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Author Topic: Whispergen in real life application  (Read 35332 times)
KenB
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« 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
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charlieb
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« Reply #1 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...
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KenB
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« Reply #2 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
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Ivan
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« Reply #3 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?
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CeeBee
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« Reply #4 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 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).
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Ivan
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« Reply #5 on: August 05, 2008, 11:23:35 PM »

drives me mad too...
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charlieb
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« Reply #6 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.
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dhaslam
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« Reply #7 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
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KenB
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« Reply #8 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

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charlieb
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« Reply #9 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.
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NickW
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« Reply #10 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.
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« Reply #11 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........ Roll Eyes
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Ivan
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« Reply #12 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.
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jude
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« Reply #13 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

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

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.
« Last Edit: August 09, 2008, 06:22:19 PM by jude » Logged

djh
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« Reply #14 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.
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Cheers, Dave
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