Wood burning vs. Natural Gas environmental impact — complete cycle study?

[Trailz]

I've been looking all over the great wide web for a good study that shows the overall impact of burning wood vs. heating with gas. By 'overall', I mean cradle to grave... excavating/harvesting, transportation, etc. — the complete life cycle of each. I suspect it takes a more energy to extract natural gas v.s harvest wood .

Does anyone have a legitimate and informative site to point me to? Or any other information?

Every comparison I can find simply shows how much less clean wood burns vs. natural gas. This is only a portion of the overall environmental equation and I'd like to understand it more fully.

 

[JRP3]

I found a lot of different papers by Googling "life cycle analysis of natural gas vs wood"

 

[NoGoodAtScreenNames]

I think you also need to differentiate the method of extraction on the wood side. I burn waste wood from dead or dangerous trees in the suburbs cut by local tree companies. Finding a productive use for a waste product is different than large scale commercial extraction from a forest with fuel being the only justification for cutting.

At least that’s my persona justification / rationalization of burning wood. Also every dollar I don’t send to an oil company is one less dollar they have to invest in future extraction. Not supporting the oil economy infrastructure has its benefits too.

 

[JRP3]

Also worth considering is how you process your wood. I use mostly electric saws and I converted my wood splitter to electric as well. Plus I do some hand splitting. Cleaner and more efficient than gas, especially 2 strokes.

 

[SpaceBus]

Also worth considering is how you process your wood. I use mostly electric saws and I converted my wood splitter to electric as well. Plus I do some hand splitting. Cleaner and more efficient than gas, especially 2 strokes.

Then you will have to take into account how that electricity is generated and what resources were utilized to gather whatever fuel is used for the generation.

 

[JRP3]

Then you will have to take into account how that electricity is generated and what resources were utilized to gather whatever fuel is used for the generation.

Of course. Here in central NY it's mostly hydro, nuclear and NG, but in almost all cases electricity is cleaner than petroleum burned in ICE's on a full life cycle analysis. Remember an electric motor is about 90% efficient compared to a gas ICE which is around 20% efficient.

 

[begreen]

Small ICE motors lack any pollution controls. They are notorious polluters. So what is more efficient, a large scale wood processor running on a single motor or many hours with a chainsaw and gas splitter?

 

[JRP3]

I'd assume the large scale wood processor will have more over all efficiency than small gas saws and gas splitters.

 

[peakbagger]

The commonwealth of Massachusetts commissioned a study abut 10 years ago by the Manonmet group an independent research organization. The study was generally referred to as the Manomet study and represented that it was an unbiased exhaustive study about biomass generated electricity versus natural gas generated electricity. It came to the conclusion that burning natural gas was far "cleaner" than burning biomass. From the outside it looked like it was the "answer" but subsequently it came under a lot of criticism. Even the authors of the report eventually issued a response to the criticism that the basis they used for the study didn't actually match the industry in New England. Its came out later that the then governor of the state had influential friends in the Berkshires of Mass (a well heeled summer colony for the residents of the prosperous areas of Mass. There were several biomass power plants proposed for the area and the friends didn't want it in their backyard so the governor called up the appropriate state department and told them top commission a study to come to the conclusion that biomass was bad. It was used by the state of Mass to phase out purchased biomass generated power to be treated as renewable. Most of the plants supplying biomass power to Mass were in NH and Maine and at least a couple of them had spent significant dollars a few years earlier to meet changes in the Mass biomass power requirement. Most of the those plants are now closed.

The major flaws is picking the boundary conditions. They assumed that virgin trees were being cut exclusively for generating power. Those trees are a carbon reservoir for the life of the tree. So softwoods might be assumed to be 50 years old and hardwoods 80 years old. So cut the tree that has been growing for decades and convert the carbon emitted to an instantaneous value. In theory this carbon released is just "borrowed as if new trees are regrown the carbon released by burning them will be absorbed when they regrow. This was not counted. The other failing is that biomass power plants in New England do not typically burn virgin wood. The economics just do not line up. Biomass might sell for $50 a ton and its not worth the diesel to go in the woods to cut it. The plants in New England burn the scrap left over from other forest operations. The choice is leave it in the woods to rot where it gives off carbon or burn it in boiler.

Forest residuals have fundamental problem that the energy density if quite low compared to natural gas. That means that it takes more energy to transport it and at some point the diesel required to move the biomass exceeds the BTU content of the wood. For biomass those economics are about a 50 mile radius around a biomass power plant. If the plant i getting sustainably harvested wood, it is probably a 20 MW plant. A small plant like that is fairly expensive to build on a $/KW basis. A natural gas plant used to be about to be built for under $2,000 per KW while a biomass plant may be $5,000/KW.

One of the drivers right now is the carbon tipping point argument. Arguably the world is well past that point but its an arbitrary level of atmospheric CO2. The argument is that the credit for Carbon re-absorption by trees is decades and it will not matter as the tipping point will be past in some arbitrary time window (usually 10 to 20 years). There is big psychological aspect to setting a short term goal, the reality is the typical person on the street could give a darn on what may happen o the world when they are in the grave. Sure their grandkids may be cute but they are not going to change their own lives to ensure the grandkids have a future. Some folks believe that any day now the heavens open up and they go to heaven so why worry about the world of the future as they will not be part of it so why worry about it.

Currently the Europeans particularly England are using creative calculations to justify the use of biomass pellets made in the US, Canada and other resource rich countries. In this case they are paying enough of premium that genetically modified "trees" are grown in farm like conditions in tight rotation and shipped across oceans.

With respect to natural gas much of it is waste product from drilling for oil. In many areas, the infrastructure for collecting it is lacking so its just flared to atmosphere or worse case vented as methane (a much more potent global warming gas). So if its burned for heating or electricity instead of being flared should it get a credit for not being flared.

Common sense is that the carbon under the ground is the result of millions of years of vegetation (biomass) being compressed into hydrocarbons. These are locked in (sequestered) deep in the ground and rarely make it to surface. Ths multimillion year resource is being burned in a less than 1000 year period releasing millions of years of carbon. Residual biomass is not taking stored carbon out of the earth, its just recycling the carbon in growing trees.

Good luck on your quest.

 

[JRP3]

So softwoods might be assumed to be 50 years old and hardwoods 80 years old.

Something else to consider is that mature trees don't absorb much carbon compared to younger trees as I understand it. So if you cut a mature tree and plant another in it's place there should be a carbon offset sooner than 50-80 years.

 

[peakbagger]

BTW, I mentioned on another recent post a method of fast torrefaction can be used on biomass, the volatile components are driven off for high value products while the cellulose is turned into carbon char.The carbon char can be buried in the soil as an ammendment. South American cultures did it on a large scale and artificially produced high value soils, called Tera Preta that had a lot more productivity than the natural soils around it. It only makes financial sense if someone is paying to sequester carbon.

 

[Highbeam]

@begreen My chainsaw has a catalytic converter! There are emissions standards and/or controls for all modern OPE though your point is correct that these things aren’t the cleanest way to burn fossil fuels.

 

[EbS-P]

I think the scale of your inquiry is important. On personal use scales I would make a wild ass guess that the complete natural gas cycle is cleaner. Basing my guess on two factors. First the natural gas Distribution network is already established. We are talking zero extra emissions** to deliver the needed BTUs. Unless a tree falls ( and they keep falling annually) in your backyard ( three hurricanes in 3 years here, I don’t want trees falling to be an annual thing anymore), I can make the case that Harvesting, processing and transporting firewood would have higher energy cost. **I made a pretty big assumption that the natural gas infrastructure doesn’t contribute much to its overall energy cost. But somebody has to keep this infrastructure operating and that takes energy.
Second natural gas will always be cleaner burning.
On larger scales 100MW and higher the bio mass just is not cost competitive hence why you are not finding great resources. Money still gets the research done. I think the sun is setting on biomass energy credits and subsidies. Solar and wind and the associated impacts to produce the products must have been studied. Just my thoughts with very little evidence.
Evan

 

[begreen]

@begreen My chainsaw has a catalytic converter! There are emissions standards and/or controls for all modern OPE though your point is correct that these things aren’t the cleanest way to burn fossil fuels.

That's very interesting. I haven't kept up with the new saws. My lawnmower does not, nor my weedeater. I'm selling my old chainsaw. The less ICE motors I have and have to maintain the better.

 

[Highbeam]

That's very interesting. I haven't kept up with the new saws. My lawnmower does not, nor my weedeater. I'm selling my old chainsaw. The less ICE motors I have and have to maintain the better.

Some chainsaws, and dirt bikes, and generators have fuel injection now too. Sort of like the evolution of car engines just decades behind. My last dirt bike had a carburetor but a catalytic converter in the muffler. That got hot.

 

[SpaceBus]

Some chainsaws, and dirt bikes, and generators have fuel injection now too. Sort of like the evolution of car engines just decades behind. My last dirt bike had a carburetor but a catalytic converter in the muffler. That got hot.

Some day folks will figure out how to make two stroke engines just as clean as regular four strokes. Maybe that will never happen, but I can dream about road legal two stroke bikes.

 

[peakbagger]

I had some hopes for Liquid Piston's design but it seems to have stalled.

 

[Highbeam]

Some day folks will figure out how to make two stroke engines just as clean as regular four strokes. Maybe that will never happen, but I can dream about road legal two stroke bikes.

I owned an older one (factory street legal 2 stroke) and my state allows street legalization of newer 2 stroke dirtbikes. Not sure how they avoid emissions regulations on that.

Fuel injection, direct injection, could allow cleaner 2 strokes not unlike direct injection diesel 2 stroke engines. Lots of those green Detroit diesels still in service. Using fuel/air mix to blow out the previous cycle’s exhaust like most two strokes can never be really clean.

Having ridden modern high power 4 stroke dirtbikes there is plenty of power! and they’re not much heavier.

 

[SpaceBus]

I owned an older one (factory street legal 2 stroke) and my state allows street legalization of newer 2 stroke dirtbikes. Not sure how they avoid emissions regulations on that.

Fuel injection, direct injection, could allow cleaner 2 strokes not unlike direct injection diesel 2 stroke engines. Lots of those green Detroit diesels still in service. Using fuel/air mix to blow out the previous cycle’s exhaust like most two strokes can never be really clean.

Having ridden modern high power 4 stroke dirtbikes there is plenty of power! and they’re not much heavier.

I just love the way a two stroke screams, especially those Yamaha 350's in the Banshee and the old 70's street bikes. I don't think any engine that burns the lubricant is ever going to be clean enough to find a home in a modern production motorcycle. I've seen some road converted two strokes back in NC and I've heard you can do it here in Maine.

 

[JRP3]

If you want high revs plus full torque from zero RPM electric motors can't be beat. As battery energy density keeps increasing and costs keep dropping I don't think anything else will compete with them. Example, a Zero electric motorcycle motor in a Yamaha Raptor quad, jump to the 13:40 mark if it doesn't auto link to it:

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[SpaceBus]

Electric motors are great from a power and performance perspective, but they lack the visceral experience of a well tuned ICE. I suspect my opinion would be different if I had experienced electric bikes first. Ever watched a Formula E race?

 

[JRP3]

Yes, I like the high pitched whine. Until you feel the push from a powerful electric motor you can't really understand it. Your brain is programed to expect noise with power, EV's change that perception.

 

[SpaceBus]

Yes, I like the high pitched whine. Until you feel the push from a powerful electric motor you can't really understand it. Your brain is programed to expect noise with power, EV's change that perception.

I don't like the whine, but I would love a practical electric vehicle that can handle our logging roads. For fun stuff I still prefer fire breathing engines.

 

[begreen]

When I am outdoors I like to hear nature, not the whirr and roar of ICE machinery. Additionally, no matter that they have a cat or fuel injection, they still have the fossil fuel footprint on the environment. What comes out of the exhaust pipe is just the end of a long chain. It starts with hauling millions of years old carbon out of the ground, flaring at wells, transporting it, refining it with more flaring off, then transporting it again, often several times. These external costs put a lot of CO2, CH4 and NO into the environment before it reaches the gas tank. We can and should do a lot better.

 

[DBoon]

The less ICE motors I have and have to maintain the better.

I couldn't agree more. I never had an older brother or father who taught me how to maintain engines, and I was never very good at learning about that myself. So the idiosyncrasies of any engine, especially a small two-stroke yard equipment engine, just flummox me.

I've been purchasing the Ego 56V line of yard tools and there is no going back. I think the electric lawn mower will be my next purchase in the spring of next year.