Need help from someone smarter than me

[derwood]

In an earlier post https://www.hearth.com/talk/threads/13306/ burning coal to make electricity is only 29% efficient.

Somewhere here there was a post about the btu content per pound of coal, and I think a pound of wood has about 6,800 btus. What I'm wondering is given the amount of coal that is required to generate electricity to run a heat pump that puts out btus, are the emissions from burning coal greater or lesser than burning wood to get the heat directly assuming a later style 70% efficient wood burning appliance?

Surely there are some smart number crunchers with a sharp pencil out there. . .

 

[colebrookman]

Well I'm certainly not the brightest bulb but I would change your thesis a little. According to some very intelligent scientists, burning fossil fuel, coal, is one of the main causes of global warming. The CO2 released. Burning wood does not cause this problem so it becomes a no brain-er. Watch that Ct. size iceberg on the evening news and decide for yourself.

 

[derwood]

OK, maybe I'm lazy. I found some real interesting stuff surfing around like how many pounds of coal it takes to light a 100w light bulb for a year and about how many watts there are in pound of coal. So that gets me closer to the answer I'm looking for. Of course I'll have to figure in how much a heat pump draws (it's about 2kw) which will go up or down depending on the SEER rating. And I found a site talking about emissions from burning coal and burning wood.

I think I've probably stumbled across most of the information I'll need to figure this out.

 

[berlin]

excluding co2, burning wood in your home will never produce less pollution then coal used to power a heatpump epa stove or not. there is a tramendous amount of pollution control equipment on powerplants, and some newer supercritical plants are in excess of 40% efficiency. as far as actual numbers go, i don't have that much free time on my hands, but rest assured that this is the case.

 

[colebrookman]

I'm to old to rest assured, but if you exclude CO2 , you still have mercury which contaminates our waters and soils. 40% comes from coal fired plants, another 10 to 15% from industrial pollution. That's two big hits that we leave for our children and grandkids. We all can make choices and I don't pretend to have the answers. We can only do what we feel is best.

 

[Redox]

I suspect the numbers could be skewed in any direction you want to go according to what you want to prove. The conversion from a low grade energy source (thermal) to electricity is going to incur a lot of inefficiency. I have always heard 30-35% as a typical number. This is something you have to get used to if you want to do something with electricity that you cannot do with anything else, like run a computer. The typical air to air heat pump manages to produce 2 to 3 times more energy than it consumes, which makes the entire coal to electric to heat process a draw. However, as soon as your auxiliary electric kicks in, your overall efficiency drops off to the point that you would be better off burning the coal in a stove.

The pollution factor is one that, I believe, we cannot keep ignoring. Burning coal in many small stoves is going to release more pollution than a single large power plant, but the distribution inefficiencies negate some of these environmental gains. Also, keep in mind that most coal plants are older and the regulations are less strict than for a newer plant. It is possible to burn coal "cleanly", but the utilities are finding that it is a lot cheaper to upgrade the older plants rather than build a new one from ground up.

I believe that CO2 is a pollutant in the strictest sense of the word; if it wasn't there before YOU got there, it is a bad thing. The majority of the scientific evidence agrees that we ARE changing the climate, and probably not for the better. I believe that using biomass like firewood or pellets or ethanol is the quickest and easiest way to reverse this change. I won't argue for ethanol from corn, but I believe wood heat is an easy way to drastically reduce our "footprint" on the planet. Wood heat is simple, proven and, some would agree, even fun! I go through the effort to burn wood mainly because I'm a cheap SOB, but it does have its benefits. I also worry for the future of our kids, and I don't believe it is healthy to burn up all our fossil fuels in just a couple hundred years.

"Take nothing but pictures; leave nothing but footprints. (or bubbles, if you're a scuba diver...)"

Chris

 

[jebatty]

Pound of coal runs about 8-13000 btus; pound of wood runs around 4500-8500 (6500 good average) btus.

Coal = net increase in CO2 to atmosphere; wood from a sustainable forest is carbon neutral.