Navitron Renewable Energy and Sustainability Forum

CHP (combined heat and power) => External Combustion (Stirling engines / hot air engines / steam engines) => Topic started by: KenB on January 15, 2008, 11:56:10 AM



Title: Whispergen in real life application
Post by: KenB on January 15, 2008, 11:56:10 AM
List,

This has been moved here from another topic area


There are several companies working on domestic scale CHP.

Whispertech has a 1kWe device on the market, being trialled by Powergen. Volume manufacture for the European market is expected this year.

With about 85% overall gas utilisation, it way exceeds the overall fuel efficiency of getting your power from a CCGT power station.

If you used the power generated to run a heat pump, you would get even more thermal advantage - although the Whispergen Stirling could directly mechanically drive a heat pump compressor  - might be a good way of doing it.

You would have to make certain changes to your lifestyle to get the best from this device.   Live and work from home - offset your commuting fuel into slightly increased gas usage but much reduced electricity usage. And the knowledge that you are extracting more useful value from the fuel that you actually use.

A Whispergen used to recharge a G-Wiz might be an interesting combination.



Post Note:  The Whispergen system works best if there is a large thermal store that it can heat up.  i.e. running at full heat demand for several hours.  The Stirling generator is more efficient when held at constant high temperature and working at constant power output.  The best way to do this is use a large thermal sore - it will not be very efficient if the boiler is stop/starting every 20 minutes.

The system is driven by the heat demand.  On a mild day like today a property might use 75kWh of gas, on a cold day it might use 120kWh.  The Whispergen is going to produce more electrical power in an older, larger house rather than a smaller well insulated one.

About 15% of the energy in the gas is converted to electricity by the Whispergen.

If the Whispergen is best running for extended periods at full power, it does not well match the electricity demand of the individuals property. It would therefore be advantageous to export this power to the grid and use the grid as your "battery"



Ken


Title: Re: Whispergen in real life application
Post by: charlieb on August 05, 2008, 04:57:04 PM
http://www.whispergen.com/content/library/WP503703000_UK_USER1.pdf

Whispergen mannual, hidden away on their web page, is interesting on how to optimise electrical output.   They finally have a mass production partner in Basque country and should be producing tens of thousands of units by 2010.   Micro-CHP units might finally be available somewhere outside Japan...


Title: Re: Whispergen in real life application
Post by: KenB on August 05, 2008, 05:32:49 PM
Charlie,

Baxi are threatening to have a free-piston Stirling wall mounted CHP system available next year.

http://www.baxi.co.uk/ecogen?gclid=CKCw_fCP95QCFQs4QgodHx9_rg


This is the same unit that Microgen developed before they went bust. Malcolm Wicks has seen it - so that's a kiss of death.


Ken


Title: Re: Whispergen in real life application
Post by: Ivan on August 05, 2008, 10:36:16 PM
would you buy a boiler from a company (Baxi) that state the following: 'The unit is capable of providing up to 24kW of thermal output for space heating and hot water as well as 1kW of electricity per hour.'

Ceebee? Is that you first in line to purchase?


Title: Re: Whispergen in real life application
Post by: CeeBee on August 05, 2008, 11:13:34 PM
would you buy a boiler from a company (Baxi) that state the following: 'The unit is capable of providing up to 24kW of thermal output for space heating and hot water as well as 1kW of electricity per hour.'

Ceebee? Is that you first in line to purchase?

Thank heaven it's not only me that spots these! I got that one back in a thread (http://www.navitron.org.uk/forum/index.php/topic,3933.msg39055.html#msg39055) last month. At least we can all work out what they meant (hopefully). Unlike whoever it was around that time that started arguing back at me saying that I was wrong!
If they correctly stated "one kilowatt hour of electricity per hour", then they might realise the pointlessness of including lengths of time in this, and just say "one kilowatt" (or I suppose they could say one kilowatt fortnight per fortnight, or whatever).


Title: Re: Whispergen in real life application
Post by: Ivan on August 05, 2008, 11:23:35 PM
drives me mad too...


Title: Re: Whispergen in real life application
Post by: charlieb on August 06, 2008, 12:01:12 PM
And me. (though it did take a while to get my head round it - I still definitely struggle with currents and voltages, but power and energy are sorted now). Various other boiler manus are working on a Microgen-based product as well as Baxi.


Title: Re: Whispergen in real life application
Post by: dhaslam on August 06, 2008, 12:45:01 PM
For domestic use a much higher percentage of energy to electricity would  be preferable.   In summer solar PV could be used for electricity but in winter it would be better to base usage on electricity demand and store heat.

This larger scale (1MW) commercial example on page 12 below has 70% of power to electricity.  Not much details of efficiency though.

http://www.netl.doe.gov/publications/proceedings/03/hybrid/Christian%20Lagier-NPS%20Hybrid%20conf.pdf


Title: Re: Whispergen in real life application
Post by: KenB on August 06, 2008, 01:49:50 PM
Dhaslam, List

You are up against the laws of thermodynamics here, and for this size of Stirling engine generator an efficiency of 15 to 20% is the best that can be delivered.

If a typical house in the UK of average insulation, needs a constant 6kW to keep it comfortable, then for all the time the gas burner is alight, the Stirling generator will produce approximately 1kW of electricity.

These systems work best where there is a constant demand for heat.  A boiler that keeps switching on and off will not successfully run a Stirling. Think of a wind turbine with grid tied inverter in gusty weather - half the time its doing nothing, the other half of the time its trying to get the GT inverter to sync with the mains.

Many people poo-poo a microCHP system with such a low electrical output. However this is a size that is best suited to a European home.  It acts as a contribution to your grid consumption, and 1000W of power is better than none.

Phillips introduces a Stirling generator set in 1953, designed to power valve wireless sets.  Its taken a further 55 years of development to get this far -so don't knock it!



Ken



Title: Re: Whispergen in real life application
Post by: charlieb on August 06, 2008, 02:35:10 PM
Yep. Various companies are developing Fuel Cell microCHP. These may have electrical efficiencies of 40% and would basically run 24-7, generating baseload electricity (much of which would be exported, hence utility interest) and trickle feeding heat into a store. Whereas stirling engine (and rankine cycle) micro-CHP would be heat led: basically a boiler that happens to generate electricity when it's running.
The economics of micro-CHP are based around long running hours (lots of electricity generation). So only running for a few hours a day in winter would make the payback on the marginal cost of a micro-CHP unit over a boiler way too high.


Title: Re: Whispergen in real life application
Post by: NickW on August 07, 2008, 11:21:14 AM
It would seem these units would work really well on commerical sites with continous demand for hot water and electricity. Fast food outlets, large restuarants, catering pubs, large butchers & meat cutters. Likewise 24 hour supermarkets would benefit from these installations.


Title: Re: Whispergen in real life application
Post by: martin on August 07, 2008, 11:28:02 AM
I suspect that godawful "Planet Thanet" hydroponic/chemical greenhouse nightmare is a large version, they're certainly generating electricity from gas, and exporting some power........ ::)


Title: Re: Whispergen in real life application
Post by: Ivan on August 07, 2008, 12:55:53 PM
Given the price difference between gas and electricity and assuming that CHP qualifies for the same buy-back prices (I think they do), it's feasible to make a device that could provide free household or industrial heating. If it was feasible on a large scale (fortunately, buy-back prices aren't as good on a large scale), it would provide economic viability for the planet thanet hot greenhouse scheme.


Title: Re: Whispergen in real life application
Post by: jude on August 09, 2008, 06:20:02 PM
Eon are curently advertising domestic size Whispergen units on their site -
http://www.eonenergy.com/At-Home/Products/Technology-And-Initiatives/WhisperGen.htm (http://www.eonenergy.com/At-Home/Products/Technology-And-Initiatives/WhisperGen.htm)

Says they will be available on a mass market basis early next year. Doesn't mention how much it will cost though. Another site has more information and says they will be 3000 including installation with a payback time of approx four years (presumably slightly less than that now that electricity prices have gone up) I assume that the figures they give are based on the trials that have already been carried out.

http://www.greenconsumerguide.com/powergenminisite/saveenergy.htm (http://www.greenconsumerguide.com/powergenminisite/saveenergy.htm)

According to the blurb they sound a really good idea. Are they likely to be as efficient as they claim and can they be used in conjunction with our already existing solar hot water system? If so, I am seriously wondering if it would be better for us to delay fitting a new gas boiler until these are available.


Title: Re: Whispergen in real life application
Post by: djh on August 09, 2008, 08:19:55 PM
Phillips introduces a Stirling generator set in 1953, designed to power valve wireless sets.  Its taken a further 55 years of development to get this far -so don't knock it!

Hargreaves' book 'The Philips Stirling Engine' is a very good read, though sobering. Sadly, it appears to be out of print. It's not quite as depressing as 'Project Cancelled' - the story of the UK aero industry.


Title: Re: Whispergen in real life application
Post by: stuartiannaylor on November 25, 2010, 02:28:36 AM
Just wondered if anyone knew what the temperature difference between the hot and cold feeds on these?

Thanks

Stuart


Title: Re: Whispergen in real life application
Post by: Ivan on November 25, 2010, 03:25:42 AM
I don't but I expect it is high - 200C or more.

The bottleneck is the fact that it is only designed to produce 1kW electrical output. The rest of the boiler output is heating only without any attempt to extract electrical energy


Title: Re: Whispergen in real life application
Post by: knighty on November 25, 2010, 11:08:11 AM
is that a typo for 20'C ?


Title: Re: Whispergen in real life application
Post by: stuartiannaylor on November 25, 2010, 01:19:50 PM
200C is much lower than I expected actually. I was having one of those could I steal the sterling engine and use it in a better ways thoughts last night. I did a liitle be of research and was expecting that it could be as high as 700C even more ...

200C is really interesting though. Please don't comment here "A better way for retro fits than common flat panel installs"   http://www.navitron.org.uk/forum/index.php/topic,12222.0.html

At the end of the thread I posted some details about a CERN flat plate evacuated design have a look as the FUTURE possibilities are there to capture 200C and above.  :genuflect please I got a kicking in there to certain respects that it is to expensive, not possible ...
This is just one of those what if scenario's but if you had an oversizied collector array to provide 100% winter DHW then instead of stagnation in summer you could theoretically drive one of these.

I was looking for a face slap emoticon to being me back to earth. Saying that when it comes to CHP and those temps then a steam turbine provides much better possible ratios of energy usuage against prodcution.
Stuart


Title: Re: Whispergen in real life application
Post by: Ivan on November 27, 2010, 03:32:19 AM
Of course, you can use any heat differential to drive something producing rotational power and thus electrical power. Stagnation temperature is a measure of a panel's ability to perform at high temperature. but you also need kW input. More area = more kW. Stagnation temperature is where power in = heatlosses out. So a panel will produce virtually no energy under stagnation conditions as the input is balancing heatlosses. It's slightly different in heatpipe systems because the heatpipe stops circulating when its contents are 100% vapour so this is the stagnation temperature, even if the tube continues to get hotter. Put a vacuum tube in front of a parabolic reflector and you'll get even more heat.

If you haven't got enough heat for steam, you can use lower boiling point organics - LPG, alcohol, ammonia etc ('rankine cycle')

I've run vacuum tubes at 150C during the summer, producing electricity from TEGs, incidentally.


Title: Re: Whispergen in real life application
Post by: Baz on November 27, 2010, 11:04:52 AM
TEG?
google didn't come up with anything needing 150C, just a few organisations probably making hot air of their own.


Title: Re: Whispergen in real life application
Post by: knighty on November 27, 2010, 12:28:46 PM
google peliter ;)


Title: Re: Whispergen in real life application
Post by: stuartiannaylor on November 27, 2010, 01:36:20 PM
"200C is really interesting though. Please don't comment here "A better way for retro fits than common flat panel installs"   http://www.navitron.org.uk/forum/index.php/topic,12222.0.html

There is a panel that could produce those temperatures but its a CERN thing that is under evaluation at the moment. Ivan doesn't like it at all, and thinks it is a white elephant.

Its strange though as many of his arguments to application might hold true and then in other threads he mentions peltier devices. I know nothing of your experiments in using peltiers as TEGs but in terms of cost that is a huge white elephant. Unless you are doing something very small scale even running a pump would be hard work.

Saying that do you have any more info on what your doing as its sounds interesting and I have an open mind to any form of generation scheme.

Stuart


Title: Re: Whispergen in real life application
Post by: stuartiannaylor on November 27, 2010, 02:04:03 PM
I guess and I will for Ivan's benefit stop mentioning the CERN evacuated plate provide a solar system for the engine of the whispergen.

If you had some direct feed evacuated tube feeding thermal oil, so you don't get that evaporation problem. Then if you sat a heat exchanger on the top of one of these then it would be interesting if all but an experiment.
My thought path has been working on the idea of some form of solar CHP where during high solar activity you generate and towards the end of the day or periods of low collection switch to DHW.
Just an idea and I really hope the wispergen takes off as to be honest personally the full unit is of not much interest to me. The availability of stirling engines in the form of spares and 2nd hand units does.
I have seen a few units like the whispergen such as BAXI and they all seem to quote exactly the same specifications. I do hope they are all just rebadging the same unit as that will increase that spares pool.
If you where recycling a loop through a heat exchanger does anyone know what the temperature difference of the input and output would be. My maths isn't all that great but is it at least a long shot ?


Title: Re: Whispergen in real life application
Post by: Ivan on November 28, 2010, 02:13:27 AM
Mention the CERN panel as much as you like, but you are right,  I do indeed think it's a white elephant. I agree it will work, and I can believe the temperatures it achieves, but I also believe that overcoming the 20tons of atmospheric force against the face of the panel will make it far too expensive to be practical (for the same reason that hot water cylinders, submarines, vacuum chambers etc are always round and not flat-sided.

My solar tubes-TEG experiments were also a white elephant. I did it for fun more than anything else (and the fact that as far as I know noone had demonstrated it previously). With a very crude experiment, I generated around 3-6Watts of electricity from 4 vacuum tubes. It could easily be improved to probably about 100W, but it would not come close to the cost of PV. It had some advantages eg it worked in partial shade, whereas PV doesn't fair well in partial shade. I believe it would be straightforward to develop a domestic solar thermal system which generated enough electricity to run the pump....but the cost would be substantially increased over a standard system. Do a search on the forum to find the details. I can't remember where it's located - search for TEG Radio or solar TEG or similar.

Navitron installed a solar thermal system somewhere near Oakham which heated  oil to 150C for an agricultural process. Give the office a call and ask Tim who used to work for the company - he should be able to tell you all about it.

There's a really interesting American Rankine cycle engine with a unique valve arrangement (the usual power-sapping component) for recycling the cooled condensed fluid. I can't remember what it's called. I've posted the details here in the past. Unfortunately, the company seems to be more active in seeking investors than developing their idea into working products.



Title: Re: Whispergen in real life application
Post by: stuartiannaylor on November 28, 2010, 03:06:10 AM
Thanks Ivan as that is of interest.

I have a little bit of inheritence money in my back pocket and it is going to stay there for a while. After finding this forum I have gone a little bit crazy as the wealth of knowledge on here is just superb. I think I will do what I usually do. Grab as much infomation as I can, get all excited and I really should grow up. Then I will prob sit back and see if anything new comes up. If I am still thinking yeah I will give it a go in six months or a year. I shall keep you all posted.

Its been really great just to throw some idea's on here and honestly I have listened. One thing occured to me and if any one is throwing stones then I will not be near those CERN panels. I bet they can implode with some effect :)

Thanks for everybodies posts and I apologise for mine ... Now sodium-sulphur batteries mmmm.


Title: Re: Whispergen in real life application
Post by: Ivan on November 28, 2010, 03:22:01 AM
One of the criteria of the standards required for the UK and European markets is that they have to withstand quite a severe impact without shattering. I was surprised that CERN did not have this for their panel - even more important when you consider how big the bang would be if they were broken!


Title: Re: Whispergen in real life application
Post by: A.L. on November 28, 2010, 01:55:21 PM
Hello stuartiannaylor,

Ivan said
Quote
There's a really interesting American Rankine cycle engine with a unique valve arrangement (the usual power-sapping component) for recycling the cooled condensed fluid. I can't remember what it's called.

I think this is what he was referring to - https://matteranenergy.us/animation.html (https://matteranenergy.us/animation.html)


Title: Re: Whispergen in real life application
Post by: Ivan on December 05, 2010, 01:21:27 AM
That's the one. I first found the site several years ago. I note that they are still 'looking for investors'


Title: Re: Whispergen in real life application
Post by: peterboat on November 28, 2018, 10:31:01 PM
Just found this thread, I am on my second whispergen, mine are the original ones that run on kero/diesel, My first did six years and 6000 hours it was a 12 volt dc model, it was sold on in full working order. My second is a 24 volt model ans I am sure it will be as good as the last one, they really are a very good piece of equipment that nothing else can do as well. This one was a bargain it cost 400 quid brand new ex MOD, I bought four and sold the other three as full kits at a healthy profit. I must add that I live on a Dutch barge and am off grid so everything has to be up to the job or its history