Dome Engineering Spec Sheet

Overview — one idea, two scales

A geodesic dome that pulls water from air. Air enters a hexagonal top intake, is compressed down a vertical Venturi funnel, turns through a large-radius 90° curve into a horizontal duct holding inline turbines and an air-to-water heat exchanger, and is cooled below its dew point so water condenses, is treated, and stored. The turbine shaft drives a flywheel and generator; solar sits on the duct; inside is a pond and gardens.

That build estimate is broken down — with a live, editable budget tracker — on the Costs & Budget page.

Structure & geometry

Airflow path (locked)

Turbine & blade design

The system is closer to turbomachinery than to a backyard windmill — a ducted axial turbine inside a Venturi accelerator, with pressure staging, flywheel smoothing, AWG extraction and a diffuser. The duct straightens and accelerates the air, so blade choice is very specific.

Recommended rotor

• Type: twisted axial-flow, lift-based airfoil blades
• Blade count: 5–7 swept blades (range 5–9); high-solidity rotor (more, narrower blades than a normal wind turbine)
• Diameter in duct: fill 92–96% of the duct diameter
• Geometry: aggressive twist root→tip (because tip speed v = ωr grows with radius), airfoil section, narrower near the tip, moderate chord
• Material: carbon / composite
• Add-ons: stator vanes before the rotor + a diffuser cone after it; a short light helical pre-rotor to condition incoming flow

AWG cooling & condensation core

Atmospheric water generation is, fundamentally, an energy-intensive refrigeration process. Two cooling stages:

1. Pre-cool — intake air through an underground earth-tube loop (~18 °C) or a heat exchanger on exhaust air, to cut compressor load.
2. Active cool — a refrigeration coil drops air below dew point; water condenses on the coil and drips to a tray.

Rendered refrigeration rig (the labelled schematic)

Refrigeration vs. desiccant

• Refrigeration (most practical): reverse-AC — scroll/rotary compressor (1–2 kW), big evaporator coil, condenser + fans, intake filters.
• Desiccant + solar regen (more off-grid): silica gel / lithium chloride absorbs moisture at night, solar heat releases it by day. Lower electrical load, better in dry air, more mechanically complex.
• Recommended direction: a hybrid — refrigeration core with a desiccant assist.

Water treatment & storage

• Tank: 1000 L target, food-grade poly or stainless, integrated in the dome base ring.
• Mineralisation stage matters — condensed water is essentially distilled and needs minerals added back for drinking.
• Optional pump to a pressure tank; overflow bypass to prevent flooding.
• Multi-stage intake filtration is mandatory — dust is a killer for the coils.

Hybrid water sources (more reliable overall)

Rather than pulling 100% from air: AWG + rainwater capture, AWG + fog-harvesting mesh, AWG + greywater recycling.

Drivetrain & power generation

• The flywheel is a solid circular disk mounted vertically at ground level — it smooths torque and stores rotational energy.
• Generated power runs fans, control systems and can assist (not replace) the compressor.
• Solar: 3 flat panels in a row on top of the external duct in the render (~400–450 W each).

Power demand vs. solar reality

Turbine output (6 m prototype)

Turbine output is far below compressor demand — it offsets fan energy, it doesn't run the system.

Water yield (the rendered rig)

This geometry actually outperforms typical small AWGs because of the large airflow volume, long evaporator path, multi-stage cooling and big condensation surface area. But yield is humidity-bound, and Adelaide is dry (summer ~30–60% RH). Run it at night when humidity is highest and ambient temperature lowest.

Efficiency moves & smart control

• Run mostly at night (higher humidity, cooler air).
• Earth-tube pre-cooling (~18 °C) + a solar-thermal updraft (chimney effect) to cut fan/compressor load.
• Variable-speed compressor matched to conditions; oversize coils for better condensation.
• Dew-point-targeting controller: temp + humidity + dew-point sensors; only run the compressor when RH > ~50%, use passive airflow first, boost with fans only when needed.

6 m prototype spec (the deck's number)

Venturi ratio recommended 1.5:1 to 2.5:1. Intake funnel 2–4 m Ø tapering to a narrow throat. Airflow need for the 100 L/day target: roughly 500–1500 m³/hour (EC axial fans or centrifugal blowers if passive airflow is insufficient).

Master 3D render prompt (verbatim)

The locked design description used to generate the concept render — kept here exactly so the design intent is recoverable.

Open problems & unknowns

• Nothing is physically validated — does the physics hold at all?
• Funnel still not aggressive enough in renders — needs a taller drop and narrower throat for real compression.
• Compressor sizing per stage (0.5–0.75 HP est.) depends on refrigerant, condenser efficiency, evaporator + ambient temps.
• Exact solar count for off-grid (15–30 panels) depends on local solar resource + battery bank.
• Bevel-gear / turbine sizing not finalised.
• Reconcile the deck's optimistic "free water" framing with the energy reality (~20–40% savings, not 100% passive).
• No proper workshop — twisted airfoil blades + tight tip clearances are genuinely hard to make DIY, around containers and a truck body.

Reconstructed from the engineering chats in the archive. Numbers are estimates from those conversations, not measured results — the project is at concept/render stage. Source files: blades, coil length, Untitled Document 1, long conversation, Image Editing Request.