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back to article Exciting MIT droplet discovery could turbocharge power plants, airships and more

Top engineers at MIT say they have come across a handy effect which could seriously boost the efficiency of a critical piece of kit used in many important technologies. The piece of kit in question is the humble water condenser, which has been in use for hundreds of years: James Watt introduced it to the earliest steam engines, …

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Anonymous Coward

Your article goes on a bit

You might want to consider condensing it.

(sorry as a coward I am not allowed the Joke icon)

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HMB

Re: Your article goes on a bit

It's wonderful news.

What made you suggest they condense it? Did you drop off while reading it? :P

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Coat

Re: Your article goes on a bit

What a drip!

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Re: Your article goes on a bit

Oi, that's a serious charge.

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Of declining importance for power generation

In the UK, and much of Europe, the obsession with subsidised intermittent renewables means that it is not cost effective to build new combined cycle plants, and in future it won't be cost effective to operate existing CCGT plant in combined cycle mode. So much of the industry are planning to downgrade the existing high efficiency CCGT to open cycle plants (cheaper to operate, quicker to respond from cold than CCGTs, but less efficient).

As a result this development will only be of interest to the fewer remaining plants run on combined cycle, and even they will probably be reluctant to invest given the uncertainty. In the US things are rather different, and I'd expect this to be explored with interest.

So our comedy energy policy will make fossil fuel plant less efficient. For comparison the electrical efficiency of an OCGT is around 40%, compared to a CCGT of 55% (thermal efficiencies are about 8% or so higher). In broad terms, this pushes the efficiency of gas back towards the higher end of the coal plants being forcibly retired under LCPD. Well done DECC and other tree huggers!

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Re: Of declining importance for power generation

So much of the industry are planning to downgrade the existing high efficiency CCGT to open cycle plants (cheaper to operate, quicker to respond from cold than CCGTs, but less efficient).

Excuse Me....do not confuse a "peaker plant" quick remote start generation with normal CCGT operation(s). During start up these plants start producing electricity from the gas turbine generators (brayton cylce) immediately after syncing to the grid, approaching nameplate output before "rolling" the steamer for the "combined" Rankine cycle output. Sheesh....

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Re: Of declining importance for power generation

"Excuse Me....do not confuse a "peaker plant" quick remote start generation with normal CCGT operation(s)."

Excuse you indeed. I work with the planners who are looking at this day in day out, and the UK will see CCGT to OCGT conversion specifically because of the short cycles and unpredictable negative demand that renewables represent.

At present there's virtually no OCGT on the UK grid even for the peaking plant (have a look at DECC DUKES data to see the detail if you doubt this) and we use CCGT of varying merit largely dependant upon age. In other countries it is more common to have a mix of OCGT for peaking and CCGT for mid merit, but with the smoothing that a truly national grid allows there's less requirement than say some regional grids in the US, that also have more variable diurnal loads.

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Anonymous Coward

Re: Of declining importance for power generation

Moving away from renewables bashing and back to the technology in the article, I for one would be interested in whether this could be used to improve efficiency of peak support in addition to base load (maybe by making CCGT more efficient in a support role?) There's clearly some knowledge floating around the comments, be nice to put it to positive use.....

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Re: Of declining importance for power generation

"I for one would be interested in whether this could be used to improve efficiency of peak support in addition to base load (maybe by making CCGT more efficient in a support role?) "

I doubt it. The issue is that you use OCGT for frequent or unpredictable peaking. Hitherto in the UK the peaks have been fairly predictable, so we were able to run inflexible legacy coal further down the merit curve as your peaking plant and use CCGT as mid merit.

In the largely post coal world after LCPD closures, gas becomes the marginal plant, but it isn't economic to maintain and run marginal gas plant as combined cycle if the demand becomes unpredictable (that's why the renewables bashing is important - they cause the problem) hence the proposals for downgrading good CCGT to OCGT. If efficiency were the sole issue rather than cost, then you would already be operating the gas turbines as combined cycle for peaking.

So improving the efficiency of the condensors on a gas turbine in combined cycle doesn't have much bearing on the choice of OCGT versus CCGT, because the technology in question probably still won't mitigate the extra O&M costs of the combined cycle plant given the expected future duty cycles.

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Anonymous Coward

Re: Of declining importance for power generation

"it isn't economic to maintain and run marginal gas plant as combined cycle if the demand becomes unpredictable"

OK, so given that this is an economic issue with no engineering issues to resolve, and the survival issue is there's only so much oil(gas/coal) in the ground, what needs to change to make the market economics reflect the real world of two/five/ten/fifty years (or more) from now?

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Re: Of declining importance for power generation

"the survival issue is there's only so much oil(gas/coal) in the ground, what needs to change to make the market economics reflect the real world of two/five/ten/fifty years (or more) from now?"

The economics reflect the short term market structures, because the longer term stuff gets discounted (as in discount rate, not as in ignored). But the point of shale gas is that although there's only so much in the ground, there's far more than the declared reserves of the energy companies. Shale gas could be supplanted in its economic significance by better means of extracting shale oil and tar sands. Certain countries have vast shale gas reserves (eg France) but are currently opposed to extracting them). When all the shale gas is gone, and the tight oil and tar is in decline, there's gas hydrates.

Eventually it all has to move away from fossil fuels. But the raw availability of fossil fuels won't be a limiting factor for a couple of hundred years, long beyond the asset life of the extraction and power generation plant.

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Nothing will make airships viable.

to compete with existing heavier than air transport., The issues are the exact same that stop ships from being ten times larger than they are.

Namely that material strengths are simply inadequate to deploy lightweight large structures, and that's what you need for serious lifting capabilities.

Hydrogen airships died fiery deaths: helium ones were torn apart by turbulence.

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Headmaster

Re: Nothing will make airships viable.

Bit "nobody needs more than 640K" of you there ?

"Namely that existing material strengths are simply inadequate to deploy lightweight large structures, and that's what you need for serious lifting capabilities."

FTFY.

Who knows what lies ahead ?

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Re: Nothing will make airships viable.

Well that graphene stuff would make them pretty well.

And why not use hydrogen - we should be able to make it workable now.

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Re: Nothing will make airships viable.

>> Nothing will make airships viable

Depends on what you want to use it for. Logically, a cruise ship shouldn't be viable - after all there are cheaper and faster ways to travel !

I wouldn't suggest airships will ever replace a large amount of other transport capacity, they do have certain advantages which (should practicalities be overcome) guarantee them a niche. If shifting large loads, fixed wing aircraft generally need very large (and strong) runways to operate from, while heavy lift helicopters are still quite constrained in lifting capacity while being very expensive and noisy to run. In flight, fixed wing aircraft have minimum speeds and are quite noisy, while helicopters also have minimum speeds (or efficiency drops) and are even noisier.

Where I see niches appearing would be things like :

Large lifts in/out of inhospitable/remote areas. The sort of movements that currently require the building of (often temporary) roads and/or the breaking up of equipment into small part.

Leisure activities where the slow speed may actually be an advantage - long distance cruises and game watching (as currently done from hot air balloons) come to mind.

I'm sure there are others.

>> Hydrogen airships died fiery deaths: helium ones were torn apart by turbulence.

In films yes. You should remember that the Hindenburg, the poster ship of the "IT BURNS" camp, wasn't destroyed by a hydrogen fire - the hydrogen only went up AFTER the rocket fuel coated outer canvas cover set on fire and the fire then burned through the gas bags.

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Re: Nothing will make airships viable.

Why not use a vacuum? Or a partial vacuum.

Holding a vacuum is only a materiel science problem, its not difficult.

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Re: Nothing will make airships viable.

It has the advantage of being able to compensate for burning off fuel by gradually allowing air into the envelope too.

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Re: Nothing will make airships viable.

I'm glad that I'm not the only one to wonder this.

AFAIK the principle of airships is that the density of the [filler] is less than the density of the air displaced thereby giving a positive lift, very much similar to the basic principle of things floating on water.

Possibly down to the pressure of the gas used as the filler keeping the containers in shape while keeping the density lower than the surrounding area, otherwise we'd need a very strong container as all the pressure would be from the outside pushing inwards, and such a container could be heavier than the weight of the air displaced.

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Re: Nothing will make airships viable.

This lot disagree with you, and so presumably do their main clients, the US Miltary:

http://www.hybridairvehicles.com

My mates working for them - pretty impressive stuff, from what I've seen.

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Re: Nothing will make airships viable.

Two words: "Diamond Age"

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Re: Nothing will make airships viable.

Have you ever heard of graphene? A "newly" discovered form of carbon. Graphene has such a high strength to weight ratio it use for a space elevator is being seriously discussed. I think it will readily handle the strength to weight ratio requirements of airships. Graphene also turns out to have incredible photovoltaic properties. You can expect it to be the new material for solar panels going forward. I can easily forsee enormous airships capable of lifting 1000's of tons of cargo with there graphene hulls generating all the power required for electric drives of the airship. So...never say never.

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Re: Nothing will make airships viable.

"So...never say never."

Alright. "Not in our lifetimes" then.

The wonder properties of graphene have yet to be scaled up, and I've likewise seen no progress on other wonder materials like artificial spider's thread, which in theory could be as strong as high grade steel and a fraction of the weight.

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bep

Re: Nothing will make airships viable.

Funny, I thought the Graf Zeppelin was broken up for scrap after nearly ten years of safe operation.

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Flame

Re: Nothing will make airships viable.

"Hydrogen airships died fiery deaths:"

Interestingly, the first German Zeppelin to be successfully killed in fiery death took a lot of R&D to come up with a workable method and the fighter pilot who did the shooting went through two complete drums of ammo[*] before finally getting the Hydrogen to burn while firing his third drum of ammo.

[*}bullets loaded alternately, one exploding bullet to make a decent size hole in the gas bags to allow air to mix, one incendiary to make it burn. Reason being that hydrogen won't burn without oxygen so an incendiary alone will just pass though the gas bag.

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Facepalm

Re: Nothing will make airships viable.

You mean something like this can never happen?

Me, I'm waiting for the light weight nuclear plant that will turn airships into the submarines of the skys.

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Re: Nothing will make airships viable.

> Well that graphene stuff would make them pretty well.

And why not use hydrogen - we should be able to make it workable now.

If you can make the material strong enough you can scrap all that heavy old hydrogen or helium and just go vacuum. The lighter than air gas is only being used to displace the heavier air.

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Re: Nothing will make airships viable.

To make them viable: condensing water from your fuel will slow down the problem, but not solve it --- a lot of other mass is lost from the fuel to the other, not-captured, gases.

So I'd think they'd condense free-floating moist air from /outside/ the airship?

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Re: Nothing will make airships viable.

'In films yes. You should remember that the Hindenburg, the poster ship of the "IT BURNS" camp, wasn't destroyed by a hydrogen fire - the hydrogen only went up AFTER the rocket fuel coated outer canvas cover set on fire and the fire then burned through the gas bags.'

No it didn't. If you watch the film of the disaster there is a closeup view of the bow as it comes crashing to earth. You can see the airship is burning inside before the outside skin catches light.

It was a hydrogen fire that destroyed the Hindenburg.

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Re: Nothing will make airships viable.

"And why not use hydrogen - we should be able to make it workable now."

Gaseous hydrogen messes up just about everything it's in long-term contact with. Metals go brittle, but so do most things you'd think of as suitable envelope material (rubber, plastics, etc etc)

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Re: Nothing will make airships viable.

"The hydrogen only went up AFTER the rocket fuel coated outer canvas cover set on fire and the fire then burned through the gas bags."

That trope has been pretty much debunked. Research on the paint used along with chunks of the surviving fabric showed that while it would burn if provoked, it was self extinguishing almost immediately whnen removed from a heat source. The only way it could have burned as seen in the newsreel is if something was keeping it going from the inside.

Indeed, if the skin had been as flammable as claimed. there wouldn't have been millions of unburned fragments of it falling to the ground - it would have all burned up before it got there.

Hydrogen burns with an almost invisible flame and it's conjectured that with the brightness of the burning fabric (lit and sustained by hydrogen flames) quite effectively masked the burning hydrogen. Some substances emit pretty bright light in a hydrogen flame too - limelight springs to mind.

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Re: Nothing will make airships viable.

"Why not use a vacuum?"

You're about 200 years late with that idea and the problem remains the same now as it was then.

The bouyancy provided by the vaccum is more than offset by the weight of the containment vessel.

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Re: Nothing will make airships viable.

The formula for burning involves combining hydrogen from the fuel with Oxygen and Carbon from the fuel with oxygen.

The Co2 is lost, but the H20 is retained. As long as you can get close to the magic "1 gallon of diesel gives 1 gallon of water" you can make up the rest by putting a compressor onboard and using that to pull helium in/out of the gasbags. (Even if it doesn't get that close, it makes the compressor's load easier provided the weight penalty isn't too high

Given the size of these aircraft, I do wonder a bit whether enough emergency lift can be generated to prevent microbursts downing the things (That's what took out most of the airships. Weather radar wasn't around back then. Piss poor designs like the R101 didn't help either)

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Re: Nothing will make airships viable.

As I recall, Mythbusters did some experiments, and concluded that it was the combination of Hydrogen and the thermite-like skin of the Hindenburg that caused it to burn so disastrously - either one wouldn't have been nearly as bad.

One solution I haven't seen suggested is to have a double-shelled airship, with the inner compartment filled with Hydrogen, and the outer compartment with Helium, keeping the Hydrogen well separated from the Oxygen in the atmosphere. This would also solve the condensor problem, as the less expensive Hydrogen could be vented, or better yet burnt along with the fuel, to compensate for the loss in weight. One would also obviously use a somewhat less flammable skin, and anti-static/anti-lightning measures (from memory it was static electricity that triggered the Hindenburg fire).

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Re: Nothing will make airships viable.

But perhaps one day with all the new Metamaterials becoming available to us we could have a viable lightweight vacuum chamber. Fingers crossed.

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Re: Nothing will make airships viable.

'a cruise ship shouldn't be viable - after all there are cheaper and faster ways to travel !'

Airships slow/low capability makes them ideal for cruise ships, they could take people to see sights they would not otherwise get to, such as vast desert, coastal cliffs, rainforest canopy etc. and all without them tramping all over it to it's detriment

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Re: Nothing will make airships viable.

If someone could instead come up with a better way to store hydrogene as fuel. The pure water exhaust would be heavier than the hydrogen alone thanks to the oxygene taken up from the air.

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Headmaster

pedantry alert

I've always been fascinated by the concept of renewable heat (or indeed renewable energy)

Surely a marketing term created by tree huggers to the sound of whale song in an incense filled innovation space?

"recoverable"?

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Re: pedantry alert

No, just shorthand for "feasible and convenient (in fact often requiring no human intervention) to recreate the initial conditions which allow for energy extraction in the first place repeatedly and rapidly over the foreseeable future."

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Re: pedantry alert

Is the opposite of a "tree hugger" a "tech tosser"?

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Happy

Even more efficient...

...washer/driers, as this is exactly how they work.

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Trollface

for the greater good

I wonder if it is possible to capture enough water from the breath of blow-hard politicians to drown them?

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Re: for the greater good

> I wonder if it is possible to capture enough water from the breath of blow-hard politicians to drown them?

and while we are at it, capturing the heat from all the excess hot air would solve our energy shortages for ever.

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Unhappy

The "vacuum" airship

Sea level air density at 15c is about 1.225Kg/m^3.

sea level pressure is around 101326 N/m^2 or .

The bottom line is the walls need to be strong to resist implosion.

Graphene might deliver a strong enough compression structure to work it.

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Anonymous Coward

Re: The "vacuum" airship

The working pressure is the difference between the atmosphere and the inside of the bags. Presumably they would not need to have a complete vacuum to achieve the same effective density as helium? However they would need to have some rigid bracing to maintain their shape. As you say - modern materials science may have some answers that can be developed.

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Re: The "vacuum" airship

Molecular weight of Helium = 4

Molecular weight of air (approx 80% Nitrogen (=28), 20% Oxygen (=32)) approximately = 28.8

Therefore Density of Helium = approx 13.9% of density of air. Therefore vacuum would have to be 86.1% (ie pressure is only 14% of atmospheric).

Using John Smith 19 's value "sea level pressure is around 101326 N/m^2", the vacship would still need to resist a pressure of 87,241.686 N/m^2 with a vacuum of the same density as Helium.

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Anonymous Coward

Steam engines weren't a curiosity before Watt

The Newcomen engine was used extensively in mines to pump water out. Saved the English mining industry. They were large devices, and were taken quite seriously.

Watt, in trying to repair a demo model of a Newcomen engine came up with an idea of the condensor unit, which greatly improved the efficiency and allowed the engines to be made smaller and therefore used in a wider range of application. Interestingly Watt had to wait about 12 years until a John Wilkinson created a way of making cylinders precise enough to make Watts steam engine work properly. - He was originally trying was to develop a way to precisely bore cannons. That is how I learned it anyway

It is interesting how all the technology interacts, and how one invention - or several leads to incremental discoveries by others.

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Any significant improvements in condensers will be of benefit to Multi-stage flash and multi-effect distillation in desalination plants in terms of output and energy efficiency.

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I wouldn't take my tablet into a sauna.

Seems like a good way to kill it to death.

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Can I have one for my tumble drier?

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Victorian House

Sod airships- will it get rid of my damp problem and give me free electricity?

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