OT_075: MBIE Embedded Hydro Generation Opportunities in NZ (Roaring40s, 2020)

OT_075: MBIE Embedded Hydro Generation Opportunities in NZ (Roaring40s, 2020)

Source

https://www.mbie.govt.nz/assets/embedded-hydro-generation-opportunities-in-new-zealand.pdf — original source (opens in a new tab; the file is not redistributed)

MBIE Embedded Hydro Generation Opportunities in New Zealand (2020)

The national small-hydro resource layer + the GIS data sources/method for siting hydro (RT_140 hydro half)

MBIE (with Transpower), prepared by Roaring40s Wind Power Ltd, V1.2 Final, 2 Oct 2020. A GIS study identifying NZ’s potential new small-scale (>1 MW) run-of-river embedded-hydro sites, with the flow/head/efficiency method and the exact NZ datasets (NIWA River Flows + LINZ 8 m DEM) — directly transferable to micro-hydro siting and the NI parcel-GIS terrain-hydro layer (§11 I4).

Summary

Identifies, by GIS modelling of NZ’s river network, the potential for new small-scale (>1 MW) run-of-river embedded hydro — schemes connected to a distribution network rather than the transmission grid. It derives the flow×head requirement for 1 MW, applies NZ flow (NIWA) and elevation (LINZ DEM) data with environmental-flow and conveyance-distance constraints, filters out National Parks / Water Conservation Order rivers / existing schemes, and reports the national and regional potential. The method and data sources are the rigorous basis for siting and sizing community micro-hydro.

Key claims

- claim: "National small-scale (>1 MW) run-of-river embedded-hydro potential: GIS modelling identified 84 potential new schemes = 236 MW capacity / 1,346 GWh/yr (at an assumed 65% capacity factor). A literature search (EHMS 2004) added 14 more = 107 MW / 609 GWh/yr → combined ~98 sites, 343 MW, ~2,000 GWh/yr. Existing NZ small-scale hydro: 78 schemes (55 ≥1 MW, IEGA list). Conclusion: small-scale hydro is too small to meet national demand growth, but locally valuable (network stability, avoided transmission, local demand)."
  source_location: "§6 Results (Tables 2–4); Final thoughts (p22)"
- claim: "Regional distribution of the 84 GIS-identified schemes (MW): West Coast dominant (17 schemes / 55.6 MW / 316.7 GWh), then Manawatū-Whanganui (10 / 31.5), Bay of Plenty (8 / 22.3), Hawke's Bay (6 / 18.7), Southland (8 / 16.6), Waikato (9 / 16.5), Taranaki (5 / 15.7), Wellington (4 / 13.6), Gisborne (5 / 12.0), Canterbury (2 / 9.7), Tasman-Nelson (3 / 9.5), Otago (3 / 5.7), Marlborough (3 / 5.6), Northland (1 / 3.5), Auckland (0). About half the sites (37 of 84) are within DOC-administered land — a consenting/access constraint."
  source_location: "§6 Results, Table 3 (p18)"
- claim: "The resource layer = GIS data sources (transferable to micro-hydro): HEAD from the LINZ 8 m Digital Elevation Model (±10 m vertical accuracy); FLOW from the NIWA 'River Flows' dataset (modelled from 485 hydrological stations to 576,000 river segments) plus the NIWA 'Percentile Flows' dataset (65th/80th-percentile flows). River segments split at tributary junctions; segment lengths 30 m–13 km (NI) / 30 m–29 km (SI). These are the exact datasets for a NZ parcel-GIS terrain-hydro layer."
  source_location: "§4.1.1 Dataset identification (p10–11)"
- claim: "Sizing method (transferable to the engine's micro_hydro): P = ρ·g·Q·h_net·η, overall efficiency 75% (turbine 85% × drive-shaft 95% × generator 95% × transformer 98%), h_net = h_gross × 0.9 → flow × head > 150.66 gives ≥1 MW. Design flow = 80th-percentile flow for penstock <1 km, 65th-percentile for ≥1 km, MINUS a residual/environmental flow (90% of MALF for rivers with mean ≤5 m³/s; 80% of MALF for >5 m³/s, per the Proposed NES on Ecological Flows 2008). Conveyance distance capped at 3–5 km (operational NZ schemes 0.7–4.5 km, mostly <3 km). Capacity factor 65% (averaged from operational small-scale schemes)."
  source_location: "§3 Hydropower Basics; §4.1.1–4.1.2 (p6, 11–12)"
- claim: "Design signal + caveats: small/micro-hydro is a MATURE technology — unlikely to see the cost declines wind and solar continue to see, so at an economic disadvantage vs PV/wind (consistent with OT_062's $8–30k/kW). Many sub-1 MW (micro, <10 kW) opportunities exist but were out of scope (also locally-only). ⚠ 2020 vintage; >1 MW scope; modelled flows (485 stations) can under/over-estimate spring-fed or small-catchment sites (e.g. the Rimu/Toronui schemes were missed); LINZ DEM ±10 m head error; storage potential not modelled (would raise output)."
  source_location: "§7 Data Limitations; §8 Final thoughts (p19–22)"

Neobiome Intelligence relevance

Resolves the hydro half of RT_140 — the national micro/small-hydro resource layer. (1) It is the NZ small-hydro resource map (343 MW / ~98 sites >1 MW; West Coast and hill-country North Island dominant, Auckland nil, Tasman-Nelson modest) — micro-hydro is inherently site-specific (a stream is there or not), so the NI model correctly gates micro_hydro on the scenario’s stream_flow_l_s / stream_head_m; the map is the deferred parcel-GIS layer. (2) It pins the parcel-GIS terrain-hydro data sources (§11 I4) to concrete datasets: NIWA River Flows / Percentile Flows (flow) + LINZ 8 m DEM (head) — confirming the spec’s §11 choices. (3) It supplies the sizing method for the engine — the power formula, 75% efficiency, residual-flow rules (90%/80% MALF), and conveyance limits let the model compute kW from a site’s flow+head, the rigorous version of the current hydro_kw lever. (4) CF cross-check: MBIE’s 65% (run-of-river >1 MW) sits above the model’s hydro_cf 0.5 (OT_062 micro) — community micro likely between; worth noting. (5) Confirms the mature-tech / locally-valuable framing (hydro wins only where a year-round stream exists, never on cost vs PV — cf. OT_062). Thesis: distributed-generation potential, run-of-river vs impoundment, NWCO/DOC consenting, West Coast energy resilience. ⚠ MBIE govt primary but 2020-vintage, >1 MW scope. Resolves RT_140 (hydro); the wind-layer half (a primary NIWA wind CF to replace CR_013’s AI-derived values) remains a separate low-priority upgrade.

Research targets

Research gaps

• RT_140 wind half (remains, low priority): a primary NIWA wind-speed/CF layer to upgrade CR_013’s AI-derived regional wind CF from assumed to sourced.
• Sub-1 MW (true micro, <100 W–10 kW) site potential was out of scope here — a community-scale micro-hydro siting pass would use the same NIWA + LINZ datasets at finer resolution (parcel-GIS, §11).

Connections

Links to

Sources (2): CR_013 · OT_062

Referenced by

Sources (4): LIT_067 · OT_100 · OT_121 · OT_160

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

Technologies (1): Micro-hydro (run-of-river, community-scale)