# An alternative method to tap high altitude winds [by producing chemical energy at altitude]

A silly idea I got while browsing a recent topic:

Make your preferred wind energy harvesting system, put it on or under a hydrogen balloon, raise the balloon to your altitude of choice and tether it to the ground.

The new idea, for me though I know the idea has been around, is to generate methane or hydrogen while airborne. That eliminates the need to constantly raise and lower batteries, or use a heavy electric cable, or use an unproven rope drive system. Instead you would have a supply of gas containers that you would send down, and you would periodically send extra gas containers up.

The enabling technologies for this would be a relatively light yet high capacity apparatus for making methane or hydrogen (from air, CO2, hydrogen, water, or a combination of the above), a good hydrogen balloon that doesn’t allow much hydrogen to escape, and of course your AWE harvesting system.

Alternatively, you could ground your system every time your gas containers (or now also batteries or other https://en.wikipedia.org/wiki/Energy_storage medium) were full.

Or transfer the hydrogen with a pipe.

The question is how much power in the form of hydrogen you would need to transmit.

Theres the question of how much weight the equipment to convert energy to hydrogen would weigh.

The hydrogen could be used to inflate a lighter than air structure. But a large one would probably not be easy to maintain in those winds. But it could solve the 24/7 airbone issue.

Finally, the energy loss related to producing hydrogen could be a dealbreaker if you want energy in the form of electricity in the end.

You could (should?) make some estimates to consider these issues (and more) to check the viability of the idea.

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Let’s say 1 day of 200km/h winds with a turbine area of 10m^2, at an altitude corresponding to 250 hPa (~11 km). This will be intermittent as the narrow band of high velocity winds moves around.

Some random numbers:

ρ = 0.365 @ 11 km (http://www.pdas.com/atmosTable2SI.html), A = 10, Cp = 0.30, V = 55, Ng = 0.9, Nb = 0.9.

And let’s add a Z for the conversion to the energy storage system of choice.

This gives 74KW*Z. Not worth the trouble, so let’s increase the area to 150 m^2 to get to atleast 1MW*Z. A day of operation then gives us 24MWh*Z. Let’s go with that for now.

Next question perhaps is the weight and volume of the https://en.wikipedia.org/wiki/Energy_storage medium of your choice to store that.

50MJ/kg for LNG. That’s 50/3600 = 0.014 MWh/kg or 1MWh/72kg or 100MWh / 7200 kg.

120MJ/kg for compressed hydrogen. That’s 12/360MWh/kg or 1MWh/30kg or 100MWh/3000kg. 4.5 MJ/L gives 1MWh/800 L or 100MWh/80 m^3 (a sphere with a radius of 2.7 meters).

A post was merged into an existing topic: Questions and complaints about moderation.

Windy Skies remains intrigued by the prospect of making methane with AWE without interest in reducing methane dependence in the face of Climate Change, nor comprehending the complex engineering impracticalities well known by previous discussions.

Let Windy Skies share a serious personal contribution to AWE engineering science, like an advanced AWES concept or prototype, or better treatment of essential Cosine Functions in kite physics.

This playful image on Windy Skies “silly idea” topic should not be censored from pique-

How much water would you need to make 1 MWh of hydrogen (30 kg)?

So weight of water needed to produce 30 kg of hydrogen in 30/0.1119 = 268 kg

Or for 100 MWh of hydrogen you would need 26,800 kilograms of water.

How much hydrogen would you need to lift 30 tonnes to an altitude of 11 kilometers?

Density of air is 0.365 kg/m^3. I can’t find the density of hydrogen at -50 degrees Celsius and 250 hPa. I’ll go with a vacuum instead, so 0.0kg/m^3.

You’d need a vacuum of (1/0.365)*30000 = 82000 m^3 to lift a payload of 30 tonnes to an altitude of 11 kilometers, a sphere with a radius of 27 meters.

A post was merged into an existing topic: Questions and complaints about moderation.

This question seems silly to me. Assuming hydrogen were an efficient means of energy storage, which it is not, why not produce said hydrogen on the ground, where the weight of the water, electrolyzer, piping, and storage container(s) don’t have to be lifted?
And if you DID make hydrogen onboard a floating station, why not send hydrogen down a lightweight tube, rather than supporting multiple storage containers at height, then worrying about how to get them up and down, transfer the hydrogen to new containers, etc.? Kids… just goes to show ya… Sheesh!

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Hose kinking is a problem. Hoses are stiff and therefore rather heavy, by design, to avoid kinking.

9 posts were split to a new topic: Info on hydrogen and (tethered) hydrogen aerostats