EPA declares biomass power carbon neutral

http://www.powermag.com/epa-declares-forest-biomass-is-carbon-neutral/?pagenum=1

After the rigged Manomet study in Massachusetts, this is good news for the biomass power industry. It still may not save most of the plants as the price of biomass generation is still much higher than natural gas.

Not sure if there is broad support that it is not scientifically based. Even the authors of the Manomet study ended up admitting that the study was rigged to come to a foregone conclusion. Unlike the majority of renewables biomass is dispatchable. Barring a pretty major technological advance with battery storage, a biomass plant is the only renewable that can inventory fuel and crank out power when needed.

Circus said:

Does CO2 emissions differ whether wood is burned or just rots on the ground?

Click to expand...

Yes and no. Its fairly complex. It depends on the how and what is rotting the wood. A pound of wood is only going to ultimately put out so much CO2 whether its burned or fully rotted. The tricky part is that natural processes may produce methane which is intermediate compound that has a far higher global warming potential than CO2. When wood is burned in a properly functioning boiler, the conversion to CO2 is pretty close to 100% especially if the unit has a downstream CO catalyst.

Where the grey areas exist is the energy used to collect and process the wood and the timespan looked at. Generally fossil fuels, specifically diesel, is used to harvest and transport the wood. The vast majority of diesel is "dynodiesel" derived from fossil fuels so even though the biomass is "green" it is being processed with fuels whose carbon is being dragged up out of ancient reservoirs thus the process is a net carbon emitter. If someone were stupid enough to grow trees strictly to burn for fuel this carbon burden is not shared with other processes. The reality is that no one grows trees to burn for power, the biomass fuel is a byproduct of other activities. Therefore the fossil carbon used to process the wood is spread amongst several ultimate products like high grade veneer, lumber, pallet wood, mulch and biomass fuel. If the other products are being produced and the biomass is left in the woods a large amount of the fossil carbon has already been expended to obtain the other products so only the extra fossil carbon used to process the fuel and transport it to a power plant should count towards the power production. Where things get tricky is comparing apples to apples with other lifecycle sources of power. Further complicating the comparison is the question is a KW of solar power on sunny day equal to a KW of power on a cloudy snowy day in the winter? The "Manomet" study played another game where they didn't look at the entire life cycle of the woods. If you take a snap shot of mature trees just before they are cut and then burn them in a power plant and take another snapshot after burning, the net result is a net large CO2 release. If you look at the overall cycle of the forest, as the trees regrow they will absorb CO2 through photosynthesis and they will be a long term CO2 sink. The net result in the long term is the CO2 is recycled over the lifespan of the forest with the exception of the fossil fuels used to manage and process the biomass products. Ideally the best thing for the environment is to let the trees stand but even then contrary to some folks beliefs is most trees have a distinct lifespan and eventually they will die off and rot. Most studies indicate that young growing forests are net carbon sinks but as they mature they transition to neutral.

The devil is in the details and in complex systems small manipulations in initial assumptions can yield widely varying results. I have no doubt that the recent declaration is far more political as was the past declaration in Mass that biomass power wasn't neutral supported by the flawed Manomet study was a political solution to preventing a biomass power plant from being built in the Berkshires.

Luckily for the benefit of the thread, the biggest US farm subsidy that isn't called one produces ethanol which is typically a replacement for gasoline. The logging and transport industry predominantly use diesel. Renewable diesel mostly comes from palm oil plantations in Indonesia with a small contribution from recycling waste vegetable oils (french fry grease). There have been various experiments growing oil crops in the US but none commercially successful.