Electrolytic accretion has been used on reefs since 1979 (Hilbertz, later “Biorock”). Exactly one shore-protection job is described in enough detail to count quantities: Pulau Gangga, Indonesia, 2016. It is a stone gabion with mesh over it, not a grown strip wall. This page keeps that record and its gaps.
measured lab or field instrument independent not a proponent paper claim asserted, weak or broken cite input your number
What the record shows
Goreau & Prong 2017: 48 mesh modules on a 200 m eroded beach, intertidal seagrass/reef flat. Each module is a 1×1×2 m gabion of 20–50 cm river stone (long axis alongshore) with a ~2.1×5.4 m welded sheet, 15 cm grid, bent over the basket. Four people carried each unit at low tide. 1 DC supply per 4 modules; ~100 m cable to shore. Electricity: “about one air conditioner” for the whole job — no kWh.
Alongshore quantities that follow from that paper: 1 m³ stone / m = 1609 m³ / mile, 0.5 mesh sheets / m = 805 sheets / mile, 0.125 supplies / m, 12.5 m cable / m. Bar diameter is not stated. Wave transmission was not measured; Goreau says those measurements still need to be made. Photographs show waves through the mesh (their Fig. 8).
Beach result in that paper (authors’ figures, not an independent survey): ~80% of the eroded beach back in <3 months; height +>1 m, width +>15 m over ~200 m; ~3000 m³ sand as a conservative estimate.
A rubble mound sized for a 3 m wave (Suwondo 2025, Indonesia) beside the Gangga gabion. Not the same structure, not the same sea. Empty cells mean the source did not publish that line.
| Line | Rubble mound, Hs 3 m | Gangga gabion + mesh |
|---|---|---|
| What the price covers | Primary armor layer only: material, fabrication, transport, install. Core and filter drawn, not priced | No invoice. Quantities from Goreau & Prong 2017; prices unpublished — use the tool below |
| Design sea | Hs 3.0 m, Tp 10 s | Intertidal reef flat; no design wave published |
| Armor / concrete | 2,500,000 IDR/m³ marine concrete; armor 85–215 million IDR/m (KD 24 → 2) | None poured |
| Core / stone | Not priced | 1 m³ river stone / m |
| Steel | Unreinforced armor units | Welded mesh 2.1×5.4 m, 15 cm grid, 0.5 sheet / m. Bar Ø not in the paper |
| Power plant | None | 0.125 supplies / m, 12.5 m cable / m. Anodes unpublished |
| Published total / m | peer-reviewed armor only 85–215 million IDR/m (Suwondo 2025) | claim $20–1,290/m vs “other methods” $60–155,000/m. Their [16] is Ferrario 2014 on coral-reef wave dissipation — not a cost study |
| Independent full-mound budget | Maligano 250 m breakwater RAB Rp 4,509,700,000 incl. VAT (~18 million IDR/m), different site and wave (Ningsi 2024) | None found for any Biorock shore job |
| Electricity after placement | None | “About one air conditioner” for 48 modules — no kWh |
| Grown mineral vs concrete, per kg | Concrete ~€0.04/kg | Deposit €1–12/kg at ~7 kg/yr from 215 kWh/yr (EUDP Table 5; a power-supply-limited test, see Physics) |
| Proponent lump sums (not bids) | — | claim GCRA: “very rough” $10,000 for a ~10×10×5 m structure incl. travel. Maldives: 20–40 million USD for 5 km “before a detailed site assessment” |
| Material strength | C32/40 concrete | primary Hilbertz 1979 Fig. 28 vs ~3500 psi concrete; patent restates 3720–5350 psi. independent EUDP puncture ≈ C20/25. claim Goreau up to ~80 MPa |
| Embodied carbon | Armor A1–A3: 11–28 tCO2e/m (Suwondo) | EUDP: 80.8 vs 328 kg CO2e for a refurbished vs concrete column — not per metre of shore |
Paper quantities per metre, then × 1609.344 m / mile. Empty price = omitted. Not a bid. Not the grown strip wall.