EDT domain: d01_renewable_energy_storage
Definition
Small- to community-scale wind turbines convert wind kinetic energy to electricity for on-site/community use. Scope here is the micro (~1 kW) to community (tens–hundreds of kW) range — the model’s small_wind technology — not utility wind farms. Output is non-dispatchable (varies with wind), so wind pairs with storage and/or a complementary source. It is the NI engine’s secondary electricity generator after solar PV, gated on a viable wind resource. OT_062
Types & scale
- Micro (~1 kW): single-dwelling; the dominant NZ domestic turbine size. OT_062
- Small / community (tens–hundreds of kW): community arrays; e.g. Chatham’s 3× Vestas V27 at 225 kW each (675 kW). URL_012
- Horizontal-axis (HAWT) is standard; siting needs clean, unobstructed wind (ridgelines, exposed coast).
Horizontal- vs vertical-axis (HAWT vs VAWT)
- HAWTs are the standard. VAWTs are less aerodynamically efficient — power coefficient Cp ~0.15–0.30 vs ~0.35–0.45 for HAWT; their advantages (omnidirectional, lower profile, simpler mechanics) are mechanical, not yield. CR_013
- At NZ’s typically low mean-wind sites, low wind caps output regardless of axis, and building/roof-mounting is a recognised failure mode (UK EST field trials: building-mounted <8% CF). VAWTs do not improve yield at low-wind sites. CR_013
- Model decision: a VAWT technology will not be added on benchmark evidence alone — a supplier datasheet (rated power, Cp, CF at NZ wind speeds) is required first (RT_202). CR_013
- First VAWT supplier datasheet now in hand (RT_202 — advanced, not resolved): the Aeolos-V 10kW — a 3-blade aluminium H-rotor VAWT, 10 kW rated / 12 kW max, 6.0 × 5.5 m rotor (≈33 m² swept, derived), cut-in 2.5 m/s, rated 11 m/s, survival 52.5 m/s; manufacturer AEP 15,026 kWh @ 5 m/s (≈17% CF, derived), ≈60% CF only at a 10 m/s mean site. But it is an uncertified marketing sheet with no Cp, no stated CF/wind-distribution basis and no price, so the model decision above still stands — a single uncertified source with no cost does not justify adding a VAWT to the engine. DS_004
NZ resource (capacity factor)
- Small-wind capacity factor mapped for all 16 NZ regions — typically ~10–30%, strongly site-dependent (exposure, terrain). Good-site ceiling ~25–30% of rated output; international year-long trials run lower (UK EST free-standing ~19%; only ~7.5% of 173 sites exceeded 10% CF). Pilot example: Tasman P50 ≈ 0.10. CR_013 OT_062
- The engine reads
@wind_cfper region (thesmall_windproduces-flow =8760 × wind_cf); 8 of 16 regions are still derived estimates (gap, RT_140). CR_013 - National deployment outlook (EECA): wind ~6% of NZ electricity (2021) → 20–34% by 2035, modelled as the largest single source by 2050; domestic turbines ~1 kW, largest onshore NZ 4.3 MW. Wind Energy Return on Carbon ≈ 56× gas / 97× coal. URL_013
- Wind-resource data layer (to source
wind_cf): NIWA national climate maps (mean wind speed, 500 m grid, 1981–2010, DataHub; >8 m/s = good resource) + the Global Wind Atlas (10 m wind speed + power density, 250 m GIS, free) — convert to a small-turbine CF via a power curve. ⚠ NZ’s ~40% utility wind CF must NOT be used for small wind — small turbines achieve 10–30% (building-mounted <8%). CR_029
Small-wind spec reference & site wind-speed → CF (RT_290)
Conversion method (US DOE, URL_017): integrate a turbine’s power curve against a Rayleigh distribution (Weibull k=2.0) at the site’s mean wind speed to get annual energy, then CF = AEO ÷ (rated kW × 8,760); quick fallback AEO = 0.01328·D²·V³ (D ft, V mph). Certified small-wind energy is quoted at a standard 5 m/s average (SWCC / AWEA 9.1) — the reference point the model converts from, and what makes turbines directly comparable.
Reference turbines (current):
- Thinair 102 — 🇳🇿 Powerhouse Wind, manufacturer-stated. 2.0 kW @ 10 m/s, 3.6 m rotor; ~16% CF @ 5 m/s (2,850 kWh, Weibull k=3). The NZ-made option, purpose-built for off-grid/remote sites (marae, woolsheds, offshore islands; single-blade → low noise; ~½ acre powers a home; RRP $17,100+GST).
- Bergey Excel 15 — US, independently certified (ICC-SWCC / AWEA 9.1, IEC 61400-2 Cl.II). 15.6 kW @ 11 m/s, 9.6 m rotor / 72.4 m²; 21.8% CF @ 5 m/s (29,800 kWh certified, Rayleigh). The certified power-curve shape at community scale.
Where credible specs live: the ICC-SWCC directory (US, 5 m/s standard), UK MCS, and the IEC 61400-12 power-performance standard; power-curve databases wind-turbine-models.com and NREL turbine-models.
Improvement over time: same family, same 5 m/s reference — the superseded Bergey Excel 10 (2013) gave 17.7% CF vs the Excel 15 (2022) 21.8% (DS_002) — a real ~4-CF-point/decade gain (lower specific power for low-wind sites), but still inside the resource-limited 10–30% band.
⚠ Method caveat: datasheet AEO examples use different distributions (the Thinair worked example is Weibull k=3; SWCC uses Rayleigh k=2), so the model must apply one consistent Rayleigh integration to every turbine rather than adopt each sheet’s own AEO number. Site wind must be extrapolated from the datum height to actual hub height (output ∝ V³).
Cost
- Installed ~NZD 7,000–22,000/kW (midpoint ~12,000 used in the model), vs solar PV ~NZD 2,500/kWp — so wind is ~5× costlier per nameplate kW than PV, and rarely economic except at windy / off-grid sites where PV underperforms or diesel is the alternative. ~20-year life, ~2%/yr O&M. OT_062
When wind beats solar (the design signal)
- At high-wind / low-solar sites, wind is more economically viable than PV for generation expansion — demonstrated at Totarabank (mean wind ≈ 6.56 m/s). LIT_032
- In a fully off-grid Stewart Island/Rakiura optimisation, wind supplied ~79% of annual generation (PV ~21%) and ~74% of non-dispatchable capital cost — wind-led where the resource is strong. LIT_033
- Wind + solar are complementary (diurnal and seasonal): wind often blows at night and in winter when solar is weakest, reducing storage needs. LIT_032 Interview II [INT_002]
NZ community / off-grid cases
- Chatham Islands / Point Durham: 675 kW (3× V27) + 576 kWh battery + diesel backstop, 62–68% renewable on a remote off-grid island. URL_012
- Stewart Island/Rakiura: 31× 100 kW turbines in a 100%-renewable multi-carrier islanded microgrid. LIT_033
- Totarabank eco-village: wind favoured over PV for expansion at this high-wind Wairarapa site. LIT_032
- Wind is a named enabler across the NZ community-microgrid literature. LIT_002
Relevance to Neobiome
Wind is the NI engine’s small_wind technology (D01) — a swept generator gated by feasibility_rule: wind_cf > 0, sized in the PV×battery×wind portfolio sweep (D15). Its slice profile is ~flat (CF ~0.28 across all three slices), so unlike solar it reaches the evening peak and overnight — valuable for off-grid reliability and storage reduction. The key model behaviour: wind is usually dominated by PV on cost, so it only enters the cost-optimal portfolio at windy and/or off-grid sites — exactly the remote-community context Neobiome targets. Cost (small_wind 12,000 NZD/kW, OT_062) and a small assumed land footprint are model inputs; the binding gap is a primary regional wind-resource layer (8/16 regions still derived, RT_140).
Open questions
- Primary NIWA/MBIE wind-speed layer to upgrade
wind_cffrom derived to sourced for all 16 regions (RT_140). - VAWT supplier datasheet (rated power, Cp, CF at NZ wind speeds) before any VAWT is added to the model (RT_202).
- Micro vs community turbine cost/CF split — OT_062’s range is wide; NZ installed-cost quotes by turbine size would tighten it.
- Maintenance burden of small turbines in remote settings (moving parts vs PV) — a community-capacity consideration (cf. int_001’s “complexity ≤ maintenance capacity”).
Connections
Links to
Referenced by
Sources (4): CR_029 · CR_054 · DS_004 · URL_013
EDT domains (1): D01: Renewable Energy & Storage Systems