UK financed research programmes are addressing the global challenges of international development. Recent break throughs in online computer-assisted simulation and design now allow us to assess in increasing detail the consequences of alternative energy infrastructure choices as the world pivots towards a low carbon future.
Hydropower is thrust front and centre as a potentially low carbon generation technology in a world of changing river flows and increasing competition for water both between sectors and between countries. The International Energy Agency (IEA) has highlighted the potential future role of sustainable hydropower in meeting energy demands and estimated that global hydropower capacity is set to increase by 17%, or 230GW, between 2021 and 2030. This is equivalent to 1150 new dams assuming an average of 200MW each.
More broadly, over 75% of new hydropower capacity worldwide through 2030 is expected to come in the form of large-scale projects in Asia and Africa commissioned by state-owned enterprises. In parallel, electricity grids are facing the challenge of delivering grid ancillary services and meeting peak demands, in grids increasingly dominated by intermittent renewables.
Complexity
One word summarises the emerging context – complexity. Hydropower developers have traditionally needed to analyse and take account of multiple water users within a river system. Now, they also need to take account of the precise needs of the electricity system. Any adjustments to dam design and/or operations have increasingly far-felt impacts on both systems, yet the technical modelling and simulation tools able to analyse the cross-sectoral implications and choices available have not been available until now.
New approaches and tools
The FutureDAMs project (Future Design and Assessment of water-energy-food-environment Mega Systems) led by the University of Manchester has successfully integrated energy and river basin modelling and simulation, working with partners on the Eastern Nile and in Ghana.
This tool is online (www.waterstrategy.org) and intends to help coalitions of planners from different sectors to work collaboratively to achieve positive and sustainable societal outcomes. The FutureDAMS approach and tools build on research and development undertaken in the last decade in collaboration with UK planners and water utilities, which will invest on the order of £50 billion to meet water supply needs up to 2050.
Simulating complex multi-resource systems (water, energy, food, and environment) helps better understand such systems and improve their design, management, and operation. The simulation models can be linked to multi-objective artificial intelligence design algorithms that help identify the synergies and trade-offs between different objectives for the best performing portfolios of interventions. This shows how an incremental change made to improve one objective and its co-benefits may come at the cost of one or more other different goals. The resulting multi-criteria trade-off analysis assists stakeholders in managing river systems, infrastructure and energy services. These methods can also explore strategies under multiple future scenarios to identify robust solutions that work acceptably over a range of possible futures.
Performance metrics within the model quantify the benefits generated by the built and natural infrastructure and allow producing strategic planning studies that, for example:
● Minimise capital costs.
● Minimise operating costs.
● Minimise load curtailment and C02 emissions.
● Minimise eco-hydrological modifications.
● Maximise basin crop yields from irrigation and hydro-ecological benefits.
Power systems typically treat water as a fixed input while water models allocate water to hydropower without considering energy system needs. Identifying advantageous integrated water-energy systems involves both a technical component and a “political” component, where stakeholders can judge for themselves the acceptability and balanced outcomes of different investment or operational interventions.
A country scale case study – Ghana
We consider the case of Ghana, where growing energy and water demands encourage a rethink of how the integrated system works. Whilst some FutureDAMS case studies considered where to build new dams and how to size them, this particular study asked the question how could existing hydropower dams nationally be re-operated to enable more low-emission solar and wind (intermittent renewables) generation.
Figure 3 compares many optimised water-energy infrastructure portfolios in Ghana; only six performance metrics are considered for simplicity. The interactive plot allows imposing limits on any of the metrics (eg minimal load curtailment, or maximum acceptable CO2 emissions from the energy system as a whole, or from new assets). This helps identify sets of infrastructure assets that meet certain requirements and demonstrates their potential impacts on other sectors. Depending on the case study, various numbers of metrics will be tracked. The parallel axis plots like the one shown in figure 3 can display between two to dozen metrics, although most studies consider three to 10. Additional metrics can be added at the request of stakeholders provided the performance measure can be evaluated by the multi-sector simulator.
Understanding
This approach can optimise investment in future assets but can also investigate changes needed to the operation of existing hydropower assets as grid energy demand changes with increasing penetration of renewables. The hydropower industry is already promoting pumped storage facilities as a way of storing off-peak or spilled power from intermittent renewables. However, for countries with large hydropower systems, such as the 1020MW Akosombo Dam in Ghana, the potential impact on daily operations is also considerable.
Reoperating a large hydropower dam will disrupt other water users in the basin as base load and the current seasonal influences are replaced with a more daily and erratic hydrological regime as hydropower complements intermittent renewables. Understanding how more variable operation affects other water users, and what limits this may impose on hydropower’s flexibility, will become a critical part of hydropower operators’ tool kits.
The FutureDAMS system evaluation and design approach illustrates how changing dam operations may impact other water users within the Volta basin in Ghana. As is to be expected, 80% penetration of renewables leads to significant hydro-ecological alteration (see figure 4).
Future work
The methods developed in FutureDAMS’ multi-sector assessment linked to strategic (optimised) design and trade-off analysis, allows hydropower planners and investors, river basin agencies and country ministries to get more benefits out of interlinked river basin-energy systems and reduce conflicts between water users and with the environment. The use of new online collaborative tools and interactive web-based graphics can facilitate effective and efficient engagement with interested stakeholders.
Today’s tools are a step change from what was available in the past; but tools alone cannot change how human-natural systems evolve. Much work remains to be done on how to integrate such approaches into planning and governance processes and embed them within institutions. Because the incentives are high, and the challenges (climate change, increasing access to electricity, achieving net zero) severe, there is considerable incentive to expand the use of the strategic design approach described here. This can only be achieved through industry, policymakers and planners working collaboratively to maximise the opportunities presented by interconnected energy and river basin systems. ●
Authored by:
Jose M. Gonzalez – Research Associate at the Department of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester.
Jamie Skinner – Principal researcher, Natural Resources at International Institute for Environment and Development and FurtureDAMS Capacity Director.
Julien J. Harou – Chair in Water Engineering at the Department of Mechanical, Aerospace and Civil Engineering, The University of Manchester and FutureDAMS Research Director
