How the Kohilo E8‑Alpha Works
Design & Safety
Aerodynamic Capture & Diffusion
The E8‑Alpha is a vertical‑axis architecture that uses curved intake/diffuser surfaces to stabilize turbulent inflow and accelerate it into a central channel. By compressing a large volume of air into a smaller path, the diffusers raise local velocity and direct flow cleanly onto the rotor blades.
Kohilo describes this as a “vortex” effect that minimizes back‑side drag—historically the key inefficiency in legacy VAWTs.
Hydraulic Powertrain & Buffering
Instead of driving generators directly, each rotor drives a hydraulic pump. The pumps charge hydraulic accumulators, storing potential energy with low losses. Controlled valves then meter pressure/flow to the ground‑level generators, delivering a stable electrical output despite wind fluctuations.
Because the accumulators regulate the hydraulic drive to the generators, the system provides near‑constant voltage/frequency suitable for direct transformer feed, reducing conversion steps and associated losses.
All hydraulic and electrical balance‑of‑plant components are containerized for transport, installation, monitoring, and maintenance.
Multi‑Stage Rotor Column (Redundancy by Design)
Inside the structure, multiple stacked rotors (“floors”) convert wind to shaft power.
Each stage operates independently, so the turbine can remain in service even if one stage is offline.
Enclosed, blade‑safe architecture (Safety by design)
The E8‑Alpha has no external blades. By enclosing the rotor, it removes exposed high‑speed tips and thereby significantly reduces bird and bat strike risk compared to open‑rotor designs.
The enclosed form means no blade throw or ice shedding typical of open rotors. Components are protected from the elements, and critical systems are accessible at ground level, supporting safer maintenance practices.
Because the rotor turns at low rotational speeds inside an enclosure, there is no shadow flicker and an ultra‑low acoustic footprint—suited to sites near homes, workplaces, and mobility hubs.
Circularity & lifetime
The system is designed for long service life (target 60+ years) with major components that are recyclable and replaceable. Modular sub‑systems allow refurbishment and upgrades without a full rebuild, supporting circular use of materials.
Operating Range & Control
Low‑wind capability
A diffuser/vortex intake conditions turbulent air and draws flow through the structure, enabling sub‑1 m/s start‑up and roughly ~1 m/s onset of power production.
This widens the window of productive hours.
High‑wind resilience
At elevated wind speeds, a mechanical louver “air‑choke” regulates inflow.
Rather than shutting down at a conventional cut‑out speed, the turbine maintains rated output by metering the air volume entering the core—protecting components and preserving uptime during gusty conditions.
Diffuser/Vortex Intake and the Betz Limit
In a diffuser/vortex intake configuration, the diffuser increases both mass flow and pressure recovery.
As a result, measured power coefficients can exceed the classic Betz limit of ~59% if you reference only the bare rotor disc.
This often raises the question: “Does the design break Betz’s law?”
The answer is no.
What the diffuser does
A diffuser/vortex intake conditions turbulent air and pulls a faster stream through the turbine. That lets the rotor start spinning below 1 m/s and begin producing around ~1 m/s, so you get more productive hours at real‑world sites.
Why numbers can look “over Betz”
In this diffuser/vortex intake setup, the diffuser draws more air through the rotor and recovers pressure behind it.
If you calculate efficiency only against the bare rotor disc and the free‑stream wind, the ratio can appear higher than ~59% (the classic Betz limit).
That’s an accounting effect: the rotor now sees accelerated local flow, so the same disc area is processing more energy.
Are we breaking Betz’s law? No.
Betz is derived for an traditional rotor in free flow—the control volume is just the air passing the rotor. A diffuser‑augmented turbine changes those boundaries: the relevant streamtube extends to the diffuser’s exit, and the diffuser/vortex intake itself does aerodynamic work (it shapes pressure and guides flow).
When you reference the larger diffuser streamtube (i.e., the air the whole system captures), the efficiency sits within physical limits. We’re not defying physics; we’re defining the system correctly.
Why it matters
Low‑wind performance: earlier start‑up, more operating hours.
High‑wind resilience: a mechanical louver air‑choke meters inflow, so the machine holds rated output without a conventional cut‑out.
Real‑world benefit: more stable yield and better uptime across varying conditions.
A diffuser/vortex intake doesn’t break Betz; it changes the game.
Diffuser/vortex intakes don’t break Betz; they change the boundaries. By using a diffuser to manage flow and pressure, the turbine harvests more usable energy per unit of rotor area while staying fully consistent with aerodynamic first principles.