Use of a Water-Cooled Diesel Generator as an Off-Grid CHP System

In summary, the author is looking at ways to provide power heat and light to a small holiday complex in rural France. He plans to run the complex using solar heat recovery, supplemented with diesel engine heat. The additional benefit of this system would be an available source of 3 phase electricity. The author thinks that the only downside to this idea is the higher maintenance cost.
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TL;DR Summary
Would it be feasible and cost effective to use a diesel powered generator as a CHP system to provide rapid hot water heating and electricity for a building containing a swimming pool.
I am looking at options I have available for providing Power Heat and Light to a collection of houses and barns I am planning to convert into a small holiday complex in rural France.

I plan to run this complex as an agricultural small holding with holiday let's in 4 x renovated French farm cottages. The cottages are located around a central barn in which I would like to install an indoor swimming pool / gym / sauna etc.

I would hope to operate Spring, Summer and Autumn seasons using mostly solar heat recovery with supplementary heat from ground source heat recovery. But I feel that if I am to make this a commercial venture I may need to consider an oil-fired back-up system for rapid warm up and Winter climate conditions.

I plan to have a ready supply of red diesel from the agricultural side of things and I'm wondering if a Water-Cooled Diesel Generator could be used just as efficiently as an oil fired boiler. I would use it to heat water both electrically and directly from the engine cooling system. I would plan to house the generator within the building insulation envelope and take measures to recover heat from the exhaust system.

The additional benefit from this system would be an available source of 3 phase electricity.

I already have a similar arrangement on a canal boat where 15 - 30 Minutes of Diesel Engine Running to charge leisure batteries produces a full tank of hot water that can be used for domestic purposes or circulated around heating radiators via a heat exchanger.

From the point of recovering the available energy from the fuel used is this a viable proposition.
 
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  • #2
I presume you mean a heat exchange between the engine's coolant and the water for heating. Yes that could work. You might also gain more heat from the engine's exhaust gasses.

But I would be surprised if you have to invent it yourself. There should be commercial heat exchangers designed for just that purpose. Do a little google searching. You might even find an integrated package with diesel, generator, and heat recovery exchangers all in one package.

Pleasure boats with diesel engines frequently heat a hot water tank. Small diesel engines are around 40% efficient, leaving 60% to be recovered as heat.
 
  • #3
CHP - is it okay for you to sell electricity for the grid? Not necessarily an easy adventure. You better check on the local regulations and customs.
Otherwise, you can try to use some mechanically connected diesel-heat pump solution. With some tinkering (hopefully done by a professional) you can get ~ 70% of the heat from the diesel and the rest is multiplied by the COP of your system.
'tkt-380pb' seems to be a good start for a search 😉
But I'm sure once you have the right words to search for you will get plenty of interesting hits.
 
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  • #4
Heh, I've often thought about this exact thing. We heat with oil and in the winter months my mind wonders and the idea of using a diesel to both generate electricity and use the waste heat for the house/hotwater crossed my mind more than once.

The only thing I can think of as a negative, assuming you can deal with the noise and vibration, is much higher maintenance cost. I think efficiency wise, if you recover much of the exhaust heat to use as low grade heat (eg pool), you should be about to get the same as a furnace (80-90%).

Just as an example the small diesel I have here as a generator (unfortunately air cooled...), wants new engine oil every 50hrs of running, fine for back up and intermittent use, but new oil every two days would get tiresome for full time use. Basically a diesel is far more complicated than an oil burner and that will reflect in the maintenance cost and effort, depending on how reliable the power has to be, you may need two units to allow one to be down for maintenance while the other is running.
 
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1. What is a water-cooled diesel generator?

A water-cooled diesel generator is a type of generator that uses water to cool its engine, as opposed to air-cooled generators which use air. This allows for more efficient and consistent cooling, resulting in better performance and longer lifespan of the generator.

2. How does a water-cooled diesel generator work as an off-grid CHP system?

A water-cooled diesel generator can be used as an off-grid combined heat and power (CHP) system by utilizing the waste heat produced during electricity generation to heat water for domestic or industrial use. This allows for more efficient use of energy and reduces the reliance on traditional energy sources.

3. What are the benefits of using a water-cooled diesel generator as an off-grid CHP system?

Some of the benefits of using a water-cooled diesel generator as an off-grid CHP system include reduced energy costs, increased energy efficiency, and reduced carbon emissions. It also provides a reliable source of electricity and heat in remote or off-grid locations.

4. Are there any limitations to using a water-cooled diesel generator as an off-grid CHP system?

One limitation is that the initial cost of purchasing and installing a water-cooled diesel generator may be higher compared to other types of generators. Additionally, the availability of water may be a limiting factor in some areas. Regular maintenance and upkeep of the generator is also necessary for optimal performance.

5. Are there any safety concerns with using a water-cooled diesel generator as an off-grid CHP system?

As with any type of generator, there are safety concerns that need to be considered. Proper ventilation and installation are important to prevent carbon monoxide poisoning. It is also important to follow all safety guidelines and regulations when using and maintaining the generator.

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