Xi Lu, Michael B. McElroy, and Nora Sluzas. 2011. “
Costs for integrating wind into the future ERCOT system with related costs for savings in CO2 emissions.” Environmental Science and Technology, 45, 7, Pp. 3160-3166.
Publisher's VersionAbstractWind power can make an important contribution to the goal of reducing emissions of CO2. The major problem relates to the intrinsic variability of the source and the difficulty of reconciling the supply of electricity with demand particularly at high levels of wind penetration. This challenge is explored for the case of the ERCOT system in Texas. Demand for electricity in Texas is projected to increase by approximately 60% by 2030. Considering hourly load data reported for 2006, assuming that the pattern of demand in 2030 should be similar to 2006, and adopting as a business as usual (BAU) reference an assumption that the anticipated additional electricity should be supplied by a combination of coal and gas with prices, discounted to 2007 dollars of $2 and $6 per MMBTU respectively, we conclude that the bus-bar price for electricity would increase by about 1.1¢/kWh at a wind penetration level of 30%, by about 3.4 ¢/kWh at a penetration level of 80%. Corresponding costs for reductions in CO2 range from $20/ton to $60/ton. A number of possibilities are discussed that could contribute to a reduction in these costs including the impact of an expanded future fleet of electrically driven vehicles.
Final Manuscript in DASH
This is from a series of papers investigating and comparing the prospects for low- and non-carbon power generation in China and the U.S.
Jintai Lin and Michael B. McElroy. 2011. “
Detection from space of a reduction in anthropogenic emissions of nitrogen oxides during the Chinese economic downturn.” Atmospheric Chemistry and Physics, 11, Pp. 8171-8188.
Publisher's VersionAbstractRapid economic and industrial development in
China and relatively weak emission controls have resulted in
significant increases in emissions of nitrogen oxides (NOx)
in recent years, with the exception of late 2008 to mid 2009
when the economic downturn led to emission reductions detectable
from space. Here vertical column densities (VCDs)
of tropospheric NO2 retrieved from satellite observations by
SCIAMACHY, GOME-2 and OMI (both by KNMI and by
NASA) are used to evaluate changes in emissions of NOx
from October 2004 to February 2010 identifying impacts of
the economic downturn. Data over polluted regions of Northern
East China suggest an increase of 27–33% in 12-month
mean VCD of NO2 prior to the downturn, consistent with an
increase of 49% in thermal power generation (TPG) reflecting
the economic growth. More detailed analysis is used to
quantify changes in emissions of NOx in January over the
period 2005–2010 when the effect of the downturn was most
evident. The GEOS-Chem model is employed to evaluate
the effect of changes in chemistry and meteorology on VCD
of NO2. This analysis indicates that emissions decreased by
20% from January 2008 to January 2009, close to the reduction
of 18% in TPG that occurred over the same interval. A
combination of three independent approaches indicates that
the economic downturn was responsible for a reduction in
emissions by 9–11% in January 2009 with an additional decrease
of 10%attributed to the slow-down in industrial activity
associated with the coincident celebration of the Chinese
New Year; errors in the estimate are most likely less than
3.4 %.
Michael B. McElroy. 2011.
Energy: Perspectives, Problems and Prospects (Chinese Language Edition). Beijing: Science Press.
Publisher's VersionAbstractThe book offers a comprehensive account of how the world evolved to its present state in which humans now exercise a powerful, in many cases dominant, influence for global environmental change. It outlines the history that led to this position of dominance, in particular the role played by our increasing reliance on fossil sources of energy, on coal, oil and natural gas, and the problems that we are now forced to confront as a result of this history. The concentration of carbon dioxide in the atmosphere is greater now than at any time over at least the past 650,000 years with prospects to increase over the next few decades to levels not seen since dinosaurs roamed the Earth 65 million years ago. Comparable changes are evident also for methane and nitrous oxide and for a variety of other constituents of the atmosphere including species such as the ozone depleting chlorofluorocarbons for which there are no natural analogues.
Increases in the concentrations of so-called greenhouse gases in the atmosphere are responsible for important changes in global and regional climate with consequences for the future of global society which, though difficult to predict in detail, are potentially catastrophic for a world poorly equipped to cope. Changes of climate in the past were repetitively responsible for the demise of important civilizations. These changes, however, were generally natural in origin in contrast to the changes now underway for which humans are directly responsible. The challenge is to transition to a new energy economy in which fossil fuels will play a much smaller role. We need as a matter of urgency to cut back on emissions of climate altering gases such as carbon dioxide while at the same time reducing our dependence on unreliable, potentially disruptive, though currently indispensable, sources of energy such as oil, the lifeblood of the global transportation system. The book concludes with a discussion of options for a more sustainable energy future, highlighting the potential for contributions from wind, sun, biomass, geothermal and nuclear, supplanting currently unsustainable reliance on coal, oil and natural gas.
Xi Lu, Jeremy Tchou, Michael B. McElroy, and Chris P Nielsen. 2011. “
The impact of production tax credits on the profitable production of electricity from wind in the U.S.” Energy Policy, 39, 7, Pp. 4207-4214.
Publisher's VersionAbstractA spatial financial model using wind data derived from assimilated meteorological condition was developed to investigate the profitability and competitiveness of onshore wind power in the contiguous U.S. It considers not only the resulting estimated capacity factors for hypothetical wind farms but also the geographically differentiated costs of local grid connection. The levelized cost of wind-generated electricity for the contiguous U.S. is evaluated assuming subsidy levels from the Production Tax Credit (PTC) varying from 0 to 4 ¢/kWh under three cost scenarios: a reference case, a high cost case, and a low cost case. The analysis indicates that in the reference scenario, current PTC subsidies of 2.1 ¢/kWh are at a critical level in determining the competitiveness of wind-generated electricity compared to conventional power generation in local power market. Results from this study suggest that the potential for profitable wind power with the current PTC subsidy amounts to more than seven times existing demand for electricity in the entire U.S. Understanding the challenges involved in scaling up wind energy requires further study of the external costs associated with improvement of the backbone transmission network and integration into the power grid of the variable electricity generated from wind.
Final Manuscript in DASH
This paper is from a series investigating and comparing the prospects for low- and non-carbon power generation in China and the U.S.
Yu Zhao, Michael B. McElroy, Jia Xing, Lei Duan, Chris P Nielsen, Yu Lei, and Jiming Hao. 2011. “
Multiple effects and uncertainties of emission control policies in China: Public health, soil acidification, and global temperature.” Science of the Total Environment , 409, 24, Pp. 5177-5187.
Publisher's VersionAbstractPolicies to control emissions of criteria pollutants in China may have conflicting impacts on public health, soil acidification, and climate. Two scenarios for 2020, a base case without anticipated control measures and a more realistic case including such controls, are evaluated to quantify the effects of the policies on emissions and resulting environmental outcomes. Large benefits to public health can be expected from the controls, attributed mainly to reduced emissions of primary PM and gaseous PM precursors, and thus lower ambient concentrations of PM2.5. Approximately 4% of all-cause mortality in the country can be avoided (95% confidence interval: 1–7%), particularly in eastern and north-central China, regions with large population densities and high levels of PM2.5. Surface ozone levels, however, are estimated to increase in parts of those regions, despite NOX reductions. This implies VOC-limited conditions. Even with significant reduction of SO2 and NOX emissions, the controls will not significantly mitigate risks of soil acidification, judged by the exceedance levels of critical load (CL). This is due to the decrease in primary PM emissions, with the consequent reduction in deposition of alkaline base cations. Compared to 2005, even larger CL exceedances are found for both scenarios in 2020, implying that PM control may negate any recovery from soil acidification due to SO2 reductions. Noting large uncertainties, current polices to control emissions of criteria pollutants in China will not reduce climate warming, since controlling SO2 emissions also reduces reflective secondary aerosols. Black carbon emission is an important source of uncertainty concerning the effects of Chinese control policies on global temperature change. Given these conflicts, greater consideration should be paid to reconciling varied environmental objectives, and emission control strategies should target not only criteria pollutants but also species such as VOCs and CO2.
Yu Zhao, Chris P Nielsen, Yu Lei, Michael B. McElroy, and Jiming Hao. 2011. “
Quantifying the uncertainties of a bottom-up emission inventory of anthropogenic atmospheric pollutants in China.” Atmospheric Chemistry and Physics, 11, Pp. 2295-2308.
Publisher's VersionAbstractThe uncertainties of a national, bottom-up inventory
of Chinese emissions of anthropogenic SO2, NOx, and
particulate matter (PM) of different size classes and carbonaceous
species are comprehensively quantified, for the first
time, using Monte Carlo simulation. The inventory is structured
by seven dominant sectors: coal-fired electric power,
cement, iron and steel, other industry (boiler combustion),
other industry (non-combustion processes), transportation,
and residential. For each parameter related to emission factors
or activity-level calculations, the uncertainties, represented
as probability distributions, are either statistically fitted
using results of domestic field tests or, when these are
lacking, estimated based on foreign or other domestic data.
The uncertainties (i.e., 95% confidence intervals around the
central estimates) of Chinese emissions of SO2, NOx, total
PM, PM10, PM2.5, black carbon (BC), and organic carbon
(OC) in 2005 are estimated to be −14%13%, −13%37%,
−11%38%, −14%45%, −17%54%, −25%136%,
and −40%121%, respectively. Variations at activity levels
(e.g., energy consumption or industrial production) are
not the main source of emission uncertainties. Due to narrow
classification of source types, large sample sizes, and
relatively high data quality, the coal-fired power sector is estimated
to have the smallest emission uncertainties for all
species except BC and OC. Due to poorer source classifications
and a wider range of estimated emission factors,
considerable uncertainties of NOx and PM emissions from
cement production and boiler combustion in other industries
are found. The probability distributions of emission
factors for biomass burning, the largest source of BC and
OC, are fitted based on very limited domestic field measurements,
and special caution should thus be taken interpreting
these emission uncertainties. Although Monte Carlo simulation
yields narrowed estimates of uncertainties compared
to previous bottom-up emission studies, the results are not
always consistent with those derived from satellite observations.
The results thus represent an incremental research
advance; while the analysis provides current estimates of
uncertainty to researchers investigating Chinese and global
atmospheric transport and chemistry, it also identifies specific
needs in data collection and analysis to improve on
them. Strengthened quantification of emissions of the included
species and other, closely associated ones – notably
CO2, generated largely by the same processes and thus subject
to many of the same parameter uncertainties – is essential
not only for science but for the design of policies to redress
critical atmospheric environmental hazards at local, regional,
and global scales.