Can you run a diesel engine on heating oil or kerosine?

[emece67]

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[Circlotron]

If you still have shortage of electricity, then consider running the genset, use the power to run the heatpump, and collect the waste heat of the genset, for >100% total efficiency.

Probably the easiest way to use part of the waste heat is to direct the warmed cooling air from the generator through the outdoor airflow of the heat pump so that is is using somewhat warm air as a heat source instead of plain cold outdoor air. This will raise the coefficient of performance of the heat pump for sure.

[Siwastaja]

If you still have shortage of electricity, then consider running the genset, use the power to run the heatpump, and collect the waste heat of the genset, for >100% total efficiency.

Probably the easiest way to use part of the waste heat is to direct the warmed cooling air from the generator through the outdoor airflow of the heat pump so that is is using somewhat warm air as a heat source instead of plain cold outdoor air. This will raise the coefficient of performance of the heat pump for sure.

Not by much - what you propose is a variation of recurring modification theme, but people fail to understand these outdoor units process just massive amounts of air through them. This is because air has poor thermal capacity, so a lot of flow is needed. Whether you mix solar-heated air (one common modification idea), warm ventilation exhaust air from the building (another), or exhaust gas of the genset (yours), it's going to mix with 10-100 times larger volume of outdoor air, so the benefit is almost negligible, maybe one-two degrees C and 0.1 units in COP.

The next step is to suggest casing the whole outdoor unit to prevent this airflow, but this is trying to break the laws of physics: the only reason why seemingly overunity efficiency is possible with heatpump, is they actually harvest thermal energy in our atmosphere, which is basically an infinite source of energy. Try to modify them to harvest some limited resource (like waste heat source), and you are going to be limited to maybe 50% efficiency, not 300% some might expect.

Probably the soot and other crap in the exhaust gas does more damage to the performance of the evaporator than it helps.

But, something I would seriously consider, if you truly need a backup system off-grid, or for backup during blackouts, or just to help with peak expensive hours of electricity, is getting a decent genset (not a cheap toy which breaks after 10 hours of use), which is water-cooled, so you can trivially just connect it to your hydronic heating circuit through a heat exchanger. Then run bog-standard air-to-air heatpump - which you should have anyway - with that electricity, of course along with all your normal electric loads. This way you can tap into most of the waste heat to heat up the radiators, some in rooms and hallways etc. that are outside the range of the air-to-air heatpump; while the air-to-air heatpump heats the living room, maybe.

If you run 30% efficient genset to run a heatpump at 300% COP, and harvest half of waste heat of the generator, you will have 125% efficiency from gasoline chemical energy to heat. Compare this to running direct electric heating with the same genset plus harvest half of the waste heat = 65%; or direct electric heating with no waste heat harvest = 30%.

But practically, just do the right thing, get a heatpump or two (air-to-air units are cheap and provide summertime cooling), get some PV, and have your neighbors do the same. Then you can forget about the whole generator idea.

[woodchips]

Thanks for further comments.

At the moment the problem is paying for the electricity, it could become a different problem with no electricity available to be bought. All the comment in the papers etc don't address this second problem.

I do have a 20kW genset bought to run a sawmill, this will actually run the Nightstor boiler if needed. Needs some drastic re-wiring so unwilling to do this unless freezing! Will shift the genset into the garage, piping the exhaust out with heat exchanger for incoming air. Then as mentioned use an aircon unit to extract the heat from the genset to pipe into the house. But it all gets more and more complicated, and would just rather pay a little more on the electricity bill, it is just what this little more ends up to be.

It does end up to be a careful balance of costs and also hassle, but in January with it at 2C and a power cut then things happen. Already run the house at 18C, wear a jumper, but 17C is definitely cold when sitting. Also the basic question of do I bother to buy some kerosine, about £1 litre, red diesel is now about £1.60 litre, substantial difference.

[wraper]

Also the basic question of do I bother to buy some kerosine, about £1 litre, red diesel is now about £1.60 litre, substantial difference.

Which in both cases is more expensive than electricity from the grid.

[abquke]

Thanks for further comments.

At the moment the problem is paying for the electricity, it could become a different problem with no electricity available to be bought. All the comment in the papers etc don't address this second problem.

I do have a 20kW genset bought to run a sawmill, this will actually run the Nightstor boiler if needed. Needs some drastic re-wiring so unwilling to do this unless freezing! Will shift the genset into the garage, piping the exhaust out with heat exchanger for incoming air. Then as mentioned use an aircon unit to extract the heat from the genset to pipe into the house. But it all gets more and more complicated, and would just rather pay a little more on the electricity bill, it is just what this little more ends up to be.

It does end up to be a careful balance of costs and also hassle, but in January with it at 2C and a power cut then things happen. Already run the house at 18C, wear a jumper, but 17C is definitely cold when sitting. Also the basic question of do I bother to buy some kerosine, about £1 litre, red diesel is now about £1.60 litre, substantial difference.

If it's to offset the electricity bill, then I'd relate that my electricity bill has been hookup fee plus taxes since mine was installed. Large initial cost, but the bills are now the same every month and there's a "time's on my side" satisfaction.

[BrokenYugo]

You'll probably never run into a scenario where burning stuff to turn an alternator yourself is cheaper than grid power. And if there ever is no more electricity to be bought, you will have far larger concerns than staying warm and keeping the lights on.

[Siwastaja]

And if there ever is no more electricity to be bought, you will have far larger concerns than staying warm and keeping the lights on.

I don't know about that. It's a perfectly valid scenario that our societies partially collapse to the point of having long and serious blackouts etc. I'm not saying I expect it to happen, but it's a perfectly valid idea to prepare for it. And I frankly don't understand what you mean by "far larger concerns". Staying warm is a pretty big concern, having some lights and a refrigerator, too. If you can prepare yourself to have technical means to stay warm, you are halfway there to survival. The other important thing you need is food (and water).

[NiHaoMike]

You'll probably never run into a scenario where burning stuff to turn an alternator yourself is cheaper than grid power.

If you can make use of the heat (generally this means only colder climates or those who have some sort of production process that needs a lot of heat for hours per day or more), it can easily end up cheaper anywhere there's a readily available fuel that's much cheaper than electricity.

[wraper]

You'll probably never run into a scenario where burning stuff to turn an alternator yourself is cheaper than grid power.

If you can make use of the heat (generally this means only colder climates or those who have some sort of production process that needs a lot of heat for hours per day or more), it can easily end up cheaper anywhere there's a readily available fuel that's much cheaper than electricity.

Burning stuff can be cheaper to directly produce heat. But not to generate electricity.

[langwadt]

You'll probably never run into a scenario where burning stuff to turn an alternator yourself is cheaper than grid power.

If you can make use of the heat (generally this means only colder climates or those who have some sort of production process that needs a lot of heat for hours per day or more), it can easily end up cheaper anywhere there's a readily available fuel that's much cheaper than electricity.

Burning stuff can be cheaper to directly produce heat. But not to generate electricity.

taxes can really mess with that calculation

[bdunham7]

Burning stuff can be cheaper to directly produce heat. But not to generate electricity.

Here in Expen$ifornia our summer peak electricity rates are over $0.50/kwh. Of course gasoline is now $7/gallon so that won't work, but during the peak times an efficient natural gas generator could probably be cheaper, at least if you are just counting the fuel--which would be reasonable if you had it already for backup purposes.

[NiHaoMike]

Burning stuff can be cheaper to directly produce heat. But not to generate electricity.

With CHP, you're doing both.