LIT_032: Mohseni, Brent & Burmester (2020) — Totarabank Eco-Village Resilience-Oriented Microgrid Capacity Expansion

LIT_032: Mohseni, Brent & Burmester (2020) — Totarabank Eco-Village Resilience-Oriented Microgrid Capacity Expansion

Source

doi:10.3390/en13153970 — original publication (opens in a new tab; the file is not redistributed)

Summary

The only peer-reviewed techno-economic study of a New Zealand intentional-community energy system. The authors develop a resilience-constrained microgrid (MG) capacity-expansion-planning method and apply it to Totarabank Subdivision, a small eco-village in central Wairarapa, NZ. Using HOMER Pro, they optimise additions of solar PV, wind, battery (BESS) and EV-charging infrastructure to an existing grid-tied 11.4 kW solar array over a 25-year horizon, subject to an 80% time-based autarky constraint and zero critical-load shortage. The headline finding is that resilience-oriented community-MG reinforcement is life-cycle profitable in the NZ context even at the low NZ0.08/kWh feed-in tariff: the baseline optimum delivers an LCOE of 0.094/kWh against a Wairarapa retail price of $0.34/kWh, with ROI 47.63%, IRR 54.51% and a discounted payback of 4.74 years. A two-way sensitivity analysis quantifies the cost of buying resilience against sustained grid outages.

Key claims

- claim: "Totarabank Subdivision = eight freehold residential lots (1200–2100 m²) plus a communal building on a ninth common lot, with ~6 ha held in common ownership; located in central Wairarapa, NZ (GPS 41°1'4\"S 175°40'0\"E). 14 inhabitants as of May 2020."
  source_location: "Section 2 (p.8), text + Figure 1"
- claim: "Existing installed generation: 11.4 kW, 100% solar PV, with an average remaining panel service life of 19.25 years; night load is met by grid import and daytime surplus is exported — the existing dispatch cannot serve critical loads at night during an upstream outage."
  source_location: "Section 2 (p.8)"
- claim: "Baseline optimum (100% reliable grid): PV +0.855 kW, WT 4 kW, battery 6.6 kWh, inverter 3 kW, EVSE 14.72 kW; TNPC = NZ$35,891; LCOE = $0.094/kWh."
  source_location: "Table 6 (p.17)"
- claim: "The optimised community LCOE of $0.094/kWh surpasses grid parity against the current average domestic electricity price in the Wairarapa region of $0.34/kWh."
  source_location: "Section 4.1 (p.17), text below Table 6 (ref [70])"
- claim: "Resilient configuration (tolerant of 2 sustained outages/year up to 4 days each): identical to baseline except one extra battery module (battery 9.9 kWh); TNPC = NZ$41,783; LCOE = $0.109/kWh."
  source_location: "Section 4.2.2 (p.22), Table 7"
- claim: "Across the grid-reliability sensitivity sweep, MG LCOE rises from ~$0.10 to ~$0.27/kWh and TNPC from ~$36k to >$110k as outage frequency (1–20/yr) and mean repair time (1–168 h) increase — the upper end (~$0.19–0.27/kWh) is the high-resilience cost, not the baseline. (Figure-derived: the upper-tail scalars are read from the sensitivity surface, not tabulated in the body text; exact values in Supplementary Tables S5–S9 — treat as approximate.)"
  source_location: "Figures 14 and 15 (p.19); Section 4.2 (p.18)"
- claim: "Capital-budgeting metrics for the resilient project vs the existing PV/grid base case: ROI 47.63%, IRR 54.51%, discounted payback period 4.74 years."
  source_location: "Table 8 (p.23), Section 4.3.4"
- claim: "Achieving resilience against two 4-day outages per year costs only ~16% more in total discounted cost (≈ NZ$5,892) than the non-resilient optimum."
  source_location: "Section 4.2.2 (p.22) and Conclusions item 1 (p.24)"
- claim: "Model parameters: nominal discount rate 4.5%, expected inflation 1.9%, project lifetime 25 years, minimum time-based autarky ratio 80%, max annual critical-load shortage 0%, load growth 1.1%/yr."
  source_location: "Table 5 (p.15)"
- claim: "Site resource (approximate, figure-derived): scaled annual mean wind speed ≈ 6.56 m/s and annual mean solar irradiance ≈ 3.72 kWh/m²/d (NASA SSE); wind is the more reliable and constant resource at the site, and a WT is more economically viable than PV for generation expansion. (Resource scalars read from Figure 6, not tabulated in body text.)"
  source_location: "Figure 6 (p.13) and Section 4.1 (p.16)"
- claim: "Component techno-economics used: PV (Trina TSM-285, $832/kW, 25-yr life, 17.4% eff); WT (X-2000L 2 kW, $1984/kW, 20-yr life); Li-ion BESS (LG Chem RESU 3.3, $1105/kWh, 15-yr life, 95% round-trip); converter ($1533/kW, 96% eff); fixed feed-in tariff $0.08/kWh."
  source_location: "Table 3 (p.11) and Table 4 (p.12)"
- claim: "Mobility assumption: 40 km/day per lot at 0.12 kWh/km (Nissan Leaf, NZ's most popular EV); EV charging is a deferrable load (avg 48 kWh/day) served by level-2 (240 V AC) EVSE; battery energy reserved for critical loads, not EV charging; V2G and population growth excluded."
  source_location: "Section 2.2 (pp.10–11) and Section 2.1.6 (p.10)"

Neobiome Intelligence relevance

• D01 Renewable Energy & Storage — the only NZ intentional-community energy system with a peer-reviewed HOMER Pro techno-economic optimisation. It supplies a NZ-grounded community-scale LCOE benchmark: 0.094/kWh baseline rising to 0.109/kWh for a modestly resilient design, with $0.19–0.27/kWh reserved for high-resilience (frequent/long-outage) scenarios LIT_032 (Table 6, Table 7, Figure 15). Wind out-competes PV for expansion at this high-wind/low-solar site, but the existing PV is retained in the cost-optimum — supports the diversified PV+wind+BESS stack the wiki already documents for D01.
• I01 Financial & Economic Sufficiency — community-owned renewable generation at 0.094/kWh is well below the Wairarapa retail price of 0.34/kWh LIT_032 (p.17), with ROI 47.63%, IRR 54.51% and 4.74-year payback (Table 8) — a fully community-financeable investment case without subsidy.
• I06 Resistance to External Shocks — the method explicitly prices energy resilience: tolerating two 4-day grid outages per year costs only ~16% more (≈ NZ$5,892) than the non-resilient optimum LIT_032 (p.22). The TNPC/LCOE sensitivity surfaces (Figures 14–15) formally quantify the cost-of-resilience trade-off a Neobiome design must navigate.
• I07 Fulfilment of Basic Needs — NZ community-scale energy-provisioning cost reference at the 14-inhabitant / 8-lot scale; the 80% time-based autarky design target LIT_032 (Table 5) is a directly reusable self-sufficiency specification. Requires upward scaling for a 50+ household pilot.

Research targets

Documents to retrieve

• RT_081 (re-scoped) — Mohseni, Brent, Burmester & Browne (2021), Energy AI (Elsevier): the Lévy-flight moth-flame optimisation sizing algorithm paper previously assumed (via CR_007) to be the LCOE source. Now that the 2020 paper is confirmed to carry the LCOE figures directly, retrieve only to compare the optimisation method, not as the LCOE provenance. → now ingested as LIT_083; RT_081 resolved. Confirms the LF-MFOA method and adds a second (larger-system) Totarabank techno-economic point; not the $0.094/kWh LCOE provenance.
• RT_082 — Mohseni et al. (2021), Energies 14(20):6522, Rakiura–Stewart Island off-grid multi-carrier microgrid: the closest off-grid analogue if Neobiome targets a non-grid-tied design, and the natural companion to this grid-tied case. (Now ingested as LIT_033 — RT_082 is closed.)
• RT (follow-on) — Supplementary Materials Tables S1–S9 (mdpi.com/…/3970/s1): the hourly numerical values behind Figures 4, 5, 11, 12 and the full sensitivity surfaces S5–S9 — retrieve if the NI energy skill needs the underlying load/price/exchange time series rather than the summary scalars.

Research gaps

• NZ retail-price recalibration: the $0.34/kWh Wairarapa figure is 2020-vintage; confirm a current (2025–2026) regional retail price for grid-parity comparisons (overlaps with the CR_011 buy-back work already in the wiki).
• Component-cost vintage: PV/BESS unit costs in Table 3 are 2020 NZ-market prices and now materially lower; a NZ recalibration of the LCOE under 2025 component costs would update the benchmark before it is used in calculations.
• Scale gap: the optimum is for 14 inhabitants / 8 lots; a sensitivity of LCOE and autarky to a 50+ household community (Tasman/Lower Moutere pilot scale) is needed before this benchmark is applied to the worked example.

Connections

Links to

Sources (2): LIT_033 · LIT_083

Referenced by

Sources (9): CR_007 · CR_051 · LIT_047 · LIT_067 · LIT_068 · LIT_069 · LIT_078 · LIT_083 · LIT_084

SSI indicators (3): I01: Financial & Economic Self-Sufficiency · I06: Resistance to External Shocks · I07: Fulfilment of Basic Needs

EDT domains (1): D01: Renewable Energy & Storage Systems

Technologies (1): community-scale)

Cases (1): Totarabank Eco-Village