Cellulosic Ethanol: Is It The Fuel of The Future?

Justin Christensen |

Download PDF 103582804

In the midst of harvest season, many are sitting down to enjoy the fruits of their labor. Nothing beats the richness of home grown flavors – who can resist a sweet cob of corn slathered in butter?

Surprisingly, those who are more interested in the stalks, leaves and husks. Yes, corn waste, otherwise known as stover, is a main basis of the latest alternative fuel to hit the market – Cellulosic Ethanol.



How Cellulosic Ethanol is Made

While traditional ethanol is obtained from soft starches, cellulosic ethanol is derived from cellulose (cell wall) biomass or plant fiber. This can range from recycled newspapers to farm and municipal waste or grass clippings and pretty well most leaves, stems and trunks.

A refinery processes the material in one of two ways – biochemically or thermo-chemically.

The first method occurs in a series of four steps. To begin, the ground up matter is soaked in sulphuric acid to break it down into four sugars. That cellulose is converted to glucose in a mixture of enzymes and from there, fermentation takes place using microbes. You’re then left with stillage, which gets processed and reused, and alcohol that is distilled to fuel.

In the thermo-chemical process, plant material is dried and burned into synthesis gas – a compound of carbon monoxide and hydrogen. A tar reformer chemically converts any residual tar and sulphur into more “syngas” which is further purified. The gases are then compressed and a metal catalyst creates either ethanol or hydrocarbon molecules, and the ethanol is separated out.

Cellulosic Ethanol’s Harvesting Benefits

Like every other fuel source, cellulosic ethanol brings its share of goodness to the table:

  • Cleaner burning than petroleum-based fuels which offers both environmental and health benefits;
  • Has infinite availability and is convenient to access;
  • Uses up waste at the same time it’s producing fuel;
  • “Energy” crops that are fast producing can make use of poor soil land areas so valuable food farms aren’t being displaced; and
  • Its organic components are biodegradable so any spills would be less harmful.
Weighing Concerns

And just the same, it carries concerns.

  • A complex refining process makes it more costly than corn ethanol and gasoline;
  • Stover helps protect against soil erosion so no more than 25 per cent can be removed;
  • Farming modifications are not quick or without cost;
  • Plant production capacities are well below the Environmental Protection Agency’s (EPA) targets;
  • The US market for ethanol is limited by the “blend wall” –10 per cent max with gasoline for cars; and
  • Fuel mileage per gallon is 25 per cent lower than gasoline.
Is Cellulosic Ethanol The Fuel of the Future?

This month marks the first of three commercial-sized plants opening in the US – two in Iowa and one in Kansas. While this progress sounds promising, the path ahead at these trial stages is littered with challenges, not to mention the failure of two similar projects in Mississippi and Florida last year. Still, the companies and governments involved move forward with a new swath of hope.

Even if these companies reach their projected targets, if and when cellulosic ethanol would reach the regular market is unknown. At the same time, there has been mention of a more viable “drop-in” fuel using perennial grasses that does not require blending. But at no time has there been mention of gasoline being replaced.

No one can predict the growing season, how the fuel market will change or what new product may dominate – “A Bright Future – How New Technology Is Developing New Fuel Alternatives.” However, partnering with a fuel distributor can help to ensure you have everything you need to make the best decisions for your vehicle(s) and your business. You’ll get all the fruits, without the labor.