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Solar powered airships

green.autoblog.com

29 pointsTelmoMenezes28 comments

I always thought this a great idea worth pursuing, especially if you are 'sailing' down the prevailing winds/jetstream, i.e. from North America to Europe it is practically a free ride.

It can be a lot more problematic 'beating upwind' the other way, especially as there is not much sunshine in northern Europe due to its considerable latitude.

This craft may be heavier than air but it still has considerable wind resistance.

Also, the dangerous static electricity buildup has to be considered seriously and solved.

Isn't it lighter than air? The article also claims its heavier, but I assumed it was a mistake.

Heavier. The article is about an hybrid vessel that uses helium to decrease its weight but is still heavier than air. I'm not a physicist, but I assume that lighter than air objects tend to have more wind resistance than heavier than air objects.

Oh, I get it now.

> lighter than air objects tend to have more wind resistance than heavier than air objects.

They have a larger cross-section relative to their mass than heavier than air vehicles. The larger the cross-section, the larger the force wind exerts on it.

The idea of heavier than air but lighter than deadweight seems to be a worthy compromise to explore but of course, if the engines fail or it runs out of sunshine/fuel, it will not be able to stay up very long, just like any other heavier-than-air aircraft.

Lest anyone brings up skilled gliders, I don't think with its wind-resistance this craft will glide for long either.

The more we use helium for stupid shit like this, the less helium we'll have in the future for MRIs and anything else that requires super-cooling.

Forget peak oil, we are, in fact, sitting at peak Helium, and selling that shit for children's balloons and crap like this.

(And for the historical context, Congress in its infinite wisdom, during the deregulation boom in the 90's, decided to mandate a price to dump all of the US's Helium reserves. As a result we are selling it at way below market rate, depleting a finite reserve of an element which we have no means of recapturing once it's released into the atmosphere. Quite a number of scientists have lamented this insanity, and begged the government to do something even if it is just allowing the rate at which the government sells Helium to float to actual market value, let alone get congress to reverse itself. Check it yourself: http://en.wikipedia.org/wiki/National_Helium_Reserve )

> The more we use helium for stupid shit like this, the less helium we'll have in the future for MRIs and anything else that requires super-cooling.

While I agree with the rest of your comment, could you explain why do you think that airships are "stupid shit"? I'd say that the insane amount of fuel we use for transportation is a big waste of oil and I really look forward to see airships back in the sky, doing heavy lifting and maybe more.

Okay, i should dial it back a bit. What they're promising is cool. Low infrastructure, high pay-load travel is indeed interesting.

But they too are depleting a natural resource, just as petrochemical fuel usage does. And while we can find other storage mechanisms for portable energy (batteries, flywheels, hydrogen, what-have-you), there literally is no substitute for Helium cooling, by virtue of the laws of physics as we know them.

This is not worth giving up cryogenics.

I always wonder why helium-based airships never took off. Are there any technological limitations I'm not aware of? Seems to be such a simple and powerful idea (even more now that oil prices are soaring).

There has been a sharp uptick in Helium consumption (He3) and a relatively small amount of reserves (a byproduct of Natural Gas drilling). This price instability can't help things.[0]

The US Military, on the other hand, has been increasing it's use of blimps for surveillance and data transmission/networking. These are useful in places were line of sight isn't available (mountains of Afghanistan, for instance) between radio/mobil cellular base stations. [1]

That and rising into the jet stream is a sorta abrupt introduction into 200knot winds. It would be disarming for most 'comercial passengers'.

[0] http://www.nature.com/scitable/blog/student-voices/the_rise_... [1] http://www.navysbir.com/n11_2/N112-169.htm

I suspect it is a factor of both relatively slow velocities, relatively low payload capacity, and substantial dependence on the weather (particularly with regard to takeoff and landing).

Fuel costs are but one consideration, and the same reasons we don't transport much cargo by sail are probably applicable.

http://www.youtube.com/watch?v=Kq-N3_plNq8

The volume of helium needed to lift the weight is physically large. This makes blimps large which results in some significant disadvantages:

* They are slow. In the beginning, they competed (effectively) against ships. "In July 1936, the airship also completed a record Atlantic double crossing in five days, 19 hours and 51 minutes." http://en.wikipedia.org/wiki/LZ_129_Hindenburg Today, they have to compete against jet aircraft - not effective.

* Given their immense volume and slow response times, they are very sensitive to wind taking off, landing, and when on the ground. This severely restricts their use under conditions that conventional aircraft have no problems handling.

They did. Ever hear of the Zeppelin? They took off all the time in their hey-day. It's a myth that they were filled with hydrogen; the Hindenburg was only had hydrogen in it because at the time helium was not available in Germany at the time because it was only produced in the United States and the US was refusing to export it.

Anyway, the reason we don't see airships much anymore is because for most things heavier than air craft are more economical. A Boeing 747 is a third the size of a Zeppelin but much faster, more reliable, and with much more usable space and lifting capacity. There's really no economic reason that an Airship should be preferred.

> There's really no economic reason that an Airship should be preferred.

What about the fuel usage per unit of mass carried?

Airships in general didn't take off because of the high rate of accidents. Almost every major airship from 1900-1940 crashed after a few years of service.

It's only now that we have better weather info and new materials that anyone is taking them seriously again.

The German company Cargolifter AG [0] was set up to develop a large airship with a freight capacity of 160 tons. This is a lot, 10 tons more than the freight version of the Airbus A380. The hangar they built for it is one of the largest buildings in the world and houses a water park.

They went bankrupt during development. I've heard that they couldn't find a solution for controlling the buoyancy, which is critical when you need to drop 100+ tons of cargo and don't want your airship to lift off into space. There's a video on Youtube in which they use water to control buoyancy of a smaller balloon [1].

[0] http://en.wikipedia.org/wiki/Cargolifter [1] http://www.youtube.com/watch?v=lralh-LwcJQ

I dug into the website of the company and the low-end model goes about 70 MPH in hybrid mode, and 35MPH in solar mode.

I would love to have a flying car. Fuel infrastructure could be awkward though. :)

Once in a while we should stop and think that Sun is the major energy supplier for the planet. Nature has found a way to turn it to plants, life, wind, petroleum etc. I truly belive we can perform equally well.

Thats an empty tree hugger comment. The amount of energy required to grow a plant over several weeks/months is much less than what's required to move a truck around.

I also don't like the argument that the amount of sunlight that hits the Earth in one hour can power the world for who cares how long. I don't like It because it assumes its actually possible to capture all the sunlight that hits the Earth, nevermind that we're actually already using a large part of that energy to grow our food and warm the planet.

The Sun should play an important part in replacing fossil fuels, which I believe we must do, but make good arguments for it, not empty ones.

Yes and no. I don't think it's an empty tree hugger comment, but I do think we need actual numbers in order to discuss these things.

World energy usage: 474 exajoules per year

Incident solar flux: 1000W per square metre

Let's suppose (optimistically but not unrealistically) we can get 10% efficiency (over day and night, so more like 20% during the day).

How much land (or indeed, water) do we need to cover with solar cells? About 150,000 square km.

So, while the cost of building all these solar cells is significant, the proportion of the Earth's surface they take up isn't.

When people propose the "cover 150,000 km^2 with solar cells solution", I like to see them go on the record as saying that if we actually tried, they would not immediately turn around and start screaming about the 150,000 km^2 of Mother Earth we just converted to industrial land.

Solar of any form has a major power density problem. At least, it does in the biosphere, which it should be observed is only a rather small percentage of the universe....

I like to see them go on the record as saying that if we actually tried, they would not immediately turn around and start screaming about the 150,000 km^2 of Mother Earth we just converted to industrial land.

Oh, don't get me confused with a tree-hugger. I'm about as anti-greenie as you can get. I'm just here to do the mathematics.

I'm for whatever source of energy is cheapest.

Transporting electricity is expensive and inefficient. If you take 150,000 sq km of the most efficient solar land, you still have the problem of transporting the electricity created from that to the places that need it.

You should not forget that, in-some point, ALL types of energy were sun energy. This was transformed to everything else including fossil fuels. Sun energy that arrives to earth is enormous. Even the planet itself uses only a tiny small portion of it to sustain life on all forms. My comment wanted to make this clear.

However, since you mention maths... here are the maths (taken from http://www.ecoworld.com/energy-fuels/how-much-solar-energy-h...)

In full sun, you can safely assume about 100 watts of solar energy per square foot. If you assume 12 hours of sun per day, this equates to 438,000 watt-hours per square foot per year. Based on 27,878,400 square feet per square mile, sunlight bestows a whopping 12.2 trillion watt-hours per square mile per year. With these assumptions, figuring out how much solar energy hits the entire planet is relatively simple. 12.2 trillion watt-hours converts to 12,211 gigawatt-hours, and based on 8,760 hours per year, and 197 million square miles of earth’s surface (including the oceans), the earth receives about 274 million gigawatt-years of solar energy, which translates to an astonishing 8.2 million “quads” of Btu energy per year.

In case you haven’t heard, a “quad Btu” refers to one quadrillion British Thermal Units of energy, a common term used by energy economists. The entire human race currently uses about 400 quads of energy (in all forms) per year. Put another way, the solar energy hitting the earth exceeds the total energy consumed by humanity by a factor of over 20,000 times.

Clearly there is enough solar energy available to fulfill all the human race’s energy requirements now, and for all practical purposes, forever. The key is developing technologies that efficiently convert solar power into usable energy in a cost-effective manner.

Your numbers are meaningless because you're not taking into account the energy that's needed to sustain the climate.

And what is this number? Without hard facts do you count this as a counter argument? My main point is that all energy on our planet was originated from the Sun.

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