Kite Energy Systems

By Christoff Muller

High Altitude Wind Power

What is Kite Energy Systems?

High Altitude Wind Potential

Optimal wind power density (left) and optimal height (right) that was exceeded 50%, 68%, and 95% of the time during years 1979-2006.Taken from "Global Assessment of High-Altitude Wind Power" by Cristina L. Archer and Ken Caldeira

Typical wind turbine: Rated power at 12m/s at sea level need about 1 kW/m2

Optimal wind power density (left) and optimal height (right) that was exceeded 50%, 68%, and 95% of the time during years 1979-2006. Taken from "Global Assessment of High-Altitude Wind Power" by Cristina L. Archer and Ken Caldeira

High Altitude Wind Potential

High Altitude Wind Potential

Optimal wind power density (left) and optimal height (right) that was exceeded 50%, 68%, and 95% of the time during years 1979-2006.Taken from "Global Assessment of High-Altitude Wind Power" by Cristina L. Archer and Ken Caldeira

Typical wind turbine: Rated power at 12m/s at sea level need about 1 kW/m2

68% of the time most of South Africa has more than 1kW/m2 wind at between 8 and 10km high95% of time, southern tip has more than 0.5kW/m2 at a meagre 2 to 4 km high!

Much higher average wind speeds Much more consistent (greater utilisation factor)Potentially capable of supplying base load!Wind might be too strong too often?Wind speed control by controlling operating height

Crosswind Kite PowerConcept of sweeping large area of wind by flying a high L/D wing was described by Miles Loyd in 1980

Identified two method of crosswind power extraction: Drag based (eg generators on wing) Lift based (eg wing pulling on the tether line)

Much smaller airfoil can capture much more powerTether angle cannot be very vertical- limited altitude, but can still reach heights 500m+

Safety

Air traffic:

need dedicated airspace zones

airband radio warning

make use of locations far from air traffic

(eg. Karoo/offshore)

Danger in case of failure (heavy parts falling from the sky)

Environment

Must automatically survive:

Very high winds (storms)No wind (auto land & launch system)Big systems could have humans in the loopLightning!

Lighter than air systems

Flies in no wind

Big & expensive per kWh

MAGENN AIR ROTOR SYSTEM (M.A.R.S.)Claims under US$0.20 per kWh Plans initial commercial units of 100kWRated power from 10 up to 23m/s wind

from http://www.magenn.com/index.php

Reel-in/Reel-out Systems: Crosswind- lift type

Not Continuous power generation- use multiple out-of-phase unitsLoss of autopilot is catastrophicDesigned for crosswind operation- limited altitude

Small size /kWLightweight, low cost kiteSimple kiteline

Flying Generator: Crosswind drag type

Heavier system (not good for light wind)Loss of autopilot is catastrophicDesigned for crosswind operation- limited altitude

Small size /kWOnboard generators act as motors for launching/landingDurable materials

Jobi Energy

Continuous Loop Systems

Generator on ground, powered by a long continous loop of kiteline turning it

Continuous Loop Systems

Continuous Loop Systems

Continuous power generation from each unitCan easily scale up to use high altitude windsDifficult to adjust height/ retrieve autonomously

Generator on ground, powered by a long continous loop of kiteline turning it

Super Turbine

More smaller turbines gives higher rpm (smaller gear ratio or direct drive)

Mass-produce turbines

Easily mounted on unique structures held up by kite/blimp (offshore) or between mountains/ buildings

Thank you