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Biomass Energy and Algae Biofuels

Lesson Plan by Cameron Coates and Tara Howell

This lesson plan was designed for a high school AP Environmental Science class in San Diego CA. The unit is focused on biomass energy with a particular emphasis on algae biofuels and is intended to teach students what biomass energy is, what the trade-off are for using biomass energy and what the current state of the art is for using biomass for energy. Our society is facing a number of serious challenges involving energy and today’s students should expect to see important decisions being made about energy in their lifetime. With a deeper understanding of the opportunities and challenges involved with biofuel and biomass energy students will be better equipped to make informed decisions about how they use energy in their personal and professional lives.

Learning Goals

  • Students will be able to identify the differences between biofuel and fossil fuels.
  • Students will be able to explain the differences between various forms of biomass energy and how algae biofuels compare.
  • Students will be able to explain the trade-off involved with the use of biodiesel.
  • Students will learn about what future biofuels might be made from and what researchers are doing to develop new biofuel technology.
  • Students will learn about the considerations involved in developing a biofuel company and the current state of biofuel industry.

Overview Lessons and Activities

  • Day 1: Biomass Energy
  • Day 2: Next Generation Biofuels and Creating a Biofuel Company
  • Day 3: Creating a Biofuel Company
  • Day 4: Creating a Biofuel Company – Presentations
  • Day 5: Creating a Biofuel Company – Presentations

How to: Outdoor Algae Biomass Production

Researchers at Cal-CAB have studied best practices for growing microalgae and cyanobacteria at a large scale at the UC San Diego Biology Field Station. Below is a brief summary of the steps needed to grow algae from a laboratory plate to a raceway pond, and how to harvest the algae. More detailed information on the process can be found in a paper by Cal-CAB research Nathan Schoepp called System and method for research-scale outdoor production of microalgae and cyanobacteria.

schoepp

  1. Scale up of liquid cultures
    1. Start from plate stocks by scraping and suspending a portion of the plate
    2. Marine strains are then grown in supplemented natural sea water using sand-filtered coastal seawater in the greenhouse and outdoors
  2. Growth in hanging polybag photobioreactors
    1. Create two connected bubble columns and suspend the polybags in a v-shape
    2.  Supply and maintain air to each culture
    3. Withdraw the samples through vent holes in the top of the polybags
  3. Growth in air-lifted stock ponds
    1. Conduct the growth in stock ponds for each of the strains tested
    2. Observe strain health in an open outdoor environment and compare productivities between the strains
    3. At regular intervals, harvest and nourish the dosing to prevent light and nutrient limitation
  4. Growth in air lift-driven raceways
    1. Construct air lift-driven raceways out of standard cinder blocks mortared, filled with cement, and placed on compacted decomposed granite
  5. Culture Monitoring
    1. Collect cultures samples daily between 8 AM to 12 PM
    2. Measure culture pH and temperature daily
    3. For some cultures, keep track of the cell counts every other day
    4. Prewash filters five times
    5. Cool filters in a desiccator before weighing
    6. Create optical density-dry weight correlation curves for each strain
  6. Harvesting
    1. Pump cultures into the centrifuge
    2. Store concentrated biomass into frozen plastic bags
    3. The volume removed from the raceway is then replaced by fresh media
Nathan G. Schoepp, Ryan L. Stewart, Vincent Sun, Alexandra J. Quigley, Dominick Mendola, Stephen P. Mayfield, Michael D. Burkart. (2014) System and method for research-scale outdoor production of microalgae and cyanobacteria. El Sevier.

How to: The Extraction of Algal Lipids and Transesterification into Biodiesel

Below is a brief summary of the steps needed to cultivate and harvest algal biomass and convert it to a transportation fuel. More detailed information on the process can be found in a paper by Cal-CAB research Jillian L. Blatti called Releasing Stored Solar Energy within Pond Scum: Biodiesel from Algal Lipids.

  1. blatti

    Algal Culturing and Harvesting of Biomass
    1. Inoculate a sterile liquid TAP starter culture from a single, robust algal colony
    2. Allow 7 days of agitation under constant white light illumination
    3. Use the algal culture to inoculate a flask containing a larger volume of media
  2. Transesterification of Algal Biomass
    1. Convert algal lipids to their methyl ester derivatives
    2.  Resuspend algae cell pellet to homogeneity in the methanolic acid solution and the mixture incubated
  3. Liquid to liquid Extraction
    1. Use hexanes to extract fatty acid methyl esters from the mixture
    2. Break emulsions with a one minute centrifugation step
    3. Repeat hexane extraction 6 times
  4. Base-Catalyzed Transesterification of Soybean Oil and Soybean Biomass
    1. Compare methods and feedstocks by raising temperature and adding soybean oil to a flask containing sodium methoxide solution
    2. Biodiesel is then washed with distilled water to remove basic residue

Jillian L. Blatti, Michael D. Burkart. (2011) Releasing Stored Energy within Pond Scum: Biodiesel from Algal Lipids. Journal of Chemical Education.

 Nathan Schoepp, Wilson Wong, Stephen Mayfield and Michael Burkart (2015). Bulk Solvent Extraction of Biomass Slurries Using a Lipid Trap, RSC Adv., Accepted Manuscript.