Do Giant Compressed Air Underwater Balloons Store Energy Well?

[Eclipse Now]

The advantage of using submerged air bags instead of conventional compressed air tanks on the surface is that they can be light and cheap, relying on the pressure of the surrounding water rather than the strength of tanks.

This is exactly why we won't be raising and lowering the bags. From the podcast I listened to, Seamus said the entire rationale for the underwater balloons is that it enables cheaper 'tanks' made from flexible materials rather than trying to manufacture a bunch of steel tanks. It's all about cost / unit.

 

A big concern I have about a system that relies on wind power from a small region is that wind vs. a solar one is often very slow for long periods, while the sun rises and sets as surely as ... well, as the sun rises and sets.

And how's solar PV with cloudy days? Night? Seasonal differences?

 

The only answer we have right now for reliable baseload power is GenIII nukes. (According to environmental scientist and clean energy activist Dr Barry Brooks.) We build them now, work on commercialising GenIV, and then GenIV can burn all the waste GenIII has made. Apparently there is ALREADY enough nuclear waste to run the world for 500 years just sitting around in our nuclear waste depositories. However, as these are breeder reactors they breed the fuel. If we were to suddenly commercialise GenIV over night there wouldn't be enough fuel to start this process, the 500 years comes after the first few generations of fuel have been 'bred'.

[Qfwfq]

So the wheel must be rotating on a horizontal axis, so its compressor pistons can be driven by their own weight.

Well I definitely wasn't fixated on his system’s Energy Bags^TM, more simply I hadn't seen the details of his system before I followed your link yesterday. When I did, I came to the conclusion that Garvey is a bit of an eedjit.

 

He does totally neglect thermodynamic considerations, so that aside from not exploiting any temperature difference, he will even be losing some of the energy in his storage. I also doubt he has made much quantitave assessment before talking about how cheap it will be to build his tubes and pistons when they are huge but, most of all, I think there is a far better way to tackle the torque problem which led him to conceive such an awkward system of compression.

[CraigD]

A big concern I have about a system that relies on wind power from a small region is that wind vs. a solar one is often very slow for long periods, while the sun rises and sets as surely as ... well, as the sun rises and sets.

And how's solar PV with cloudy days? Night? Seasonal differences?

My concern is about the relative unpredictability of wind speed in a given region, compared to that of sunlight intensity.

 

That there is no sunlight at night, and that it’s intensity varies with the time of day, is very predictable. Clouds blocking it is less predictable, but averages to a predictable value over a fairly short period – days, not months. Based on my anecdotal observations, heavy cloud cover rarely last more than a few days. While seasonal, there are no periods of the year in most regions where unbroken cloud cover is constant.

 

Again based on anecdotal observations, first hand (ie: drifting becalmed for days) and historic (various famous month-plus long becalming of pre-motorized ships and fleets), wind appears to me to be more vulnerable to long, unpredictable periods of low speed.

 

Energy storage systems like Garvey/NIMROD’s Energy Bags are, I gather, designed to even power delivery over short high/low periods of a few days or less. Thus, I worry that a small location (ie: my hypothetical island residence/resort) dependent on them might be frequently “becalmed”, suffering electric brow/blackouts, while the same location dependent on solar like that described in the Solar Grand Plan (but scaled down to something less grand) would not be.

 

Well I definitely wasn't fixated on his system’s Energy Bags^TM, more simply I hadn't seen the details of his system before I followed your link yesterday. When I did, I came to the conclusion that Garvey is a bit of an eedjit.

…

I also doubt he has made much quantitave assessment before talking about how cheap it will be to build his tubes and pistons when they are huge but, most of all, I think there is a far better way to tackle the torque problem which led him to conceive such an awkward system of compression.

I’ve had similar suspicions about Garvey – that he’s more of an entrepreneur/celebrity than a mathematical engineer – but to his credit, he secures funding and builds large prototypes.

 

My personal read on him is that he’s a bit heavy on hype, but not a complete crank. Time and the success or failure of his and similar projects will tell.

[HydrogenBond]

The heat generated by the compression is part of your energy input. If this heat is lost or removed, then the stored energy goes down. The heat loss causes a pressure drop PV=nRT

 

I like the idea of using wind power to generate low voltage current to run electrolysis to make O2 and H2. Instead of energy stored within pressure and heat, the energy is stored in relatively stable chemicals, which have a lot of potential energy when recombined. Maybe we connect wind power to a H2 refilling station for cars. The O2 sold to industry.

[Eclipse Now]

The heat generated by the compression is part of your energy input. If this heat is lost or removed, then the stored energy goes down. The heat loss causes a pressure drop PV=nRT

 

I like the idea of using wind power to generate low voltage current to run electrolysis to make O2 and H2. Instead of energy stored within pressure and heat, the energy is stored in relatively stable chemicals, which have a lot of potential energy when recombined. Maybe we connect wind power to a H2 refilling station for cars. The O2 sold to industry.

 

If you can deliver this at a cost equivalent to the compressed air balloon, why not? But I personally think hydrogen will be for certain niche energy fuels. Why take X amount of renewable or nuclear electricity, waste half of it splitting water, then waste more of it trying to store the hydrogen and compress the hydrogen into a car's tank, and then halve it again when burning it in a fuel cell... just to get electricity again?

 

Surely it makes more sense to put the original clean electricity straight into a car's batteries for storage?

 

Now there's a subject... what if VTG cars really became economical, and our fleet of electric cars really could run the grid when the wind and / or sun stopped? Imagine cars are always plugged in when motionless, which tends to be 22 hours a day. They'd be charging much of the time, but most would be able to sell a good amount back to the grid when needed and still have plenty of charge to get home.

 

Just a thought. But I think in reality, we'll be heading for stable, reliable, baseload power from GenIV nukes.

[CraigD]

Slightly off-topic history

… But I personally think hydrogen will be for certain niche energy fuels. Why take X amount of renewable or nuclear electricity, waste half of it splitting water, then waste more of it trying to store the hydrogen and compress the hydrogen into a car's tank, and then halve it again when burning it in a fuel cell... just to get electricity again?

 

Surely it makes more sense to put the original clean electricity straight into a car's batteries for storage?

I personally agree with you, EN. :thumbs_up

 

I think that to understand why hydrogen as a fuel, either burned in a heat engine, or generating electricity in a fuel cell, has been and remains a popular idea - the "why" of it - you have to consider some history.

 

Burning hydrogen and hydrogen electric fuel cells are old, 19th century technology, but because of practical difficulties, remained primarily scientific curiosities until the mid 20th century, when liquid hydrogen + oxygen fuel rockets appeared as the best way to lift the large payloads of the burgeoning space programs. Since these vehicles carried lots of liquid hydrogen and oxygen, PEM fuel cells were a obvious choice for their electrical power supplies, with the additional benefit that their by product, pure water, is useful in manned vehicles. That these powerful, compact systems were expensive – thousands of US dollars per watt – wasn’t an issue, as everything about spaceflight was expensive.

 

Shortages of petroleum fuel in the 1970s led to widespread interest in alternative fuels, primarily for cars and trucks, so naturally, there was interest in adapting the space program’s proven PEM fuel cells to this use. At this time, battery technology was fairly primitive, so despite the great cost of handling hydrogen and fuel cell material (to this day, lower cost alternatives to costly platinum catalysts remain elusive), hydrogen power remained attractive, yet just beyond practical reach.

 

Meanwhile around 1990, the emerging popularity of small battery powered devices, primarily mobile phones, resulted in a revolution in battery technology, so that as of 2011, you can buy 86 or 36 MJ Li-ion battery powered car (specifically, a Nissan Leaf or a Chevy Volt) for $US 33,000 to 41,000. The niche that hydrogen fueled cars were once intended to fill is ably filled now by proven battery powered ones.

 

In short, if your vehicle is a liquid hydrogen fueled rocket, complete with the cryogenic facilities and ground crew to fill and maintain it, and money was no object, hydrogen fuel cells are your electric power supply of choice. Otherwise, it’s prohibitively expensive and technically troubled, and less or only marginally better than existing batter technology.

 

 

One potential advantage of hydrogen over batteries – that it can be refueled quicker than a battery – I expect may disappear in the near future, with the introduction of improved battery technology such as lithium titanate.

[Eclipse Now]

Slightly off-topic history

 

One potential advantage of hydrogen over batteries – that it can be refueled quicker than a battery – I expect may disappear in the near future, with the introduction of improved battery technology such as lithium titanate.

Even if quick-charges were not coming, I think EV's would still have a big place in tomorrow's world. Personally I'm a fan of New Urbanism... just check this 4 minute video which explains what we could enjoy instead of being stuck in traffic for hours each day. We could be fitter, cleaner, healthier, with nicer air and a less stressed lifestyle. It asks, "What is the greatest threat to our planet?" You'll love the answer!

 

Now, having said that we need a world with less cars in the first place, here is an Indian company that will soon be offering $10 grand EV's that have a 200km range on a single charge. I'd buy one tomorrow if they were already in Australia!

 

 

http://nextbigfuture.com/2010/12/tata-reveals-indica-vista-electric-car.html

 

And if I need to drive between Sydney and Melbourne? Well, maybe I need my head checked. Maybe we all need our heads checked! :lol: Why not train there and hire a car the other end?

 

 

But, if people REALLY want to do a 'road trip' down the highway as part of their holiday fun, there are other options for EV's. Cities could easily support most driving with normal charging of EV's, but down our highways we could have Better Place battery swaps. Check this out. Faster than filling up with petroleum!

[Eclipse Now]

I've heard these might be far cheaper than air-balloons. Its about building BIG centralized energy storage to get a lower per unit cost.

 

http://scienceforums.com/topic/23494-giant-hyrdo-batteries-anywhere-there-is-a-cliff-next-to-the-sea/

[kowalskil]

OK, here are a list of the claims for the energy storage, used to make wind power baseload.

 

 

 

 

But a pro-nuclear guy I respect as level headed and very technical replied:

 

 

 

Seamus responds — in another discussion with another person raising the same argument — that:

 

 

(from second comment down, under the show description and transcript)

http://www.abc.net.au/rn/scienceshow/stories/2010/2952227.htm

 

Hmm, interesting.

.