Comment by semi-extrinsic | Hacker News Reader

Comment by semi-extrinsic | Hacker News Reader

From TFA:

> Typically hydroelectric power requires a huge head of water to function, relying on blades submerged in high-velocity water streams.

From Wikipedia's page on "Water turbines":

> Turbine selection is based on the available water head (...). Kaplan turbines with adjustable blade pitch are well-adapted to wide ranges of head conditions (...), since their peak efficiency can be achieved over a wide range of flow conditions.

They even provide this handy chart for turbine selection:

https://upload.wikimedia.org/wikipedia/commons/b/bf/Water_Tu...

illustrating that Kaplan turbines work well down to 1 m head.

This turbine is an interesting concept for illustrating fluid mechanics, but I think trying to spin it as a good alternative for a new hydroelectric turbine type is ultimately misleading. Just from the basic function of the turbine I sincerely doubt it can compete with a more classic type like a Kaplan or cross-flow turbine (e.g. the viscous losses and the un-utilised pressure in the outflow both look high).

Disclaimer: I am the inventor's son.

Sure, Kaplan turbine is way more efficient but it is difficult and expensive to use it on such low water head. This bladeless ball is so dumb it can be manufactured in sweatshops and run in dirty irrigation canals from 30cm water head. The potential is huge exactly because we can not build huge river dams any mor. This turbine could utilize micro flows, tidal energy even waste water. By the way it is very efficient as a garden or kitchen cleaning tool on the standard water main.

This is an important aspect, for sure. A similar concept in spirit that a colleague has worked on is the cross-flow turbine. It can be made easily and cheaply by cutting up pieces of steel pipe and welding them back together. There is an organization called Remote Hydrolight that supports the building and maintenance of these for power across rural Afghanistan:

http://www.remotehydrolight.com

For micro-hydropower in Europe or the US, I believe we are still running into the environmental issue. I understand in most countries, it is illegal to build hydropower even in small streams, and even if you own the land, without a lot of red tape and approval from environmental authorities.

But I would love nothing more than to be proven wrong! I hope your father succeeds in this!

When I was staying at a mountain motel in the middle of Sichuan, the power went out. Turns out, they only had power from a stream of water, and the pipe feeding the turbine was blocked. It was all very haphazard, but it worked!

Thanks for explaining further about your father's invention. Is there any additional news you can share regarding working installations beyond what was mentioned in the video?

>This turbine is an interesting concept for illustrating fluid mechanics, but I think trying to spin it as a good alternative for a new hydroelectric turbine type is ultimately misleading.

Well, if you watch TFV they show a working prototype at around the 6min mark. So it's clearly a concept worth investigating further for use as a power source.

Incidentally, your comment is the type of "middlebrow dismissal" that plagues this site. You picked one small explanatory point from a relatively poorly written article, disputed it with a source from Wikipedia, and concluded by dismissing the subject of the article, an engineer's highly promising work. [Edited]

> Piss off with your "middlebrow dismissal".

And that's where you went from being part of the solution to being part of the problem.

You're right; thank you. On reflection I edited my response for tone. (I get fired up the way people's good work sometimes gets treated.)

I'm sorry if my comment appears too "middlebrow dismissal". My dayjob is working as a fluid mechanics researcher, and I have colleagues who work on hydropower turbine design. And I did watch the video, hence my comments about viscous losses. My point being that I know turbine design is an extremely well-understood and mature field, I didn't just google it.

Also, as you say they've built a prototype to test the result. To be taken seriously, they should have also put a few students on the task of building a similarly sized Kaplan turbine and then compared the efficiency. It would have been very simple; there are probably even scale model Kaplan turbines that you can buy for this purpose. (It's basically just a propeller in a tube.) TFA is a bit like an SW dev coding up a new webserver, claiming it solves a case where existing ones do poorly, but then not bothering to benchmark it on that case against, say, Apache or Nginx.

Finally, the big challenges in hydropower are not in increasing efficiency or lowering cost. The challenges are that we've interrupted/dammed most large rivers already, and any new plans to build hydropower face great resistance both from NIMBYs and environmental protection groups.

>Finally, the big challenges in hydropower are not in increasing efficiency or lowering cost. The challenges are that we've interrupted/dammed most large rivers already, and any new plans to build hydropower face great resistance both from NIMBYs and environmental protection groups.

That's what makes this new turbine such a brilliant fit for our times: it can work at a small, distributed scale that to my knowledge hasn't been possible with hydro before, and at significantly reduced capital costs. Additionally, there are hardly any moving parts. Of the pieces that are required, they are intrinsically durable and easy to manufacture shapes, suitable for manufacture in relatively low-tech economies.

BTW, thanks for clarifying your initial response.

This is exactly the sort of comment that keeps me coming back to hacker news. Thank you for it.

But when you look at manufacturers it seems that a 500W Kaplan turbine requires 3 metres of head and costs almost US$4,000. http://www.aurorapower.net/products/categoryid/4/list/1/leve... (Linked from Wikipedia, certificate is invalid :/ )

A 500w version of this turbine requires only 1.2m of head and costs $1,550 including inverter.

I think that's significant, especially for the developing world.

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