NEOBIOME

Totarabank Eco-Village

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Totarabank Eco-Village

Overview

Totarabank Eco-Village (Totarabank Subdivision) is a small intentional eco-community in central Wairarapa, New Zealand (GPS 41°1’4”S 175°40’0”E), designed around sustainability principles and committed to sustainable rural living. It comprises eight freehold residential lots (1200–2100 m²) plus a communal building on a ninth common lot, with ~6 ha held in common ownership. As of May 2020 (the time of the Mohseni et al. study), the community had 14 inhabitants and an existing grid-tied 11.4 kW solar PV system. LIT_032

Energy system

  • Existing system (2020): grid-tied, 11.4 kW installed generation, 100% solar PV (no wind turbine), average remaining panel life 19.25 years; night demand met by grid import, daytime surplus exported. LIT_032
  • Optimised expansion (HOMER Pro, baseline 100%-reliable grid): adds PV 0.855 kW, WT 4 kW, battery 6.6 kWh, inverter 3 kW, EVSE 14.72 kW; TNPC NZ35,891; **LCOE 0.094/kWh** vs Wairarapa retail $0.34/kWh; ROI 47.63%, IRR 54.51%, discounted payback 4.74 yr. LIT_032
  • A configuration resilient to two sustained 4-day outages/year adds one battery module (9.9 kWh): LCOE 0.109/kWh, ~16% more total discounted cost (≈ NZ5,892). The NZD 0.19–0.27/kWh figure is the high-resilience tail of the grid-reliability sensitivity sweep (Figure 15), not the design point. LIT_032
  • Mohseni et al. (2020) modelled capacity expansion under an 80% time-based autarky constraint and EV-charging uptake; the project is life-cycle profitable even at the NZ$0.08/kWh feed-in tariff. LIT_032
  • Second peer-reviewed techno-economic study of the site (Mohseni et al. 2021, Energy and AI, Lévy-flight MFOA method): a full re-sizing to the existing transformer limit — 17.5 kW PV + 30 kW wind + 41 kWh battery + 9 kW inverter — versus LIT_032’s small, resilience-oriented expansion of the existing 11.4 kW PV. Reports LCOE −0.02/kWh at a site retail tariff of 0.23/kWh (cf. LIT_032’s 0.094/kWh at 0.34/kWh); the two differ because of different objective functions, horizons (20 vs 25 yr) and solvers, not a data conflict. MIRR 5.4%, DPI 1.43; investment recouped in ~10 years. LIT_083

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Sources (2): LIT_032 · LIT_083

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