| 英文摘要: | The deployment of renewable energy systems, such as solar energy, to achieve universal access to electricity, heat and transportation, and to mitigate climate change is arguably the most exigent challenge facing humans today1, 2, 3, 4. However, the goal of rapidly developing solar energy systems is complicated by land and environmental constraints, increasing uncertainty about the future of the global energy landscape5, 6, 7. Here, we test the hypothesis that land, energy and environmental compatibility can be achieved with small- and utility-scale solar energy within existing developed areas in the state of California (USA), a global solar energy hotspot. We found that the quantity of accessible energy potentially produced from photovoltaic (PV) and concentrating solar power (CSP) within the built environment (‘compatible’) exceeds current statewide demand. We identify additional sites beyond the built environment (‘potentially compatible’) that further augment this potential. Areas for small- and utility-scale solar energy development within the built environment comprise 11,000–15,000 and 6,000 TWh yr−1 of PV and CSP generation-based potential, respectively, and could meet the state of California’s energy consumptive demand three to five times over. Solar energy within the built environment may be an overlooked opportunity for meeting sustainable energy needs in places with land and environmental constraints. Technology, economics and environmental values are decisive factors in identifying areas most compatible for renewable energy development, including solar energy systems. Environmental values are underlying determinants of attitudes, behaviours and beliefs about the environment8, 9. These attitudes, behaviours and beliefs can, in turn, guide decisions concerning which ecosystems and human assets to protect. They can also inform the way that the emphasis on different kinds of impact changes with the scale of the solar energy deployment10, 11. Solar energy systems integrated within the built environment have several advantages if protecting ecosystems and their services are priority values. They confer the lowest environmental and land-use and land-cover change impacts6, 12, reduce energetic losses from and load on transmission, and are co-located with the energy needs of a growing population expected to be concentrated entirely in urban areas (that is, 62% by 2035; refs 13, 14). Such installations are modular in their capacity, ranging from small-scale (<1 MW) to utility-scale (≥1 MW), and can use existing infrastructure within the built environment (for example, residential rooftops, commercial rooftops). Utility-scale solar energy (USSE) systems are uniquely advantageous with their large economy of scale, compatibility with a wide range of sites, and numerous environmental co-benefit opportunities6. With a land-use efficiency of 35 W m−2 at a capacity factor of 0.20, a single terawatt of USSE capacity scales to 142,857 km2 (roughly the area of the state of New York)12, providing challenges for the integration of potentially massive projects into complex and fragmented landscapes. Criteria for siting USSE can be diverse, emphasizing, for example, warehouse rooftops, degraded lands, deserts, or sites remote from human populations. However, resource constraint and opportunity modelling can be used to assess value-based trade-offs and technical potential at large spatial scales where energy development is needed7, 15, 16, 17. The state of California (USA) has been a long-standing model system for understanding the land–energy–environment nexus owing to its early and aggressive adoption of renewable energy systems (predominately wind and geothermal), vast land area (larger than 189 countries, for example, Germany, the Philippines and Zimbabwe), large population (that is, 38 million) and economy (that is, the eighth largest in the world), vulnerability to climate change, and sensitive ecosystems12, 18, 19. Abundant solar resources and diverse storage technology options suggest that small- and USSE technologies within the built environment and in places that minimize environmental impacts may be underutilized within California’s current resource mix. Here, we test the hypothesis that land, energy and environmental compatibility can be achieved with small-scale solar energy and USSE within landscapes that are already managed for human uses in the state of California (USA), a global solar energy hotspot6, 20, 21, 22. To determine whether land, energy and environmental compatibility can be achieved within existing developed areas in the state of California, we developed the Carnegie Energy and Environmental Compatibility (CEEC) model (Supplementary Methods) to achieve four objectives. First, we seek to quantify the capacity-based technical potential (that is, satellite-based estimates of PV and CSP technologies operating at their full, nominal capacity over 0.1° surface cells). Second, we seek to quantify the (accessible) generation-based technical potential (that is, realized potential incorporating a satellite-based capacity factor model with 0.1 × 0.1° surface resolution) for PV and CSP. Owing to California’s limited water resources, we model dry-cooled CSP parabolic trough technology. Photovoltaic technologies included three sub-types: fixed tilt (TILT25), single-axis (AX1FLAT), dual-axis (AX2). Third, we seek to create a compatibility index (that is, ‘compatible’, ‘potentially compatible’ and ‘incompatible’ areas) to categorize and quantify land resources meeting land, energy and environmental compatibility for solar energy infrastructure. Last, we seek to determine to what extent energy and climate change goals can be met therein. California has a total area of over 400,000 km2 with a solar resource of 881,604 TWh yr−1 and 1,000,948 TWh yr−1 for PV and CSP, respectively (Table 1 and Fig. 1a). However, CSP is economically maximized where direct normal irradiance (DNI) is 6 kWh m−2 d−1 or greater. California comprises approximately 310,000 km2 of land where solar resources meet this criterion, conferring a theoretical capacity-based CSP potential of 795,973 TWh yr−1. Although PV systems can be deployed on water, conferring reduced evaporation as a co-benefit (for example, floatovoltaics, Supplementary Table 1), we excluded open bodies of water and perennial ice and snow (Supplementary Section 1).
- IPCC Special Report: Renewable Energy Sources and Climate Change Mitigation (Cambridge Univ. Press, 2011)
- IPCC Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects (Cambridge Univ. Press, 2014)
- Hoffert, M. I. et al. Advanced technology paths to global climate stability: Energy for a greenhouse planet. Science 298, 981–987 (2002).
- Barthelmie, R. J. & Pryor, S. C. Potential contribution of wind energy to climate change mitigation. Nature Clim. Change 2035, 8–12 (2014).
- Dale, V. H., Efroymson, R. A. & Kline, K. L. The land use–climate change–energy nexus. Landsc. Ecol. 26, 755–773 (2011).
- Hernandez, R. R. et al. Environmental impacts of utility-scale solar energy. Renew. Sustain. Energy Rev. 29, 766–779 (2014).
- Cameron, D. R., Cohen, B. S. & Morrison, S. A. An approach to enhance the conservation-compatibility of solar energy development. PLoS ONE 7, 1–12 (2012).
- Ando, A., Camm, J., Polasky, S. & Solow, A. Species distributions, land values, and efficient conservation. Science 279, 2126–2128 (1998).
- Schultz, P. W. et al. Values and their relationship to environmental concern and conservation behavior. J. Cross. Cult. Psychol. 36, 457–475 (2005).
- Carbajales-Dale, M., Barnhart, C. J., Brandt, A. R. & Benson, S. M. A better currency for investing in a sustainable future. Nature Clim. Change 4, 524–527 (2014).
- Gaffin, S. R., Rosenzweig, C. & Kong, A. Y. Y. Adapting to climate change through urban green infrastructure. Nature Clim. Change 2, 704 (2012).
| http://www.nature.com/nclimate/journal/v5/n4/full/nclimate2556.html
|
