Entropy: It’ll get you every time.

I’m basically a reasonable kind of person, which is why, following yesterday’s ructions with Nikkogen, I think its only fair that I explain in a little more detail why I’m rather skeptical about their proposed power generation system and the claims made for it, not least because, to fair to them, this also gives them a chance to respond in technical terms and demonstrate that they have overcome the technical limitations that are the cause of my own… err… uncertainties about the merits of their system.

Let’s set the parameters first – and don’t worry, I will try to keep out of the serious brain crunching physics as much as possible.

What Nikkogen are pitching is a sizeable power generation system in the 40-240 megawatt output range, which they claim will offer the following benefits:

# Zero Emissions – No harmful gases emitted from our Power Stations.
# Zero Carbon-Based fuel source – Does not use coal, gas or oil.
# Minimum ongoing costs – There are NO ongoing fuel costs only a small maintenance cost.
# Managed Power Generation – We can provide Zero-Emission Power Stations with Operating Staff, allowing non-utility companies into the power-generation industry.
# Modular design and low maintenance costs.
# Small physical “footprint” area for complete Power Station.
# No large storage yards and cooling towers are required.
# Location independent – can be built almost anywhere.
# Can be configured for grid or local electricity distribution – Where two or more nikkogen Power Stations are co-located.
# No heavy rail access required.
# Clean limited-noise operation.
# No dust or particulate emissions.
# No potentially harmful or dangerous gases or fluid storage required
# The whole power station facility is less dangerous than a Petrol/Gas filling Station– which we are happy to have located in our business and residential areas.
# Electricity generated available 24 hours, 365 days a year.

All very impressive, if it can be delivered.

What we also know, from communications with the company is this:

Our technology is not rocket science it’s a well proven system. What we have done is to apply the latest engineering technology to it. All I am prepared to say is that Its fluid based and it has an interesting flywheel mechanism. It provides enough continuous energy output to drive a single 3 phase electrical alternators sized between 40 Megawatts through to 240 Megawatts .

It’s not a perpetual motion machine as it’s not 100% efficient – what it does however is self regulate for increasing loads as the alternator output current increases.

So there’s a flywheel arrangement in there somewhere driven, in some way, by ‘fluid’ – quite how this is achieved or what the fluid actually is, is not made clear, but then with a patent pending you wouldn’t expect such detailed information anyway.

The last piece of information of relevance is that Nikkogen refer to this a ‘Prime Mover’ system, which unless they’re going to redefine the term as its currently used, refers to an electronic torque management system that’s already in use in conventional power generation systems (i.e gas turbine, oil, etc.) and which, from the technical information I’ve managed to trace, does indeed offer improvements in efficiency but at a premium in terms of capital costs – i.e. these systems are not cheap, by any means. but they do appear commercially viable so, somewhere along the line the benefits they provide must outweigh their initial capital cost.

Now for the science bit.

For the time being we’ll put the question of powering this system to one side and consider only what happens from the flywheel onwards.

A flywheel does not generate energy its, rather it stores energy (as kinetic energy) which can then be released to drive an alternator – and to be fair, a well designed and implemented flywheel can be a very efficient means of storing energy (anything up to 90% efficiency is possible), far more efficient, in fact, than a conventional chemical battery.

However, if you look at where flywheels are currently being used, what you find is that its pretty small scale stuff. Aside from cropping up in the area of electric cars, as in this patent – which, interestingly, describes a hydraulically driven electric motor that could be considered ‘fluid powered’ but at a much, much smaller scale than anything proposed by Nikkogen – the main uses of flywheel energy storage appear to be in some uninterruptable power supply (UPS) systems, but only as a shortlived last resort to enable an orderly emergency shutdown if everything fails, even the UPS, or as backup energy storage in wind-powered microgeneration systems, to keep the juice coming when the wind drops.

In terms of power output, the largest current project I’ve been able to find anywhere is a 50kWh system being developed by the Central Japan Railway Company, which aims to use a superconducting magnet to levitate the flywheel – giving near zero friction – for which the projected development costs are 1.1 billion yen. Now that’s not that badly priced for a high tech R&D project – a shade under £5 million at current exchange rates, but it does make for interesting point of comparison with Nikkogen’s proposed system. The Japanese system, according to its base specifications, will use a flywheel of approximately 2 metres in diameter, weighing 20 tons and rotating at 2000 rpm.

To get from this Japanese system to the kind of power output are promising from the smallest generation system necessitates an increase in the kinetic energy of the flywheel by a factor of 800, in fact more as the alternator will not be 100% efficient (this is impossible due to the 2nd Law of Thermodynamics) so to make matters easier we’ll assume 80% efficiency in the alternator, giving a nice round factor of 1000.

To increase the energy of the flywheel, you can increase its mass (actually you increase its moment of inertia, which is bit more complicated to work out as it depends on the shape and construction of the flywheel, but for our purposes here maas will do nicely) in which case the energy of the flywheel will increase in direct proportion to the mass – double the mass, double the energy.

Alternatively you can increase the angular velocity of the flywheel’s rotation – this is the more productive route as the energy increases in proportion to the square of the angular velocity – double the velocity means four times the energy, but this introduces massive stresses into the flywheel – and believe me, if anything were to go pear shaped with the 20 ton Japanese system while it was rotating at its full 2000 rpm, such a failure in the magnetic levitation system or the flywheel disintegrating under the stresses of its angular velocity, then you really don’t want to be anywhere in the vicinity when it goes. 20 tons at 2000 rpm is a hell of a lot of momentum to have suddenly flailing around the place.

To upscale the Japanese system to the 50 megawatt mark that Nikkogen would need, approximately, for its smallest generation system, would require a 20000 ton flywheel rotating at 2000 rpm or a 20 ton flywheel rotating at something of the order of 63,000 rpm or some combination in between.

So far as I am aware – and I stand ready to be corrected – a flywheel energy storage system at the scale suggest is beyond current engineering capabilities and materials technology – the small flywheels used in some UPS systems, which run at speeds up from 40,000-100,000 rpm, have to be made of spun kevlar to withstand the stresses. The underlying science is basically sound, but a 40-50 megawatt flywheel is, so far as I understand the technology, too much of an ask at the present time.

However, to pursue this further, lets assume for the sake of argument, that Nikkogen could produce just such a flywheel energy storage system with a 40-50 megawatt capacity. That’s still only half of the equation – before you can store 40MW of power in the flywheel you got to generate at least 40MW (actually 45-5oMX, assuming 80-90% efficiency) to put into the flywheel to begin with.

Now, remember, leaving aside the fluid issue, Nikkogen are promising zero emissions, zero carbon and no ongoing fuel costs, which rather limits your options.

Hydrocarbons are right out, as Nikkogen make entirely clear, and with no ongoing fuel costs we can also rule out hydrogen cells and nuclear energy (as the fuel certain does cost money, and plenty of it). The system is also location independent, so we can forget wave/tidal power, water power (as in hydroelectricity) and conventional geothermal energy (for which there’s no working system anyway).

Unless anyone can think of something I’m missing here (millions of hamsters?) this leave three main conventional possibilities, wind, solar and a Sterling engine, plus the mysterious fluid drive mentioned in Nikkogen’s patent.

Again we butt against problems of scale.

Wind power could drive a flywheel energy storage system – indeed such arrangements are used in wind-powered microgeneration systems which store energy in a flywheel as a hedge against the loss of direction should wind drop off. But… and its a big but, the largest current wind turbines max out at 6MW output and comes in at a stonking 186m (610ft) tall with a diameter of 114m (384ft) – for perspective, Britain’s tallest building, Canary Wharf Tower, is 235.1m tall. To generate the 45-50MW input to the system, you’d need 8-9 of those, and some extreme good fortune with the planning system. A more conventional wind power solution, using the 90m towers one sees in commercial wind farms, would require 25 turbines as these deliver 2MW output.

As for Solar energy, we can forget the photovoltaic cells that people are most familiar with. At 7-17% efficiency they’re just not up to the job and even the best current system, which used solar energy focussed by parabolic mirrors to drive a Sterling engine (a heat engine) delivers only 30% efficiency at 1KW per square metre.

That said, a solar-powered Sterling engine system could deliver the kind of power input needed, but to put these requirements into perspective Southern California Edison are currently constructing the worlds largest solar installation, using Sterling engines, which will deliver, when complete, 500MW. The downside to this is this installation will require 20,000 generation units covering an area of 4,500 acres (19 square kilometres), so scaling down to match the requirements of Nikkogen’s smallest proposed plant would still require 450 acres. Oh, and solar-powered Sterling engines don’t tend to work well in British conditions, in fact they don’t work at all if its overcast, which rather puts a dampener on that idea.

Which, at last, brings us to the mysterious realms of fluid power, and as much as I think about it, I just can’t ‘see’ it, if you get what I mean. The generate energy from a fluid medium, other than by means of chemical reaction, you have to get it moving somehow, either under gravity (as in the case of hydro-electric power), pressurising it or by generating convection currents by applying heat.

In all cases, unless to take advantage of potential energy arising from natural sources, natural height differentials, river flows, tides, ocean currents, you have to put energy into the system to get the fluid moving and out dear friend the second law of thermodynamics comes into play – you cannot get more energy out that you put in.

This all a bit dry, to say the least, so its time for a comic song, if not the comic song of all-time, by Flanders and Swann, which coincidentally also explains thermodynamics.

[Michael:] Snow says that nobody can consider themselves educated who doesn’t know at least the basic language of Science. I mean, things like Sir Edward Boyle’s Law, for example: the greater the external pressure, the greater the volume of hot air. Or the Second Law of Thermodynamics – this is very important. I was somewhat shocked the other day to discover that my partner not only doesn’t know the Second Law, he doesn’t even know the First Law of Thermodynamics.

Going back to first principles, very briefly, thermodynamics is of course derived from two Greek words: thermos, meaning hot, if you don’t drop it, and dinamiks, meaning dynamic, work; and thermodynamics is simply the science of heat and work and the relationships between the two, as laid down in the Laws of Thermodynamics, which may be expressed in the following simple terms…

After me…

The First Law of Thermodymamics:
Heat is work and work is heat
Heat is work and work is heat
Very good!
The Second Law of Thermodymamics:
Heat cannot of itself pass from one body to a hotter body
(scat music starts)
Heat cannot of itself pass from one body to a hotter body
Heat won’t pass from a cooler to a hotter
Heat won’t pass from a cooler to a hotter
You can try it if you like but you far better notter
You can try it if you like but you far better notter
‘Cos the cold in the cooler with get hotter as a ruler
‘Cos the cold in the cooler with get hotter as a ruler
‘Cos the hotter body’s heat will pass to the cooler
‘Cos the hotter body’s heat will pass to the cooler

First Law:
Heat is work and work is heat and work is heat and heat is work
Heat will pass by conduction
Heat will pass by conduction
Heat will pass by convection
Heat will pass by convection
Heat will pass by radiation
Heat will pass by radiation
And that’s a physical law

Heat is work and work’s a curse
And all the heat in the Universe
Is gonna cooool down ‘cos it can’t increase
Then there’ll be no more work and there’ll be perfect peace
Yeah – that’s entropy, man!

And all because of the Second Law of Thermodynamics, which lays down:

That you can’t pass heat from the cooler to the hotter
Try it if you like but you far better notter
‘Cos the cold in the cooler will get hotter as a ruler
‘Cos the hotter body’s heat will pass to the cooler
Oh, you can’t pass heat from the cooler to the hotter
You can try it if you like but you’ll only look a fooler
‘Cos the cold in the cooler will get hotter as a ruler
That’s a physical Law!

Oh, I’m hot!
Hot? That’s because you’ve been working!
Oh, Beatles – nothing!
That’s the First and Second Laws of Thermodynamics! 

Right, so that’s thermodynamics, which is enough of problem to be tackling, except that if we’re dealing with fluid systems that we also, very possibly, will have to deal with turbulence as well.

I’m not even going to attempt to explain turbulence in any great detail, and certainly not the maths, which legitimately frightens even the particle physics mob. Put it this way, there is a wonderful, if apocryphal, story regarding the physicist Werner Heisenberg, who was reputedly askedwhat he would ask God, given the opportunity.

His reply was: “When I meet God, I am going to ask him two questions: Why relativity? And why turbulence? I really believe he will have an answer for the first.”

You get the general picture. Turbulence is a flow regime characterised by chaotic stochastic property changes, i.e. a complete bugger to deal with.
However, there is a lovely little poem by Lewis F Richardson, which nicely illustrates the problem:

Big whorls have little whorls
That feed on their velocity,
And little whorls have lesser whorls
And so on to viscosity.

Turbulence creates drag, and drag dissipates energy, so a turbulent fluid flow in inherently inefficient. Throw turbulence into the mix, and it’ll turn up unpredictably and where you least expect it, and you’re again losing energy from the system and increasing the amounts of energy you have to put into the system to begin with to get your required output.

From what I can tell about Nikkogen’s project, some of it makes sense, in principle, particularly the flywheel and torque management system arrangement which could well provide a very efficient means of driving an alternator to generate power – and were I approached about this in the context of a microgeneration system that claims to offer zero emission and a small (or even zero) energy cost using an established renewable energy source then I’d certain give it very good look over.

But, at the kinds of power output being talked about, I have to be skeptical and we’re talking of a system that exceeds any other existing/prototype system that I’m aware of by some orders of magnitude – the flywheel alone would appear represent a major engineering feat akin to leaping straight from a Greek Trireme to the SS Great Britain, never mind that simply to get that flywheel moving with sufficient energy to deliver 40MW of electricity would require, in a best case scenario, an input of 50MW of free, no fuel, zero emissions energy.

That’s not to say that the patent is entirely without merit. We have a saying in the Black Country, ‘Yo’m eyes am bigger than yer bally’ (your eyes are bigger than your belly), which describes situations in which someone is being vastly overambitious or overreaching themselves, and it strikes me that this could well be the situation here – the science might stack up at the small scales required for a scale prototype or even a working microgeneration system – a fliud-based heat engine, like a Sterling engine or the hypothetical Carnot Engine, coupled with flywheel energy storage is possible and, with the right engineering, likely to be very efficient – but I just can’t see that the technology will scale to the degree that Nikkogen suggest, at least not within kinds of timescales that venture capitalists consider in looking for a return on their investment.

Tim Worstall will have a better view of the ‘investment potential’ of this system but from my own economic laymans perspective, one has to wonder quite what the underlying business model is here, whether it is the actual delivery of a working power generation system or a South Sea bubble model in which the primary objective is to sell the possibility of such a system all the way to an IPO on the promise that what look to be pretty insurmountable technological hurdles, at the moment, could be overcome in five or ten years time, and then get out before the bubble bursts.
Having said all that, the one truly troubling statement in all this, knowing the history of flywheel systems, is this one:

It’s not a perpetual motion machine as it’s not 100% efficient – what it does however is self regulate for increasing loads as the alternator output current increases.

I could be misreading this statement, but this looks a little too suspiciously like the holy grail of all past flywheel systems, most of which tended to suggest magnetism rather than fluids as a motive force, the creation of a self or near self-sustaining feedback loop to drive the system.

The idea sounds plausible enough if you don’t understand thermodynamics – you get the flywheel rotating up to speed and then tap just a little of the power output of the alternator, which you feed back into the system (usually in bursts or pulses) to keep the flywheel turning.

The classic interpretation of such a system generally proposes the use of magnetic repulsion to push the flywheel – a simplified version of this it that you mount a magnet in only location one the flywheel’s edge with the north pole facing outwards, with a correponding electromagnet housed in the casing surround in the flywheel in line with the its axis rotation. As the magnetic section of the flywheel passed the electromagnet, you briefly shunt a pulse of electricity from the output alternator to the electromagnet which gives the flywheel a ‘push’ to keep it turning at a constant velocity, while tapping off the alternator’s output for the rest of the cycle as ‘free’ energy to be sold.

It sounds incredibly plausible, because, like a flywheel-powered ‘friction’ motor in a child’s toy, you’re just giving it a bit of push to get it started and then it appears to retain retain energy for a relatively long time after that push…

But it still doesn’t work because you cannot get more energy out of the system than you put in – the electromagnetic force generated by the pulse taken from the output generator is not sufficient to sustain the flywheel at a constant velocity, it doesn’t push hard enough, and the flywheel will eventually run down, just as a ‘friction-powered’ toy car will come to a stop.
You see that’s the thing about entropy – it’ll get you every single time.

4 thoughts on “Entropy: It’ll get you every time.

  1. In your discussion of large flywheel energy storage systems, you’re forgetting the 9m, 775 ton devices that are used to augment baseload power supply at the JET fusion experiment at Culham. These store 3750MJ with a peak power output of 400MW. An overview is here.

    That aside, this Nikkogen thing sounds like pie-in-the-sky. If I were an analyst advising an investor on whether this was a good opportunity, the lack of specifics would lead me to recommend that he run away as fast as possible. In fact, the sketchy nature of the technical information is typical of scams.

  2. I’ll happily bow before the expertise of the high energy physics crew – should have figured that if anyone was going to to have a real monster flywheel it would be them – although I dread to think what those brutes cost to manufacture.

    FFS, a moment of internia of 13.5M kg per metre squared… phew!

    In any case, from their latest news, their best peak output so far is 22.9MW for three seconds, and their best ‘sustained’ output, 8.6 MW for 20 seconds.

    Guess that rules out fusion power as well.

  3. (Hope I’m not too late for this: I’ve just found it)

    (1) Second Law of Thermodynamics: can also be expressed as Murphy’s Law: “You can’t win”.

    (2) I’d have thought the business model of our Welsh friends is quite obvious: that of the snake oil salesman throughout the ages.

    (3) I think you’ll find it’s the ‘Stirling” engine, not “Sterling”. But in any case it’s a heat engine: All it does is turn an external heat source into useful work, like any other heat engine. And like all heat engines, that process cannot better about 60% efficiency, with a following wind…

  4. No, come join the party, JEM, it’s still nice and fresh.

    The typo on Stirling Engine is, of course, of my own mistaken fabrication and, yes, as far as I know, 60% efficiency is about top whack for a usable model, although in the lab and using very low temperature differentials, they’s have got engines up into the 80-90% range.

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