How coal stacks up against other sources of heat

Many energy equivalence charts fail to take the efficiency of the stove, furnace, or boiler into consideration when attempting to equate one energy source to another. I've worked to include burning efficiency in the mix. They also assume laboratory dry coal. By my calculation:

One ton of anthracite with 6% moisture content when burned at 80% efficiency is roughly the heating equivalent of the following:

1) 5,777 KWH of electricity at 100% efficiency.

2) 164 gallons of #2 heating oil at 87% efficiency.

3) 229 gallons of propane at 94% efficiency.

4) 210 therms of natural gas at 94% efficiency.

I think your efficiency numbers are a little high for oil & gas. Most pin-type oil boilers that have been in service a while would be lucky to break 80%; triple pass units would be higher. The gas units would have to be condensing all the time to approach 94% efficiency.

Based on my experience 175:1 is pretty close when going from a good-running pin-type oil boiler to an EFM 520. Btu for btu may be closer to 200:1, but all else is not equal...i.e. we keep the house warmer with the EFM, so that skews things.

lsayre wrote:One ton of anthracite with 6% moisture content when burned at 80% efficiency is roughly the heating equivalent of the following:
2) 164 gallons of #2 heating oil at 87% efficiency.

Hmm, I don't know how this works, but applying this to my house, let me see. Last winter, and it was a long and cold one here, I went through just under 4 tons of coal. So according to the above, I would have had the same result burning 164 X 4 or 656 gallons of fuel oil. Now, I have a 250 gallon tank, that would have been about 3 tanks of fuel oil, with some left over in the last tank. But, when I did burn fuel oil full time in this house, I would go through a tank of oil a month, and in the coldest part of the winter, in 3 weeks. That means I would have gone through about 6 tanks of fuel oil as near as I can figure. So I'm seeing a major discrepancy in what I see and what you are predicting. Now add onto that, when I was burning fuel oil, I was keeping the house around 60 F - compare that to burning coal where I keep the house at 72 F (and above)...

My fuel oil furnace has been checked and runs at 88% efficiency - darned close to what you are using...

for what it's worth...

dj

At the top of the screen you will see a Fuel Comparison Caluclator, this is up next to the knowledge base, above where you log in, the Mayor has taken care of it for us again.
http://nepacrossroads.com/fuel-comparis ... ulator.php

markviii wrote:I think your efficiency numbers are a little high for oil & gas. Most pin-type oil boilers that have been in service a while would be lucky to break 80%; triple pass units would be higher. The gas units would have to be condensing all the time to approach 94% efficiency.

I was basing it on modern condensing natural gas and propane furnaces/boilers, and on some of the highest efficiency modern oil units I've seen that are not classified as condensing (though condensing oil units are out there). This gives the benefit of the doubt to the conventional fuels (favoring them), and robs from the potential of coal as you have noticed. But then again, if 80% is too high of an efficiency for coal then it may all come out in the wash.

Older oil burners are notoriously less efficient than 87%. Older NG and propane units are vastly less than 94% efficient as well. Really old units (dating to the 1960's and before) for all of these conventional fuels can be as low low as roughly 65% efficient I believe.

Efficiency variations can be all over the board all around, so that makes it tough to equate the various fuels.

I think it is a safe assumption that many of the people shopping for coal boilers don't have modern oil or gas boilers. Most of us on this forum have big and/or leaky houses with heating appliances a little "long in the tooth". There are exceptions, but I think most people fall in that category.

I agree that the efficiency variable is different for everyone. As usual, "your mileage may vary".

I think this last post has me thinking of why coal works so well for me compared to what the calculator tells me. Since my house is one of the "leaky" ones, the constant heat output of coal vs. oil might make more of a difference than it looks on the surface.

A hand fed coal stove constantly puts out heat, no cycling as the furnace does. If my house were a lot tighter (hopefully in the foreseeable future) then the two heat sources might get closer to what the calculator predicts. Even putting my coal stove up to 95% efficient, I'm still short in how much I'd really spend in fuel oil compared to what's predicted from those calculations. And that still isn't taking into consideration the difference in how much warmer I run the house with coal...

No question in my mind... Coal wins - no contest!

dj

The numbers are always skewed and very rarely ever equate to real world performance. Every installation is different and therefore comparisons between any 2 installations even with like appliances will yield varying results. The efficiency numbers on a boiler or furnace are combustion efficiency numbers reflecting how completely thefules is being burned in the appiance. For instance my L.L. 110 boiler has a stated oil combustion efficiency of 87%. I had the unit tested on coal @ 88% combustion efficiency. The numbers fail to take into account standby losses, and radiant losses to the room's surrounding and overall system efficiency

jpen1 wrote:The numbers are always skewed and very rarely ever equate to real world performance. Every installation is different and therefore comparisons between any 2 installations even with like appliances will yield varying results. The efficiency numbers on a boiler or furnace are combustion efficiency numbers reflecting how completely thefules is being burned in the appiance. For instance my L.L. 110 boiler has a stated oil combustion efficiency of 87%. I had the unit tested on coal @ 88% combustion efficiency. The numbers fail to take into account standby losses, and radiant losses to the room's surrounding and overall system efficiency

I understand that there will be variation in real world performance, but a difference of 30% or greater was not expected. There is clearly something that is not being taken into consideration there. Maybe it's the overall system efficiency - that is a hard nut to crack...

dj

dlj wrote:
I understand that there will be variation in real world performance, but a difference of 30% or greater was not expected. There is clearly something that is not being taken into consideration there. Maybe it's the overall system efficiency - that is a hard nut to crack...

dj

I hope coal is on the winning side of that 30%!

If your old dinosaur oil boiler or furnace is only 65% efficient, then it would take a whopping 219 gallons of #2 heating oil at 65% efficiency to give you the same heat as one ton of anthracite burned at 80% efficiency.

dlj wrote:

jpen1 wrote:The numbers are always skewed and very rarely ever equate to real world performance. Every installation is different and therefore comparisons between any 2 installations even with like appliances will yield varying results. The efficiency numbers on a boiler or furnace are combustion efficiency numbers reflecting how completely thefules is being burned in the appiance. For instance my L.L. 110 boiler has a stated oil combustion efficiency of 87%. I had the unit tested on coal @ 88% combustion efficiency. The numbers fail to take into account standby losses, and radiant losses to the room's surrounding and overall system efficiency

I understand that there will be variation in real world performance, but a difference of 30% or greater was not expected. There is clearly something that is not being taken into consideration there. Maybe it's the overall system efficiency - that is a hard nut to crack...

dj

The oil burner is in the basement and will lose heat to that basement both in radiant and standby. there will also be distribution losses. Because it is on and off there will be efficiency loss until it gets up to heat.
I assume the stove is in the living area so does not have all those losses.

Last year i got brave with the 1 year old Keystoker90. I never turned on the oil fired thermostats The bride never complained The old Buderus hand fed (for 27 years) had temperature swings that required themostats set to minimum settings just in case the weather changed or we miscalucated the days temperature. The Keystoker with the Coal-trol takes the guessing out of your day and or nite settings. Oil now gets delivered once a year to heat hotwater, in my New Cadillac Buderus oil boiler,which I could care ever turns on again. $3500.00 just in materials 6 years ago Keystoker KAA2 or KAA6 would have done it all. Oh well the Keystoker looks nice in the family room. I wish I lived long enough to know it all.

franco b wrote:

dlj wrote:

jpen1 wrote:The numbers are always skewed and very rarely ever equate to real world performance. Every installation is different and therefore comparisons between any 2 installations even with like appliances will yield varying results. The efficiency numbers on a boiler or furnace are combustion efficiency numbers reflecting how completely thefules is being burned in the appiance. For instance my L.L. 110 boiler has a stated oil combustion efficiency of 87%. I had the unit tested on coal @ 88% combustion efficiency. The numbers fail to take into account standby losses, and radiant losses to the room's surrounding and overall system efficiency

I understand that there will be variation in real world performance, but a difference of 30% or greater was not expected. There is clearly something that is not being taken into consideration there. Maybe it's the overall system efficiency - that is a hard nut to crack...

dj

The oil burner is in the basement and will lose heat to that basement both in radiant and standby. there will also be distribution losses. Because it is on and off there will be efficiency loss until it gets up to heat.
I assume the stove is in the living area so does not have all those losses.

Excellent point. He already mentioned that the furnace was ~30 years old. I have seen some older furnaces that were way oversized, short cycled, etc. Add in some poorly insulated duct work and it is easy to see how a constantly burning coal stove (and a very efficient one at that) would edge out the oil furnace in operating efficiency.

Lets not forget wood also.

One ton of anthracite is equal too 1.3 cords of dry hard wood. Plus you don't have to saw, split, season or stack it. Priceless!