Stronger winds are a headwind, but as this 2022 study shows, higher-mounted turbines that capture stronger winds don’t necessarily equate to the lowest energy costs. Given the cost of strong foundations and tall support towers, heights above 120 metres (39feet) will actually result in more expensive electricity and a price-sensitive energy market. That’s bad news.
According to NREL, about half of the average commercial wind farm’s levelized cost of energy (LCOE) comes directly from the price of the wind turbines. About half of that money is in the hood at the top, with the rest split between the rotors, which produce about 13.7% LCOE, and the tower itself, at about 10.3%.
But as the towers grow, their share of the initial investment (capital costs) increases disproportionately. A 110-meter (361-foot) tower can account for 20% of the project’s investment, while a 150-meter (92-foot) tower accounts for 29% of the cost. not to mention the additional logistical issues involved in handling such heavy machinery.
Keystone says it has a tower-building solution that lowers the cost of large towers so much that it “makes wind power the most affordable energy source, not just in open fields, but anywhere in the world.”
The idea is quite simple: instead of manufacturing multiple cylindrical “boxes,” transporting them to the turbine site, and welding them together to form the final tower structure, Keystone proposes to quickly build small fabrication facilities on site and then use bulk steel.
It is supplied in rolls or even in flat sheets that can be welded together into long strips. These coils or strips are fed into angle-bending machines, which bend them into spiral shapes that are then welded together along a continuous common line as the steel is rotated. Much of the process is automated, as you can see in the video below.
Keystone Spiral Welding
According to Keystone, the result is full towers, or shorter sections when logistically easier, which can be pressed 10 times faster than in a conventional plant, using up to 80% less work. You can also save on spiral-welded tower foundations. The factory will be ready in about a month, and on-site production means you can make such large parts that might not fit under the bridges if they were made in a factory. and send them.
This shipping restriction currently limits the maximum diameter to 4.3 metres (1feet) and limits the tower height to about 80 metres (262 feet), according to Reuters. The technology of Keystone can vary from towers more than 7 metres (23 feet) in diameter to heights of 180 metres (590 feet). Thus, onshore wind farms can have tall towers with longer blades that use larger turbines and produce more energy.
Spiral welding is an established technique in pipeline manufacturing, so the manufacturing and quality control for these long pipe sections are already proven. Keystone says it also results in “improved fatigue and bending,” which allows towers of a given height to be built using less steel. And since the production unit is largely mobile, it is quite easy to move it temporarily alongside the dock and take down dozens of sections or entire towers for offshore installations.
Keystone has established its own production facility in Texas, but the real benefits will emerge when the tubes are rolled on site at the wind farm.
Keystone Tower Systems
While the mobile manufacturing unit is an important part of Keystone’s game, it also established its own manufacturing facility in Texas, and from that facility it worked with General Electric Renewable Energy to produce the tower for the first time.
This first product is an 89-meter (292-foot) spiral-welded tower for a GE 2.8-127 turbine.
The tower is certified for aIt has a zero-year lifespan and is intended to simply replace GE’s standard towers. This would potentially provide a case study with good commercial scale to build on.
Sure, Keystone is currently a small operation, mostly supported by the US government. This type of production requires huge economies of scale before you can promise big savings to customers. But the tower is clearly a significant part of the cost of a finished wind turbine and a limiting factor in the size-power equation, so Keystone’s spiral welding technology could still become a powerful lever for changing renewable energy costs. You can go