Syrupy sweet fuel Biodiesel processing is yielding surpluses of glycerin that may be burned for energy

By Dan Lemke

Marshall, Minn. — Quickly scan the product ingredient panels in a medicine cabinet and “glycerin” will show up frequently. The sweet, thick liquid has hundreds if not thousands of uses — from toothpaste, lotions and cosmetics to livestock feed and medicine.

But the demand for glycerin may not exceed a growing supply.

Crude glycerin is the main coproduct of biodiesel processing. As the biodiesel industry grows, so does the supply of crude glycerin, which decreases its value.

But AURI-sponsored research is looking at using glycerin for fuel — a new use with huge potential.

In January, 150,000 pounds of glycerin will be combusted at a Minnesota industrial plant to evaluate it as a fuel. An independent testing company will evaluate stack emissions.

“We’re looking for the full gamut of emissions information … particulate matter, nitrous oxide levels, metals, sulfur and particularly acrolein,” says AURI chemist Rose Patzer.

Acrolein is a regulated toxin that forms when certain pollutants break down in outdoor air or from burning gasoline, turbine engine emissions, forest fires, spray painting and other sources.

Emissions test results will be sent to the Minnesota Pollution Control Agency for review. If results are positive, crude glycerin could be an option for powering industrial turbines or boilers. The test will provide baseline fuel information and “identify boiler and operational parameters for that could be used elsewhere” Patzer adds. The baseline tests won’t cover every possibility because each boiler setup may react differently, requiring specific adjustments.

Besides emission tests, AURI will analyze crude glycerin for its energy value, moisture levels and ash, carbon and hydrogen content.

Mixing 100 pounds of oil with 10 pounds of alcohol yields about 100 pounds of biodiesel and about 10 pounds of glycerin. Each gallon of glycerin weighs about 10 pounds. At full capacity, Minnesota biodiesel refineries would produce about 63 million gallons of biodiesel and 63 million pounds of glycerin annually. Other biodiesel producing states are dumping glycerin on the market as well, creating a huge surplus.

Just four years ago, crude glycerin sold for around 35 cents a pound — today it may fetch a nickel. In some cases, manufacturers are paying to get rid of excess glycerin.

The glycerin in personal care and food products is highly refined. Most biodiesel refineries lack the necessary equipment to further purify glycerin, because of the expense. Finding a large-scale
use for crude glycerin would help alleviate growing supplies and give the biodiesel industry a new revenue stream.

Pure glycerin contains about 19,000 Btu energy value per pound, while crude glycerin yields just under 7,000 Btu. But the price may be right. At 5 cents per pound, crude glycerin could produce one million Btu of industrial fuel for less than $7 — a good buy for industry. ■