ENV100 Lecture Notes Mar 9, 2012

Report 5 Downloads 29 Views
ENV100 Lecture Notes

Mar 9, 2012

Black: The New Green? Guest Lecture: By: Carolyn Winsborough OUTLINE 1) What is Biochar 2) How is Biochar produced? 3) Environmental Benefits • Soil Improvements • Climate Change and Energy Production • Pollution • Food Security 4) My Research WHAT IS BIOCHAR? Terra preta do Indio-- ‘If you read the text books, it shouldn’t be here!” • An anomaly in the Tropics • Typically soil is: o Red and yellow soil o Highly weathered o Acidic o Low in organic matter o Low in essential nutrients What did they find: • Thousands of burial urns and ceramic pieces (date back 2000 yrs – 7000yrs) • Terra preta found on low hills overlooking rivers • 70% more charcoal than adjacent soils Why more charcoal??? • “Slash- and-Burn”: an agricultural practice where farmers clear their fields and burn the biomass to flush enough nutrient into the soil • “Slash and Char”: farmers burned biomass incompletely creating charcoal, and stirred this into the soil then added nutrients (animal bones and excrement) To test if charcoal was the culprit: • A trial was performed on the “infertile” soils of the Amazon by adding various treatments of charcoal and nutrients • In two years, treatments of charcoal and fertilizer grew as much as 880% more than plots with just fertilizer alone!

Basis For Strong Recent Interest: • High amounts of charcoal substances explained the high carbon content and sustained fertility of soil in the Amazon. • Over last 5 years, research has demonstrated that charcoal is more stable than, and retains more nutrients than any other organic matter in soil What is Biochar? • A fine-grained, porous charcoal high in organic carbon and resistant to decomposition • Obtained when biomass is heated in a closed container with little or no oxygen at relatively low temperatures (500 – 700oC) • Similar to charcoal production, but differs in its intended use. Environmental Benefits • Improvement of Soils • Mitigation of Climate Change • Energy Production • Reduction of Environmental Pollution • Food Security Increased Nutrient Retention in Soils • Cation Exchange Capacity (CEC): o > surface area  moisture retention  more microbes o > surface  negative charge • Can strongly adsorb phosphate (PO43-) (not sure why) o Keep this in mind!!! Reducing Pollution • Nitrates and Phosphates, when leached to waterways can cause EUTROPHICATION • Scrubbing Air Pollutants • Reduces the need for Fertilizers OTHER GREENHOUSE GASES: • NITROUS OXIDE (N2O) o 300 times more potent than CO2 o 50-80% reduction in emissions in greenhouse experiments • METHANE (CH4) o 21 times more potent than CO2 o Emissions completely suppressed in a grassland with biochar additions

Biomass Energy: derived from living or recently deceased organisms Direct Combustion for Heating -Wood cut from trees (fuel wood) -Charcoal from charred wood -Manure form farm animals Biofuels for Powering Vehicles

-Corn grown for ethanol -Bagasse (sugar cane residue) for ethanol -Soybenas/rapeseed etc. For biodiesel

Biopower for generating electricity

-Crop residues (corn stalks) burned at power plants -Forestry residues -Processing wastes -Landfill Gas

Biomass energy brings PROS and CONS:  Carbon-neutral, releasing no net carbon into the atmosphere. o But…Harvesting fuelwood can lead to deforestation and soil erosion if over harvested  Economic benefits o Supports rural communities o Reduces dependence on fossil fuel imports  But…We would need to expand acreage by 60% to achieve what we achieve today (and Biofuel vsFood Production) $$$$Million Dollar Question$$$$  Can biochar sequestration coupled with bioenergy production make a difference to the national and global carbon budgets??? Johannes Lehmann of Cornell Univeristy calculates: 3 scenarios that could sequester 10% of US fossil fuel emissions:  Pyrolysis of forest residues (~3.5 tonnes per hectare/yr) from 200 million hectares of US forest used for timber production)  Pyrolysis of fast-growing vegetation (20 tonnes of biomass per hectare per year grown on 30 million hectares of idle US cropland)  Pyrolysis of crop residue (5.5 tonnes biomass per hectare per year from 120 million hectares of harvested US cropland) o If captured gases are used for biofuel, even more carbon can be sequestered! FORESTS IN CANADA • Canada contains 10% of the world’s forest area and is the largest exporter of forest products worldwide



Forests are facing a major anthropogenic environmental disturbance in the form of nitrogen deposition

STUDY SITE: HALIBURTON FOREST • Largest private land- holding forestry operation in Ontario • Research has shown a lack of phosphorous (P) rather than nitrogen (N) currently limits the growth of maple dominated forests in this region GAS MEASUREMENTS • Commence in spring • Every two weeks • Continue to snowfall • Nitrous Oxide • Carbon Dioxide • Methane SOIL MEASUREMENTS • Soil coring (5cm diameter) Measure: o Moisture o Nitrogen o Phosphorus o pH