Teachers TryScience

To start, you may want to watch the What is Engineering video below.

• What is Engineering

Environmental engineers design products and processes that are friendly to the Earth. Today we are going to investigate ways to provide energy without using environmentally harmful fossil fuels. What are some possible alternative energy sources we could use? (Possible answers: solar, wind, hydropower, nuclear, or biomass.) Let’s focus on solar power. Some engineers have worked on creating cars or homes that use solar panels that generate electricity. Does anyone have another idea for how we could harness the sun's energy to use in a car? Here’s a hint: it uses a natural way of storing the sun's energy, and we can put it into the car just like gasoline. The answer is biofuels!

Biofuels are a renewable form of fuel that biochemical engineers have created from biological material such as plants. These engineers figured out a way to turn the starch and sugar of corn and other plants into fuel called ethanol. With current technology, ethanol can only be efficiently made from the edible part of corn. However, biochemical engineers are currently trying to find a way that we can also use the nonedible parts, such as the husks, which much first be converted into starches before they can be used T his would be a great way to use all of the biomass that is left over after the corn is harvested.

Now, you may be wondering what this has to do with solar energy. Well, instead of converting the sun’s energy into electricity directly, like solar cells, plants convert the sun’s energy into sugars and starches – the food they need. The plant does this through a process called photosynthesis. The chlorophyll in the plant’s leaves uses the sun's energy to turn carbon dioxide and water into glucose and oxygen. Later, in a biorefinery, the glucose is combined with an enzyme found in yeast so that it can be turned into ethanol, which provides the chemical energy that can be used to power cars.

Sugar + Enzyme Found in Yeast = Ethanol + Carbon Dioxide

Many different kinds of engineers work together to create alternative energies, such as the biofuel called ethanol. For example, biochemical engineers work out the process for converting corn and other plants into ethanol. Bioengineers alter the genetic make-up of the plants themselves to make them more effective as raw materials for the biorefinery process. Mechanical engineers design the machines that harvest the plants and transform them into ethanol.

It’s important to note that other types of engineers are using plants in other ways besides biofuel production. Civil engineers may use plants to act as purifying agents in biological water treatment processes. Many treatment facilities rely on artificial or natural lagoons of plants and fauna for the removal of contaminants before release into the environment. Meanwhile, some environmental engineers are developing ways to seed the ocean with algae. Photosynthesis from the algae removes CO₂ from the atmosphere, as a way to combat global warming. (Algae can be used to produce biofuel as well.) These are just a few ways that engineers use living things in professional applications to build technologies that make our lives more comfortable and sustainable.

While biofuels might be less detrimental than fossil fuels, they do have some downsides. For example, to grow corn to produce ethanol, farmers must use potentially harmful fertilizers,as well as fossil fuels to power equipment like tractors. Additionally, using items like corn for fuel instead of food could lead to food security issues, due to both the amount of food available and rising prices for food when the amount of that food decreases. Similarly, the land used to grow biomass for biofuels might be needed for other things like food production. While corn is currently a highly publicized source of biofuel, other plants such as switchgrass or even grass clippings, might be more environmentally friendly. Switchgrass is not used as food and requires little fertilizer,while at the same time containing enough sugar to make it a viable source of fuel. It’s interesting to note that while ethanol production causes CO₂ to be released, the CO₂ will be absorbed by the next crop of plants. This cycle prevents CO₂ from becoming a problem.

In this lesson, we will design an experiment to compare the amount of ethanol produced by the fermentation of various organic materials such as corn, grass, and fruits. We will then research the pros and cons of growing and processing these materials for use as biofuels. Finally, we will use the information from their experiment and research to design a biorefinery plant.