Introduction

Water and energy are conventionally managed in isolation, with the result that synergies between these resources are rarely recognized, much less exploited. It is increasingly known that water service provision is energy intensive, while energy generation and distribution require significant water resources. Furthermore, water and energy policy and decision-making must be harmonized, or at least mutual inconsistencies need to be identified and accounted for. Research by the Water Policy & Resources Group and our partners addresses the water-energy nexus from the perspective of coupled resources and policy.

Water-Energy Nexus Funding

2011-14 Towards an Integrated Assessment of Water Security Under Global Change in the Americas
(C. Scott, PI; Francisco Meza, Universidad Catølica de Chile, co-PI). $300,000, Inter-American Institute for Global Change Research (IAI), pending release of funds committed by National Science Foundation to to IAI. Objectives include: Improve understanding of agricultural water use and electrical energy supply and pricing; Identify and assess feedbacks between environmental conditions and adaptation decisions.

2008-12 Optimization of Dual Conjunctive Water Supply and Reuse Systems with Distributed Treatment for High-Growth Water-Scarce Regions
(C. Scott, co-PI, 20%). $1,999,558 (plus $80,384 supplements), National Science Foundation, Resilient and Sustainable Infrastructures.

2010-12 Arid Cities in Changing Climates: Urban Land and Water Use in the Desert Southwest
(C. Scott, co-PI, 25%). $138,837, Dept. Interior, Bureau of Reclamation WaterSMART; and $29,973, Univ. Arizona Water Sustainability Program. Objectives include: surface energy balance assessment of urban canopy.

2008 Water and Energy Sustainability with Rapid Growth in the Arizona-Sonora Border Region
(C. Scott, PI, 50%). $50,000, Arizona Water Institute.

2007-08 Geospatial Analysis of Urban Thermal Gradients
Application to Tucson, Arizona’s Projected Water Demand (C. Scott, PI, 33%). $12,000, United States Geological Survey 104B administered by University of Arizona Water Resources Research Center. See: www.dingo.sbs.arizona.edu/~cascott/urbanheat/

Water and Energy Sustainability under Climate Change and Rapid Growth

Research to assesses the energy implications of the full cycle of human water use in southern Arizona and the US-Mexico border region, with emphasis on the nexus for Tucson and Phoenix, and Nogales, Sonora and for agricultural groundwater use in Mexico.

  • Data collection on energy use for water services and mapping of major water and energy infrastructure
  • Assessment of agricultural groundwater – energy – climate nexus in Mexico
  • Trend analysis of population growth, water and energy use in Arizona
  • Outreach to binational organizations such as the Arizona-Mexico Commission

Contacts

Christopher Scott (Principal Investigator) – Udall Center for Studies in Public Policy, and School of Geography and Development, University of Arizona, cascott@email.arizona.edu

Martin Pasqualetti (Co-PI) – School Of Geographical Sciences and Urban Planning, Arizona State University,pasqualetti@asu.edu

Status

  • Presentations at the Binational Institute for Water and Renewable Energy Workshop (Feb, 2008)
  • Presentation at the Border Energy/Watergy Forum, Monterrey, Mexico (Oct, 2008)
  • Researcher-managers workshop at Arizona Water Institute (June, 2009) see details>>

Water-energy nexus sessions:

  • Border Energy Forum Chihuahua, Mexico (Sept, 2010) details>>
  • Sustainable Groundwater in Agriculture, International Science – Policy Conference, San Francisco CA (June 2010) details >>
  • Association of American Geographers Annual Meetings (Mar, 2009) details >>; (Apr 2010) details >>; (Apr 2011) details >>)
  • American Institute of Professional Geologists and Arizona Hydrological Society, Flagstaff AZ (Sep, 2008) details >>
  • Panelist, Energy and Water, Southwest Renewable Energy Conference, Flagstaff, AZ (Sep, 2009) details >>

Publications

Scott, C.A., R.G. Varady, A. Browning-Aiken, T.W. Sprouse. 2007. Linking water and energy along the Arizona/Sonora border. Southwest Hydrology 6 (5): 26-27,31. >>PDF

Scott, C.A., M.J. Pasqualetti. 2010. Energy and water resources scarcity: Critical infrastructure for growth and economic development in Arizona and Sonora. Natural Resources Journal 50(3): 645-682. >>PDF

ABSTRACT
Climate change, rapid urbanization, and the emerging carbon economy, among other factors, have elevated the energy-water nexus from an operational tool to a new joint-resource management and policy paradigm. Nowhere in North America, and in few regions globally, is this need greater than in the Southwest United States and Northwest Mexico. In the states of Arizona and Sonora, investment is inadequate to meet energy and water infrastructure needs. On par with critical infrastructure in economic development terms, agriculture is likewise energy-intensive and currently consumes the largest share of water resources in both states. The important gains to be made through coupled energy- and water-based conservation, including the potential of certain types of renewable energy development to reduce water requirements for electricity generation, raise questions over conventional plans to rapidly increase investments in infrastructure. The purpose of this paper is to assess the region’s energy-water nexus through analysis of data on water supply, electrical power generation, and energy consumption. Four cases are examined to illustrate the coupled nature of policies for energy and water: (1) rapidly growing urban centers; (2) water consumed in power generation and the ?virtual water implications of regional interstate power trade; (3) the irrigation-electrical power nexus in agriculture; and (4) coastal desalination and proposed transboundary transfer schemes. The paper concludes that conventional water management for cities has a large and rising energy footprint. Conversely, power generation that is often considered ?non-consumptive in this arid region is a major consumer of water. Similarly, there is a major opportunity for energy and water conservation in groundwater irrigation. Finally, desalination may hold promise, particularly for coastal communities, but current costs and institutional barriers suggest that transboundary transfer of desalinated water for general purposes, including environmental conservation and agriculture, has low feasibility.

Scott, C.A. In review. The Water – Energy – Climate Nexus: Resources and Policy Outlook for Aquifers in Mexico. Water Resources Research.

ABSTRACT
Three inter-linked processes constitute a nexus that drives groundwater balances in numerous regions globally: a) intensification of groundwater irrigation, b) electrical energy supply for agriculture, and c) climatic variability. Mexico represents an evolving case of the water-energy-climate nexus, which has widespread visibility due to its prevailing water scarcity and water sector institutional reforms that are emulated by decision-makers in other emerging economies. This paper analyzes newly available data for 280 aquifers in Mexico, over 400,000 records of registered water users, population of over 2,400 municipalities projected on U.N. medium-variant and constant-fertility scenarios, precipitation and temperature projections for 2010-2100 under A1B and A2 emissions scenarios statistically downscaled at 2-degree resolution from fifteen models of the CMIP3 ensemble, and 1999-2009 electrical power supply and pricing data for agriculture in 32 Mexican states. Climate-based drivers of aquifer balances exhibit important spatial variation, particularly trends and variability in recharge. Population growth exerts non-agricultural water demand that peaks mid-21st Century but then declines marginally by 2100. Price-elastic demand for agricultural power offers a nexus-based policy tool to address aquifer depletion, a lost opportunity when reduced nighttime tariffs for groundwater pumping were introduced in 2003. Accentuated by Mexico’s expanding groundwater-irrigated vegetable and fruit exports, virtual groundwater trade has negative implications for aquifer balances. Regulatory and user-based groundwater management initiatives suggest that awareness of aquifer depletion is increasing; however, the long-term outlook for aquifers in Mexico raises the need for policies centered on specific interlinkages of the water-energy-climate nexus that address the aquifer depletion challenge.

Eden, S., C.A. Scott, M. Lamberton and S. Megdal. 2011 in press. Energy Demand and Displaced Environmental Impacts of Long-Distance Water Conveyance: The Central Arizona Project’s Water-Energy Nexus. In D. Kenney and R. Wilkinson (eds.) The Water-Energy Nexus in the American West, Edward Elgar, Cheltenham, UK.

ABSTRACT
Long-distance water conveyance infrastructure and the organizations for its management enable agricultural and urban development in water-scarce regions. This growth exerts demands for energy and water, in a cycle of expansion. Large-scale inter-basin transfer systems are uniquely complicated by such water-energy interdependencies and displaced impacts. The Central Arizona Project (CAP), which delivers Colorado River water to central and southern Arizona, provides a case of multiple inter-connections between water supply and energy that characterize water transportation in the American West. CAP faces multiple water-energy challenges resulting from sole-source energy dependence on the coal-fired Navajo Generating Station and from infrastructural design, which are not easily remediable. While drought and climate change are introducing new uncertainties into water planning, population growth continues to place increasing demands on supplies. The amount of water allocation that CAP will deliver in some future years is likely to be reduced by a combination of drought, climate change and upper basin development. Simultaneously, air quality regulation and potential requirements for mitigating carbon emissions promise to push CAP’s energy costs significantly higher. As the perceived impacts of displaced costs continue to find their way into social discourse and onto the political agenda, their economic implications are becoming better understood. For CAP, this will inevitably entail operational and pollution mitigation expenses that must be passed on to water users. In broad outline CAP’s energy-water interdependencies and displaced impacts are typical of water conveyance systems and are globally illustrative of economic growth, water scarcity, and the need for environmental stewardship.

Scott, C.A., S.A. Pierce, M.J. Pasqualetti, A.L. Jones, B.E. Montz, J.H. Hoover. In review. Policy and Institutional Dimensions of the Water-Energy Nexus. Energy Policy.

ABSTRACT
Energy and water are interlinked at multiple scales. Jointly managing these resources presents institutional challenges, yet offers opportunities for adaptive response to global change driven by shifts in climate, rapid urbanization, globalized energy markets, human-induced environmental impacts, growing scarcity of fresh water, and the imperative of secure energy. We examine resource use along with institutional and policy dimensions of energy-water cases from the United States: 1) water and energy development in the urbanizing and water scarce Southwest; 2) “clean coal” tradeoffs driven by global energy demand with local environmental quality impacts in the East; and 3) the tension between competing local interests due to environmental concerns and economic development of shale natural gas in Central and Northeast regions. Case-based scenarios are compared with regional stakeholder priorities collected in a national effort and evaluated using a systems dynamics model to project hypothetical energy-water portfolios. Localized challenges tend to be diminished when considered from broader perspectives, while regionally important challenges may not be prioritized locally. The transportability of electricity, and to some extent raw coal and gas, makes energy more suitable than water to regionalized adaptive approaches. We assess new lines of enquiry and contributions for energy-water decision-making.

Kumar, M.D., C.A. Scott and O.P. Singh. In review. Inducing the Shift from Flat-rate or Free Agricultural Power to Metered Supply: Implications for Groundwater Depletion and Power Sector Viability in India. Journal of Hydrology.

ABSTRACT
India’s farm sector sustains rural livelihoods for hundreds of millions of people, ensures food security for well over a billion, and faces serious management challenges for land, water, and energy resources. The stakes could not be higher: growing dependence on groundwater – the backbone of irrigation supply – threatens land productivity, water resources sustainability, and power sector viability. Continuing the marvel of India’s rising prosperity rests on getting the groundwater equation right. Raising social and economic equity nationally and minimizing inter-regional disparities are essential to under-gird urban-led economic growth. This will require continued growth of agriculture while at the same time, the farm sector must internalize it share of the effects of groundwater depletion and bankrupt power utilities. Agricultural power – supplied flat-rate or free and viewed as an entitlement – must increasingly be managed as a scarce input. This study shows that pro rata farm power pricing, which induces marginal-cost use of electricity, motivates farmers to: 1] use water more efficiently through prudent farm-level irrigation practices; 2] make more judicious use of other costly agronomic inputs; and 3] improve overall farm operations by optimizing cropping patterns and livestock composition to secure higher returns to scarce water. It also shows that increased cost of irrigation will not lower net returns per unit of water, provided timely power supply ensures the quality of irrigation service. Further, a shift of power tariffs from flat rate to pro rata will not adversely affect access and equity of groundwater use, nor will it increase the monopoly power of well owners. Pro rata pricing reduces groundwater pumping per unit of land. It also reduces aggregate pumping, disproportionately higher than the reduction in net returns per unit of land, leading to more sustainable groundwater use. In sum, in water scarce regions, it would be possible to introduce metering and higher power tariff without compromising on the economic prospects of farming. Raising power tariffs in the farm sector to achieve efficiency, equity and sustainability of groundwater use is both socially and economically viable and urgently necessary. The fundamental question addressed is how to induce this shift. This paper discusses five different options for power supply, metering and energy pricing in the farm sector and the expected outcomes of implementing each vis-a-vis efficiency of groundwater and energy use, equity in access to groundwater and sustainability of groundwater. It concludes that the option of establishing an energy quota for each farm based on sustainability considerations (in effect rationing the amount of energy), and metering and charging pro rata for power used are the best options to manage groundwater and the energy economy.

Scott, C.A. In preparation (at Editor’s invitation). The Water-Energy Nexus in a Global Context. International Journal of Water Resources Development.

ABSTRACT
Water, energy, and their interlinked use are critical drivers of population growth, food security, urbanization, and climate change – the environmental challenges that define our era. The collective ability of societies to address conjunctive water and energy dependencies by devising and applying comprehensive policy frameworks will determine how these challenges are resolved. Growing attention is being paid to the water-energy nexus in a diversity of specific locations. Nevertheless, global energy demand trends in the context of climate change and variability portend a rethinking of water management. This ‘think-piece’ considers that a) technological obstacles are surmountable, b) resource conservation is inevitable, driven by financial limitations and efficiency gains, and c) institutional arrangements remain the most intractable constraint to the virtuous water-energy-climate cycle. The first two conditions are especially true in developing and emerging societies, i.e., here, technological transition can rapidly respond to alternatives because of reduced installed capacity, and low per-capita resource consumption is already the norm. Institutional innovation, however, can be thwarted by decision-making that diminishes the role of the scientific community and civil society, which seek to better integrate water and energy planning.

GROUNDWATER-ENERGY NEXUS IN AGRICULTURE

Groundwater irrigation accounts for up to a fifth of total electrical power consumption in part of northern and central Mexico, and upto a fifth in much of India, with very major implications for greenhouse gas emissions. Christopher Scott continues research in both locations initiated with the International Water Management Institute.

Goals and Activities

  • Documentation of groundwater irrigation and aquifer sustainability.
  • Estimates of electrical power consumption.
  • Management and policy alternatives to capture the ‘virtuous cycle’ of the water-energy nexus (conservation, demand management, and regulatory instruments).

Contacts

Christopher Scott (Principal Investigator) – Udall Center for Studies in Public Policy, and School of Geography and Development, University of Arizona, cascott@email.arizona.edu

Publications

Scott, C.A., B.R. Sharma. 2009. Energy supply and the expansion of groundwater irrigation in the Indus-Ganges basin. International Journal of River Basin Management 7(2): 119–124. [PDF]

Sinha, S., B.R. Sharma, C.A. Scott. 2006. Understanding and managing the water-energy nexus: moving beyond the energy debate. In B.R. Sharma, K.G. Villholth, and K.D. Sharma (eds.) Groundwater Research and Management: Integrating Science into Management Decisions. International Water Management Institute, Colombo, Sri Lanka, pp. 242-257. [PDF]

Scott, C.A., T. Shah, S.J. Buechler, P. Silva-Ochoa. 2004. La fijación de precios y el suministro de energía para el manejo de la demanda de agua subterránea: enseñanzas de la agricultura mexicana. In C. Tortajada, R. Sandoval, E. Castelán (eds). Hacia una Gestión Integral del Agua en México: Retos y Alternativas. Porrua Editores, Mexico City, pp. 201-228. [PDF]

Scott, C.A. and T. Shah. 2004. Groundwater overdraft reduction through agricultural energy policy: insights from India and Mexico. International Journal of Water Resources Development 20(2): 149-164. [PDF]

Scott, C.A., H. El-Naser, R.E. Hagan, A. Hijazi. 2003. Facing water scarcity in Jordan: reuse, demand reduction, energy and transboundary approaches to assure future water supplies. Water International 28(2): 209-216. [PDF]

Shah, T., C.A. Scott, A. Kishore, A. Sharma. 2003. Energy-irrigation nexus in South Asia: improving groundwater conservation and power sector viability. IWMI Research Report No. 70. International Water Management Institute, Colombo, Sri Lanka. [PDF]