Which Starch Plant Produces the Most Fuel?

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Updated on Sep 30, 2013

Difficulty of Project


Grade Level

High School

Safety Issues

This project needs to be supervised by an adult or professional because ethanol, a volatile substance is extracted from starch plants.

Material Availability

All materials for the project can be obtained from a grocery store or market place.

Approximate Time Required to Complete the Project

2-3 months


To identify a starch plant that produces the largest quantity of ethanol.

The goals of the project include evaluating the efficiency of fermentation as it relates to the volume of ethanol produced and to compare the quantity of ethanol produced by various starch plants.


  • Potatoes
  • Corn
  • Soybeans
  • Thermophilic enzymes
  • Natural Yoghurt
  • Baker’s yeast
  • Sprouting barley malt


Biomass is an alternative energy resource scientists are tapping into as renewable energy resources are in growing demand. Starch plants can be fermented to produce ethanol. Ethanol can be extracted and used as an alternative fuel. Upon combustion, ethanol yields a large quantity of energy that can be used to power cars and generate electricity. Since starch plants can be harvested to produce the ethanol, the supply of ethanol is renewable during the life cycle of the plant. Fermentation is a natural biochemical process involving the decomposition of starches producing ethanol as a byproduct in the absence of oxygen. The process of fermentation can be enhanced by using yeast and heating the vegetation. In this project starch plants will be setup to maximize the fermentation process.

Research Questions

  • How do plants produce ethanol?
  • What is the fermentation process?
  • What factors optimize the fermentation process?
  • How can mixtures be separated?
  • What industries ferment organic materials to produce products of economic value?

Terms, Concepts and Questions to Start Background Research

  • Anaerobic
  • Fermentation
  • Ethanol
  • Cellular Respiration
  • Byproduct

The diagram illustrates the transformation of sunlight to biochemical and mechanical energy

Experimental Procedure

  1. Measure the initial masses of the starch plants and record the mass in a data table.
  2. In large aluminum trays place the starch plants in separate trays and mix with an equivalent mass of sprouting barley malt, natural yoghurt, and place the trays inside an incubator/greenhouse where the average daily temperature is regulated at greater than 35 degree Celsius.
  3. Sprouting Barley malt releases amylases into the starch plants. Amylases are thermophillic enzymes that function to initiate the fermentation process. Cover each tray with a lid to prevent the entry of oxygen.
  4. Leave each tray for one week in the incubator/greenhouse.
  5. At the end of the initial week, remove the lids from each tray.
  6. Add several packages of bakers yeast to the decomposition mixture in each tray.
  7. Replace the lids on each container and place the trays inside an incubator or oven. The incubator/oven should be set at 45 degree Celsius.
  8. Ethanol is a viscous liquid that can be decanted from the fermentation mixture and collected in a graduated cylinder about a week after fermentation.
  9. The volatile mixture of organic ethanol is a mixture of aldehydes, ketones, and esters. The ethanol can be purified and separated from the homogenous mixture by distillation. During distillation, the liquid is placed inside a distilling flask and attached to a condensation tube and conical flask. The distilling flask is heated to 78 degree Celsius. At this temperature, the ethanol vaporizes and can be condenses. The ethanol can be collected in the conical flask as pure ethanol.
  10. To determine the mass of the ethanol, the volume of the ethanol can be measured in a graduated cylinder and recorded. From the chemical formula of ethanol, it can be inferred 22.4 Liters of ethanol can be found in the value of the compounds molar mass. The mass of the purified ethanol can be deduced from the volume of ethanol extracted.
  11. Compare the mass of ethanol that each starch plant produced to determine which starch plant produced the largest quantity of ethanol.


  1. Startup Says It Can Make Ethanol for $1 a Gallon, and Without Corn, By Chuck Squatriglia, The New Yorker, 01.24.08
  2. BioLab: Using Yeast Fermentation as a Model for the Scientific Method, Helen K. Pigage, Lt. Col. Milton C. Neilsen and Michele M. Greeder, Department of Biology Center for Educational Excellence United States Air Force Academy

Christine Ryder Combs, B.A. Honors Biochemistry, teaches high school Chemistry and Biology and serves as her school's science fair coordinator and science club sponsor. Since the development of an intensive science research program at her school, Christine has been nominated as an exemplary science teacher and has won awards for exemplary student participation at the regional science fair and recognized as teacher of the year.

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