This post was written by Simon Mahan, former Energy Resources Policy Manager for SACE.Guest Blog | August 30, 2016
Last year, the internet was abuzz with a bizarre looking “wind turbine” that was designed to look like a tree. The aesthetically designed “wind tree” had all the hallmarks of a bad wind turbine: it’s not certified by the Small Wind Certification Council, it’s not scalable, its performance levels were over-promised and it costs are ridiculously high. QZ.com posted a new story on the Wind Tree with some updated figures. Turns out, the wind tree is actually worse than initially thought.
A 5.4 kilowatt wind tree is expected to generate 2,400 kilowatt hours (kWh) annually. That means the wind tree can achieve a capacity factor of just 5 percent, which is right in line with other short vertical axis wind turbines (VAWT) installed in areas with terribly low wind speeds. Utility-scale wind farms readily achieve 40+ percent capacity factors, or about 8x higher performance.
The installed cost for a wind tree is $56,000, or roughly $10,370 per kilowatt of capacity. Utility-scale wind turbines are installed at a cost of roughly $1,690/kW of capacity. The wind tree is 6x more expensive per kilowatt of capacity than utility-scale turbines.
Over a 20-year lifespan, the wind tree’s levelized cost of energy (LCOE) could run about $1,167 per megawatt hour generated ($1,167/MWh). Utility-scale wind farms readily achieve $20-$30 per megawatt hour ($20/MWh) power purchase agreements. That’s a 5,800 percent price premium for the wind tree.
Why is this such a big deal? Well, the Wind Tree promised enough energy to “power a whole home for a full year”, and it can’t. It also promised cheaper power than “industrial scale” wind turbines, which isn’t true. It also promises to use less land space than a wind farm, but that, too, is a bogus claim. To generate as much energy as a single utility-scale wind turbine (or 7,008,000 kilowatt hours annually), you’d need a forest of 2,940 wind trees. With that many metal structures that attract birds, assuredly the bird deaths alone would be massive.
Meanwhile, reporters and bloggers write gleaming reviews of the “wind tree”, while spreading misinformation about utility-scale wind farms. The QZ.com article says, “Unlike larger industrial turbines, which need winds of over 22 miles per hour to function, the leaves captured energy from wind speeds of less than five mph.” First of all, utility-scale wind turbines can have a “cut-in” speed (or the speed at which they begin generating power) in wind speeds as low as 3 meters per second (3 m/s), or 6.7 MPH. Secondly, “winds of over 22 miles per hour” represent 9.8 m/s, which is an amazingly high wind speed and a speed at which utility-scale wind turbines reach full output – or a 100 percent capacity factor. Comparing the “wind tree” cut-in wind speed (startup wind speed) to a utility-scale wind turbine’s full output wind speed is apples and oranges.
Fad wind turbines bad-mouth utility-scale wind farms, and then frequently fail to live up to their promises. That’s bad news for renewable energy. People can be misled into a false techno-optimism, that we should delay using today’s technologies because the future technology will be perfected, if we just wait a little longer. One positive aspect from the QZ.com article is it points out that a residential solar array costs about half as much as the wind tree. One thing the article doesn’t mention is that residential solar panels can achieve 20-30 percent capacity factors, or 4-5x higher performance than the wind tree (at 5 percent). At half the price and 4-5x the performance, residential solar panels are way, way better investments than the wind tree.
Innovation in renewable energy is a good thing. Research and development should continue to happen. But in the case of the wind tree, we now know it’s a flop. Let’s not let the (im)perfect of tomorrow be the enemy of the good of today.