greenheatman

Brian, no I am not proposing that at all! We're discussing tidal streams so that figures can be put on it. I pointed out that simplistic TSGs discard 7/8ths of the power and attempt to extract as much of the remaining 1/8th as possible - this is bad engineering because a) the output is intermittent and the output is a tiny ~4% of the resource. Maths can simply prove this to be true. If you have a 1MW TSG it can only generate a maximum of 1MW irrespective of how much shaft power is available during a Spring tide. To calculate the power in one tide the formula is P = (4 x h x b)/(3 x pi) so for a Spring tide maxxing at 8MW there will have been 26MWh of mechanical power available on that tide (for conversion to heat in my system). The electromechanical 1MW TSG may have generated a rather pitiful 3 to 4MWh electrical on the same tide throwing away >22MW(mech) in the process.

Brian, to understand what I am proposing you have to understand the dodgy engineering practices by the self-promoting 'experts' in the field of marine renewables. It is easier to to put hard and fast numbers on tidal streams but the same principles apply to other renewables. Let's look at Bluemull Sound. The water courses through there about 2 days after a full or new moon at, say a nice round 5m/s on the zenith Spring tide. However, our academic 'experts' are intent on generating electricity in real time from this prime mover and are not interested in Spring tides and design their Tidal Stream Generators (TSGs) to work on the mean Neap tide velocity which, for convenience, we will say is half of the Mean Spring Tide (actually it is around 56%). Mathematically, they are simply discarding 7/8ths of the resource because velocity is cubed in the power equation (ie 1/2 x 2/2 x 1/2 = 1/8). This 'extra' power is discarded by feathering the blades of their TSGs The may be able to convert about 35% of this remaining 1/8 into predictable varying pulses of practically worthless electricity with a maximum capacity factor of ~22% so that ~4% of this huge resource is converted into dodgy electricity that requires fossil backup for 78% of the year! (please ignore claims by MCT of 66% because they have reduced the hours in the denominator by a third to attract inward investment!) Now some people will say that this is 'brilliant engineering' but I don't. Simply by converting ALL of the power under the power graph for each and every tide my calculations show that you can generate 10 times more thermal electricity 24-7-365 that does not require any back up whatsoever.

Of course it is an issue with all 'real time' tidal stream generators because they all use the mean Neaps' velocity which approximates to a half of the means Springs' mean velocity. This means that only 1/8th of the tidal stream resource is actually used because velocity is cubed in the power equation (1/2 x 1/2 x1/2 = 1/8) These low tech machines struggle to convert more than 40% of this 1/8th into electricity so that an absolute maximum of 5% of the resource becomes low quality intermittent insecure power - pretty pathetic really. My Gentec venturi converted almost all of the power in each and every tide into heat and this amounts to around 50 times more thermal power put into storage. Covering it back into generator shaft power @ at a lowly 20% thermal efficiency gives you the ability to generate 10 times more electricity to meet fluctuating electrical demand 24-7-365 As to costs of production my price per MWh will be around 2 pence - real time TSGs are 'happy' with 6 pence per kWh!

No - I couldn't get any funding but I have walked away from Gentec venturi because, despite it being capable of generating 10 times more 24-7-365 electricity my wave machine will generate 50 times more 24-7-365 electricity per linear metre of wave front. I made the classic mistake of being up too close to Gentec venturi to realise that Neap tides make too big a 'hole' every other week.

I find it incredible that the wave energy industry continues to use flawed mathematics to calculate the power in a wave. it is well known that the kinetic energy in a wave is equal to the potential energy in the same wave. What Prof MacKay does in his 'without the hot air' book on wave power (page 308 I think) is calculate the potential power, assumes that he is right, and simply doubles it to give his formula - which is wrong as it happens. The beauty of mathematics is that it is a pure science but you must prove your formula to confirm that you are correct. In wave power they simply have not bothered to do a mathematical proof. What I have done below in calculated first the potential energy and came up with pretty much the same answer as Prof MacKay except that he has a 4 in his denominator but this has to be pi. I then do the same with kinetic energy and come up with the same answer - adding them together gives the correct and proven formula for wave power. Assuming a perfect sinusoidal oceanic wave, one metre high between crest and trough with a period of 10 seconds in deep water, its velocity is calculated using the formula (gT/2Ï€) = 15.613 m/s The wavelength, λ = vT =(gT^2/2Ï€) = 156.131 m The potential energy passing per unit time, per unit length, is Ppotential =m*gh/T where m* is the mass per unit length and h is the change in height at the centreline of the sinusoidal mass of seawater. The cross-section area of the wave’s amplitude is calculated using the following formula Area = (2 x base x height)/pi, (2 (λ/2) a)/ Ï€ because a = h/2 this can be rewritten as (λh/2Ï€). Ppotential =m*g h/T = (2 λ h g h Ï) / 4 Ï€ T = (λ h2 g Ï) / 2Ï€ T and because λ/T is velocity, substituting we get, Ppotential = h^2 g Ï v / 2Ï€ = (1 x 1 x 9.81 x 1025 x 15.613)/ 2Ï€ = 24.986kW/m The potential and kinetic energies in waves are exactly equal. I now will calculate the kinetic energy of deep water dispersive waves independently to see if the answers are the same. P kinetic = ½ m v^2 (kW/m) The simultaneous vertical descending and ascending velocity of all oceanic waves irrespective of their height is always √2 (m/s) which I will call vd and va respectively. Substituting we get P kinetic = ½ [(vd h)(va h)(g v Ï)]/2 Ï€ (kW/m) = ½ [(√2 h) (√2 h) (g v Ï)]/2 Ï€ (kW/m) = ½ 2h^2 g v Ï)/2 Ï€ (kW/m) Therefore, P kinetic = (h^2 g v Ï)/2Ï€ (kW/m) = 24.986 (kW/m) = P potential P potential + P kinetic =24.986 + 24.986 = 49.972 kW/m Therefore, P potential + P kinetic = (h^2 g v Ï)/ Ï€ (kW/m) so that for a dispersant pelagic ocean wave in deep water, the following formula is true; Ptotal = (h^2 g v Ï)/ Ï€ Questions & Answers Q1) The idea of converting wave shaft power into heat, storing it and converting it back into (generator) shaft power sounds very inefficient – wouldn’t it be better to convert the wave power into electricity directly? A1) I have shown that the near shore raw resource power is 474kW/m. Conventional ‘real time’ wave energy to electricity converters have very poor resource to wire conversion efficiencies. The following link describes how an oscillating water column device, the Limpet 200 could only generate @21kW at best during optimum wave conditions. The effective length of the device was 10m so 2.1kW/m from a possible 474kW/m gives this failed wave energy converter a resource to wire efficiency of just 0.44% http://www.inference.phy.cam.ac.uk/withouthotair/c12/page_75.shtml The Pelamis Sea Snake developers claim that their device gleans a raw resource power of 72kW/m in deep water well off-shore. This still has be converted into intermittent pulses of electricity using hydraulics and, assuming a generous efficiency of 25%, only 18kW(e)/m is generated from a possible 1,333kW/m giving a resource to wire efficiency of 1.35%. http://www.icrepq.com/icrepq-08/380-leao.pdf Gentec WaTS on the other hand, in the same deep water, has a resource to wire efficiency of 48%. Q2) If you invention is as good as you say – why wasn’t it invented before? A2) Well, it has all been invented before! Every element of my invention is well proven science – all I have done is ‘rearranged’ these components to solve the ‘intermittency problem’ and generate over 50 times more secure thermally generated electricity as a result. Converting the power in waves in direct proportion into heat and storing it is pretty obvious when you consider that almost all of the world’s electricity is generated thermally. Providing thermal power stations with an alternative ‘heat source’ without burning anything or splitting atoms is all that is needed to generate electricity using well proven thermodynamic processes.

The sad reality is that the best Tidal Stream Generators (TSGs) convert no more than 5% of the resource into electricity. This is because these machines operating velocity is based on the mean Neap tide velocity which is approximately 1/2 of the Mean Spring Tide. Velocity in the power equation is cubed that means that 1/2 x 1/2 x1/2 =1/8 of the tidal resource is made available for conversion. Only a maximum of 40% of this remaining 1/8 can be converted into variable pulses of electricity dependant on the phases of the moon. Another point worth making is that the maximum capacity factor is 22% which means that a TSG has to have backup for 78% of the time. Perhaps a new term needs to be used when describing an intermittent renewable energy scheme such a Back up Required or BR of 78% for a TSG, BR of 50% for a Shetland windfarm, or a BR of 80% for a near shore wave energy convertor.

Dearie me, It now looks that Shetland will be generating 25% of the UK's electricity courtesy of a HUGE wind farm - by the time the cable comes ashore there will not be much of it left.

Very, must be off-season.

Say, you wanted to generate at 500MW continuously then the size of the ship's store would need to be 500,000m3. Using a 50 metre artificial beach on the vessel the thermal store will put 1383MWh(thermal) into storage every hour with a deep ocean wave amplitude of 4m: a 6m wave would put 3112MWh hourly. It would take just 7.5 hours to raise the store temperature through 40C. The cube root of 500000 is 79.4m so the ship would need to be perhaps 80m wide and 200m long to accommodate the thermal store - part of which will form part of the vessel's displacement - to allow it to float! The store itself will be very well insulated but any precalculated losses in transit back to its berth will be compensated by taking more waves on board - ie by 'overcharging' the store. The onshore store will be 10 times larger with an internal dimension of 171m on each edge if it were a cube - which I hasten to add it will not be. The onshore facility can generate at 500MW for 6.5 days without being recharged from the sea. Over this period the store temperature will drop by just 40C - while steam turbines continue to generate at full capacity by increasing the steam flow rate to compensate for the small drop in thermal efficiency.

Yes, one thing is certain is that any renewable energy system that can generate renewable base load, peak shaving or load following electrcity is not going to be cheap. However, building the vessels, berths and retro-fitting existing thermal power stations with new green heat sources will be about 10 times cheaper than building new nuclear, new 'clean coal' new carbon sequestration systems pumping liquified CO2 (@ -56C or lower) out into the North Sea, AND building millions of silly wind, and marine turbines over and above. To convert Scotland's thermal power stations may cost a few tens of £billions but the cost of implementing all of the above will cost 100s of £billions plus you have to buy in the coal from Poland and beyond on top of the capital outlay. So from a financial standpoint a few £billions is 'much cheapness' in the scheme of things.

The power from waves in the North Atlantic is infinite provided that you are allowed to move about a bit to find them. The waves in one fixed location will be poor and unusable for about 30% of the year. There will be good waves somewhere in the NA - you just need a ship to go and get them. The "flaw" as you put it applies to tidal stream itself NOT any of the devices that are put in the water to extract its energy. Speed reading again?

First of all I did not drop Gentec venturi because there was anything wrong with it - I dropped because this predictable renewable energy is predictably poor during Neap tides - this applies to all real time tidal generators. Again you are mixing apples and oranges. My system's overall efficiency may be a bit lower because it will deliver Class A electrcity - current renewables deliver third rate Class C subject to the state of the tide or the weather. Surely, even a member of MENSA can see that comparing like with like is a valid thing to to - otherwise it is merely mathematical illiteracy.

Mind you, it was a complex machine which might not have proved practical in open sea conditions. If his wave machine just produced heat it would have been more robust to stand open sea conditions - besides waves lose a lot of their power as the seabed shoals - but had he thought of wave to heat then - the whole world would have followed suit. Sadly, we need to change direction which will be very difficult now that the planet is covered with pathetic and puny wind, wave and tidal machines.

Hooray! At last! Now we finally get a tiny inkling into how this magic system actually works. My god, that took some doing, worse than pulling teeth. Why didn't you just say this in the first place, GHM, instead of wasting six pages of Shetlink space saying nothing and insulting the regulars. So, is this going to be a nodding paddle type thing a la the Salter Duck , or a rotary thing like a Mississippi paddle steamer? In the 70s it was routine to burn oil to raise steam - the call for an alternative way was answered by S Salter's Duck. He struggled for years to get it to generate electricity and failed - poor man - his big mistake was to not generate heat from the waves - that way he would have replaced the burning oil to raise steam. We have been lumbered with his mistake for the last 40 years. Renewable energy should be used to generate heat not electricity. If this strategy had been adopted then renewable energy may have replaced some coal fired power stations by now - 40 wasted years is enough to make you weep!

now i know your science is faulty. your claiming that you can change a form of energy into heat without loss. this indicates that your paddles are friction free. that the energy generated loses nothing in transmittion to your heat generator this also loses nothing. very impressive. one moment your using heat pumps next your using paddles. your ship is also going to be steam driven which is using the power created to move it. Which should be classed as a loss in production. Don't put word in my mouth - I did not say that there would not be losses. In fact losses in heat may amount to around 25% - this is easily compensated for by putting 125% of free energy in at the front end QED