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4.6.2. Hydropower expansion in response to increased glacier melt

Landsvirkjun, the national power company of Iceland, has included adaptation to climate change in managing, designing, updating and expanding its assets. Almost all Icelandic glaciers have been losing mass since the early 1990s, and this trend is expected to continue with the warming climate. It has been projected that almost no Icelandic glaciers will be left in 2200. As a result of the increased melting, increased river flows and changes in their seasonal distribution have been observed over the last decades. Further increases in flows are expected in the next 50 years, after which the runoff from glacial melt is expected to decline. Hydropower stands to gain from increased water flow due to climate change induced glacier melt in the coming decades, but reservoir management will have to be adjusted to account for this increased flow.

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Overall inflow volume is projected to increase by an additional 15 % by 2050, compared to 2015. The existing power system can only utilise 30% of that increase. Without increasing installed turbine capacity and reservoir storage at existing hydropower plants, the rest of the increased flow would be spilled over the spillways.

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Landsvirkjun has improved projections of water flows under climate change. Better projections facilitate adaptation measures that minimize unnecessary water spills through the spillways. These measures include modification of reservoir-management plans, installation of additional infrastructure, and/or the re-design of existing infrastructure to manage increased runoff. A co-benefit is increased flood protection, as the reservoirs can function as extra buffer capacity in the case of extreme flooding. Landsvirkjun uses hydrological modelling to project future water flow, taking climate change impacts into consideration. In essence, the management and design of existing and planned assets is adjusted to take advantage of increased glacier flows, based on improved data on current and future flows.

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At the Búrfell plant, improved water flow data were used to plan a capacity increase from 70 MW to 100 MW. This increase was implemented by building a new hydropower plant, which extends the original power capacity and reduces its load. Furthermore, the capacity of the Búðarháls Hydropower Plant, a new project commissioned in 2014, was increased from the originally planned 80 MW to 95 MW in response to climate change.

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Key factors in achieving these results have been a collaboration with other power companies, universities and institutions, the involvement of the Executive Board of Landsvirkjun in the adaptation process, and a step-by-step approach to climate change adaptation. The long-term relevance of this approach is however hindered by the fact that the increased water flow is expected to be temporary. By 2080, the volume of the glaciers is projected to have decreased so much that the flows will start reducing. The current expansion is still economically sound given the project time horizon of 50 years. However, once water flows are returning back to lower levels, the existing hydropower plants may have higher capacity than needed. Still, in the medium run, the improved hydrological modelling has yielded valuable information for decision-making regarding future investment on hydropower plants, leading to is increasing annual revenues. Moreover, increased reservoir capacity installations can ensure increased general flood protection. The most extreme flood events in Iceland are glacial outburst floods due to volcanic eruptions.

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