Wednesday, September 22, 2010

Biomass Energy & Carbon Accounting (Part 1)

During the past year, biomass energy has come under the microscope with numerous environmental groups questioning the carbon cycle neutrality argument and also the EPA's "Tailoring Rule". Our understanding of these concerns center on when the accounting cycle should start (called a carbon debt). The below chart illustrates the concept of carbon debt using the logarithm function of tree growth:

Should the accounting period begin as the biomass source is originally created, or should the accounting period begin at harvest and fuel use? For example, there is a big difference between (1) harvesting an old growth forest versus (2) growing energy crop trees on marginal lands that only had weeds before tree planting.

While the topic of life-cycle carbon accounting is complex, two key carbon capture components that we rarely see in this discussion are (1) below ground carbon sequestration and greenhouse gas emissions (primarily, NOx); (2) biochar created through biomass gasification technology.

Through our field work in Florida (i.e., growing energy crop trees on marginal mined lands) our collaborative work with the University of Florida and Oak Ridge National Lab documented that in accumulating total carbon:
(A.) 62% was contained above ground (harvestable trees) and,
(B.) 38% was below ground (i.e., root systems).

Also, according to the U.S. Department of Energy's NETL, approximately 50% of the biomass harvested feedstock (i.e., the 62%) could be captured in biochar (31% of the total biomass) through gasification pyrolysis.

Clearly, biochar has the potential to be a "major player" in carbon cycle accounting ranging from the gasification process to its ability to capture NOx emissions from soils. The problem is that so little empirical data exists outside of laboratory study (the need for commercial scale field documentation).

(1) Per UF/ORNL field measurements of eucalyptus tree plantation (62% + 38% = 100% total tree mass).
(2) Per NETL estimates of 50% biochar carbon capture through gasification.
(3) Assumes biogas would be scrubbed downstream from the gasifier through a Wet ESP (electrostatic precipitator), emitting almost no greenhouse gas nitrous oxide emissions (and also no sulfur emissions).
(4) Lehmann (Cornell) research that biochar may capture ~80% of NOx and ~100% of methane (CH4).
(5) Current Proxy of ~10% using Life Cycle Assessment developed by University of Michigan, SUNY (Heller, Keoleian, Volk, July, 2002)


Anonymous said...

For those looking for an overview of biochar and its benefits, These authors have done a very nice job of distilling a great deal of information about biochar and applying it to the US context:

US Focused Biochar report: Assessment of Biochar's Benefits for the USA

Agriculture allowed our cultural accent and Agriculture will now prevent our descent.

Wise Land management; Organic farming and afforestation can build back our soil carbon,

Biochar allows the soil food web to build much more recalcitrant organic carbon, ( living biomass & Glomalins) in addition to the carbon in the biochar.

Every 1 ton of Biomass yields 1/3 ton Charcoal for soil Sequestration (= to 1 Ton CO2e) + Bio-Gas & Bio-oil fuels = to 1MWh exported electricity, so is a totally virtuous, carbon negative energy cycle.

Biochar viewed as soil Infrastructure; The old saw;
"Feed the Soil Not the Plants" becomes;
"Feed, Cloth and House the Soil, utilities included !".
Free Carbon Condominiums with carboxyl group fats in the pantry and hydroxyl alcohol in the mini bar.
Build it and the Wee-Beasties will come.
Microbes like to sit down when they eat.
By setting this table we expand husbandry to whole new orders & Kingdoms of life.
( These oxidised surface charges; carbonyl. hydroxyl, carboxylic acids, and lactones or quinones, have as well a role as signaling substances towards bacteria, fungi and plants.)

This is what I try to get across to Farmers, as to how I feel about the act of returning carbon to the soil. An act of penitence and thankfulness for the civilization we have created. Farmers are the Soil Sink Bankers, once carbon has a price, they will be laughing all the way to it.
Unlike CCS which only reduces emissions, biochar systems draw down CO2 every energy cycle, closing a circle back to support the soil food web. The photosynthetic "capture" collectors are up and running, the "storage" sink is in operation just under our feet. Pyrolysis conversion plants are the only infrastructure we need to build out.

Since we have filled the air , filling the seas to full, Soil is the Only Beneficial place left.
Carbon to the Soil, the only ubiquitous and economic place to put it.

WorldStoves in Haiti ; and
The Biochar Fund deserves your attention and support.
Exceptional results from biochar experiment in Cameroon

NSF Awards $1.6 million in grants;
BREAD: Biochar Inoculants for Enabling Smallholder Agriculture

Thanks for your efforts.

Erich J. Knight
Chairman; Markets and Business Review Committee
US BiocharConference, at Iowa State University, June 27-30

MarkAnthony said...

Can anyone tell me the different amounts of CO2 by mass from a very wide range of alternative energy feedstocks???? I can't find any good references on the web...


Krista Hiles said...

Great post. Your attempt of providing info on such topic graphically is really wonderful. Keep updating.

Sterling Energy