Letsi is a 486 MW hydro power station in Norrbotten, Sweden. It is operated by 100% Vattenfall. Based on reported annual generation of 2,087 GWh, it can supply roughly 596,314 homes. It ranks #9 of 168 Sweden power plants by installed capacity. Commissioned in 1967, it is around 59 years old — an older, legacy facility. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, hydro supplies about 40.0% of Sweden's electricity; the national grid averages 35 gCO₂/kWh (98.8% low-carbon) (2025).
Plant data: WRI Global Power Plant Database (CC BY 4.0), id WRI1002101.
Annual generation (GWh), WRI Global Power Plant Database (CC BY 4.0).
Operated by 100% Vattenfall. All plants by this company →
This hydro plant converts the energy of falling or flowing water through hydro turbines. It sits in a subarctic (boreal) climate (Köppen Dfc) — Northern Hemisphere, latitude 66.5°N — which shapes how much energy it can produce and how its output varies through the year.
Monthly mean temperature
Heating degree-days here run 161% above the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.
Climate heat-demand index: 99/100 — this site sits in the top third of the power plants we cover by heating degree-days.
In colder climates, uninsulated hot equipment (boilers, turbines, valves, steam lines) loses proportionally more heat to ambient air — exactly the loss Inzonex modular insulation is designed to cut.
Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.
The #4 largest hydro power plant of 142 in Sweden by capacity.
Sweden has 142 hydro power plants in this dataset, together about 12,823 MW of capacity.
Coordinates 66.5024, 20.3797 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
