A GIS analysis of electricity production using pressure retarded osmosis in the Nordic countries
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Osmotic power is an unexploited source of renewable energy that is based on mixing two types of water with a different salinity gradient. Osmotic power production (if life-cycle analysis of all necessary components is ignored) does not emit greenhouse gases to the atmosphere as opposed to fossil fuels employed in electricity production today, thus osmotic power does not systemically contribute to global warming and climate change.
This thesis investigates the annual electricity production potential in the Nordic countries using pressure retarded osmosis (PRO) as a method of producing electricity. PRO is a controlled process of mixing two types of water – the feed and the draw – in a water tank equipped with a semi-permeable membrane that separates the solutions and allows for transfer of water in one direction only – feed to draw. Due to osmosis, the draw solution (seawater) draws the feed (river water) through the membrane. This overpressures the draw which is used as the force to propel a turbine. The greater the difference in salinity of the two waters, the greater the power output per volume of mixed waters. The magnitude of osmotic power production is limited by the river discharge. This thesis focuses on a scenario where fresh water discharged by a river is mixed as the feed with seawater available at a given estuary as the draw.
In the Nordic countries, PRO power generation opportunities were analysed using a geographic information system (GIS) with parameters like seawater salinity, annual average water discharge as the feed, regional impact of climate change on precipitation, and contemporary hydropower and river basin management. With respect to thermo-dynamics, power generation using PRO proves most sensible in Norway and on the west coast of Jutland (Danish mainland) where the sites for hypothetical osmotic power-plants were suggested as estuaries. Estuaries were categorized by the level of nature protection, hydropower management and river basin management in the area (if any).
For each estuary where seawater has salinity 30 psu or greater, the annual power production potential was quantified at the applied pressure of 9 bars. As a technological point of reference, I assume an ideal osmosis process (which presumes no salt accumulation inside of the membrane) in a system with 81% efficiency. The membrane technology applied in all cases is a thin-film hollow composite membrane with a water permeability of A = 9.22 . 10-12 . m3 . m-2 . s-1 . Pa-1.
The annual work potential in Norway and on the west coast of Jutland outside of environmentally protected areas is 88.87 TWh and 0.13 TWh, respectively. There are another 12.94 TWh and 0.82 TWh within nature protected zones of Norway and Jutland, respectively, which gives around 102.76 TWh altogether. The total membrane area necessary to utilize the annual average water discharge of all investigated rivers is 1190 km2. Due to climate change between 2021 and 2050, there will be relatively more precipitation in the region, therefore the potential for osmotic power production in the region is going to grow as more feed will be available. Out of the total annual potential identified in Norway (101.81 TWh), 13% is situated in areas with an active river basin management and 62% lies in areas with some form hydropower management up the stream.
Place, publisher, year, edition, pages
2015. , 51 p.
Examensarbete vid Institutionen för geovetenskaper, ISSN 1650-6553 ; 264
osmotic power, pressure retarded osmosis, sustainable development, carbon neutral renewable energy, GIS, NORDEL
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:uu:diva-259456OAI: oai:DiVA.org:uu-259456DiVA: diva2:844290
Master Programme in Sustainable Development
2015-06-05, Hamberg, Villavägen 16, Uppsala, 09:00 (English)
Höök, Mikael, DocentNygren, Else, docent, TeknDDavidsson, Simon, M. Sc.