4 ms·

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 on

by antr 12y ago

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?

exDM69 12y ago
I fly stunt kites and power kites, and what is not immediately apparent to someone who doesn't is that the movement of the kite itself will generate apparent wind (and lift) on the sail/airfoil. Flying in a circle or a figure eight pattern will add a lot of "pull" on the tether. Ie. the load factor of a moving kite is far greater than a stationary kite or propeller. Here's another kite related technology that uses this to their advantage, they have built a giant computer controlled power kite that is used to power cargo ships (they claim 50% fuel savings in favorable conditions). They're also prototyping for electrical power generation. http://www.skysails.info/english/ http://www.skysails.info/english/
ansible 12y ago
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.
- antr 12y ago
  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.
  - ansible 12y ago
    After they get going, I don't see how the capex could possibly be higher than for a traditional tower wind turbine. Everything is smaller, and closer to the ground. Less site preparation, and you don't need to rent giant cranes. You're also not shipping giant blades and pylons with special trucks. Also, using smaller generators means that you've got a higher production volume, which can mean significant cost savings. You're also not dealing with giant bearings, gearboxes, etc. which are expensive to produce. And if you're taking a kite offline, you might as well replace all the motor-generators at the same time. I assume they'll be designed to easily detach and replace. Then, back at the shop, you can check them out on your test bench, and see which ones can return to service in the spares stock. I agree that the tether is a big question mark.

by antr 12y ago

exDM69 12y ago

I fly stunt kites and power kites, and what is not immediately apparent to someone who doesn't is that the movement of the kite itself will generate apparent wind (and lift) on the sail/airfoil. Flying in a circle or a figure eight pattern will add a lot of "pull" on the tether. Ie. the load factor of a moving kite is far greater than a stationary kite or propeller. Here's another kite related technology that uses this to their advantage, they have built a giant computer controlled power kite that is used to power cargo ships (they claim 50% fuel savings in favorable conditions). They're also prototyping for electrical power generation. http://www.skysails.info/english/ http://www.skysails.info/english/

ansible 12y ago

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.

antr 12y ago
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.
- ansible 12y ago
  After they get going, I don't see how the capex could possibly be higher than for a traditional tower wind turbine. Everything is smaller, and closer to the ground. Less site preparation, and you don't need to rent giant cranes. You're also not shipping giant blades and pylons with special trucks. Also, using smaller generators means that you've got a higher production volume, which can mean significant cost savings. You're also not dealing with giant bearings, gearboxes, etc. which are expensive to produce. And if you're taking a kite offline, you might as well replace all the motor-generators at the same time. I assume they'll be designed to easily detach and replace. Then, back at the shop, you can check them out on your test bench, and see which ones can return to service in the spares stock. I agree that the tether is a big question mark.