EIA Fuel Comparison Calculator Shenanigans

The heat calculator on the EIA site has been revised.

http://www.eia.doe.gov/neic/experts/heatcalc.xls

Version:  heatcalc_Vsn-D_1-09; Reivsed and Updated 1/16/09

The most notable changes:

BTU per ton of coal has been lowered from 24,916,000 to 22,069,000 and they dropped the efficiency of coal stoves from 75% to 70%.

Richard S. wrote:The heat calculator on the EIA site has been revised.... BTU per ton of coal has been lowered from 24,916,000 to 22,069,000 and they dropped the efficiency of coal stoves from 75% to 70%.

Justified changes, do you think? Has BTU per ton really varied that much over the years?
According to the calculator, I should shut down my coal stove and return to burning oil, given the $320 per ton price in Maine.

I'd like to see the data myself regarding coal. I'm sure the BTU/lb varies depending on source. Makes me wonder if the lower rating is factual or political? Seems that fuel oil and pellets would vary somewhat too depending on wood type and crude source.

Will

22 million will be on the low end of the scale, it can go as high as 28... 24 to 25 is probably average. At least that's my understanding.

The efficiency on the other hand is a joke, they have almost the same efficiency for coal as they do for wood and anyone that has ever owned a wood stove knows the stack temperatures are very high. The only real rating I'm aware of for a coal stoker is for the AA and that is almost 90%. The other manufacturers have suggested around 80% plus.

With out having it tested there really is no exact number and it vary depending on where you're getting it, even from load to load.

What's great about the EPA fuel calculator is that it is a spreadsheet. You get to see the method of calculating the efficiencies and if you don't like what you see you can change it. I don't buy the theory that there's a political influence in the numbers. If there's an bias it's from the personal views of the spreadsheet creator.

If you really want to know just telephone the author which is listed on line 63 of the "INSTRUCTIONS" tab. Quoting: "For more information on this calculator, contact: Paul Hesse: 202-586-8800; [email protected]"

Edit added info:

If you look at the properties of the actual spreadsheet XLS file, you will see "Paul Hesse, Capstone Corp for EIA/NEIC". Capstone Corp appears to be a information technology subcontractor to the National Energy Information Center.

I'm wondering they are using the lowest values, wood is listed at 55% efficiency.

Edit: sent him an email.

If you look at the properties of the actual spreadsheet XLS file, you will see "Paul Hesse, Capstone Corp for EIA/NEIC". Capstone Corp appears to be a information technology subcontractor to the National Energy Information Center.

If you look on the properties tab it cites him and that company as creator but gives later modified date than the one above:

10/5/2009 USC

Now that I really looked they dropped all the efficiencies for the solid fuel appliances across the board. The dropped the pellet and corn stoves from 80% to 68%. that's a significant change.

Richard S. wrote:22 million will be on the low end of the scale, it can go as high as 28... 24 to 25 is probably average. At least that's my understanding.

The efficiency on the other hand is a joke, they have almost the same efficiency for coal as they do for wood and anyone that has ever owned a wood stove knows the stack temperatures are very high. The only real rating I'm aware of for a coal stoker is for the AA and that is almost 90%. The other manufacturers have suggested around 80% plus.

With out having it tested there really is no exact number and it vary depending on where you're getting it, even from load to load.

Anthracite coal starts at 12.500 BTU's per lb and goes up to 14.000 BTU's per lb In some readings and testing labs
They have it as high as 15.000 but I never seen those Number's in the real word
Efficiency on that AA report was 84 % to 86 % depending on the size of coal and where the coal came from
they tested Pea and Buckwheat and came up with two different numbers do to the size of coal used.
The EFM's will run 80% to 85% aslong as there are sealed up correctly and are cleaned & Set up properly .
Aswell as most of the other's brands will and if your unit does not burn at least 80% then I would look for one that does.

I had a pleasant email conversation with the author and he said he would review it next month. The data used for the new calculations on the heat content is from here but the data used to compile those numbers must be getting skewed somewhere. My guess is they are lumping a lot of products together.

http://www.eia.doe.gov/emeu/aer/pdf/pages/sec13_5.pdf

I suspect those numbers are closer to real world numbers for most stoves.

A stove that is capable of running at 80% or even 90% is very frequently not fired at the optimal point. When air is closed down for a long burn then CO2 goes down and CO goes up. If it were a wood stove then this can be seen as smoke. Those short dancing blue flames that are so pretty are really a sign of excess air. The blue flame ideally should be long lazy and rolling. Any stove that commits enough fuel for say a twelve hour burn can't help but to lose efficiency somewhere in the burn cycle.

Stoker and pellet stoves feed fuel as needed to a smaller hotter firing chamber so can be adjusted much closer to ideal over a larger firing rate. These stoves I think can be run at 80 to 90 percent efficiencies.

Richard

franco b wrote:I suspect those numbers are closer to real world numbers for most stoves.

A stove that is capable of running at 80% or even 90% is very frequently not fired at the optimal point. When air is closed down for a long burn then CO2 goes down and CO goes up. If it were a wood stove then this can be seen as smoke. Those short dancing blue flames that are so pretty are really a sign of excess air. The blue flame ideally should be long lazy and rolling. Any stove that commits enough fuel for say a twelve hour burn can't help but to lose efficiency somewhere in the burn cycle.

Stoker and pellet stoves feed fuel as needed to a smaller hotter firing chamber so can be adjusted much closer to ideal over a larger firing rate. These stoves I think can be run at 80 to 90 percent efficiencies.

Richard

Not talking about Natural draft burning stove's Talking about stoker's boiler's stoves or furnaces that have force air / Fans coming in and burning the coal Natural draft stove's will be 65% to 75% depending on make and model .
Stoker stoves around 75 % 80% again depending on make and model stoker boiler's furnaces 80% to 85% depending on make and model and set up. There is nothing on the market that I am aware of that burns 90% on coal .

franco b wrote:These stoves I think can be run at 80 to 90 percent efficiencies.

No stove, wood, coal or other will achieve those numbers, coal berner's numbers are real.

What about the highly modified "Anthracite Dust Pink Ash Top Fuel Burner" Stoker Scott has been testing down in Provincetown, Ma and on the shores of Ogunquit, Maine. Something about the moisture content is optimized near the coast.... That has to be in the high 80's or lower 90's.

coaledsweat wrote: No stove, wood, coal or other will achieve those numbers, coal berner's numbers are real.

The high on the AA was around 87.6% I believe.

Richard S. wrote:

coaledsweat wrote: No stove, wood, coal or other will achieve those numbers, coal berner's numbers are real.

The high on the AA was around 87.6% I believe.

That's correct. Only the Axeman boilers and its copies can achieve those numbers, from there its a long slide downhill.

Those numbers are ones I've seen for years also, and in all testing documents available.(In controlled conditions)
AA's and AHS's function most efficiently when working moderately to full tilt, and not as efficiently at low demands. Unburned coal is an issue any of us that have had them for years deals with. Having said that, the efficiency in the real world operation is lower than proposed, but still very economical.
No complaints, but when you see black unburned coal in the ash, it makes you wonder how to make it NOT happen.

I don't think it's worth the aggravation to screen out the unburned portion, however if you just have to live in a "perfect world", better get an EFM, Keystoker or the new Royall to get a 100 % burn rate.

I liken the AA's and AHS's to a Detroit diesel: They operate best at a constant demand; are VERY economical at that rate, and last forever requiring almost no tinkering. Hard to believe you can get 260K with a 6" flue pipe on a 260, but 32 years of doing it doesn't lie. Perhaps the better the coal, the better the results and efficiency.
For all those who think "Cheap Coal" is a good as all other coals, here is a 'NEWS FLASH' for you! Just like wood pellets, it depends upon where the raw material comes from. You likely can't get the best for cheap, and it wouldn't be fair to the provider, hence when it is cheaper, there is probably a reason. I love the guys looking for bagged at 200 a ton! If they could find an unlimited supply at that rate, everyone would stock up for the next 20 years! It's nice to be frugal, but downright 'CHEAP' won't endear you to any providers. Fair is fair, at whatever level of the 'totem pole' you are at.