| 英文摘要: | Previous studies have demonstrated the possibility of maintaining a reliable electric power system with high shares of renewables, but only assuming the deployment of specific technologies in precise ratios, careful demand-side management, or grid-scale storage technologies1, 2. Any scalable renewable technology that could provide either baseload or dispatchable power would allow greater flexibility in planning a balanced system, and therefore would be especially valuable. Many analysts have suggested that concentrating solar power (CSP) could do just that3, 4, 5, 6, 7, 8. Here we systematically test this proposition for the first time. We simulate the operation of CSP plant networks incorporating thermal storage in four world regions where CSP is already being deployed, and optimize their siting, operation and sizing to satisfy a set of realistic demand scenarios. In all four regions, we show that with an optimally designed and operated system, it is possible to guarantee up to half of peak capacity before CSP plant costs substantially increase. Greenhouse gas emissions will need to fall substantially over the coming decades if the worst impacts of climate change are to be avoided, a conclusion reflected in mid-century emissions reduction targets of 80% in numerous political jurisdictions, including California and the European Union9, 10, 11, 12. Given the suite of technologies now available, there is widespread belief that renewable sources of energy, and above all renewable sources of electricity, will have to play an important role in this decarbonization13, 14. Wind and solar power offer an abundant supply potential, but both are intermittent, with their output determined by diurnal and annual cycles, as well as by local weather conditions15, 16, 17. Recent studies have used data with high spatial and temporal resolution to study the feasibility of integrating large amounts of wind and solar within a portfolio of renewable energy sources. They have found it to be possible, but that it requires optimizing the system design across several technologies1, 2, and incorporating excess solar and wind capacity of up to twice the peak power demand if the need for grid level storage is to be avoided18, 19. These factors could make integration difficult in practice, first because of the complexity of optimizing across multiple technologies, and second because the land required for excess renewables capacity may be a binding constraint in densely populated regions, such as Europe or South Asia. Using technologies that either use less land or can be built in remote, sparsely inhabited regions would hence be beneficial20, as would identifying whether there is a single technology that on its own could offer a high level of reliability, so as to give energy system planners and policy-makers greater flexibility with respect to balancing a decarbonized electricity system. We therefore study the reliability of CSP, which can best be deployed in deserts where land-use limitations do not appear to be a constraining factor, and which offers the promise of overcoming intermittency by making use of short-term thermal storage to bridge the day–night cycle and periods of cloudy weather. Some existing CSP plants can already operate at full capacity around the clock in summer6, 7. In winter, or when cloudy conditions are prolonged, however, even these CSP plants need to cease power production. Two well-known strategies can increase the availability of renewable power. First, for all wind and solar technologies, an interconnected fleet taking advantage of anticorrelation between weather at geographically dispersed sites can provide greater availability than a single plant21, 22, 23, 24. Second, for CSP plants specifically, the size of an individual plant’s solar field relative to its power block can be increased, allowing the plant to more rapidly fill its heat storage during sunny conditions. We illustrate the effects of both strategies in Fig. 1 for CSP plants operating in the Mediterranean countries (see Supplementary Fig. 1 for the results in the other regions, Supplementary Fig. 6 for the possible sites and Supplementary Table 2 for plant design parameters). Figure 1a shows hourly generation curves for a hypothetical network of 100 CSP plants in the Mediterranean basin, revealing that there are extended periods in winter when the fleet must operate at or near zero generation. Figure 1b illustrates the effect of including a reserve buffer by doubling the solar collection area of each plant, while maintaining the storage and turbine capacity. This allows individual plants with beneficial conditions at a given time to compensate for adverse weather elsewhere in the system, and improves fleet availability, although as shown in the figure still does not provide 100% reliability. Oversizing comes at a financial penalty because it discards much of the thermal energy collected: assuming 2010 technology costs, the levelized cost of electricity for the case in Fig. 1a is 0.15 USD/kWh, compared to 0.19 USD/kWh in Fig. 1b.
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