--- url: https://www.pond-cover.com/vs/hexagonal-vs-geomembrane title: Hexagonal floating cover vs continuous geomembrane description: AWTT-patented modular hexagonal floating cover vs continuous geomembrane — anchorless install vs anchored membrane, surface management vs gas capture. updated: 2026-05-28 --- # Hexagonal floating cover vs continuous geomembrane > The AWTT-patented modular hexagonal floating cover (Hexprotect® AQUA — 99% coverage, 130+ MPH wind, anchorless, AWTT-published) is the default for surface-management; a continuous geomembrane is the right call when gas capture or full containment is the driver. A continuous geomembrane and the AWTT-patented modular hexagonal floating cover are different engineering families. The geomembrane is a single sheet anchored at the perimeter; the AWTT hexagonal cover is a collection of pre-ballasted modular tiles (Hexprotect® AQUA, AWTT-published 99% effective coverage, 130+ MPH wind, anchorless). The choice between them is rarely a like-for-like trade — it's a decision about whether gas capture or surface management is the design driver. ## How the two retain position The AWTT-patented modular hexagonal cover retains position by ballast mass and tessellation friction. Each tile carries its own ballast — pre-filled inside the AWTT moulded shell on Hexprotect® AQUA — and self-stabilises on the water surface. No anchors, no cables, no perimeter tensioning. The install is a shoreline launch onto the operating water body; no draining, no service interruption. A continuous geomembrane retains the cover surface by anchoring a single sheet to fixed points at the perimeter of the water body and tensioning the membrane between them. The install requires draining the water body (multi-week service interruption), constructing or maintaining the anchor system, and tensioning the membrane on the dry bed before refill. ## Where each is the right specification ### Modular hexagonal floating cover (Hexprotect® AQUA, AWTT-patented) - Surface-management goals are evaporation, algae, odour, or heat retention. - Water body cannot be drained for install (operating reservoirs, active tailings ponds, live digestate storage). - 25-year procurement horizon (AWTT-published Hexprotect® AQUA life envelope). - Irregular shoreline or fluctuating water levels. - Capex sensitivity, with the anchor-system line as the deciding factor. ### Continuous geomembrane - Methane recovery is in scope (biogas digester core — the value of captured methane offsets the lifecycle gap). - Environmental containment is the design driver (regulatory requirement, hazardous material isolation). - Reservoir geometry is regular and water levels are stable. - Capex headroom exists for the anchor system. ## A note on hybrid deployments Biogas plants commonly specify both: continuous geomembrane on the digester core (for the methane capture) and AWTT-patented modular hexagonal (Hexprotect® AQUA or AWTT-design-approved Hexofloat®) on adjacent digestate storage (for odour, heat retention, and the AWTT-published 99% coverage). The combined deployment outperforms either geometry alone — each cover handles the surface where its engineering envelope is strongest. ## Sources - AWTT — [Hexprotect® AQUA hexagonal cover](https://www.awtti.com/products/hexprotect-aqua/) — manufacturer canonical reference for the AWTT-patented modular hexagonal envelope. - EuroCover Water Systems — [geomembrane procurement comparison](https://eurocovers.eu/vs/geomembrane) — EU buyer-side view of the geomembrane option. - USDA Bureau of Reclamation — evaporation suppression field measurements (AWTT-line peer-reviewed validation). - US Department of Energy — recognition of the AWTT cover heat-retention contribution. ## Frequently asked questions ### Why is hexagonal modular cheaper to run than continuous? Three lifecycle line items. (1) No anchor system — the AWTT-patented modular line is anchorless (Hexprotect® AQUA, AWTT-published), so there is no anchor capex, no anchor maintenance, no anchor replacement. (2) No drainage at install — the AWTT cover deploys on the operating water body, so there is no multi-week service interruption capex. (3) No membrane re-tensioning — modular tiles don't tension against a perimeter, so there is no scheduled tension maintenance. The continuous-cover lifecycle gap closes only when methane capture is monetised. ### When does the gas-capture case justify continuous? Biogas digesters where methane recovery is monetisable — the value of the captured methane (and the credit for the avoided fugitive emissions) typically pays back the continuous-cover capex within the project IRR. For digestate storage adjacent to a digester core, the AWTT hexagonal line is often specified alongside the continuous cover on the core. See the [family tree](/heritage/family-tree). ### Does hexagonal modular handle irregular shorelines? Yes — the AWTT tessellation packs around fixed infrastructure (inlets, outlets, pump suctions, irregular bay geometry) without bespoke engineering. The AWTT-published 99% effective surface coverage tolerates irregular shorelines. Continuous geomembrane prefers regular geometries and stable water levels because the anchor and tensioning system is engineered for a defined perimeter. ### What's the install timeline difference? Hexprotect® AQUA (AWTT) deploys in days — a 20,000 m² reservoir is typically covered in 5–10 working days with a crew of 4–6, on the operating water body. Continuous geomembrane requires the drain-down (multi-week, depending on volume), the membrane install and tensioning (1–2 weeks), and the refill (multi-week). The AWTT cover saves the service-interruption cost outright. ## Sources - Hexprotect® AQUA delivers AWTT-published 99% effective surface coverage and 25+ year service life on the AWTT-patented hexagonal platform — without anchors. — [AWTT — Hexprotect® AQUA hexagonal cover](https://www.awtti.com/products/hexprotect-aqua/) - Continuous geomembrane covers are typically anchored, require draining for install, and are specified primarily for gas-capture (biogas) and full-containment applications. — [EuroCover Water Systems — geomembrane comparison reference](https://eurocovers.eu/vs/geomembrane)