Lecture 31 BIOMASS BIOFUELS

Overview of Petroleum Products

  • Petrol production is widely associated with various materials and processes in everyday life.
  • Many items in our environment and experiences (e.g., food packaging, clothing, household products) are either products of or contain petroleum products.

Environmental Interaction with Petroleum

  • Human actions significantly impact the environment; items are discarded improperly, leading to pollution in various environments including rivers and oceans.
  • Contaminants enter water sources via:
    • Erosion
    • Rainfall runoff

Example: Creek Pollution

  • Items found in creeks raise questions about their origin.
  • Considerations include:
    • Illegal dumping
    • Natural decomposition processes

Decomposition and Formation of Fossil Fuels

  • As materials decompose in marine systems under varying conditions, they transform into petroleum products.
  • Key transformation factors include:
    • Pressure
    • Temperature
    • Water content (moisture)
  • Example: Plastic's transformation in a creek differs from its original state due to degradation under natural elements.

Natural vs. Lab-Made Petroleum Processes

  • Fossil fuel formation via natural processes takes years, occurring within the Earth's crust.
  • Lab environments mimic these processes in a shorter time span through hydrothermal liquefaction.

Hydrothermal Liquefaction (HTL)

  • HTL is the conversion of organic materials into usable products under high pressure and temperature.
  • Steps:
    • Biomass is processed in a reactor, akin to a pressure cooker.
    • Moisture in the biomass is critical to efficiently convert it into useful biofuels.

Key Products from HTL

  • The liquefaction process yields:
    • Bio-oil
    • Biogas
    • Biochar

Thermal Liquefaction Comparison

  • Biomass used can be wet or dry.
  • In contrast to HTL, in thermal liquefaction:
    • The biomass does not necessarily have to be dry due to the presence of fluids.

Pyrolysis Process

  • Similar to HTL but differs mainly by the state of the biomass:
    • Pyrolysis uses dry biomass and operates under specific conditions (no pressure).
    • Focused on achieving gaseous products rather than liquid.
  • Important parameters include:
    • Temperature
    • Gas flow rate
    • Residence time of materials

Critical Aspects of Hydrothermal Liquefaction

  • HTL necessitates:
    • Wet biomass (might require pre-processing with solvents)
    • Use of a solvent to assist in the reaction process
    • Adjustments in operating conditions for optimal yield

Solvents and Biomass in HTL

  • Commonly used solvents are organic (e.g., ethanol, methanol).
  • Moisture content in biomass is vital for successful HTL production.

Temperature and Catalysts

  • Catalysts enhance reaction rates within the process, promoting faster transformations and higher yields.
  • Key considerations include:
    • Increased residence time correlates with improved bio-oil yield in both HTL and pyrolysis.

Research and Advancements in HTL

  • Historically, WT processes have developed over years since the 1920s.
  • The continuous improvement aims to create refined products for various energy applications.

Classification of HTL Processes

  • Hydrothermal carbonization (HTC) mainly produces chars, not relevant for current discussions.
  • Hydrothermal gasification produces gaseous products, which are also secondary to HTL.
  • Hydrothermal liquefaction, on the other hand, focuses on lipid-rich products suitable for further refinement.

HTL Yield Analysis

  • HTL generates higher liquid phase products, such as biocrude, compared to solid and gaseous by-products.
  • The focus is on separating and purifying these products:
    • Aqueous phase (bio-crude) must undergo further treatment to yield usable energy forms.

Comparison with Pyrolysis and Other Methods

  • The yield distribution in HTL differs from pyrolysis:
    • Pyrolysis aims for a solid char, while HTL targets liquid (bio-oil) predominately.
    • In both processes, the type of biomass used is crucial to determine product yield.