Coal power plant in New Hampshire, United States of America. Approximate location 43.1411, -71.4692.
CoalNew HampshireUnited States of America
Merrimack is a 496 MW coal power station in New Hampshire, United States of America. It is operated by Granite Shore Power. Based on reported annual generation of 302 GWh, it can supply roughly 86k homes. It ranks #1289 of 10,938 United States of America power plants by installed capacity. Commissioned in 1966, it is around 60 years old — an older, legacy facility. In context, coal supplies about 16.3% of United States of America's electricity; the national grid averages 384 gCO₂/kWh (43.0% low-carbon) (2025).
Plant data: WRI Global Power Plant Database (CC BY 4.0), id USA0002364.
Known, modelled and calculated values are kept separate. Missing fields are shown as unavailable.
The capacity and/or fuel fields on this page include a source-backed provenance label from GEM, an official registry, Wikidata, OSM, or a cross-source match.
capacity: Wikidata P2109 nameplate capacity; fuel: WRI source-record fuel
At 496 MW, Merrimack is below the median coal plant in United States of America (558 MW). Coal plants burn pulverised coal to raise high-pressure steam for a turbine; they run as baseload but are the most carbon-intensive mainstream source and the first targeted for retirement or efficiency retrofits.
Capacity comparison computed from the WRI Global Power Plant Database; fuel-type context is general engineering background.
Annual generation (GWh), WRI Global Power Plant Database (CC BY 4.0).
Operated by Granite Shore Power.
This coal plant burns coal to raise high-pressure steam that spins a turbine-generator. It sits in a warm-summer humid continental climate (Köppen Dfb) — Northern Hemisphere, latitude 43.1°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 57% 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: 82/100 — this site sits in the top third of the power plants we cover by heating degree-days.
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.
For a plant’s outdoor hardware — heat-recovery steam generators (HRSG), expansion joints, valves, flanges and their insulation — the local climate sets how fast unprotected steel and coatings degrade. This site sits in a moderately corrosive environment (estimated ISO 9223 class C3 — Medium), with thermal cycling the leading environmental stress.
Higher environmental severity is exactly where protective removable insulation pays back most: a sheltered micro-climate slows corrosion, UV and thermal-cycling damage and extends outdoor hardware service life. This is an indicative site-climate context — not a condition assessment of any specific plant or operator.
Indicative estimate via the ISO 9223:2012 informative method (atmospheric corrosivity from temperature, time-of-wetness and airborne salinity), using WorldClim climate normals, the Köppen-Geiger class and coast distance. Indicative, not a measured corrosion rate.
The #423 largest coal power plant of 802 in United States of America by capacity.
United States of America has 802 coal power plants in this dataset, together about 621,194 MW of capacity.
Coordinates 43.1411, -71.4692 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
Merrimack is a 496 MW source-record coal power plant in New Hampshire, United States of America, commissioned in 1966.
Merrimack generates about 302 GWh of electricity per year.
Its output is enough to supply roughly 86,200 homes.
Merrimack is operated by Granite Shore Power.
