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California Drought Increases CO2 Footprint of Energy

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Abstract

This Commentary discusses the CO2 footprint of California’s drought during 2012–2014. We show that California drought significantly increased CO2 emissions of the energy sector by around 22 million metric tons, indicating 33% increase in the annual CO2 emissions compared to pre-drought conditions. We argue that CO2 emission of climate extremes deserve more attention, because their cumulative impacts on CO2 emissions are staggering. Most countries, including the United States, do not have a comprehensive a nationwide energy-water plan to minimize their CO2 emissions. We argue that developing a national water-energy plan under a changing climate should be prioritized in the coming years.

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... In addition, as variable energy resources like wind and solar expand their share of the power mix, the grid is becoming more sensitive to fluctuations in wind speeds and solar irradiance (Collins et al., 2018;Staffell and Pfenninger, 2018). By influencing supply and demand for electricity, hydrometeorological processes have direct impacts on pollution (e.g., increased greenhouse gas emissions (Collins et al., 2018;Hardin et al., 2017;Tarroja et al., 2016)), wholesale electricity prices (Boogert and Dupont, 2005;Collins et al., 2018;Seel et al., 2018), and the financial standing of suppliers of electricity (e.g., retail utilities, renewable energy producers) and consumers (Bain and Acker, 2018;Boogert and Dupont, 2005;Foster et al., 2015;Kern and Characklis, 2017;Kern et al., 2015). ...
... However, with few exceptions (Turner et al., 2019), previous investigations fall short in assessing the holistic influence of hydrometeorological variability on bulk power systems. Past research efforts assess operational and financial risks from exposure to variability in a more limited set of hydrometeorological processes (Collins et al., 2018;Kern et al., 2015) (e.g., streamflow and temperatures, or wind speeds and solar irradiance); do not consider these effects within the context of large, interconnected power systems ; and/or do not assess impacts probabilistically (Hardin et al., 2017). These shortcomings may be partly attributable to the challenges of modeling bulk electric power systems at sufficient scale and resolution to simulate system operations in a realistic way, and over sufficient time horizons to explore joint uncertainty in multiple, correlated input variables. ...
... During this period, in-state hydropower generation decreased by an average of 40% (Gleick, 2017), forcing the state to rely significantly more on electricity from natural gas power plants. There has been considerable interest in exploring the impacts of this recent drought on pollutant emissions (Hardin et al., 2017), as well as system costs and prices for retail electricity consumers (Gleick, 2017). Particularly when determining the latter, an understanding of impacts on wholesale electricity prices is necessary. ...
Article
Variability (and extremes) in streamflow, wind speeds, temperatures, and solar irradiance influence supply and demand for electricity. However, previous research falls short in addressing the risks that joint uncertainties in these processes pose in power systems and wholesale electricity markets. Limiting challenges have included the large areal extents of power systems, high temporal resolutions (hourly or sub-hourly), and the data volumes and computational intensities required. This paper introduces an open source modeling framework for evaluating risks from correlated hydrometeorological processes in electricity markets at decision relevant scales. The framework is able to reproduce historical price dynamics in high profile systems, while also offering unique capabilities for stochastic simulation. Synthetic generation of weather and hydrologic variables is coupled with simulation models of relevant infrastructure (dams, power plants). Our model will allow the role of hydrometeorological uncertainty (including compound extreme events) on electricity market outcomes to be explored using publicly available models.
... Electricity generation requires water resources to drive turbines in hydroelectric dams and to cool thermoelectric power plants that are fueled by nuclear, coal or natural gas. This dependence on water makes the electricity sector vulnerable to droughts (van Vliet et al 2012, 2016b, Bartos and Chester 2015, Voisin et al 2016, Gleick 2017, Hardin et al 2017, Miara et al 2017, Eyer and Wichman 2018. ...
... The increased use of fossil fuel power plants for peak generation induced by droughts may last from months to years, which can lead to significant increases in pollutant emissions from the electricity sector (Gleick 2017, Hardin et al 2017, Eyer and Wichman 2018. In addition, decreased in-state electricity generation due to droughts may increase the need to import electricity from neighboring states (van Vliet et al 2013, Voisin et al 2016), potentially causing remote increases in pollution. ...
... Recent plant-scale econometric analyses found a positive relationship between water scarcity and emissions from the US electricity sector (Eyer and Wichman 2018), and for the recent California drought (Gleick 2017, Hardin et al 2017. Eyer and Wichman (2018) found that in the Western Interconnection, (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) of in-state net-generation from hydropower, natural gas, coal, nuclear, petroleum, and solar and wind (combined); and average yearly deficits and surplus of in-state electricity generation compared to total electricity sales. ...
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Water is needed for hydroelectric generation and to cool thermoelectric power plants. This dependence on water makes electricity generation vulnerable to droughts. Furthermore, because power sector CO2 emissions amount to approximately one third of total US emissions, droughts could influence the inter- annual variability of state- and national-scale emissions. However, the magnitude of drought-induced changes in power sector emissions is not well understood, especially in the context of climate mitigation policies. Using multivariate linear regressions, we find that droughts are positively correlated to increases in electricity generation from natural gas in California, Idaho, Oregon, and Washington; and from coal in Colorado, Montana, Oregon, Utah, Washington, and Wyoming. Using a statistical model, we estimate that this shift in generation sources led to total increases in regional emissions of 100 Mt of CO2, 45 kt of SO2, and 57 kt of NOx from 2001 to 2015, most of which originated in California, Oregon, Washington, and Wyoming. The CO2 emissions induced by droughts in California, Idaho, Oregon, and Washington amounted to 7%–12% of the total CO2 emissions from their respective power sectors, and the yearly rates were 8%–15% of their respective 2030 yearly targets outlined in the Clean Power Plan (CPP). Although there is uncertainty surrounding the CPP, its targets provide appropriate reference points for climate mitigation goals for the power sector. Given the global importance of hydroelectric and thermoelectric power, our results represent a critical step in quantifying the impact of drought on pollutant emissions from the power sector—and thus on mitigation targets—in other regions of the world.
... Conventional water supplies may be supplemented by nonconventional sources such as desalination of seawater or brackish water, importation of water from adjacent regions, or reuse of treated wastewater (Grant et al., 2013;Gude, 2016). While desalination and imported water are already used to augment potable water supplies, they are associated with high and rising energy costs, a significant greenhouse gas (GHG) footprint, and other environmental concerns (Hardin et al., 2017;Shahabi et al., 2017;Stokes et al., 2014;Tarroja et al., 2014b;Zhou et al., 2014). Treated wastewater has most commonly been used for non-potable purposespartially due to challenges associated with public acceptability (Dolnicar et al., 2011;Hering et al., 2013;WWAP, 2017). ...
... Further possible extensions of WaterSET include scenario-based analysis modelling seasonal or long-term changes in the electricity mix (Hardin et al., 2017;Stokes and Horvath, 2009), simulating the impacts of climate change on chemical and energy requirements of water supply (Mo et al., 2016), as well as optimisation of the overall water supply mix encompassing multiple WSOs (Stokes et al., 2015). Consideration of net impacts of water treatment trains would ideally consider the full urban water cycle including topographic effects, the potential for offsets in pumping of conventional water, and a detailed inclusion of different wastewater treatment stages. ...
... This coincides with severe drought conditions repeatedly experienced in this region. Starting approximately in the 1990s, large parts of the South-Western United States, and in particular the South of California, started to encounter exceptional drought conditions [55,56]. A most recent drought period started in 2011/2012 and is estimated to represent the worst cumulative rainfall deficit on record, resulting in reduced generation of hydroelectricity [57] and a subsequent boost of CO 2 emissions due to increasing consumption of natural gas [55], diminished snowpack, and reduced water levels in the Colorado River as well as in Lake Mead and Lake Powell reservoirs [56]. ...
... Starting approximately in the 1990s, large parts of the South-Western United States, and in particular the South of California, started to encounter exceptional drought conditions [55,56]. A most recent drought period started in 2011/2012 and is estimated to represent the worst cumulative rainfall deficit on record, resulting in reduced generation of hydroelectricity [57] and a subsequent boost of CO 2 emissions due to increasing consumption of natural gas [55], diminished snowpack, and reduced water levels in the Colorado River as well as in Lake Mead and Lake Powell reservoirs [56]. Both reservoirs feed large urban agglomerations, e.g., the rapidly growing Phoenix metropolitan area with an approximate population of 4.5 Mio in 2015, and projected 6.8 Mio in 2040 and 7.7 Mio in 2050 [58]. ...
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Over the 20th century, urbanization has substantially shaped the surface of Earth. With population rapidly shifting from rural locations towards the cities, urban areas have dramatically expanded on a global scale and represent crystallization points of social, cultural and economic assets and activities. This trend is estimated to persist for the next decades, and particularly the developing countries are expected to face rapid urban growth. The management of this growth will require good governance strategies and planning. By threatening the livelihoods, assets and health as foundations of human activities, another major global change contributor, climate change, became an equally important concern of stakeholders. Based on the climate trends observed over the 20th century, and a spatially explicit model of urbanization, this paper investigates the impacts of climate change in relation to different stages of development of urban areas, thus evolving a more integrated perspective on both processes. As a result, an integrative measure of climate change trends and impacts is proposed and estimated for urban areas worldwide. We show that those areas facing major urban growth are to a large extent also hotspots of climate change. Since most of these hotspots are located in the Global South, we emphasize the need for stakeholders to co-manage both drivers of global change. The presented integrative perspective is seen as a starting point to foster such co-management, and furthermore as a means to facilitate communication and knowledge exchange on climate change impacts.
... Another open question from the 2012-2016 drought has to do with the role of the state's growing reliance on variable renewable energy (wind and solar) in mitigating the environmental impacts of drought. In particular, the substitution of natural gas generation for hydropower during drought is known to increase carbon dioxide (CO 2 ) emissions in California (Fulton and Cooley 2015, Hardin et al 2017, Herrera-Estrada et al 2018. Previous studies have pointed to the state's growing fleet of wind and solar capacity as a counterbalancing force that was able to mitigate increases in CO 2 emissions that would have occurred during the 2012-2016 drought due to a loss of hydropower (Hardin et al 2017, Zohrabian and Sanders 2018, He et al 2019. ...
... In particular, the substitution of natural gas generation for hydropower during drought is known to increase carbon dioxide (CO 2 ) emissions in California (Fulton and Cooley 2015, Hardin et al 2017, Herrera-Estrada et al 2018. Previous studies have pointed to the state's growing fleet of wind and solar capacity as a counterbalancing force that was able to mitigate increases in CO 2 emissions that would have occurred during the 2012-2016 drought due to a loss of hydropower (Hardin et al 2017, Zohrabian and Sanders 2018, He et al 2019. In fact, carbon dioxide (CO 2 ) emissions from California's electric power sector actually decreased over the years 2012-2016 (California Air Resources Board 2019). ...
Article
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Over the period 2012–2016, the state of California in the United States (U.S.) experienced a drought considered to be one of the worst in state history. Drought’s direct impacts on California’s electric power sector are understood. Extremely low streamflow manifests as reduced hydropower availability, and if drought is also marked by elevated temperatures, these can increase building electricity demands for cooling. Collectively, these impacts force system operators to increase reliance on natural gas power plants, increasing market prices and emissions. However, previous investigations have relied mostly on ex post analysis of observational data to develop estimates of increases in costs and carbon dioxide (CO 2 ) emissions due to the 2012–2016 drought. This has made it difficult to control for confounding variables (e.g. growing renewable energy capacity, volatile natural gas prices) in assessing the drought’s impacts. In this study, we use a power system simulation model to isolate the direct impacts of several hydrometeorological phenomena observed during the 2012–2016 drought on system wide CO 2 emissions and wholesale electricity prices in the California market. We find that the impacts of drought conditions on wholesale electricity prices were modest (annual prices increased by $0–3 MWh ⁻¹ , although much larger within-year increases are also observed). Instead, it was an increase in natural gas prices, punctuated by the 2014 polar vortex event that affected much of the Eastern U.S., which caused wholesale electricity prices to increase during the drought. Costs from the drought were very different for the state’s three investor owned utilities. Overall, we find that increased cooling demands (electricity demand) during the drought may have represented a larger economic cost ($3.8 billion) than lost hydropower generation ($1.9 billion). We also find the potential for renewable energy to mitigate drought-cased increases in CO 2 emissions to be negligible, standing in contrast to some previous studies.
... Climate change is projected to shift the temporal and spatial availability of water across the globe (IPCC 2013). Shifts in regional hydrology may have significant impacts on electricity generation dispatch, electric grid reliability, and regional emissions (Hardin et al. 2017). In California, where hydroelectric capacity mainly resides in the Sierra Nevada, inflow to reservoirs has historically been regulated by the melting snowpack. ...
Article
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Climate change is expected to significantly reshape hydropower generation in California. However, the impact on the ability of hydropower to provide reserve capacity that can provide on-demand, back-up electricity generation to stabilize the grid in the case of a contingency has not been explored. This study examined the impact of climate change-driven hydrologic shifts on hydropower contributions to generation and ancillary services. We used projections from four climate models under Representative Concentration Pathways (RCP) RCP4.5 and RCP8.5 to evaluate the impact of climate change conditions, comparing the future period 2046–2055 to the baseline 2000–2009, and observed a net increase of inflow into large hydropower units in northern California. However, as extreme events yield greater spillage, increased overall inflow did not necessarily yield increased generation. Additionally, higher winter generation and summer reservoir constraints resulted in decreases in the spinning reserve potential for both RCP scenarios. We also examined a regionally downscaled “long drought” scenario under RCP8.5 to assess the impact of an extended dry period on generation and spinning reserve bidding. The long drought scenario, developed as part of the California 4th Climate Assessment, involves rainfall congruent with 20-year historical dry spells in California under increased temperatures. In addition to decreased generation, the long drought scenario yielded a 41% reduction in spinning reserve bidding tied to a decline in reservoir levels. The decreased spinning reserve bidding from hydropower may require increased reliance on other electricity resources that can provide the same dynamic support to maintain grid stability under climate change.
... This followed the Federal Energy Policy Act (FEPA) of 2005, which called for the development of at least 10,000 megawatts of renewable energy generation on public lands by 2015. Due to these pieces of legislation, and other policy and economic incentives [1,2], solar and wind power generation in California has increased relatively rapidly (by 270%) since 2011 [3]. As covered 400,000 km 2 of land, more than in Germany and 188 other countries [4]. ...
Article
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In 2010, The Nature Conservancy completed the Mojave Desert Ecoregional Assessment, which characterizes conservation values across nearly 130,000 km² of the desert Southwest. Since this assessment was completed, several renewable energy facilities have been built in the Mojave Desert, thereby changing the conservation value of these lands. We have completed a new analysis of land use to reassess the conservation value of lands in two locations in the Mojave Desert where renewable energy development has been most intense: Ivanpah Valley, and the Western Mojave. We found that 99 of our 2.59-km² planning units were impacted by development such that they would now be categorized as having lower conservation value, and most of these downgrades in conservation value were due to solar and wind development. Solar development alone was responsible for a direct development footprint 86.79 km²: 25.81 km² of this was primarily high conservation value Bureau of Land Management lands in the Ivanpah Valley, and 60.99 km² was privately owned lands, mostly of lower conservation value, in the Western Mojave. Our analyses allow us to understand patterns in renewable energy development in the mostly rapidly changing regions of the Mojave Desert. Our analyses also provide a baseline that will allow us to assess the effectiveness of the Desert Renewable Energy Conservation Plan in preventing development on lands of high conservation value over the coming decades.
... The projected hydrological impacts on surface water reservoirs can affect the ability of hydropower plants to counterbalance wind and solar variability. The reduction or absence of hydropower resources may result in the increased reliance on available conventional natural gas power plants to balance electric loads and generation, which occurred during the recent 2015 drought [17]. ...
Article
This study investigates how hydropower generation under climate change affects the ability of the electric grid to integrate high wind and solar capacities. Using California as an example, water reservoir releases are modeled as a function of hydrologic conditions in the context of a highly-renewable electric grid in the year 2050. The system is perturbed using different climate models under the Representative Concentration Pathway 8.5 climate scenario. The findings reveal that climate change impact on hydropower can increase greenhouse gas emissions up to 8.1% due to increased spillage of reservoir inflow reducing hydropower generation, but with minimal effects (<1%) on renewable utilization and levelized cost of electricity. However, increases in dispatchable power plant capacity of +2.1 to +6.3% and decreases in the number of start-up events per power plant unit up to 3.1%, indicate that the majority of dispatchable natural gas power plant capacity is offline for most of the climate change scenarios. While system-wide performance metrics experience small impacts, climate change effects on hydropower generation increase both the need for dispatchable generation and the costs of electricity from these power plants to support large-scale wind and solar integration on the electric grid.
... This will likely increase the vulnerability of the electric power industry, which should prepare to absorb the additional agricultural energy load. In addition, increased electricity production is likely to be associated with increased greenhouse gas emissions (as observed in other parts of the world, e.g., California [50]). From a long-term sustainability perspective, however, it is critical to recognize the extensive and widespread groundwater table decline as a serious warning signal to implement adaptive agricultural water management measures to mitigate, or better yet, prevent future socioeconomic repercussions (e.g., job losses) associated with exhausting high-quality or marginal-quality groundwater. ...
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This paper presents the first groundwater‒energy‒food (GEF) nexus study of Iran’s agronomic crops based on national and provincial datasets and firsthand estimates of agricultural groundwater withdrawal. We use agronomic crop production, water withdrawal, and energy consumption data to estimate groundwater withdrawal from electric-powered irrigation wells and examine agronomic productivity in Iran’s 31 provinces through the lens of GEF nexus. The ex-post GEF analysis sheds light on some of the root causes of the nation’s worsening water shortage problems. Access to highly subsidized water (surface water and groundwater) and energy has been the backbone of agricultural expansion policies in Iran, supporting employment in agrarian communities. Consequently, water use for agronomic crop production has greatly overshot the renewable water supply capacity of the country, making water bankruptcy a serious national security threat. Significant groundwater table decline across the country and increasing energy consumption underscore dysfunctional feedback relations between agricultural water and energy price and groundwater withdrawal in an inefficient agronomic sector. Thus, it is essential to implement holistic policy reforms aimed at reducing agricultural water consumption to alleviate the looming water bankruptcy threats, which can lead to the loss of numerous agricultural jobs in the years to come.
... Affluence and trade openness cause to increase and decrease in energy consumption, respectively. The study by Hardin et al. (2017) shows that drought can significantly increase the speed of CO 2 emissions in the energy sector. Rafindadi and Ozturk (2017) illustrate that there is a relationship 2 Middle East and North Africa 3 Middle East and North Africa region 4 Greenhouse gas 5 Gulf Cooperation Council countries 6 Environmental Kuznets Curve 7 Association of South East Asian Nations between consumption of renewable energy and economic growth. ...
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Iran should pay special attention to its excessive consumption of energy and air pollution due to the limited availability of water resources. This study explores the effects of the consumption of energy and water resources on air pollution in Iran from 1971 to 2014. It utilizes the non-linear autoregressive distributed lag approach to establish a robust relationship between the variables which show that both long- and short-run coefficients are asymmetrical. The positive and negative aspects of the long-run coefficients of energy consumption and water resources were found to be 0.19, − 1.63, 0.18, and 2.36, respectively, while only the negative ones were significant for energy consumption. Based on the cumulative effects, it can be established that there are important and significant differences in the responses of air pollution to positive and negative changes in water productivity and energy consumption. In particular, CO2 gas emissions are affected by negative changes in H2O productivity both in terms of the total and the GDP per unit of energy use in Iran. In regard to short-run results, considerable asymmetric effects occur on all the variables for CO2 emissions. Based on the results obtained, some recommendations are presented, which policymakers can adopt in efforts to address the issues of pollution and consumption.
... In California, utilities increased fossil fuel generation of electricity to compensate for the drought-driven decline in hydroelectricity, increasing state carbon dioxide emissions in the first year of the drought (2011 to 2012) by 1.8 million tons of carbon, the equivalent of emissions from roughly 1 million cars. 338,339 A drop in the price of natural gas also contributed to the increase, although the shift from hydroelectric to fossil fuels cost California an estimated $2.0 billion (in 2015 dollars). 340 Other southwestern states also shifted some generation from hydropower to fossil fuels. ...
... Air temperatures (which influence heating and cooling demands) are the primary driver of day-to-day and seasonal changes in electricity demand [54]. By influencing both supply and demand for electricity, hydrometeorological processes can directly affect GHG emissions [52,61,65], wholesale electricity prices [52,66,67], and costs for power utilities and consumers [55,66,68,69]. Deeper understanding of the effects of hydrometeorological variability on power system operations can help inform operational decisionmaking and related agents. ...
Article
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Power grid operations increasingly interact with environmental systems and human systems such as transportation, agriculture, the economy, and financial markets. Our objective is to discuss the modelling gaps and opportunities to advance the science for multisector adaptation and tradeoffs. We focus on power system operational models, which typically represent key physical and economic aspects of grid operations over days to a year and assume a fixed power grid infrastructure. Due to computational burden, models are typically customized to reflect regional resource opportunities, data availability, and applications of interest. We conceptualize power system operational models with four core processes: physical grid assets (generation, transmission, loads, and storage), model objectives and purpose, institutions and decision agents, and performance metrics. We taxonomize the representations of these core processes based on a review of 23 existing models. Using science questions around grid and short term uncertainties, long term global change, and multisectoral technological innovation as examples, we report on tradeoffs in process fidelity and tractability that have been adopted by the research community to represent multisectoral interactions in power system operational models. Our recommendations for research directions are model-agnostic, focusing on core processes, their interactions with other human systems, and consider computational tradeoffs.
... They reported that this relation might be due to cheap and wasteful energy use in this sector. Likewise, high energy consumption, particularly electricity in the agricultural sector will increase the vulnerability of the electric power industry and increasing electricity production is to be linked with enhanced greenhouse gas emissions (Hardin et al., 2017). In the same vein, Mirzaei et al. (2019) stated that increasing energy consumption underscore dysfunctional feedback relations between agricultural water and energy price and groundwater withdrawal in an inefficient agronomic sector. ...
Article
The increasing demands of the population and the need for development obliged the optimal use and adaptive management of the watershed resources. Accordingly, it is necessary to adopt comprehensive measures to reach sustainable development goals. This objective can be achieved by the application of interdisciplinary and professional approaches through establishing dynamic and optimal balance in supply and demand resources. However, such important optimization approaches have been rarely practiced at the watershed scale. The present study has been therefore formulated to apply a linear water-energy-food nexus optimization for the Shazand watershed, Markazi Province, Iran. This approach was applied for planning 14 crops planted in orchard, irrigated farms, and rain-fed farms, between 2006 and 2014, and targeting water-energy-food nexus index (WEFNI) maximization. The connections among the water, energy, and food were then evaluated through determining the amount of consumption, mass productivity, and economic productivity of water and energy. The results of WEFNIs revealed that almond has the highest WEFNI with values of 0.92, 0.76, 0.76, 0.83, 0.86, 0.86, 0.87, 0.87, and 0.88. Whilst, potato with WEFNI of 0.05, 0.05, 0.05, 0.06, 0.09, 0.10 and 0.11, sugar cane with WEFNI of 0.10 and cucumber with WEFNI of 0.13 had the lowest scores and the corresponding lowest performance among the study crops. The outcomes of optimization study explained that the current situation of land use in the Shazand Watershed is unsuitable to minimize water and energy consumption and maximize benefit. The results can be used as an effective tool for designating proper soil and water resource management strategies in the region.
... They reported that this relation might be due to cheap and wasteful energy use in this sector. Likewise, high energy consumption, particularly electricity in the agricultural sector will increase the vulnerability of the electric power industry and increasing electricity production is to be linked with enhanced greenhouse gas emissions (Hardin et al., 2017). In the same vein, Mirzaei et al. (2019) stated that increasing energy consumption underscore dysfunctional feedback relations between agricultural water and energy price and groundwater withdrawal in an inefficient agronomic sector. ...
... In recent years, California has experienced a series of flooding events (Vahedifard et al., 2017) on the heels of a 5-year drought (e.g., AghaKouchak et al., 2014;Hardin et al., 2017;Shukla et al., 2015). In 2017, a major flood in Northern California led to structural failure of Oroville Dam's spillway that triggered the evacuation of about 200,000 people. ...
Article
In this study, we investigate changes in future streamflows in California using bias-corrected and routed streamflows derived from global climate model (GCM) simulations under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. Unlike previous studies that have focused mainly on the mean streamflow, annual maxima or seasonality, we focus on projected changes across the distribution of streamflow and the underlying causes. We report opposing trends in the two tails of the future streamflow simulations: lower low flows and higher high flows with no change in the overall mean of future flows relative to the historical baseline (statistically significant at 0.05 level). Furthermore, results show that streamflow is projected to increase during most of the rainy season (December to March) while it is expected to decrease in the rest of the year (i.e., wetter rainy seasons, and drier dry seasons). We argue that the projected changes to streamflow in California are driven by the expected changes to snow patterns and precipitation extremes in a warming climate. Changes to future low flows and extreme high flows can have significant implications for water resource planning, drought management, and infrastructure design and risk assessment.
... They reported that this relation might be due to cheap and wasteful energy use in this sector. Likewise, high energy consumption, particularly electricity in the agricultural sector will increase the vulnerability of the electric power industry and increasing electricity production is to be linked with enhanced greenhouse gas emissions (Hardin et al., 2017). In the same vein, Mirzaei et al. (2019) stated that increasing energy consumption underscore dysfunctional feedback relations between agricultural water and energy price and groundwater withdrawal in an inefficient agronomic sector. ...
Article
Full-text available
The increasing demands of the population and the need for development obliged the optimal use and adaptive management of the watershed resources. Accordingly, it is necessary to adopt comprehensive measures to reach sustainable development goals. This objective can be achieved by the application of interdisciplinary and professional approaches through establishing dynamic and optimal balance in supply and demand resources. However, such important optimization approaches have been rarely practiced at the watershed scale. The present study has been therefore formulated to apply a linear water-energy-food nexus optimization for the Shazand watershed, Markazi Province, Iran. This approach was applied for planning 14 crops planted in orchard, irrigated farms, and rain-fed farms, between 2006 and 2014, and targeting water-energy-food nexus index (WEFNI) maximization. The connections among the water, energy, and food were then evaluated through determining the amount of consumption, mass productivity, and economic productivity of water and energy. The results of WEFNIs revealed that almond has the highest WEFNI with values of 0.92, 0.76, 0.76, 0.83, 0.86, 0.86, 0.87, 0.87, and 0.88. Whilst, potato with WEFNI of 0.05, 0.05, 0.05, 0.06, 0.09, 0.10 and 0.11, sugar cane with WEFNI of 0.10 and cucumber with WEFNI of 0.13 had the lowest scores and the corresponding lowest performance among the study crops. The outcomes of optimization study explained that the current situation of land use in the Shazand Watershed is unsuitable to minimize water and energy consumption and maximize benefit. The results can be used as an effective tool for designating proper soil and water resource management strategies in the region.
... For instance, a sound FEW nexus analysis can remediate the intertwined issues of local air pollution, urban heat island (UHI) effect, regional air pollution, and global climate change, which are directly related to fossil derived fuels combustion for energy supply and transportation in urban areas. Interdisciplinary sustainability solutions in a sustainable city for counteracting different scales of such impacts can, in turn, mitigate climate change impacts on regional water, carbon, and ecosystem footprints that can affect water supplies directly and food production indirectly (Bibri, 2018;Chang et al., 2020a, 2020b, Hardin et al., 2017Tsolakis & Anthopoulos, 2015). ...
Article
The integration of food-energy-water (FEW) sectors is essential for addressing the co-evolution of urban infrastructure systems during urban growth. But how these evolutionary pathways can affect an urban growth model is unclear. This review paper offers a synthesis of the current philosophy of a FEW nexus in connection with the realm of urban growth models (UGMs) to signify the paradigm collision and shift with interdisciplinary sustainability insights. Findings indicate that urban metabolism and urban ecology in relation to FEW sectors can be incorporated into UGMs with scales via multi-criteria decision analysis as FEW technology hub integration can play a critical role in UGMs via a common cellular automata (CA) architecture for both model construction and solution procedure. Synergies between FEW sectors and CA-based UGMs as well as tradeoffs across FEW technology hub integration are highlighted to reflect the cascade effects and higher order impact on urban metabolism and urban ecology. This concept was confirmed with a case study in Miami, Florida, the United States for demonstration.Such synergistic framework is helpful for fostering more sustainable, green,smart,forward-looking, environmentally-sound, socially equitable, risk-informed, resilient,and cost-effective urban growth simulations. It is anticipated that the proposed hybrid FEW-CA-based UGMs can fully account for interactions of context-and culture-driven issues for multi-scale and multi-agent urban planning and design in different countries.
... Recent droughts foreshadow how the state's energy-water nexus may fare under these impacts of climate change [19]. California's water sector's drought responses transferred and compounded vulnerability to its electricity sector-increased groundwater pumping spiked electricity consumption, while hydropower deficits were replaced by greenhouse gas (GHG)emitting fossil generation [37,42]. In addition, the state has already seen several unprecedented climaterelated impacts to the electricity grid, such as the August 2020 West-wide heat wave that triggered California's rolling blackouts [43]. ...
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Electricity and water systems are inextricably linked through water demands for energy generation, and through energy demands for using, moving, and treating water and wastewater. Climate change may stress these interdependencies, together referred to as the energy-water nexus, by reducing water availability for hydropower generation and by increasing irrigation and electricity demand for groundwater pumping, among other feedbacks. Further, many climate adaptation measures to augment water supplies—such as water recycling and desalination—are energy-intensive. However, water and electricity system climate vulnerabilities and adaptations are often studied in isolation, without considering how multiple interactive risks may compound. This paper reviews the fragmented literature and develops a generalized framework for understanding these implications of climate change on the energy-water nexus. We apply this framework in a case study to quantify end-century direct climate impacts on California's water and electricity resources and estimate the magnitude of the indirect cross-sectoral feedback of electricity demand from various water adaptation strategies. Our results show that increased space cooling demand and decreased hydropower generation are the most significant direct climate change impacts on California's electricity sector by end-century. In California's water sector, climate change impacts directly on surface water availability exceed demand changes, but have considerable uncertainty, both in direction and magnitude. Additionally, we find that the energy demands of water sector climate adaptations could significantly affect California's future electricity system needs. If the worst-case water shortage occurs under climate change, water-conserving adaptation measures can provide large energy savings co-benefits, but other energy-intensive water adaptations may double the direct impacts of climate change on the state's electricity resource requirement. These results highlight the value of coordinated adaptation planning between the energy and water sectors to achieve mutually beneficial solutions for climate resilience.
... VRE production is sensitive to fluctuations in wind speeds and solar irradiance(59,60), representing a growing concern as power systems increase their reliance on these resources(69,70). Air temperatures (which influence heating and cooling demands) are the primary driver of day-to-day and seasonal changes in electricity demand(64).By influencing both supply and demand for electricity, hydrometeorological processes can directly affect GHG emissions(60,65,71), wholesale electricity prices(60,72,73), and costs for power utilities and consumers(61,72,74,75)). Deeperunderstanding of the effects of hydrometeorological variability on power system operations can help inform operational decision-making and feed into long-term planning efforts in the power sector and other areas. The effects of hydrometeorological uncertainty on power system operations have been explored either by subjecting a deterministic power system model to an ensemble of exogenous weather-based stressors (34, 61, 76) or by embedding stochastic representations of generation and load within the optimization itself (77, 78) (Figure 3). ...
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Power grid operations increasingly interact with environmental systems and human systems such as transportation, agriculture, the economy, and financial markets. Our objective is to discuss the modelling gaps and opportunities to advance the science for multisector adaptation and tradeoffs. We focus on power system operational models, which typically represent key physical and economic aspects of grid operations over days to a year and assume a fixed power grid infrastructure. Due to computational burden, models are typically customized to reflect regional resource opportunities, data availability, and applications of interest. While there are model intercomparison papers, there is however no model-agnostic characterization and systematic overview of the state-of-the-art process representations in operational power system models. To address our objective, we conceptualize power system operational models with four core processes: physical grid assets (generation, transmission, loads, and storage), model objectives and purpose, institutions and decision agents, and performance metrics. We taxonomize the representations of these core processes based on a review of 23 existing open-source and commercial models. As we acknowledge the computational burden of certain representations, we leverage this taxonomy to describe tradeoffs in process fidelity and tractability that have been adopted by the research community to address interactions between the power grid and hydrometeorological uncertainties, global change, and/or technological innovation. The core process taxonomy along with the existing computational tradeoffs are used to identify technical gaps and recommend future model development needs and research directions to better represent power grid operations as part of integrated multisector dynamics modeling and interdisciplinary research.
... The work by Chowdhury et al. (2021) facilitates an interesting discussion on the role of water resources management in electricity production and subsequent greenhouse gas emissions under hydrologic uncertainty. Chowdhury et al. (2021) compliment work regarding the electricity sector in California, which showed the 2012-2016 drought in California caused an estimated increase of carbon emissions by 10%-33% compared to predrought conditions (Gleick, 2015;Hardin et al., 2017;Kern et al., 2020). The drought in California resulted in reduced water availability, which impacted the production of hydroelectricity and forced increased reliance on carbon intensive fuel-based generation. ...
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Water resources are required for cooling of thermoelectric power plants and in the production of hydroelectricity. Scarcity of water resources impacts the ability to generate electricity in grids across the globe. There is extensive literature and research on the electricity‐water nexus, spanning hydrology, policy, and energy sectors. Existing research often focuses on quantifying a static relationship and rarely accounts for expectations of annual, seasonal, and subseasonal water variability in nexus research. This omission leaves an important, unanswered question in the field: how can the water footprinting framework be operationalized in the electricity‐water nexus with hydroclimatic forecasts? Building off the work by Chowdhury et al. (https://doi.org/10.1029/2020EF001814), we comment on the opportunities for climate‐informed, seasonal, or subannual assessments of the electricity‐water nexus to facilitate decision‐making.
... The opposite is also plausible; heavy rains in the arid west of the United States connected to the 1997-1998 El Niño event are thought to have contributed to increased hydropower output, leading to reduced energy costs (Changnon 1999). Although regional impact may be relatively small, the cumulative impact can be staggering (Hardin et al 2017), especially when multiple regions are affected by ENSO simultaneously. The scale of these impacts is likely to depend on both the magnitude of the hydropower production shortfall and the relative importance of hydropower in regional energy supplies. ...
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Potential global climate change impacts on hydrology pose a threat to water resources systems throughout the world. The California water system is especially vulnerable to global warming due to its dependence on mountain snow accumulation and the snowmelt process. Since 1983, more than 60 studies have investigated climate change impacts on hydrology and water resources in California. These studies can be categorized in three major fields: (1) Studies of historical trends of streamflow and snowpack in order to determine if there is any evidence of climate change in the geophysical record; (2) Studies of potential future predicted effects of climate change on streamflow and; (3) Studies that use those predicted changes in natural runoff to determine their economic, ecologic, or institutional impacts. In this paper we review these studies with an emphasis on methodological procedures. We provide for each category of studies a summary of significant conclusions and potential areas for future work.
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Observations have shown that the hydrological cycle of the western United States changed significantly over the last half of the 20th century. We present a regional, multivariable climate change detection and attribution study, using a high-resolution hydrologic model forced by global climate models, focusing on the changes that have already affected this primarily arid region with a large and growing population. The results show that up to 60% of the climate-related trends of river flow, winter air temperature, and snow pack between 1950 and 1999 are human-induced. These results are robust to perturbation of study variates and methods. They portend, in conjunction with previous work, a coming crisis in water supply for the western United States.
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Climate warming is expected to alter hydropower generation in California through affecting the annual stream-flow regimes and reducing snowpack. On the other hand, increased temperatures are expected to increase hydropower demand for cooling in warm periods while decreasing demand for heating in winter, subsequently altering the annual hydropower pricing patterns. The resulting variations in hydropower supply and pricing regimes necessitate changes in reservoir operations to minimize the revenue losses from climate warming. Previous studies in California have only explored the effects of hydrological changes on hydropower generation and revenues. This study builds a long-term hydropower pricing estimation tool, based on artificial neural network (ANN), to develop pricing scenarios under different climate warming scenarios. Results suggest higher average hydropower prices under climate warming scenarios than under historical climate. The developed tool is integrated with California's Energy-Based Hydropower Optimization Model (EBHOM) to facilitate simultaneous consideration of climate warming on hydropower supply, demand and pricing. EBHOM estimates an additional 5% drop in annual revenues under a dry warming scenario when climate change impacts on pricing are considered, with respect to when such effects are ignored, underlining the importance of considering changes in hydropower demand and pricing in future studies and policy making.
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