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EuroCover Water Systems

Hexagonal cover vs. geomembrane — comparison

Modular hexagonal covers tessellate without anchors; geomembrane covers are continuous, sealed, anchored. Comparison on cost, maintenance, and use-case.

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Hexagonal modular covers tessellate without anchors and deploy without draining; geomembrane (continuous) covers seal completely (better for gas capture) but require anchoring, draining for installation, and have shorter lifecycle on dynamic water bodies.

At a glance

Metric Hexagonal floating cover Geomembrane (continuous) cover
Surface coverage 99% effective (AWTT modular) 100% sealed
Methane capture Limited (modular) Full (sealed)
Installation No anchors, no draining Anchors + draining
Lifecycle on dynamic water bodies 25+ years 5–15 years (anchor wear)
Capex / m² Moderate Higher
Capability on irregular shorelines Native Requires custom fabrication

For most EU industrial surface-water projects EuroCover quotes, the modular hexagonal cover is what we recommend — capex, installation cost, and 10-year TCO usually favour modular over continuous on dynamic water bodies. Continuous geomembrane stays the right pick when gas capture or environmental containment is the design driver. The engineering reference for this comparison sits at pond-cover.com/vs/hexagonal-vs-geomembrane.

How they differ

Modular covers float independently and tessellate; continuous covers are a single anchored membrane. The difference drives every other characteristic.

When geomembrane is the appropriate choice

  • Full methane capture (digester gas recovery)
  • Complete sealing required for environmental containment
  • Stable water level and regular reservoir geometry
  • Application requiring residual environmental liability protection

When hexagonal modular covers are the appropriate choice

  • Surface-issue focus (evaporation, algae, odor, heat retention)
  • Dynamic water levels
  • Irregular shorelines
  • Anchorless deployment requirement
  • 25-year lifecycle priority

When Geomembrane (continuous) cover makes sense

Continuous geomembrane covers are the appropriate choice when full gas capture is the goal (e.g. biogas methane recovery), when the water body has stable level and regular geometry, or when the application requires complete sealing for environmental containment. Modular hexagonal covers are not a substitute for environmental containment membranes.

Total cost of ownership over 10 years

Line itemHexagonal coverGeomembrane (continuous) cover
CapexModerate one-timeHigher one-time
Anchor inspectionNot requiredPeriodic
Damage repairPer-element replacementPatch / weld
Service-life replacementNot required in 10 yearsPossibly required

Frequently asked questions

Can I use both? #
Yes — hybrid deployments (continuous geomembrane on the digester core, modular hexagonal on adjacent storage) are common in biogas operations.
Which is better for environmental containment? #
Continuous geomembrane. Hexagonal covers are surface covers, not containment liners.
What is the lifecycle difference between the two formats? #
AWTT publishes a 25+ year life expectancy and a 10-year manufacturer warranty for the Hexprotect® AQUA hexagonal element, certified to 130+ MPH (209+ km/h) wind. Continuous geomembranes typically last 10–30 years depending on anchor system maintenance, membrane grade (HDPE vs LLDPE vs PVC), and reservoir geometry. Dynamic water levels and wind exposure shorten geomembrane life.
Can hexagonal modular cover support methane capture? #
Modular covers reduce methane release substantially through surface coverage but do not provide capture. For full methane recovery (CHP feed, biomethane upgrade), continuous geomembrane with gas-handling infrastructure is required.
How does installation cost compare? #
Continuous geomembrane installation is substantially more expensive: requires draining the reservoir, welding seams, sizing and installing anchor systems. Modular hexagonal deploys without draining and without anchors, often at one-third to one-half the per-m² installation cost.
Are there hybrid biogas deployments in practice? #
Yes — continuous geomembrane on the digester core for methane capture, hexagonal modular on adjacent digestate storage for odor + heat retention. This pattern is common in well-engineered biogas operations across Germany, Italy, and the Netherlands.

Sources & further reading