To begin:
Engineers of the world, I love you, but stop being seduced by interesting technical challenges and money into working on stuff you know in your heart-of-hearts is nonsense or actively harmful.
A small incise on AWE:
Many of you have track records, having come from the equally clearly non-viable airborne wind energy space. Fly like an eagle, don’t crash like a turkey.
The last Barnard’s article about aerospace and aviation. AWE is no longer on his radar screen. That said, if Mike Barnard was forced to build an AWES, some options would likely be ruled out, such as blimp, eVTOL, eSTOL, hydrogen and synfuel production…
He seems to have a few sensible ideas.
I don’t think AWE belongs in this diagram though, as everythibg else is related to aviation transport, while AWE is related to windmills. But if he took it off the diagram in a recent revision, that could be a sign.
I would like to point out something; humans have different roles. If you are an investor (who presumably are Barnard’s customers), you want to balance risk with price. The one that makes the best picks will grow their money faster. Their role is being sceptical and picking apart business plans, and keeping and eye on trends and whatnot (I am no real investor to put it that way).
For the entrepeneur, the role is a little opposite. The task is to find something with potential, then try to take that something and make it more interesting for investors. So the entrepeneur would normally be more concerned with hilighting potential than risk items. Or maybe also resolving risk items by doing prototyping or testing.
If the entrepeneur took on the role of the investor, they would probably end up starting companies that make products that already exist in the market. Maybe try to win on marketing or pricing rather than creating something new.
There is room for all of this. There is no good or bad, just different. But I think it makes sense to have an opinion of «to which community does this person cater» and then keep that it mind.
Mike Barnard did not plan to include AWE in his air transport scheme. In the case of wind power, it is well known that he clearly had a negative view of the viability of AWE, considering otherwise that the current HAWT were working very well.
That said, some of his criticisms of certain choices for transport aviation could perhaps be applied to AWE, although…
Mike Barnard is a member of the Flimax team. It would seem that his choices are reflected in the making of the Flimax electric aircraft. About us | FLIMAX
I would say the FliMAX is a pretty conservative place to be though. Small electrical aircrafts. I don’t think there are huge techical hurdles to do this, just add a wing, motors and get it certified.
Its a good thing and the world needs it. But its nowhere near as hard as AWE from my viewpoint. So it would seem odd to me that someone working on an electrical aircraft should be in a position to say whether AWE could make it or not. Frankly I think you would be better off listening to someone in AWE than this guy.
I reread his analysis from almost 10 years ago. You’d think it had just been written, so relevant remain the questions raised.
Perhaps (but not for sure) AWE could make more progress if his observations were taken into account, which is far from being the case.
Some significant points:
Unpowered launch approaches also have to deal with winds aloft often being from different directions than winds on the ground, so neighbouring device tethers may easily intrude into the launch and initial flight path until devices get to the appropriate altitude. This potential for mid-air collisions due to varying wind directions does not appear to be addressed, as all solutions proposed focus on single devices, not arrays of devices. This is true for all devices, but more problematic for unpowered launch approaches especially with cross-wind generation. This is an unexplored problem in the current literature.
Crosswind flight drags very strong, very thin, very long tethers at high speeds. Mast concepts expect low attachment points to avoid unnecessary forces acting on the masts. They claim this as an advantage. However, this means that the high-speed tethers are moving low to the ground near the attachment point, and failure conditions would cause the tether to sweep across the ground. This creates a high-risk situation for people working in wind farms for whatever reason. It’s unlikely that this would create conditions amenable to secondary uses of the ground between wind generators.
Tether failure is a constant concern of kite generation devices. If the tether fails near the base, it can cause situations where it is dragged downwind for kilometres.
Safety challenges eliminate secondary land uses which will drive up the cost of generation. Energy density of generation schemes is generally understood as an anti-renewables disinformation point, however it becomes much more relevant with airborne wind generation systems. Effectively, each airborne wind generation site is an airport with multiple devices in the air, high-strength tethers moving constantly and in many approaches at great speed close to the ground, and with devices landing and taking off regularly. The safety and operational requirements effectively prohibit other uses for the area used for generation, unlike for conventional ground based wind energy. For most approaches, much more of the ground-area around the devices must be cleared and smooth at least. This has direct economic impacts that are not factored into any attempted life cycle cost of electricity for these approaches that I’ve been able to identify.Ground-based wind generation requires a bit less than 1% of productive farmland including tracks, gates, transformers and wind turbine bases, and approaching 2% for ridge-based deployments, with very reasonably lease rates from landholders compared to the electricity generated. With greater safety setbacks and no secondary uses, airborne wind energy systems will likely have to lease all of the land that they are set upon, and in offshore configurations this eliminates all surface uses such as fishing, not just a small portion of those surface uses.
It doesn’t mean that there isn’t a way out of the thicket to something viable. But all conceptual and prototyped solutions so far appear to multiply complexities and risks. There is no concinnity of design. It’s all platypuses instead of cheetahs.
His conclusion suggested the possibility of a more favorable design. Little has been achieved since then. Maybe one of the keys would be something leading to highly scalable units.
At the time of Barnard’s analysis, Windswept networked lifting kites and Daisy rotary blades were not yet as well known as they are today. They have the potential to escape some of the drawbacks described. Other architectures may also emerge.
