AECH 2112 Sustainability & Renewable Energy - Biomass

Biomass Overview

  • Biomass is organic material from living things, mostly plants and animals. It's a carbon-based energy source.

  • Common sources include plants like wood, crops, waste from farms, and garbage.

  • Biomass can be renewable if harvested sustainably, meaning new growth replaces what's used.

Conversion Processes

  • Biomass can be turned into fuel or energy through several methods:

    • Burning it (Combustion): Directly burns biomass for heat or electricity.

    • Digestion: Microbes break down organic matter without air to make biogas (mostly methane, CH_4).

    • Pyrolysis: Heating biomass without much oxygen to get bio-oil (liquid fuel), biochar (solid), and syngas.

    • Fermentation: Microbes turn plant sugars into bioethanol (alcohol).

    • Gasification: Heating biomass with limited oxygen to create syngas (a gas fuel).

  • Electricity is often made by directly burning biomass in power plants.

Biomass Energy Storage and Usage

  • Biomass energy can be used as solids, liquids, or gases:

    • Solid fuel: Wood, crop waste for burning.

    • Liquid fuel: Bioethanol and biodiesel for vehicles.

    • Gaseous fuel: Methane (biogas) for electricity, heating, or vehicles.

Biomass Energy Conversion

  • Main ways to convert biomass:

    • Thermal Conversion: Uses heat (like combustion, pyrolysis, gasification) to make heat, electricity, or fuels.

    • Biological Conversion: Uses tiny living things (like in digestion and fermentation) to make biogas and bioethanol.

  • Biofuels (like biogas, bioethanol, biodiesel) are made from biomass to replace fossil fuels.

Advantages and Disadvantages

  • Advantages:

    • Storable: Can be stored and used when needed, unlike solar or wind.

    • High energy density: Biofuels pack a lot of energy, good for transport.

    • Waste reduction: Uses up organic waste.

    • Potential carbon neutral: Plants absorb CO_2 as they grow, offsetting what's released when burned, if managed well.

  • Disadvantages:

    • Low net energy gain: Can take a lot of energy to grow, collect, and process some biofuels.

    • Pollution: Burning biomass still releases greenhouse gases (CO2, NOx) and air pollutants.

    • Environmental harm: Growing large amounts of biomass can lead to deforestation, habitat loss, and water pollution from fertilizers.

    • High carbon footprint: The overall environmental impact can be higher than other renewables when considering transport and processing.

    • Food vs. Fuel: Using land for energy crops can reduce land for food crops.