Optimal and robust combination of energy storage systems for massive integration of renewable energy - a focus on hydropower/hydrostorage solutions
Final Report Abstract
To reduce the environmental footprint of our energy-hungry society, a transition from conventional to renewable energy sources is required. Energy storage systems (ESS) can help buffer the weather-driven fluctuations and uncertainties from renewable generation. Our project studied the optimal combination of storage technologies, including hydropower solutions, with a newly developed optimization tool for electricity expansion planning. The results have widely been made public in over 30 journal and conference contributions, as well as in invited talks, a PhD dissertation, and an open-source model, as a product of teamwork surrounding this project. We would like to highlight the following findings: 1. The model we developed, called LEELO (Long-term Energy Expansion Linear Optimization), is open-source and available on a permanent repository (Zenodo). LEELO’s advantages, compared to other tools, are the endogenous modeling of power reserves and energy autonomy, the detailed modeling of hydropower cascades, and its multi-objective formulation taking into account dimensions beyond costs. We recently extended it to –what we think is the most complete model for– South America. It now comprehends 43 nodes, 8760-time steps (a fully resolved sequential year), and over 30 technologies. 2. When comparing the results from traditional planning tools to our multi-service model (with endogenous equations for power reserves and energy autonomy), we found that the investment recommendations for storage technologies differ significantly. In particular, storage power capacities and storage energy capacities increase up to 1.6 and 3.2 times, when taking into account these services (with most impact attributed to the provision of energy autonomy). Also, the resulting storage mix is profoundly affected: in our multiservice model, batteries are substituted to a large extent by hydrogen, a result which might be even more relevant now for the green hydrogen discussion. 3. To integrate renewable generation, we need flexibility, also stemming from hydropower. However, if hydropower is operated with too much flexibility, it can provoke ecosystem harm because the generated power directly translates into strong and unnatural flow fluctuations downstream (hydropeaking). We looked at the system-wide tradeoffs between an ecological hydropower operation, new transmission lines, and costs. And we found that the tradeoff is soft in many regions, meaning that for little extra costs, an ecologically-sound hydropower operation can be achieved at the same time as requiring little new transmission capacities for fully renewable systems. In a more localized study, batteries showed to soon be cost-effective to mitigate hydropeaking by coupling them to hydropower plants. 4. Another product on refining the modeling of hydro storage solutions is a method for mapping the economic potential of pumped hydro energy storage. We applied this method to South America to derive the techno-economic potentials of pumped hydro for diverse (pumped hydro) topologies. 5. Finally, we applied the most recent version of LEELO to plan the transition of South America’s electricity sector, confirming that the road to sustainability is not only technically feasible but economically the most effective solution. Furthermore, South America is attractive for producing green hydrogen. When doing so, the overall average electricity costs decrease, due to the synergies that hydrogen offers for integrating renewable generation; hydrogen here is a non-regret option. As lines for future research, we propose to increase the understanding of flexibility from hydropower and the water-energy nexus, to plan the transition of the other energy sectors with a focus on green hydrogen technologies and desalination plants, and to address the deep uncertainty inherent to planning large-scale multi-national infrastructure.
Publications
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Düsseldorf, Germany: International Renewable Energy Storage (IRES) Conference. Considering ecological sustainability in planning the future electricity supply of Chile – how much more does it cost?
Junne T, Haas J, Moreno-Leiva S, Naegler T, Nowak W
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New Orleans, USA: American Geophysical Union Fall Meeting. Agrivoltaic systems in Latin America: Mapping the synergies for climates and crops
Campoverde A, Haas J, Reyes L, Marrau H, Jung D
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New Orleans, USA: American Geophysical Union Fall Meeting. Exporting sunshine: Planning South America’s energy transition with hydrogen exports
Galván A, Haas J, Moreno-Leiva S, Nowak W, Palma R, Breyer C
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New Orleans, USA: American Geophysical Union Fall Meeting. Planning South America's energy transition: Hydropower inflows and spatial resolution
Galván A, Haas J, Bustamante M, Mendoza P, Olivares M, Marques G
