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Google Makani – Wind Energy Kites

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Re: Google Makani – Wind Energy Kites

#151

Post by exDM69 »

TylerE wrote: post #5
elevensies wrote: post #3

I'm still a bit confused about how the forces line up for the flight path. If I'm understanding: - the wing flies in a circle which is perpendicular to the wind (oriented the same way an ordinary wind turbine would be) - the tether is up-wind from the wing, so the force from the tether pulls the wing into the wind which generates lift, which is used to propel the wing along the circular path - the propellers are driv…

I think that's more or less it. I think what they're doing is a milder version of dynamic soaring, which is a popular technique used among RC glider pilots (and some birds). The speeds attainable are pretty insane, the current RC record is 505 MPH, which in a rather fascinating twist is faster than the fastest POWERED RC aircraft. This a video that shows a pretty good idea of what it looks like, at compartively slowe…

My understanding is that dynamic soaring takes advantage of a cliffside or a ridge to provide upward air current. This project seems to be working on flat ground, so as far as I understand, it's not really using dynamic soaring.

I think it works more like regular stunt and power kites, just relying on the "trim" of the airfoil to produce lift and thrust (and the tether's pull) to make it go upwards and then "fall" down.

Re: Google Makani – Wind Energy Kites

#152

Post by antr »

ansible wrote: post #150
antr wrote: post #11

The 60% load factor seems a dream come true... well above offshore wind levels (c. 50%). Having said that, I'm very curious to know the capex per MW, and the ongoing O&M costs for each of the kites. Onshore wind has experienced a considerable decline both in the cost of the turbine and O&M... my impression is that this technology is not going to be cheap to run. Anyone has any insight?

What gives you the impression that it won't be cheap to run? Presumably, if they've got the automation figured out, each unit will just manage itself, launching when wind conditions are favorable.

The underlying technology for the Makani kites and a standard turbine are the same. In the Makani case you have one kite with eight turbines, and like a standard wind turbine, all turbines need to be serviced. If you have to service 1 turbine, the other 7 stop operating. Hence, on a per turbine basis, I believe availability won't be around the 98-99% level (the industry standard), but lower.

Additionally you have the tether, a new variable, which is another moving piece, and will also need to be serviced.

I've done some back of the envelope numbers, and without assuming a higher capex (which I'm fairly certain it is), on an recurrent basis, an increase in production doesn't really lead to cheaper $/MWh on an O&M basis.

                        Standard Turbine	Makani
  Capacity (MW)		1.5			0.6
  Load factor		23%			60%
  Production (MWh)	3,022			3,154
  Availability		98%			95%[1]
  Net Production	2,962			2,996
  O&M $/turbine/yr	20,000			20,000[2]
  $/MWh/year		$6.75			$6.68
[1] I think I'm being generous at a 95% availability, but I haven't got enough data to make another assumption.

[2] O&M can be contracted on a turbine or MW basis. Still, given the "complexity" of Makani, the price of this could be higher than the standard cost.

This is a new technology, and not much info is available e.g. how big can these get, what's the investment cost per MW, what are the potential maintenance issues, how does availability look like, etc. My above argument is an educated guess, but I'd really like to know more about it. I really like the idea and I would like the economics to work out.

Re: Google Makani – Wind Energy Kites

#153

Post by Gravityloss »

a8da6b0c91d wrote: post #112

Off topic but I have been toying with building a small catamaran powered by a Darrieus turbine or a kite setup such as depicted. The point is wind powered navigation of busy rivers and the east coast intracostal waterway. Obviously this makes zero sense on the open sea or in wide bays, where long tacks are easy and more efficient. Tacking on the intracoastal is practically infeasible in today's world, yet there is lo…

http://www.boatdesign.net/forums/attachments/projects-propos...

Re: Google Makani – Wind Energy Kites

#154

Post by Thiz »

proexploit wrote: post #147
Thiz wrote: post #126

Earlier quoted context omitted.

I have a default zooming of 125% and nobody seems to know how to make the web work for us with disabilities, not even gmail works well. Scrolling pages always look weird for me. Image libraries like lightbox are a special pain in the ass.

Would you willing to provide me any detail about the issues you run into with Gmail?

The most prominent, composing a new email. The floating window appears out of bounds and it's impossible to click any buttons on the lower bar, including the send button.

What I do is tabbing all the way down so the floating window reorganizes allowing me to send the email.

Re: Google Makani – Wind Energy Kites

#155

Post by Khao »

Thiz wrote: post #126
callesgg wrote: post #10

Good, could people just stop messing with how scrolling works.

I have a default zooming of 125% and nobody seems to know how to make the web work for us with disabilities, not even gmail works well. Scrolling pages always look weird for me. Image libraries like lightbox are a special pain in the ass.

I use window 8's built-in scaling to put everything at 125% too because my laptop screen is a 15-inch 1920x1080 and I find with that kind of pixel density I need to make things a little bit bigger. It's ridiculous how many things are broken when doing this.

Re: Google Makani – Wind Energy Kites

#156

Post by tmd83 »

Thiz wrote: post #126
callesgg wrote: post #10

Good, could people just stop messing with how scrolling works.

I have a default zooming of 125% and nobody seems to know how to make the web work for us with disabilities, not even gmail works well. Scrolling pages always look weird for me. Image libraries like lightbox are a special pain in the ass.

I think in the last major updated they made it really worse. No horizontal scrolling ever. My father has severe AMD (Age-related Macular Degeneration) and has to zoom very heavily. One day I went to his computer to fix his gmail to be welcomed with a white screen. It was just after they made the shiny new compose popup. It was placed so nicely that only the empty white center was visible. It confused the hell out of me for a moment let alone my father.

I know scaling Gmail is a gigantic effort but I don't really understand this part (can anyone enlighten me). Gmail essentially has two core pages, the inbox (or list) and compose and tens of millions of users. If they can't fix the positioning of one compose popup how will the rest of us manage?

A fair disclaimer in my own work I'm not sure how good we are in handling these issues but we do have a lot more UI and UI changes. It just makes me feel hopeless.

Re: Google Makani – Wind Energy Kites

#157

Post by tmd83 »

mkl wrote: post #129
TylerE wrote: post #5

Earlier quoted context omitted.

I think that's more or less it. I think what they're doing is a milder version of dynamic soaring, which is a popular technique used among RC glider pilots (and some birds). The speeds attainable are pretty insane, the current RC record is 505 MPH, which in a rather fascinating twist is faster than the fastest POWERED RC aircraft. This a video that shows a pretty good idea of what it looks like, at compartively slowe…

This video explained dynamic soaring for me: https://www.youtube.com/watch?v=SVN-oF6tPLc The key thing seems to be having different wind speeds available at different heights so you can do the upwind part through slower moving air.

That video helped a lot. I was getting hopelessly lost with the image. In one part the object is moving in still or slow air where the resistance isn't enough to nullify the gain gained at the higher speed upper layer if I'm understanding this correctly.

And finally learned the difference between airspeed vs. groundspeed :D

Re: Google Makani – Wind Energy Kites

#158

Post by Agustus »

Retric wrote: post #121
giggles_giggles wrote: post #20

Earlier quoted context omitted.

My understanding is that, among other things, the generators come under extreme stress during exceptionally windy occasions, causing a lot of wear and tear that happens way up at the top of these giant windmills. These require a lot of manual maintenance, which is dangerous and expensive due to the nature (and location) of the work. Additionally (and as a demonstration of just how much stress they come under), while…

Current designs are not standardized, so the worst case is fairly poor. However, economically on average wind is fairly close to Coal Power and in some cases actually cheaper even without subsidies. So, there is no way for it to be a net loss energy wise because electricity is vary cheap energy. PS: For scale wind is on target to hit ~8% of total electricity generation in 2018.

Could you cite sources for the coal to wind economics?

Re: Google Makani – Wind Energy Kites

#159

Post by Retric »

Agustus wrote: post #158
Retric wrote: post #121

Earlier quoted context omitted.

Current designs are not standardized, so the worst case is fairly poor. However, economically on average wind is fairly close to Coal Power and in some cases actually cheaper even without subsidies. So, there is no way for it to be a net loss energy wise because electricity is vary cheap energy. PS: For scale wind is on target to hit ~8% of total electricity generation in 2018.

Could you cite sources for the coal to wind economics?

The LCOE can also be regarded as the cost at which electricity must be generated in order to break-even over the lifetime of the project.

http://en.wikipedia.org/wiki/Cost_of_electricity_by_source

Note, wind has gotten much better over time so 2013 numbers look much better than 2006 numbers.

Germany levelized cost of electricity generation in 2013 (EUR/MWh)

  Onshore wind farms 45–107
  Coal-fired power plants (brown coal) 38–53
  Coal-fired power plant (hard coal) 63–80
Though I may have undersold things for new generation:

  Regional Variation in Levelized Costs of New Generation Resources
  Conventional Coal Minimum 87.0, Average 95.6, Maximum 114.4
  Wind Minimum  71.3, Average 80.3, Maximum 90.3
IMO one of the more interesting numbers was Wind, onshore Operating Cost (USD/kW) Min 10.95 Max 60.00. That's a wide gap.

PS: Granted, these don't seem to account for time value of money but that's often overstated in terms of economic impact. Basically, if you turn 1oz of gold into 2oz of gold for free it's a net gain even if it takes 50 years, time value really just means there might be better uses of your personal money not that something is a net loss.

Re: Google Makani – Wind Energy Kites

#160

Post by hrehhf »

It is strange that their map of the USA left off the entire state Alaska, where electricity is among the most expensive in the country: http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm...

Makani seems ideal for their needs: "Alaska’s electricity infrastructure differs from that of the lower 48 states in that most consumers are not linked to large interconnected grids through transmission and distribution lines; rural communities in Alaska rely primarily on diesel electric generators for power. " -- http://www.eia.gov/state/?sid=AK

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