{"openapi":"3.1.0","info":{"title":"Hydropower API","version":"1.0.0","description":"Hydroelectric-power engineering maths as an API, computed locally and deterministically. The power endpoint computes the electrical power a hydro plant generates with P = ρ·g·Q·H·η, from the water flow rate, the net head (the effective drop), the overall turbine-generator efficiency (typically 0.80–0.92) and the water density, returning both the gross power at 100 % efficiency and the net electrical output. The sizing endpoint inverts the relation to size a scheme — given a target power it solves the flow rate needed at a known head, or the head needed at a known flow, Q = P/(ρ·g·H·η). The annual-energy endpoint computes the yearly energy from the rated power and a capacity factor (typically 0.3–0.6 for hydro, accounting for water availability and downtime), E = P × 8760 h × capacity factor, and an optional revenue from an electricity price. Flow is in cubic metres per second, head in metres, efficiency 0–1, power in watts, kilowatts and megawatts. Everything is computed locally and deterministically, so it is instant and private. Ideal for renewable-energy, micro-hydro, civil-engineering, feasibility and sustainability app developers, run-of-river and reservoir tools, and energy education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is hydroelectric generation; for wind-turbine power use a wind-power API, for solar resource a solar API and for pump (energy-consuming) duty a pump API.","contact":{"name":"PremiumApi","url":"https://www.oanor.com/by/premiumapi"}},"servers":[{"url":"https://api.oanor.com/hydropower-api","description":"oanor gateway"}],"tags":[{"name":"Hydropower"},{"name":"Meta"}],"components":{"securitySchemes":{"oanorKey":{"type":"apiKey","in":"header","name":"x-oanor-key","description":"Get your key at https://www.oanor.com/developer/keys"}}},"security":[{"oanorKey":[]}],"paths":{"/v1/annual-energy":{"get":{"operationId":"get_v1_annual_energy","tags":["Hydropower"],"summary":"Annual energy","description":"","parameters":[{"name":"power","in":"query","required":false,"description":"Rated power (kW)","schema":{"type":"string"},"example":"1667"},{"name":"flow_rate","in":"query","required":false,"description":"Or flow (m³/s)","schema":{"type":"string"}},{"name":"head","in":"query","required":false,"description":"with head (m)","schema":{"type":"string"}},{"name":"capacity_factor","in":"query","required":false,"description":"Capacity factor (0–1)","schema":{"type":"string"},"example":"0.5"},{"name":"electricity_price","in":"query","required":false,"description":"Price per kWh","schema":{"type":"string"},"example":"0.10"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"note":"Annual energy = rated power × 8760 h × capacity factor. 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