model is developed allowing for higher horizontal
(0.5×0.667) resolution as compared to global models. CO
transport over a heavily polluted region, the Beijing-Tianjin-
Hebei (BTH) city cluster in China, and the pattern of outflow
from East China in summertime are investigated. Comparison
of the nested-grid with global models indicates that the
fine-resolution nested-grid model is capable of resolving individual
cities with high associated emission intensities. The
nested-grid model indicates the presence of a high CO column
density over the Sichuan Basin in summer, attributable
to the low-level stationary vortex associated with the Basin’s
topographical features. The nested-grid model provides good
agreement also with measurements from a suburban monitoring
site in Beijing during summer 2005. Tagged CO simulation
results suggest that regional emissions make significant
contributions to elevated CO levels over Beijing on polluted
days and that the southeastward moving cyclones bringing
northwest winds to Beijing are the key meteorological mechanisms
responsible for dispersion of pollution over Beijing in
summer. Overall CO fluxes to the NW Pacific from Asia are
found to decrease by a factor of 3–4 from spring to summer.
Much of the seasonal change is driven by decreasing
fluxes from India and Southeast Asia in summer, while
fluxes from East China are only 30% lower in summer than in
spring. Compared to spring, summertime outflow from Chinese
source regions is strongest at higher latitudes (north of
35 N). The deeper convection in summer transporting CO
to higher altitudes where export is more efficient is largely
responsible for enhanced export in summer.