Half a croissant, on a plate, with a sign in front of it saying '50c'
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Power Station With Alcohol Second Stage

Extract a touch more electrical energy from your chosen heat source.
  [vote for,

Power stations are simple machines. First, you acquire a source of heat. Burning things is the traditional approach but there's also nuclear fission, geothermal and a couple of variations of solar. The heat is then used to boil water and make pressurized steam. This has been the gold standard for a long time, since Newcomon was a lad.

Steam is good at making things move, pistons were fashionable while chaps with regional British accents were inventing the Industrial revolution*. Subsequently, the steam turbine was invented by a British chap with probably a non-regional accent. He immediately attached it to an electrical generator** and things haven't changed much since.

So, a power station might involve the burning of gas, the boiling of water to make pressurized steam, passage of that steam through a turbine and.... well, you could just let it out the back, but then you'd waste the nice, pure and expensive water. Instead, they route the steam through pipes immersed in pools of regular water until it condenses, then pipe it back to the start of the loop. This is a good system, you can recycle the pure water and condensing at the back of the turbine makes a lovely pressure gradient.

Sadly, condensing steam heats the cooling water and it evaporates in huge clouds out of the cooling towers so often seen at power stations. This is wasted energy. Quite a lot of it. There have been schemes to distribute this spare heat, heating nearby communities and such but almost always it is just dumped to the atmosphere.

Now, the sort of turbines power stations operate have an exhaust temperature around 75C range as far as I can work out. This can be used to boil a range of liquids but ethanol and methanol spring to mind. Using your exhaust steam you can boil alcohol to create whole lot of pressurized alcohol vapor*** while condensing your primary circuit MORE efficiently. This alcohol vapor may spin another turbine and another generator. After this, you'll need to condense your alcohol vapor to get the optimal delta p across the turbine, just like the steam in a normal station. This will have a smaller temperature differential, so the cooling tower will be less efficient, but the total heat being rejected is now smaller, so probably a swings and roundabouts situation. Anyhow, if it doesn't work I've got plans for a 3rd stage using ether.... while Canada/Russia/Scandiwegia may be interested in my Butane 4th stage.

Once this is up and running, small amounts of alcohol might be drawn off and sold in the gift shop for those who really appreciate efficiency, and booze with just a hint of dissolved turbine lubricant.

*The crank was key here, before that industry was entirely linear. Progress was constrained by the number of young boys available to retrieve and re-install pistons. **Attaching one to a battleship caused a bit of a kerfuffle in the Naval world. ***Annoying how "steam" only applies to water..

bs0u0155, Feb 09 2018

The Museum Of RetroTech http://www.douglas-...m/MUSEUM/museum.htm
You name it, it's been tried. [8th of 7, Feb 09 2018]


       Sounds good to me. Presumably, a liquid/vapour nitrogen loop could be appended for yet further efficiencies.
MaxwellBuchanan, Feb 09 2018

       "Topping" and "Bottoming" cycles for energy recovery, using all sorts of working fluids - sodium, hydrogen, mercury, gasoline - are Baked and WKTE.   

8th of 7, Feb 09 2018

       Water boils at 373.15 K and ethanol boils at 351.65 K.   

       If you condense your steam to water at 373.15 K while also producing ethanol vapour at this temperature, the subsequent ethanol-based stage can achieve a maximum efficiency of 1 - (351.65 / 373.15) = ~5.8%, by the Carnot cycle. This hardly seems worth it.   

       With butane you can get down to 272.15 K giving you an extra 27% efficiency. You'll need a way of getting rid of a few gigawatts of heat at -1 deg C, though.   

       (Maybe the methane clathrate at the bottom of the ocean could be used as a heatsink? Nah, that might upset a few people.)
Wrongfellow, Feb 09 2018

       // This hardly seems worth it. //   

       When you're generating Gigawatts, it most assuredly is. Just a few percent of net gain, in a highly competitive market, is worthwhile.   

       Obviously the capital outlay can be high but if it's built with the plant, rather than as bolt-on accessory, the costs can be kept down to an acceptable level.
8th of 7, Feb 09 2018

       I think the power station people would take 5%. That's a pretty big jump.   

       [8th] I'm going to be stuck in that website for some time.
bs0u0155, Feb 09 2018

       I was kind of assuming that most of that theoretical 5.8% would be lost as heat due to inefficiencies in the plant, but I suppose if you're generating gigawatts, you have to be able to reduce your inefficiencies to way below a few percent, or your power station will melt.
Wrongfellow, Feb 09 2018

       // I'm going to be stuck in that website for some time. //   

       Yes, sorry about that. Look, for the next month, we'll drop food parcels and flares and stuff ... if we don't see you again by then we'll send in the search teams.   

       Remember, the food is only useful if you actually eat it. It's no good getting hypnotised by the gyrocars, or the square-piston engines, and forgetting to take in any nutrients. The bleached skeletons all around, still staring in rapture at the exhibits, should be sufficient warning.
8th of 7, Feb 09 2018

       Forewarned is forearmed... bookmarked for later devouring.
FlyingToaster, Feb 09 2018

       //The bleached skeletons all around, still staring in rapture at the exhibits, should be sufficient warning.//   

       You assume starvation is the cause of bleached skeletons? Not the boiling potassium exhibit?
bs0u0155, Feb 09 2018

       No, it calcines the bones completely.   

       // bookmarked for later devouring. //   

       <doubles up order for survival packs>   

       We''l get you out, but you actually have to want to leave. So very many are happy just to stay there, and die with a huge cheesy grin on their face.   

       It's not such a bad way to go.
8th of 7, Feb 09 2018

       Don't look to me for help. I just found my 35 year old copy of the CMOS Cookbook and I'm good for nothing.
MaxwellBuchanan, Feb 09 2018

       Will we need some more accents?
pertinax, Feb 09 2018


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