The role of glacier retreat for Swiss hydropower production

TLDR: In this article, the authors provided the first regional quantification for the share of Alpine hydropower production that directly relies on the waters released by glacier mass loss, i.e. on the depletion of long-term ice storage that cannot be replenished by precipitation in the coming decades.

About: This article is published in Renewable Energy.The article was published on 2019-03-01 and is currently open access. It has received 60 citations till now. The article focuses on the topics: Glacier mass balance & Glacier.

Figures

Figure 8 (corrected): Spatial distribution of the hydropower production from glacier mass loss; a) hydropower production from glacier mass loss in GWh yr -1 for the period 1981-2010, b) for the period 2040-2060 based on GloGEM simulations, c) ratios ρij for the period 1981- 2000, d) ratios for the period 2040-2060 based on GloGEM simulations.

Table 5: Estimated average HP ratios from glacier melt, CH , estimated either from ratios of net glacier melt to total discharge (labeled discharge ratios) or from glacier-averaged electricity coefficient (see Table 3), labeled EC. Confidence limits (given in brackets) can be calculated for the EC method only; discharge-based estimations are weighted averages over the schemes, with weights corresponding to the expected annual production of each scheme. For the simulations, the net ice melt corresponds to the melt between two simulation time periods.

Figure 1: Swiss hydrological regimes in terms of the ratio between mean monthly streamflow and the mean annual streamflow (denoted as Q); a) for south of the Alps, b) for north of the Alps. Data source: (Pfaundler and Schönenberger, 2013).

Figure 2: Distribution of main types of HP powerhouses according to the nine main Swiss river catchments; the Limmat and Reuss feed into the Aare river, which itself feeds into the Rhine river; own representation based on the HP powerhouse type and feeding catchment contained in (WASTA, Swiss Federal Office for Energy, 2015); other data sources: glacier outline (Fischer et al., 2014), digital elevation model (SwissTopo, 2005), lake vector data: (SwissTopo, 2008), catchment vector data: Swiss Hydrological Atlas HADES (Schädler and Weingartner, 2002)

Table 1: Overview of Swiss annual hydropower production (1980 – 2016), including energy consumption for water pumping from lower to upper reservoirs (Swiss Federal Office for Energy, 2016).

Figure 7: Annual glacier mass loss and corresponding hydropower production as a function of scheme catchment elevation for the period 1981-2000; a) annual glacier mass loss in mm yr -1 (log-scale) b) estimated hydropower production from annual glacier mass loss (multiplied with the electricity coefficient j ) in GWh yr -1 .

Frequently asked questions

Q1. What are the contributions mentioned in the paper "The role of glacier retreat for swiss hydropower production (running title: glacier retreat and swiss hydropower)" ?

In this paper, the first quantification of how hydropower production in an Alpine country, Switzerland, depends on annual glacier mass loss is presented. 

Q2. What future works have the authors mentioned in the paper "The role of glacier retreat for swiss hydropower production (running title: glacier retreat and swiss hydropower)" ?

The simulations suggest that, on a Swiss-wide basis, HP might receive a significantly lower share of water from annual glacier mass loss already in the near future. Compared to 1981- 2000, the future simulations predict a reduction of the HP ratios from 3. 1 % to 2. 5 % for the period 2040-2060 and to 1. 2 % for 2070-2090. This share of HP from glacier mass depletion has to be put into relation to other changes expected for HP in the near future. The presented analysis shows, however, that for most schemes, the future temporal pattern of glacier melt water inflow will result in a redistribution of less than 10 % of the total available water. 

Q3. What is the effect of the warming on streamflow in non-glacierized catchments?

For non-glacierized catchments, the annual flow might slightly decrease by 2100 due to a warming-related increase of evapotranspiration and a potential (small) decrease of precipitation. 

Q4. What is the key variable to understand the interplay of glacier melt water and HP?

The temporal distribution of streamflow, or the streamflow regime, is key to understand the interplay of glacier melt water and HP. 

Q5. How much of the world’s electricity is produced by hydropower?

Hydropower represents around 55% of the Swiss electricity production, which in 2015 was 61.6 TWh (Swiss Federal Office for Energy, 2017c). 

Q6. What is the timing of maximum glacier melt volumes in mountainous catchments?

In mountainous catchments, significant shifts in the hydrological regime are expected with increasing streamflow in spring and early summer and declining streamflow in July and August (Horton et al., 2006;Finger et al., 2012;Addor et al., 2014). 

Q7. What is the implication of climate warming for glacier-influenced storage HP?

A third implication of climate warming for glacier-influenced HP is a potential modification of the year-to-year variability of available water. 

Q8. What might affect glacier-influenced storage HP schemes?

This might in particular affect glacier-influenced storage HP schemes that usually have a high number of water intakes (e.g. the Grande Dixence scheme has 100 km of tunnels to route the water of 75 water intakes to its main reservoir; (Grande Dixence, 2010). 

Q9. What is the future of glacier mass loss?

For the future, the GloGEM simulations predict that 55% and 79% of the 2010 glacier volume will be lost by 2040-2060 and 2070-2090, respectively (Table S3). 

Q10. How many headwater catchments are used in the Swiss HP schemes?

On average, the water from the 134 headwater catchments is used in 12 HP stages, with 12 headwater catchments that are not part of a larger production network.