Technology

New heights for wind power

 By Esteban Pages

Wind power-based electricity generation is gaining momentum at a steady pace on a global scale

The World Wind Energy Association reported in February 2019 that worldwide wind power installed capacity reached 597GW, with 50.1GW added in 2018 alone.
With this new milestone, the association claims wind power can cover close to 6% of global energy demand. To continue consolidating its deep-rooted footprint on the worldwide energy mix, wind power research and innovation are focusing on taller, larger wind turbines using equally bigger blades.
Berkeley Lab’s Electricity Markets & Policy Group November 2016 study, “Reducing Wind Energy Costs through Increased Turbine Size: Is the Sky the Limit?” estimated that by 2030, onshore wind turbines will be able to reach an average hub height of 115m, a rotor diameter of 135m and an installed capacity of 3.25MW. Offshore wind turbines are expected to stand tall at a hub height of 125m, a rotor diameter of 190m and an installed capacity of 11MW.
In March 2019, GE got ahead of Berkeley Lab’s prediction and revealed a new 5.3 MW onshore wind turbine. It is composed of 77-meter blades and hub heights of up to 160 m.

Berkeley Lab, Electricity Markets & Policy Group Summary Brief

Does size matter?

GE claims that its newest wind turbine, Cypress Onshore, provides “significant annual energy production (AEP) improvements, increased efficiency in serviceability, improved logistics and siting potential”. The platform also offers up to a 50% increase in AEP over the life of the platform and is said to perform best on low and medium wind speed sites. Considering the added power output reduces the USD/MW ratio, at first glance it seems rather straightforward that bigger is better when it comes to wind power claiming the clean generation crown.

Cypress Onshore wind platform

While these new developments are encouraging, O&M experts have raised concerns over this specific trend. During the Wind O&M Canada Conference in October 2019, North American wind experts warned the New Energy Update that “the continuing drive toward lower wind CAPEX costs could reduce long-term operational reliability, creating new challenges for operations and maintenance teams”. During the event, experts stressed that “maximizing power generation assets’ lifespans is key to reducing the levelized cost of energy (LCOE), and many operators are already making major component decisions to extend the lifespans of operational assets. Larger towers and rotors will impact major components”.

Airborne wind energy systems: turbine substitute or complement?

Harnessing wind for power generation has more versatility than relying solely on land based wind turbines, however. In 2015, ELSEVIER‘s Renewable and Sustainable Energy Reviews published an analysis of a series of Airborne Wind Energy Systems (AWES). The report concluded that high altitude wind energy was a very promising resource for the sustainable production of electrical energy at the time.
According to its findings, “the amount of power and the large availability of winds that blow between 300 and 10,000 meters from the ground suggest that AWES represent an important emerging renewable energy technology“.
The report also highlighted that over the previous decade, several companies entered in the business of AWESs, patenting diverse principles and technical solutions for their implementation. In addition to being cost-effective, these alternatives grant wind power the scalability that wind turbines lack when it comes to residential and commercial solutions—much to the advantage of solar PV panels.

ELSEVIER, “Airborne Wind Energy Systems: A review of the technologies”

A first-mover and award-winning Italian startup that designed an AWES prototype, KITEnrg, was able to develop a kite-based, high-altitude power generation system as early as 2010. The premise of KITEnrg was to bypass wind tower’s structure costs: “In the actual wind towers, the outermost 30% of the blade surface contributes for about 80% of the generated power”. The thinkers behind KITEnrg saw a window of opportunity to develop a light wing coupled with ropes to obtain a wind generator considerably lighter and cheaper.

raise-wind-power-based-electricity
KITEnrg-yoyo generator (KITEnrg)

“In a 250 kW wind turbine, for example, the weight of the rotor and the tower is typically about 50 t. A KITEnrg-yoyo generator of the same rated power can be obtained using a 250-m2 wing and ropes 1000-m long, with a total weight of about 10 t only. Therefore, it is expected that the construction costs of a KE-yoyo generator will be lower than those of a wind tower of the same rated power”.
Another worthy mention is Makani. This California-based energy kite developer is a subsidiary of Alphabet Inc., founded in 2006. It started developing fabric kites as early as 2008, and in December 2016 unveiled its first large-scale rigid kite, the M600. It is designed to produce up to 600kW and has a wingspan of 26m. It is currently working on an offshore version of the device.

Makani’s first commercial-scale energy kite

While these new devices remain experimental and have yet to reach the scalability to enter the realm of large-scale commercial phase, it is worth keeping an eye on these new innovations poised to propel wind power to new heights.

READ MORE: Offshore wind power gaining strength by Robin Wylie


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Esteban Pages