# Small, airborne and traditional wind: Techniques

From Dutch drainage mills to kites and rotor-sail ships

Source page: https://www.materialinsights.org/energy/e_small_wind/techniques/

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)**^[2](https://doi.org/10.1016/j.rser.2012.02.056)^[11](https://www.mdpi.com/2227-9717/11/5/1473) | 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 turbines**^[3](https://www.pnnl.gov/sites/default/files/media/file/DW%20Energy%20Tech%20Data%20Update%20-%202026%20Summary.pdf)^[4](https://www.nrel.gov/docs/fy25osti/91775.pdf)^[5](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2026/Jul/IRENA_TEC_RPGC_in_2025_2026.pdf)^[9](https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7) | 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 drones**^[6](https://e360.yale.edu/features/after-a-shaky-start-airborne-wind-energy-is-slowly-taking-off) | 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 windmills**^[8](https://werelderfgoed.nl/en/world-heritage/mill-network-kinderdijk-elshout) | 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 sails**^[7](https://www.ajot.com/news/wind-powered-cargo-ships-sail-past-the-100-vessel-milestone) | 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.^[2](https://doi.org/10.1016/j.rser.2012.02.056)^[11](https://www.mdpi.com/2227-9717/11/5/1473)
**Small and micro turbines**

Horizontal-axis turbines up to 100 kW on masts at homes, farms and remote sites.^[3](https://www.pnnl.gov/sites/default/files/media/file/DW%20Energy%20Tech%20Data%20Update%20-%202026%20Summary.pdf)^[4](https://www.nrel.gov/docs/fy25osti/91775.pdf)^[5](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2026/Jul/IRENA_TEC_RPGC_in_2025_2026.pdf)^[9](https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7)
**Airborne wind: kites and tethered drones**

A 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](https://e360.yale.edu/features/after-a-shaky-start-airborne-wind-energy-is-slowly-taking-off)
**Traditional windmills**

Sails on a timber or brick tower turn a shaft driving millstones, saws or drainage pumps directly.^[8](https://werelderfgoed.nl/en/world-heritage/mill-network-kinderdijk-elshout)
**Sails, rotor sails, kite sails and wing sails**

Rotor sails (spinning cylinders using the Magnus effect), rigid or suction wings and kites add thrust to a ship's engine.^[7](https://www.ajot.com/news/wind-powered-cargo-ships-sail-past-the-100-vessel-milestone)

#### Sources

1. [A review on the performance of Savonius wind turbines (Akwa, Vielmo and Petry, Renewable and Sustainable Energy Reviews 16(5), 3054-3064)](https://doi.org/10.1016/j.rser.2012.02.056) Elsevier, 2012
2. [Distributed Wind Energy Technologies Data Update: 2026 Summary (calendar year 2025 data)](https://www.pnnl.gov/sites/default/files/media/file/DW%20Energy%20Tech%20Data%20Update%20-%202026%20Summary.pdf) Pacific Northwest National Laboratory, 2026
3. [Cost of Wind Energy Review: 2024 Edition (NREL/PR-5000-91775), reference projects in 2023 USD](https://www.nrel.gov/docs/fy25osti/91775.pdf) National Renewable Energy Laboratory, 2025
4. [Renewable Power Generation Costs in 2025 (Executive summary, Figure S1)](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2026/Jul/IRENA_TEC_RPGC_in_2025_2026.pdf) IRENA, 2026
5. [After a shaky start, airborne wind energy is slowly taking off](https://e360.yale.edu/features/after-a-shaky-start-airborne-wind-energy-is-slowly-taking-off) Yale Environment 360, 2022
6. [Wind-powered cargo ships sail past the 100-vessel milestone](https://www.ajot.com/news/wind-powered-cargo-ships-sail-past-the-100-vessel-milestone) American Journal of Transportation, 2026
7. [Mill Network at Kinderdijk-Elshout](https://werelderfgoed.nl/en/world-heritage/mill-network-kinderdijk-elshout) Werelderfgoed Nederland (Dutch World Heritage foundation), 2024
8. [Climate Change 2014: Mitigation, Annex III Technology-specific cost and performance parameters, Table A.III.2 (life-cycle emissions, min/median/max)](https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7) IPCC AR5 Working Group III, 2014
9. [Investigation of performance enhancements of Savonius wind turbines through additional designs (Altan and Gultekin, Processes 11(5), 1473), review](https://www.mdpi.com/2227-9717/11/5/1473) MDPI, 2023

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_small_wind/index.md)
- [Overview](https://www.materialinsights.org/energy/e_small_wind/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_small_wind/correlation/index.md)
- [Efficiency](https://www.materialinsights.org/energy/e_small_wind/efficiency/index.md)
- [Resources and labour](https://www.materialinsights.org/energy/e_small_wind/resources/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_small_wind/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_small_wind/links/index.md)