Seaweed as a Biofuel

Biofuel is any fuel that comes from plants and can be used to power cars, airplanes, and other automobiles. There are many biofuels from other plants, but many people think seaweed could be the future of biofuels because of their abundance and sustainability. In fact, the U.S. Department of Energy is investing nearly 1.5 million dollars in two seaweed farm projects to research seaweed based biofuels.

First of all, what is biofuel?

Biofuel is any fuel that comes from a biomass. Biofuels, such as ethanol and biodiesel, are environmentally-friendly because they can be blended into gasoline to reduce carbon dioxide emissions while also minimizing the use of fossil fuels.

Biofuels are made by first breaking down tough plant cell walls into vapor or liquids.There are two ways to do this: one method is called high temperature deconstruction and it involves using extreme heat and pressure, and the other is called low temperature deconstruction and it involves using enzymes, biological catalysts.

After deconstructing the plant cell wall, scientists add microorganisms such as yeast and cyanobacteria to “upgrade” the biomass by fermenting it. Crude oils, sugars, or other chemicals are also added in this step. Afterwards, the product can be finished in a petroleum refinery or a chemical manufacturing plant, or can be sold.

Above: the seaweed biofuel making process

One well known biofuel is ethanol, an alcohol. It comes from corn and sugarcane and is fermented. Ethanol can be mixed into gasoline to cut down emissions because it contains oxygen, which helps the fuel burn more efficiently. Surprisingly, 97% of the gas in the U.S. contains some amount of ethanol, and there is even a blend of gas called E10 that is 10% ethanol. Biodiesel is another biofuel and is made from alcohol and vegetable oil. Like ethanol, it can be blended into gasoline called B20, a gasoline that is 20% biodiesel.

Pros and Cons of seaweed based fuels

There are many pros of using seaweed as a biofuel, including:

  • No use of freshwater- means no water is wasted

  • It is easy- seaweed only need seawater and sunshine

  • It is easy to grow in the water- it can cling to ropes, or be grown in circles

  • Seaweed can absorb many nutrients from the water

  • Seaweed can absorb carbon dioxide while growing, reducing global warming

  • Availability- seaweed is very abundant

  • It takes less place- you can grow a lot of seaweed in very little space

Below: a seaweed farm

However, using seaweed as a biofuel also has drawbacks, one of them being that seaweed can steal nutrients from the water. This can affect life higher up the food chain, and maybe even disrupt food chains. In the worst case scenario, overpopulation of seaweed and algae can result in an algal bloom and a dead zone, an area completely devoid of oxygen and nutrients. There is also the question of how to grow seaweed on an industrial scale, as that hasn’t been attempted much so far. In addition, seaweed based fuels are very expensive currently.

There are already many things being done to research seaweed biofuel, but one problem is how to grow seaweed on a huge scale: what it would require, where they would be grown, etc. Seaweed will also need to go through processing, and there are not many places that can process seaweed; therefore, many people are unwilling to start seaweed farms as a business. Although seaweed farming is already the fastest growing aquaculture sector, the seaweed grown in farms are mostly used for cosmetics, food, and conservation, rather than biofuel. Scientists estimate that it will take around 25 years for the seaweed biofuel industry to be profitable.

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