The strongest winds tend to occur higher, but as this 2022 study shows, higher-mounted turbines that capture higher winds don’t necessarily have the lowest cost of energy. not. Indeed, factoring in the cost of stronger foundations and taller, more robust towers, anything above about 120 m (394 ft) tends to be more expensive power, and is as price sensitive as energy. For the market, this is bad news.
According to NREL, about half of the levelized cost of electricity (LCoE) of an average commercial wind energy installation comes directly from the cost of the wind turbine itself. Of that, nearly half is in the upper nacelle, and the rest is split between the rotor and the tower itself (about 10.3%), which contributes about 13.7% to LCoE.
However, as the tower grows, the initial CAPEX share increases disproportionately. A 110 m (361 ft) tower could make up 20% of his CAPEX on a project, while a 150 m (492 ft) tower would make up 29% of the cost. Not to mention the additional logistical issues involved in handling such a large machine.
Keystone says it has a tower manufacturing solution that keeps the price of large towers very low.[s] Wind energy is the lowest cost power source available not only on the plains, but around the world. ”
The idea is simple. Instead of building a number of cylindrical “cans”, trucking them to the turbine site, and welding them together to create the final tower structure, Keystone could quickly build a small manufacturing facility on site. It proposes to build and then transport coils of steel in bulk or even by truck. Flat sheets that can be welded together to form longer strips. These coils or strips are fed into an angled bending machine that bends them into a helical shape that is continuously welded together along the bond line as the steel rotates. Much of the process is automated, as you can see in the video below.
keystone spiral welding
As a result, according to Keystone, full-length towers, or shorter sections if logically easier, are produced 10 times faster and with up to 80% fewer people than in a standard factory. There may also be savings in the foundations used for spiral welded towers. The factory was completed in about a month, and making it on-site means that we can make a cross section with a large diameter that would not fit under the bridge just by making it at the factory and shipping it.
According to Reuters, the transport restrictions currently limit the maximum diameter to 4.3 m (14 ft) and limit the tower height to about 80 m (262 ft). Keystone’s technology can be scaled to produce towers over 7 m (23 ft) in diameter for towers over 180 m (590 ft) in height. As such, onshore wind farms can run taller towers with longer blades to drive larger turbines and produce more energy.
Spiral welding is a well-established technology when it comes to pipeline manufacturing, so the process of creating and quality-checking these long tube sections is already proven. According to Keystone, this will “improve fatigue and buckling performance” and allow towers of a given height to be built with less steel. And since the manufacturing plant is mobile in nature, it’s easy to pop one temporarily next to a dock and launch dozens of sections or entire towers for offshore installation.
keystone tower system
Mobile factory units are a key part of Keystone’s strategy, but it also has its own manufacturing facility in Texas, from which it will work with General Electric Renewable Energy to manufacture towers for its first live installations. Did.
This first product is an 89 m (292 ft) spiral welded tower for GE’s 2.8-127 turbine. Certified for a 40-year service life, this tower is designed to be an easy replacement for GE’s standard towers. This will probably provide a good commercial scale case study from which you can move forward.
Granted, Keystone is a small business at this point, surviving primarily on US government grants. This kind of manufacturing needs to take advantage of economies of scale before they can promise their customers significant savings. But the tower is clearly a significant part of the cost of a completed wind turbine and a limiting factor in the relationship between size and power, making Keystone’s spiral welding technology a powerful tool to drive renewable energy costs. may become.
Source: Keystone Tower Systems via Recharge
