Alternative Energy Production - Tidal / Wave etc.

[Pooks]

I pledge £10.

 

You can buy a kettle for a tenner.

 

Seriously though Mr Greenheatman I hope for your sake that your invention does as it is told. I am a very open minded person and I would happily see the 'little man' succeed, however, the posts that I have read so far from yourself seem to be an attempt to undermine everybody that you are trying to sell your invention to. If it is as good as you say then I suggest that you hire someone to organise and front your public relations as I will not part with any money to someone who believes they are wasting their time even explaining the ideology to me.

 

Never upset your outlet, lose them and you have no hope of achieving your final goal.

[Pooks]

P.S. Do you know how much energy an electric kettle burns?

 

P.P.S Being a clueless un-technical-minded fool, that is maybe the whole idea.

 

P.P.P.S Greenheatman, ever thought of a job as a Shetland Councillor?

[islandhopper]

Come on, sombody give the guy £50 to come up to Shetland. We could all share the price of his fare. It could be a Shetlink sponsored tour of the isles. ...

and other quotes ...

 

May I humbly ask you whether there is/you know someone who would like to sponsor my ferryticket? Would be highly interested in watching any kind of presentation and /or demonstration! ...

[edit] I'm prepared to do any translation work up to 100 pages DIN-A-4 (two lines less than US standard letter) for compensation!!![end of edit]

 

@greenheatman:

Sorry, but according to your statements so far, we should not discuss about thermal accumulators in general. Could you please specify the quality of stainless high-grade steel you want to use to keep sea(salt)water at 300C and under pressure of >100 Bar to guarantee an average lifespan of let us say 20 years.

[greenheatman]

Sorry, but according to your statements so far, we should not discuss about thermal accumulators in general. Could you please specify the quality of stainless high-grade steel you want to use to keep sea(salt)water at 300C and under pressure of >100 Bar to guarantee an average lifespan of let us say 20 years.

 

Stainless steel - yet another erroneous assumption. I do not propose keeping seawater at 300C for more than a few seconds.

 

This is hard work!

[islandhopper]

This is hard work!

May be, may be - but that's simply due to your kind of mixture of Babylonian menetekels and Delphi styled soothsayings:

For anybody else would calculate that it takes more than a few seconds to heat saltwater harvested at some 6 to 14 ° C in Shetland waters up to 300C, to transport it through some kind of pipe to some kind of generator and then to cool it down or leave it to the environment ...

 

Well then: You might need 300C for a few seconds only, agreed, and so I correct my question: What kind of steel to keep it at least for the majority of processing time above 200C at an average pressure well above 75 Bar ...

You may correct the °C or the pressure to your standards, but, please, give us some idea about the standard config of your proposed system from harvesting the water, heating it up with what kind of collector, get it transported through what quality of pipes to what quality of generator ...

[greenheatman]

"Well then: You might need 300C for a few seconds only, agreed, and so I correct my question: What kind of steel to keep it at least for the majority of processing time above 200C at an average pressure well above 75 Bar ..."

 

There is no steel.

 

"You may correct the °C or the pressure to your standards, but, please, give us some idea about the standard config of your proposed system from harvesting the water, heating it up with what kind of collector, get it transported through what quality of pipes to what quality of generator "

 

Here is a typical closed Rankine Cycle circuit used to turn a steam turbine. Replace "Geothermal Water" with "Tidal Stream Heated water in a Thermal Accumulator" and Bob's your uncle. In an open cycle, if you want desalinated water, the 'cooling water' is seawater and it comes in through the condenser, pump and preheater(aka the heat exchanger), the hot water is now fed into the evaporator (aka flasher/separator), goes through the steam turbine that converts the enthalpy in the superheated steam into useful shaft power which in turn drives the generator, the steam is then condensed into water and pumped into the nearest water main. The seawater in the condenser, now warmed, is pumped through the pump and the process is repeated into infinity because tidal stream is replenishing the heat source with every turn of the tide.

http://www.geothermie.de/gte/gte36-37/al.gif

[islandhopper]

There is no steel.

No steel??? Sounds interesting!!!

The more than the rest of the world uses qualities like "Nirosta 4565S" to process most aggressive heated saltwater to avoid rapid corrosion.

So, what material will you be using? Might be a crucial point when it comes to the overall costs!

[greenheatman]

There is no steel.

No steel??? Sounds interesting!!!

So, what material will you be using? Might be a crucial point when it comes to the overall costs!

 

I am looking at composites at the moment with special laminates to suit each part of the process.

 

Besides, the desalination is an option - the system is flexible so could operate at almost any temperature gradient (see OTEC) in a closed loop like the diagram posted above.

[Sudden Stop]

I must (and probably am to be fair) missing something. I thought the idea of the thermal batteries were to store the energy produced by the flowing tide and then release it when the tide is slack. So, from any power that is produced whilst the tide is flowing more than half of the power will be going away to heat water to store energy for later in the day. The energy stored will need to be stored for several hours (such is the nature of the tide).

 

Storage of energy will be more than a 'few seconds'. Perhaps it may work better when using a constant thermal source such as geothermal but tidal power will not be constant. Thus much more than a 'few seconds'

 

I've seen air tanks that'll take a couple of hundred bar of pressure that are made for composites to save weight, but these are very expensive and they are very small in comparsion to the size of tanks you would need. I ask again, have you operationally tested examples of your proposal at full scale or is this all just theoretical? I'm not arguing with the theory, as it is fairly sound, but in practice, i think this would be very complex, and as I hinted at early, dangerous.

[islandhopper]

the system is flexible so could operate at almost any temperature gradient (see OTEC) in a closed loop like the diagram posted above

... agreed - as can any kind of a modern heat exchanging device.

 

As I read your graph your device is nothing else but a MSF (Multi Stage Flash Evaporation) device and in the end just ahead of your turbine you have to handle temperatures well above 100°C and/or corresponding pressure and not just "any temperature gradient" ...

 

Despite that, I can't see from your graph how you would like to handle the brine resulting from heated and evaporated saltwater - the more you intend to work your device as a "closed system" what will increase corrosion probs drastically ...

Handling it as an open system and thus pumping all back to the sea might increase environmental probs due to long term "oversalting" the voes which have a lowered water exchange rate anyway. Just the same probs we are facing with the desalination plants based on MSF in Saudi Arabia and elsewhere ...

[islandhopper]

The energy stored will need to be stored for several hours (such is the nature of the tide).

Not neccessarily for hours ... what you have to cover is the time when there is no tidal stream at the point when tides are changing. No idea if the 8t store will be enough for that ... but from the pure physical facts it seems to be possible, at least if you look at the preheater in the graph not as a single unit but as a multiphased / multistaged one. Such units only need a relatively small energy input of about 100Kwh/t enthalpy of evaporation at about 2 bar hot steam (+ a little added for the pumps) all of it won from the tidal stream and released just for the time when the tidal stream actually stops.

 

Well typing this: Sounds a bit like the perpetuum mobile ...

[greenheatman]

"I must (and probably am to be fair) missing something."

 

 

Well, yes you are.

 

 

"I thought the idea of the thermal batteries were to store the energy produced by the flowing tide and then release it when the tide is slack. "

 

Wrong, the idea is to store all the power (under the power graph) when the tide is flowing or ebbing. All the electrical power generated is derived from the thermal store.

 

" So, from any power that is produced whilst the tide is flowing more than half of the power will be going away to heat water to store energy for later in the day."

 

Wrong again. The generation of grid electricity (from storage) is continuous, the generation of water heating electricity(from tidal stream) is intermittent.

 

"The energy stored will need to be stored for several hours (such is the nature of the tide)."

 

Wrong, the energy stored will be stored over each and every lunar month into infinity. Energy will be going into the store when the tidal stream is present, energy will be coming out of the store when it is not, also surplus energy stored during Spring tides is carried forward to fill in the 'hole' during Neaps."

 

 

"Storage of energy will be more than a 'few seconds'. Perhaps it may work better when using a constant thermal source such as geothermal but tidal power will not be constant. Thus much more than a 'few seconds'"

 

 

Wrong, yet again, Are you 'speed reading' this because I did not say that? The cold seawater is passed through a permamently hot store and picks up the heat in a couple of seconds as it passes through the heat exchanger. The very hot seawater is flashed to steam whereupon it goes through the steam turbine where it is then condensed back into liquid H2O at around 35C.

 

This process takes a couple of seconds and has continuous flow of feedwater.

 

Composites are expensive but who cares what the fiscal costs are when we are trying to save the planet by closing down all the fossil fuel power and desalination plants in the world?

[greenheatman]

The energy stored will need to be stored for several hours (such is the nature of the tide).

Not neccessarily for hours ... what you have to cover is the time when there is no tidal stream at the point when tides are changing. No idea if the 8t store will be enough for that ... but from the pure physical facts it seems to be possible,

 

The surplus Springs' energy stored will need to be stored for over a week to cover the Neaps' period. A 8000kg thermal store can do that nae bother at all

[Sudden Stop]

I'll ask again, have you built and successfully tried this from an intermittant power source, such as tidal at full scale??????????

[greenheatman]

"Despite that, I can't see from your graph how you would like to handle the brine resulting from heated and evaporated saltwater - the more you intend to work your device as a "closed system" what will increase corrosion probs drastically ... "

 

 

"Handling it as an open system and thus pumping all back to the sea might increase environmental probs due to long term "oversalting" the voes which have a lowered water exchange rate anyway. Just the same probs we are facing with the desalination plants based on MSF in Saudi Arabia and elsewhere ..."

 

Ideally, the concentrated saline solution should be dumped into mighty river estauries like the Ob which is dumping huge volumes of fresh water from accelerating glacial ice melt into the NE Atlantic. This has drastically reduced the Ocean's salinity levels and the NA Conveyor may just stop!

 

(In OTEC the temperature gradient avers to the difference between the top and bottom seawater temperatures.)