Stirling Engines and LENR

Many thanks to ajp for posting a comment today which included this link to an article from the Guardian, which reports on how a solar installation in South Africa’s Kalahari desert built by a Swedish company called Ripasso is converting solar energy directly into electricity using a Stirling engine.

The solar plant uses mirrors to focus the sun’s energy that drives the Stirling engine, and is reportedly able to convert 34 per cent of the solar plant’s energy into grid-usable electricity (compared to 15% in photovoltaics solar plants according to the article).

From the article:

“The technology works by using the mirrors as giant lenses that focus the sun’s energy to a tiny hot point, which in turn drives a zero-emission Stirling engine.

“The Stirling engine was developed by Reverend Robert Stirling in Edinburgh in 1816 as an alternative to the steam engine. It uses alternate heating and cooling of an enclosed gas to drive pistons, which turn a flywheel. Because of the material limitations at the time, the engine was not commercially developed until 1988, when Swedish defence contractor Kokums started making them for submarines”

This article prompts the question: could the Stirling engine be an important partner-technology for LENR, and spefically the E-Cat? Andrea Rossi has recently said that while his team is finding that the Hot Cat is proving to be a promising technology when it comes to making home heating units, they have not yet been able to find a suitable way of converting heat to electricity for home power generation.

If, as Rossi says, heat can be produced at a high COP level with the Hot Cat, even if heat-to-electricity efficiencies were not terribly high using a Stirling engine, it still might be worthwhile to use some of the heat being produced by the Hot Cat to drive a Stirling engine to make at least some electricity.

Rossi has shown interest in Stirling engine technology in the past, but so far has failed to find an off-the-shelf Stirling engine that could be combined with the E-Cat. Perhaps this is still the case — but this article indicates that there is at least one company that is finding important success with the technology, and perhaps this is a sign that there is a promising future for Stirling engines.

Since all you need for a Stirling engine to operate is a heat source, and the output of LENR is heat (which can be produced cheaply), there could be an important synergy between these two technologies.

  • e-dog

    Rossi: Hot Cats to be Used for Domestic Unit — ‘Very Long’ Self-Sustain Periods in Single Units
    If the above statement is true then why haven’t they hooked up a Sterling Engine to an e-cat reactor/set-up, and pumped out Carbonless, +COP, free energy that is pumping out more than is going in. Measure the power coming out of the Sterling engine (when the e-cat hits SSM and), there is your proof that more power is coming out than is going in… (and literally no power would be going in in SSM, in my understanding of the SSM)

    I just dont understand why something like this isnt possible (hasnt been done) for Rossi and co. to put together and “prove” to the world that LENR and the e-Cat is legit? We wouldnt need the 400+ day tests, like literally they could put a sterling engine sitting on top of the shipping container, hooked up to a watt-meter, and compare it to the watt-meter that is hooked up to the shipping container.
    Yes there would be some delays with residual heat but it would show more heat coming out than going in when its in SSM.

    Time for coffee I think Im rambling.. great article though!

    • Gerrit

      They may have hooked up a sterling engine as a proof of concept that we don’t know of.

      Just assume that they have already proven to themselves their technology is working and their goal is to deliver working plants to the world (==their customers) . What is the benefit for them to “prove to the world” that LENR is real, before the reactors are 100% bullet proof tested ?

      For sure, they could prove the viability to the world anytime they like, but they are going to do that with 400 days worth of data to back it up.

      I can understand they don’t see a necessity to prove anything before that.

      I am impatient too and I fear that even after the 400 days we’ll still be left with some doubts.

      LENR will be real for me, when it provides my energy, my heating, my electricity. It will take years to get there, unfortunately.

  • Ophelia Rump

    I am waiting for Dean Kamen and Rossi to surprise everyone. In the history of merging inventions this has the greatest potential.

    Segway Inventor Dean Kamen Thinks His New Stirling Engine Will Get You Off The Grid For Under $10K

  • pelgrim108

    company called Ripasso is solar energy directly into
    should be
    company called Ripasso is converting solar energy directly into

    • Gerard McEk

      Pelgrim108, can you contact me via facebook?
      I assume you are Dutch and we are organizing a LENR meeting in R’dam.

      • pelgrim108

        Ik zit niet op Facebook en ga voorlopig ook niet op Facebook 🙂

        • Gerard McEk

          LinkedIn kan ook, als je in zo’n bijeenkomst bent geïnteresseerd.

          • pelgrim108

            Ik ben maar half of minder geintereseerd. Ik denk dat ik niet goed ga passen tussen alle succesvolle ingenieurs en wetenschappers. Ik ben zelf socialy akward en een ongeschoolde loser. Ik heb zelf wel een leuk leven maar omgaan in real life met anderen is niet iets waar ik naar uitkijk.
            Ik hoop dat het een succesvolle meeting word, maar de drempel is voor mij te hoog. Ik waardeer alle Nederlanders hier op EcatWorld. Geef me een upvote zodat ik weet dat je dit gelezen hebt dan maak ik deze comment weer leeg.

          • Gerard McEk

            Bedankt voor je antwoord. Een goed verder leven gewenst.

  • ecatworld


  • MontagueWithnail

    I’ve thought about this a lot myself and concluded that LENR
    probably will be the first commerical-scale use for Stirling engines, eventually,
    for small scale combined heat and power units. I don’t really expect it to be
    at a domestic level – except for in very isolated locations – because I think
    operation and maintenance will be much more cost effective at a district level,
    but for small commercial and industrial uses, isolated domestic locations (down
    to the kW level) and mobile generators (for e.g. construction sites, or
    festivals), in the single digit MWe scale.

    At a larger scale, steam turbines are going to be more cost effective for a
    number of reasons, but steam turbines do not scale down terribly well (whereas Stirling
    engines don’t scale up very well). At this scale the other benefits of Stirling
    engines should really come into their own – lower operation and maintenance
    cost, inherently safer, lower noise etc. The main disadvantage is that they are
    quite bulky and the capex is relatively high because there are effectively
    going to be 3 sets of heat transfer surfaces – unless you buy that the reactor
    itself would form the hot end, which I absolutely don’t.

    Someone else mentioned about batteries and that’s an important point, sterling
    engines don’t respond terribly well to a variable load regime (unlike internal
    combustion engines) and so some way to balance load demand – or connection to a
    grid to do the same job – would be important.

    One last point, people tend to get very fixated about efficiency. That will be
    an important point if we have a reactor COP in the single digits. The long term
    goal is to get reactors running a COPs well over 10, at which point the cost of
    the heat is tending towards irrelevance and efficiency per se is no longer a
    very pertinent consideration. It will all be about the lifetime cost (capex and
    opex) of the engine and generator, and operational considerations such as
    space/weight, flexibility, safety etc.

    • Nicholas Chandler-Yates

      i agree that Steam is more efficient at large scales, but stirling engines do not require maintenance. Modern stirling engines are usually sealed for the life of the unit, and have inert gasses inside. this results in an extremely efficient wear cycle, because unlike internal combustion engines, there is no dirty fuel exploding in them, and there is no oxidation of any of the moving parts.

      The Microgen stirling engine uses gas bearings, reducing mechanical wear to practically nil as well.
      see this video:

      you can easily see the ‘boiler’ in this unit replaced with a hot cat boiler instead.
      this is, in my mind, the perfect home heating/power set up.

      • MontagueWithnail

        I agree that Stirling engines are cheaper to maintain than other engines, which I also mentioned in my post, but they are not the only component of the system are they? We have no idea what the maintenance or operational regime will look like for the reactor itself, plus (again unless you believe the reactor will be physically built into the hot end of the Stirling engine, which I don’t) there will be a heat transfer fluid, probably a specialist high temperature liquid, with attendant high-temperature pumps, reservoirs, valves etc which will require maintenance, and will fail occasionally. There will also be a power supply for the reactor, a control system and a generator unit, all of which should be low maintenance but these things do fail from time to time as well. That, combined with the physical bulk of the overall system, the cost, and the fact that there will be some noise (although admittedly low relative to an IC engine) will not make it terribly attractive for most people to put units in their own dwellings. People are already connected to the power grid, it will make far more sense to have interconnected centralised units supplying distributed power to a local grid and heat to a few hundred homes via a district heating system. The initial capex of the district heating network will be easy to amortise over an appropriate period (where it doesn’t already exist) and it will anyway be much cheaper to have one large unit than hundreds of smaller units.

        As I acknowledged, this will not apply to every domestic property. The factors that will tend to lead to home units will be: the density of the housing, the premium on space, the per-residence consumption of energy, and the societal preference for self-reliance. I expect Americans will be far more likely to have home units than Europeans but there will be an economic penalty to pay for that.

  • malkom700

    Do not forget that the issue of effectivity is primary only for local installations, because the interconnected units will have practically endless effectivity. Of course, also the question of local facilities is infinitely important.

  • Alain Samoun

    Don’t forget the slingshot of Dean Karmen:

    That will be the solution for an LENR reactor to produce electricity.

    • parallelB

      ps. The compressor would have to be like the turbine in a turbocharged car, but the micro turbines borrow a lot from that technology anyway. You would need a heat exchanger of course but the waste heat could be used to heat the house and for hot water.
      It doesn’t matter that the efficiency is low if the fuel costs nothing.

  • EEStorFanFibb

    Hot cats when coupled with another device will certainly be able to produce electricity in a reasonable fashion. BUT I think nobody will be able to buy such a setup for their personal use / homes for decades.

    I think all LENR devices for the home will have to be home made contraptions. Even if Rossi / IH allowed sale of home units, no regulator would allow it to be sold for that purpose until it was tested in an industrial setting for several years. The closest thing we’ll get to home units before 2025 imo, is municipalities buying these devices for cogeneration for whole neighborhoods. It will still be a revolution of immense proportions.

    • Fyodor

      It’s not just regulators. Getting a heat-to-electric device reliable enough for unsupervised home use is just an entirely different ballgame than making something for industrial use.

      • Omega Z

        I fully agree.
        Home heating will be available, but electric generation of any consequence will be quite a while down the road. There are multiple issues to be addressed.
        Aside from safety, There is also the issue of how we use electricity. Very little most of the time & large quantities in a very short period. Given certain aspects of the technology at this time makes it quite complex to make it cost/benefit effective.

  • GreenWin

    A massively beneficial technology assigned “exclusively” to toadies of NASA – is the equivalent of suppressing polio vaccine in 1960. We will NEVER get an “actual product” as long as the IP remains in the hands of corrupt toadies.

    And I shall take another opportunity to disparage the programmers of our inadequate simulation. You do not know human behavior. But you CAN learn!

  • Henry Oegema


    After reading about Stirling engines yesterday, I received
    this information on a thermoacoustic generator made in Texas. Simple, quiet and
    efficient. Look at the efficiency curve on the graph.

    Like many other good things, this is not yet in production.
    But a hot cat driving this for home use, should make for a nice compact unit.

    I think the small one is 500 w, the bigger one I don’t know.

    • Omega Z

      I’ve been aware of these for a long time. Long enough it was called junk science. 🙂
      This is interesting, but I wish they would give a better idea about exactly what efficiency to expect. Seems it should be possible to make an app calculator for input temp & ambient temperature & give a reasonably accurate efficiency rating with plus/minus range. Estimated Price would also be appreciated.

  • GreenWin

    Ha! Little Bessie suspects illogical programming from HIS basement. As would Sam Clemens, had he stuck around. Hundreds of His minions hacking away… and we get this?? Almost makes NIF look like a success!

    • Nicholas Chandler-Yates

      I asked Rossi a set of questions:

      I have several questions for Mr. Rossi:

      1. Have you considered the application of stirling engines for smaller, domestic (in the 1 kw range), Micro CHP (combined heat and power) applications? Several stirling engine Micro CHP devices exist on the market already usually with nat. gas boilers.
      such as this one:
      or this one:

      2. Has the customer of the industrial plant that is currently undergoing testing agreed to inspections by outside sources (news representatives, scientists etc.) once the test is completed?

      3. With current progress on the plant seemingly going well, how does this make you feel?

      thanks, NCY

      Rossi’s Response:

      1- Yes, this is one line of our R&D
      2- The customer that has installed the 1MW E-Cat in his factory is not a R&D laboratory, is a factory that makes an industrial activity. I have no idea what they will do inside their factory after the end of the contractual test on course, but for obvious reasons I would not be surprised if the access to their factory will be limited to the persons involved in their activity. Anyway, this is an issue doesn’t depend on me.
      Let me add also that being for sale in the market the E-Cats, it will not be necessary to inspect the E-Cat of others, since anybody can buy one and use it.
      3- Troubles have always a tomorrow, and ” tomorrow never dies” ( Bond, James Bond).

  • GreenWin

    Here is a well-made Stirling designed to burn biogas – producing 20kWt, and 7kWe from 12M(cubic) low quality biogas per HOUR. A unit like this might match E-Cat better than those requiring higher temps. It is a CleanEnergy C9G (Sweden) available today in the UK! But only for landfill biogas use. Heaven forbid anyone put this in community center, factory or municipal building!!

  • bkrharold

    I just saw an interesting post about a potential rival to the stirling engine.

    This invention generates electricity in a novel way. I’m not sure if it is more efficient than the stirling engine, but I believe the ecat could be used to provide the energy to power this device. It relies on the bouyancy provided when air is introduced into an inverted container full of water. The energy input comes from compressing gas and forcing it into the apparatus. The manufacturer is claiming over unity for this device, which is obviously nonsense. However if it is reasonably close to unity, this would be a big win for the ecat, since the heat from an ecat can easily expand the gas enough. to make this work.