Energy from Biomass (College Board AP® Environmental Science): Flashcards
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Define biomass.
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Define biomass.
Biomass is organic material from plants and animals, a renewable energy source derived from living or recently living organisms.
Give three types of biomass used for energy.
Types of biomass include wood and agricultural products, municipal solid waste, landfill gas and biogas, alcohol fuels, and algae.
Burning biomass directly to produce heat is called direct .
Burning biomass directly to produce heat is called direct combustion.
True or False?
Biomass is carbon neutral because burning it releases no CO₂.
False.
Burning biomass does release CO₂, but this is offset by the CO₂ absorbed while the biomass was growing.
What is thermochemical conversion of biomass?
Thermochemical conversion uses processes such as pyrolysis and gasification to convert biomass into liquid or gaseous fuels.
How does biochemical conversion turn biomass into biofuels?
Biochemical conversion uses microorganisms to turn biomass into biofuels through anaerobic digestion and fermentation.
True or False?
Burning biomass does not contribute to acid rain.
False.
Biomass has less sulfur than fossil fuels, but burning it still releases nitrogen oxides, which contribute to acid rain.
Which air pollutants are released when biomass is burned?
Burning biomass releases particulates, carbon monoxide, carbon dioxide, and volatile organic compounds.
Define ethanol.
Ethanol (ethyl alcohol) is a renewable biofuel produced mainly by the fermentation of sugars by yeast.
How can growing biomass crops harm ecosystems?
Biomass crops need large areas of land, which can lead to deforestation and habitat loss.
True or False?
Ethanol-powered cars get better mileage than gasoline-powered cars.
False.
Ethanol is less energy dense than gasoline, so ethanol-powered cars get lower mileage.
What is cellulosic ethanol made from?
Cellulosic ethanol is made from non-food plant materials, such as agricultural residues, grasses, and wood chips.
Ethanol is commonly blended with to make E10 and E85 fuels.
Ethanol is commonly blended with gasoline to make E10 and E85 fuels.
How can ethanol production raise food prices?
Diverting crops such as corn and sugarcane to ethanol production can lead to higher food prices, affecting food security.
What does it mean that ethanol has a low energy return on energy investment?
It means the energy needed to produce ethanol can be close to or greater than the energy it provides.
Why is ethanol not fully carbon neutral in practice?
Ethanol is not fully carbon neutral because farm machinery, energy-intensive processing of corn, and transport by tanker all produce extra CO₂ emissions.
Which process converts algae oil into biodiesel?
Algae oil is converted into biodiesel by transesterification.
Why do algae biofuels compete less with food crops than land-based biofuels?
Algae can be grown on non-arable land using wastewater, which reduces freshwater demand and competition with food crops.
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