Vätgasproduktionens påverkan på lokalt havsklimat : Modellering av punktutsläpp i en grund vik

Sammanfattning

Shipping accounts for a significant proportion of global greenhouse gas emissions, and a transition is currently underway towards alternative fuels with a lower environmental impact. One such alternative is hydrogen, which can be a carbon-neutral fuel if produced from desalinated seawater via electrolysis powered by fossil-free energy. By-products arising from seawater desalination include brine, and from electrolysis plants, hot water from the cooling system. To keep costs down, it is desirable to locate these plants adjacent to the sea and to discharge these by-products into the adjacent water. However, discharging hot water and brine into a confined coastal area may affect local conditions. This study therefore aims to investigate the potential impact arising in a shallow bay in the Baltic Sea as a result of point source discharges of brine and hot water along the shoreline. To investigate this, a review was first conducted of existing technologies for desalinating salt water, as well as the composition of the resulting by-product in terms of salinity and volume. To investigate the spread of point source discharges, the Mike 3 FM Flow Model simulation tool was used. The model was constructed using Burgsviken on Gotland as a case study area, initial data from databases, data from the literature and other external sources. The simulations showed a significant temperature increase in the bay, primarily in the inner part closest to the point source discharge. The greatest temperature increase occurred adjacent to the discharge, with a maximum increase of 8.3°C and a linear monthly increase of 3.6°C. The lowest increase occurred at the far end of the bay, with a linear increase of 0,04°C per month. However, the effect of the brine discharge did not affect the natural salinity of the bay; instead, a decrease in salinity was observed, which is believed to be due to the inflow of fresh water.