Small, airborne and traditional wind: Techniques
From Dutch drainage mills to kites and rotor-sail ships
What this tab covers The methods used to capture this energy: how each works, and how they compare on efficiency, cost, life-cycle emissions, maturity and scale.Wind captured at small scale, at altitude or as motion: niche methods that reach places large turbines cannot.
Comparison
| Method | Efficiency | Cost | Life-cycle emissions | Maturity | Scale |
|---|---|---|---|---|---|
| Vertical-axis turbines (Darrieus, Savonius)211 | Savonius power coefficient mostly 5-30%; best modified designs about 40% | No separate benchmark | No specific life-cycle studies found | early commercial | Small numbers, mainly on buildings |
| Small and micro turbines3459 | 14% average capacity factor (US, 2025); 29.5-32.5% assumed for NREL's reference sites | USD 9,630/kW (US 2025, 5 projects reporting); USD 8,910/kW average 2016-2025; LCOE USD 174-240/MWh (NREL reference projects, 2023 USD) | No small-turbine figure found; onshore wind median 11 g CO2e/kWh (IPCC AR5) | mature | 1.7 MW (737 turbines) installed in the US in 2025 |
| Airborne wind: kites and tethered drones6 | No reliable field data; SkySails' Mauritius unit delivered a little under 100 kW | Competitive above about USD 0.30/kWh diesel power (developer claim) | No studies found | pilot | Five SkySails units sold by 2022; Google's Makani closed in 2020 |
| Traditional windmills8 | No reliable figure found | Not applicable (heritage use) | Not studied | mature | Heritage use, e.g. the 17 drainage mills at Kinderdijk built in 1738-1740 |
| Sails, rotor sails, kite sails and wing sails7 | 5-20% of a ship's propulsive energy for retrofits | No public benchmark found | Over 100,000 t CO2 a year saved across the fleet (industry association) | early commercial | More than 100 large cargo ships with over 230 systems by mid 2026, up from 21 in May 2022 |
Small turbines cost about 9-10 times as much per kW as utility-scale onshore wind (calculated from USD 8,910-9,630/kW against USD 976/kW, IRENA 2025) and produce less per kW, so they suit off-grid sites where diesel is the alternative. Airborne wind remains at pilot stage. Wind-assisted ships are growing fastest, because every tonne of fuel saved is a direct cost and emissions saving.
How each method works
Vertical-axis turbines (Darrieus, Savonius)The rotor turns on a vertical shaft, so it takes wind from any direction. Savonius rotors are scoops pushed by drag; Darrieus rotors use lift-generating aerofoil blades.211
Small and micro turbinesHorizontal-axis turbines up to 100 kW on masts at homes, farms and remote sites.3459
Airborne wind: kites and tethered dronesA kite flown in figure-of-eight loops pulls a tether off a drum driving a ground generator, then is reeled in and the cycle repeats.6
Traditional windmillsSails on a timber or brick tower turn a shaft driving millstones, saws or drainage pumps directly.8
Sails, rotor sails, kite sails and wing sailsRotor sails (spinning cylinders using the Magnus effect), rigid or suction wings and kites add thrust to a ship's engine.7
Sources
- A review on the performance of Savonius wind turbines (Akwa, Vielmo and Petry, Renewable and Sustainable Energy Reviews 16(5), 3054-3064) Elsevier, 2012
- Distributed Wind Energy Technologies Data Update: 2026 Summary (calendar year 2025 data) Pacific Northwest National Laboratory, 2026
- Cost of Wind Energy Review: 2024 Edition (NREL/PR-5000-91775), reference projects in 2023 USD National Renewable Energy Laboratory, 2025
- Renewable Power Generation Costs in 2025 (Executive summary, Figure S1) IRENA, 2026
- After a shaky start, airborne wind energy is slowly taking off Yale Environment 360, 2022
- Wind-powered cargo ships sail past the 100-vessel milestone American Journal of Transportation, 2026
- Mill Network at Kinderdijk-Elshout Werelderfgoed Nederland (Dutch World Heritage foundation), 2024
- Climate Change 2014: Mitigation, Annex III Technology-specific cost and performance parameters, Table A.III.2 (life-cycle emissions, min/median/max) IPCC AR5 Working Group III, 2014
- Investigation of performance enhancements of Savonius wind turbines through additional designs (Altan and Gultekin, Processes 11(5), 1473), review MDPI, 2023