GOAL: Cheaper, Better Windmills

PROJECT: Makani Airborne Wind Turbine (aka the Flying Windmill)

Thesis
Wind power can be cheaper than solar and greener than coal, which bodes well for the $77 billion (and counting) annual market. But turbines are clunky and expensive--both huge barriers to adoption. So what if they soared like kites?

Method
Makani built a carbon-fiber wing, with triblade propellers to mimic traditional windmills. The gizmo, which flies in circles, is tethered to the ground by a wire that transmits the electricity its propellers generate. Onboard sensors and a computer chip work automatically to direct its path. "Once the blade gets high enough, it can coast without help from a motor," says CEO Corwin Hardham. "It flies by hitting the wind flow perpendicularly, like a kite."

Remaining Challenges
1. Refine navigation
"The wing can already be controlled with the tech in your iPhone," says Hardham. But his team is still perfecting the autopilot algorithms, so the wings don't careen off course.

2. Build bigger, stronger turbines
Although Makani's 20-kilowatt prototype has withstood all kinds of stress, the company plans to market a 600-kilowatt version. It must now make sure its materials hold up at that high capacity.

3. Reduce noise
During early development, Makani used loud hobby motors. It has since upgraded, but may need to fine-tune to meet noise standards.

RESULTS:

	TRADITIONAL TURBINE*	MAKANI TURBINE
WEIGHT	60 metric tons	1.1 metric tons
CONSTRUCTION COST (PER MEGAWATT)	$1.4 million	~$1 million
HEIGHT	262 feet	656 feet
ANNUAL ENERGY PRODUCTION	1.6 million kWh	2.1 million kWh
UTILITY COST (PER KILOWATT-HOUR)	5-10 cents	3-6 cents

*NEG-Micon NM44/750

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