APES Unit 6.7 Biomass

When Biomass is burned…

Several pollutants are released

• Traditional: wood/charcoal

Biomass

organic matter (wood/charcoal, dried animal waste, dead leaves/brush) burned to release heat - primarily for heating homes/cooking

• Utilized primarily in developing world for heating homes & cooking food

• Easy to harvest, available, cheap/free (subsistence fuel)

• Can also be burned in PPs to generate electricity (less common than FFs)

Carbon Dioxide (CO2)

A by-product of all combustion, carbon dioxide from biofuels contains modern carbon from woody material, rather than fossil carbon from fossil fuels

• Biomass burning releases CO2, but doesn’t increase atmospheric CO2 levels like FF burning does

• Burning biomass releases modern carbon (CO2 that was recently sequestered, or taken out of the atmosphere) whereas FF burning releases fossil carbon that had been stored for millions of years

• Biomass burning is considered “carbon neutral”

• Think of spending a dollar someone just gave you vs. withdrawing

from your long-term savings account to spend

Carbon Monoxide (CO)

Colorless, odorless gas that is formed during incomplete combustion of most materials

• Respiratory: Emphysema + cancer

Nitrogen Oxides

A by-product of combustion of any fuel in the atmosphere (which contains 78 percent nitrogen)

• Biomass burn. indoors for heat/cooking worsens effects (pollutants trapped & conc.)

  ○ Worsened asthma, bronchitis, COPD, emphysema, eye irritation

Particulate Matter

Solid or liquid particles suspended in the air (also known as soot)

• Biomass burn. indoors for heat/cooking worsens effects (pollutants trapped & conc.)

○ Worsened asthma, bronchitis, COPD, emphysema, eye irritation

Volatile Organic Compounds (VOCs)

Organic compounds that evaporate easily

• Biomass burn. indoors for heat/cooking worsens effects (pollutants trapped & conc.)

○ Worsened asthma, bronchitis, COPD, emphysema, eye irritation

Biomass vs. Ethanol: Carbon Impact

1. CO2

2. Doesn’t introduce additional carbon via combustion

Biomass vs. Ethanol: Primary Drawback

1. Deforestation: Overharvesting trees for fuel

2. Low EROEI

Biomass vs. Ethanol: Economic Factor

1. Relied on by 2-3B b/c inexpensive

2. Supports US farmers b/c reduces foreign oil

The Carbon Balance: Explain why burning ethanol is considered

"carbon neutral" regarding combustion, even though it still releases CO2

into the air.

Burning Ethanol = Carbon neutral

• Comes from bio material w/ new CO2

Resource Management: Describe the relationship between the "low

cost" of biomass energy and the environmental risk of deforestation.

Inexpensive → High Demand

• Harvest Rates too High: Permanent deforestation + soil erosion

3. Energy Investment: Define Energy Return on Energy Investment

(EROEI) in your own words. If ethanol has a "low" EROEI, why might we

still use it as a gasoline substitute?

EROEI = ration of energy produced compared to the energy used to create it

• Ethanol = Reduces reliance on foreign oil + safer for environment

Manure/Biogas: Primary Source

Waste products of animals

Manure/Biogas: Process

Dried and burned for fuel

• often when wood is scarce

Manure/Biogas: NRG Output

Heating

• Cooking

Biodiesel: Primary Source

Oils from plants or algae (soybean, palm)

Biodiesel: Process

Extracting and chemically altering oil from plants or algae

Biodiesel: NRG Output

Used as a sub for regular petroleum diesel

Manure-Based NRG: Pros

• Usually free waste product from owning livestock

Manure-Based NRG: Cons

• Releases pollutants

• dangerous when burned in poorly ventilated areas

Biodiesel: Pros

Lowers CO2 emissions

• Made from waste

Biodiesel: Cons

Usually more expensive

• Soybeans = land

• Transfers CO2 from soil