Renewable Energy Sources: Biomass

and Biogas

What is BIOMASS?

• Organic matter produced by photosynthetic producers

• Total dry weight of all living organisms at each trophic level

in a food web

METHODS OF USING BIOMASS

ENERGY • Method #1

–Burning Biomass to create heat

• Method #2–Gaseous Biofuels–Liquid Biofuels

Method #1 - Burning

• Dung, Reeds, Wood, Trash

• Biomass must not be removed faster than can be replaced

• Developing countries

• Burning takes nutrients from fields

Cow Pie Anyone?

More Dung

Dung Beetle

METHOD #2• Convert solid biomass

into gas and liquid biofuels

• Ethanol– distilled and

fermented grains• Methanol

– prod. from sewage sludge, wood, agricultural wastes, garbage & coal

• Grain stocks (corn) can be fermented by bacteria (yeast) which can then be burned as fuel

• Cons: pesticides, fertilizers, CO2 emissions, land could be used for food!

Ethanol = Ethyl

Alcohol

Traditional Ethanol vs New Algae

• Traditional: corn fermentation

• New: algae make ethanol. Same process use algae instead of corn to ferment by

yeast.

• Algae can be farmed and harvested in smaller facilities.

• Algae: Sargassum, Glacilaria

Biogas - Landfills• Fieldtrip to a Conn. Methane

Recovery Plant• Uses local solid waste for biogas

Old Landfill Mound• “Capped” landfill mound• Methane bubble trapped beneath

Gas Extraction Wells

• Wells are on top of mounds

• Collect methane/ other biogases

• Gas pressure constantly checked

Gas Compressor• Concentrates methane

Turbine for Electricity

• Gas mixture burned

• Generates steam; turns turbine

PROS - BIOMASS

• A renewable resource if managed

• CO2 levels have no net increase

• Makes use of agric. or timber wastes.

• Much biomass supply

Disadvantages of Biomass

• Use plantations to grow wood use pesticides, fertilizers which pollutes drinking water.

• Soil erosion sedimentation• Little nutrients go back in soil. • Loss of habitat for orgs.

Air Pollutants

• Wood smoke contains PM and HCs– ex bronchitis,

emphysema, cancer

– 820 estimated deaths per yr

ETHANOL

PROS• High octane• Emission

reduction of carbon dioxide

• Reduction of CO• Potentially

renewable

CONS• Negative net energy• Larger fuel tank need• High cost• Competition 4 land• Smog formation• Corrosive• Hard to start in cold

METHANOL

PROS• High octane• Emission

reduction of carbon dioxide

• Reduction of total air pollution 30%-40%

CONS• Large fuel tank need• Corrosive on metal,

rubber & plastic• Increased emissions of

formaldehyde• Hard to start in cold• High cost• Created by coal = high

CO2 emissions