While grid-scale electricity storage (hereafter 'storage') could be crucial for deeply decarbonizing the electric power system, it would increase carbon dioxide (CO2) emissions in current systems ...across the United States. To better understand how storage transitions from increasing to decreasing system CO2 emissions, we quantify the effect of storage on operational CO2 emissions as a power system decarbonizes under a moderate and strong CO2 emission reduction target through 2045. Under each target, we compare the effect of storage on CO2 emissions when storage participates in only energy, only reserve, and energy and reserve markets. We conduct our study in the Electricity Reliability Council of Texas (ERCOT) system and use a capacity expansion model to forecast generator fleet changes and a unit commitment and economic dispatch model to quantify system CO2 emissions with and without storage. We find that storage would increase CO2 emissions in the current ERCOT system, but would decrease CO2 emissions in 2025 through 2045 under both decarbonization targets. Storage reduces CO2 emissions primarily by enabling gas-fired generation to displace coal-fired generation, but also by reducing wind and solar curtailment. We further find that the market in which storage participates drives large differences in the magnitude, but not the direction, of the effect of storage on CO2 emissions.
We assess the economic value of life-cycle air emissions and oil consumption from conventional vehicles, hybrid-electric vehicles (HEVs), plug-in hybrid-electric vehicles (PHEVs), and battery ...electric vehicles in the US. We find that plug-in vehicles may reduce or increase externality costs relative to grid-independent HEVs, depending largely on greenhouse gas and SO2 emissions produced during vehicle charging and battery manufacturing. However, even if future marginal damages from emissions of battery and electricity production drop dramatically, the damage reduction potential of plug-in vehicles remains small compared to ownership cost. As such, to offer a socially efficient approach to emissions and oil consumption reduction, lifetime cost of plug-in vehicles must be competitive with HEVs. Current subsidies intended to encourage sales of plug-in vehicles with large capacity battery packs exceed our externality estimates considerably, and taxes that optimally correct for externality damages would not close the gap in ownership cost. In contrast, HEVs and PHEVs with small battery packs reduce externality damages at low (or no) additional cost over their lifetime. Although large battery packs allow vehicles to travel longer distances using electricity instead of gasoline, large packs are more expensive, heavier, and more emissions intensive to produce, with lower utilization factors, greater charging infrastructure requirements, and life-cycle implications that are more sensitive to uncertain, time-sensitive, and location-specific factors. To reduce air emission and oil dependency impacts from passenger vehicles, strategies to promote adoption of HEVs and PHEVs with small battery packs offer more social benefits per dollar spent.
Climate change introduces an uncertain risk to power plant operations as ambient conditions potentially constrain generation through thermodynamic limitations. Previous studies aiming to quantify ...this risk have suggested a wide range of results, from minimal to disastrous capacity loss. In this analysis, we used a power plant modeling tool to study how a variety of power plant configurations respond to varying meteorological conditions. We developed tools that enable the analysis of the climate impacts on power plant operations for a spectrum of geographic situations and technological configurations. We also used these tools to conduct a case study for US coal and natural gas power plants in 2050, under climate change scenario representative concentration pathway 4.5. Our study indicates that rising air temperatures are unlikely to seriously threaten capacity and efficiency at power plants at most locations, provided that wet recirculating and dry cooling systems are designed adequately. Our results allow for simpler modeling of power plant capacity deratings given ambient conditions, highlight potential regions of risk, and underscore the importance of incorporating climate factors into the electric power system’s design and planning.
We perform a consequential life cycle analysis of plug-in electric vehicles (PEVs), hybrid electric vehicles (HEVs), and conventional gasoline vehicles in the PJM interconnection using a detailed, ...normative optimization model of the PJM electricity grid that captures the change in power plant operations and related emissions due to vehicle charging. We estimate and monetize the resulting human health and environmental damages from life cycle air emissions for each vehicle technology. We model PJM using the most recent data available (2010) as well as projections of the PJM grid in 2018 and a hypothetical scenario with increased wind penetration. We assess a range of sensitivity cases to verify the robustness of our results. We find that PEVs have higher life cycle air emissions damages than gasoline HEVs in the recent grid scenario, which has a high percentage of coal generation on the margin. In particular, battery electric vehicles with large battery capacity can produce two to three times as much air emissions damage as gasoline HEVs, depending on charge timing. In our future 2018 grid scenarios that account for predicted coal plant retirements, PEVs would produce air emissions damages comparable to or slightly lower than HEVs.
The water demands of power plant cooling systems may strain water supply and make power generation vulnerable to water scarcity. Cooling systems range in their rates of water use, capital investment, ...and annual costs. Using Texas as a case study, we examined the cost of retrofitting existing coal and natural gas combined-cycle (NGCC) power plants with alternative cooling systems, either wet recirculating towers or air-cooled condensers for dry cooling. We applied a power plant assessment tool to model existing power plants in terms of their key plant attributes and site-specific meteorological conditions and then estimated operation characteristics of retrofitted plants and retrofit costs. We determined the anticipated annual reductions in water withdrawals and the cost-per-gallon of water saved by retrofits in both deterministic and probabilistic forms. The results demonstrate that replacing once-through cooling at coal-fired power plants with wet recirculating towers has the lowest cost per reduced water withdrawals, on average. The average marginal cost of water withdrawal savings for dry-cooling retrofits at coal-fired plants is approximately 0.68 cents per gallon, while the marginal recirculating retrofit cost is 0.008 cents per gallon. For NGCC plants, the average marginal costs of water withdrawal savings for dry-cooling and recirculating towers are 1.78 and 0.037 cents per gallon, respectively.
The Inflation Reduction Act sets the stage for substantial greenhouse gas emissions reduction in the United States. However, analyses show that on its own, the IRA is insufficient to meet the ...nation's stated climate goals. We use an energy system optimization model to understand how the U.S. can build on the IRA to meet climate goals. We model two carbon taxes and a suite of efficiency, fuel, and technology standards, including a clean electricity standard (CES), electrification standards for commercial and residential buildings, a zero-emission vehicle (ZEV) standard, and a clean fuel standard for industry. We compare these three policy scenarios to the U.S.’s stated climate goals (Nationally Determined Contribution). The two carbon taxes and the suite of standards achieve the GHG emissions goals outlined in the Paris Agreement, but no scenario reaches net-zero GHG emissions by 2050. Notably, we find that the average GHG abatement cost under the modeled standards is comparable to a carbon tax set at ∼$200/ton, and both policies achieve similar emissions reductions. Temoa's cost-minimization structure results in the carbon tax always reducing emissions more cheaply than a set of standards; but the similarity in cost emphasizes the near-optimal second-best nature of well-designed standards.” The marginal cost of GHG emissions reduction in each scenario is less than 2% of total system costs. While the modeling results indicate that meeting climate targets may still be possible, they demonstrate that doing so will require rapid and sustained deployment of zero-emission technologies across the energy system.
We use time- and frequency-domain techniques to quantify the extent to which long-distance interconnection of wind plants in the United States would reduce the variability of wind power output. ...Previous work has shown that interconnection of just a few wind plants across moderate distances could greatly reduce the ratio of fast- to slow-ramping generators in the balancing portfolio. We find that interconnection of aggregate regional wind plants would not reduce this ratio further but would reduce variability at all frequencies examined. Further, interconnection of just a few wind plants reduces the average hourly change in power output, but interconnection across regions provides little further reduction. Interconnection also reduces the magnitude of low-probability step changes and doubles firm power output (capacity available at least 92% of the time) compared with a single region. First-order analysis indicates that balancing wind and providing firm power with local natural gas turbines would be more cost-effective than with transmission interconnection. For net load, increased wind capacity would require more balancing resources but in the same proportions by frequency as currently, justifying the practice of treating wind as negative load.
Toxicity refers to the potential of a substance such as a pesticide to cause damage to the structure or functions of an exposed organism. Pesticides can lead to harmful biological effects in exposed ...animals and their offspring over the medium and long term. They can affect the immunological, nervous, endocrine, and reproductive systems. DNA damage has also been linked to exposure to pesticides, and this damage can cause abortions, degenerative diseases, and cancer. The aim of this work was to establish whether women who are indirectly exposed to pesticides exhibit a compromised health status, including genotoxic effect. Women exposed indirectly to pesticides in Chimchanga and Colaisaca in the south of Ecuador underwent hematological and biochemical tests and micronucleus assay in buccal cells. The subjects were also genotyped for
GSTM1
,
GSTT1
,
GSTP1
, and
PON1
polymorphisms, which can modify an individual’s capacity to metabolize pesticides and relation with damage of DNA. The study revealed hepatic toxicity in Colaisaca women (AST and ALT) and an increase in the rate of micronucleus (MN) in Colaisaca individuals. In addition, genetic polymorphisms in
PON1
and
GSTP1
showed effects of modulating the frequency of karyolytic cells, karyorrhectic cells, and condensed chromatin cells.
The U.S. Department of Energy has estimated that if the United States is to generate 20% of its electricity from wind, over 50 GW will be required from shallow offshore turbines. Hurricanes are a ...potential risk to these turbines. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built in the United States. We present a probabilistic model to estimate the number of turbines that would be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind farms in four representative locations in the Atlantic and Gulf Coastal waters of the United States. In the most vulnerable areas now being actively considered by developers, nearly half the turbines in a farm are likely to be destroyed in a 20-y period. Reasonable mitigation measures—increasing the design reference wind load, ensuring that the nacelle can be turned into rapidly changing winds, and building most wind plants in the areas with lower risk—can greatly enhance the probability that offshore wind can help to meet the United States' electricity needs.
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