Greener diesel with forest industry wastes as raw material.

All over the world, people are looking high and low for the fuel of tomorrow. Rising oil prices and growing environmental requirements from regulators and consumers put pressure on companies to innovate and improve fuels. Biogas, electricity and ethanol are some of the options already on the market, and new solutions are on the horizon.

Diesel from the forest

In collaboration with a group of forestry companies, the Swedish oil company Preem has developed a method to refine diesel from raw pine oil, a waste product from the paper industry known as “tall oil,” an anglicization of the Swedish “tallolja.”

Evolution Diesel, as it’s been named, is marketed as a green alternative to standard fuel, with 16 percent lower carbon emissions compared to conventional “MK1” diesel produced from fossil petroleum. The comparison is made with the help of a “well-to-wheel” analysis, an established model for calculating fuel lifecycles that takes into account the entire production chain.

Comparable technical features

Most biodiesels on the market today are transesterified lipid fuels blended with petroleum diesel that require engine conversion to burn properly. Evolution Diesel is different, as it’s produced through a hydrogenation process in which fossil petroleum and renewable tall oil are refined together to make a fuel that is molecularly identical to standard diesel. For the final step in the process, the refinery adds 5 percent rapeseed methyl ester, a biofuel produced from rapeseed oil. No engine conversion is required, and drivers can switch between Evolution and standard diesel.

In hydrogenation, gasified oil is heated to about 300 degrees Celsius and hydrogen is added. The hot mixture is fed into the biorefinery, where the hydrogen reacts with the oxygen and sulfur present in both petroleum and tall oil, removing these unwanted molecules. Finally, environmentally harmful aromatic hydrocarbons are extracted, resulting in a diesel fuel with 20 percent renewable content.

Performance, fuel consumption and price are the same for Evolution Diesel as for conventional fuel; the only difference is reduced emissions. In a test conducted in cooperation with several Swedish trucking companies, Evolution Diesel powered vehicles that were driven some 1 million kilometers, equivalent to about 25 times around the world.

Reduced carbon emissions

“With Evolution Diesel, you can use today’s infrastructure, today’s cars and today’s filling stations,” says Preem CEO Michael G:son Löw. “If all diesel vehicles were to reduce emissions of carbon dioxide, that would of course have an immediate impact. We’re making a difference here and now, and we continue to research and plan for even greater reductions.”

Preem has converted a refinery in Gothenburg, on Sweden’s west coast, into a biorefinery producing pine oil diesel, and projections call for replacing about 100,000 cubic meters of fossil petroleum annually. These volumes are sufficient to reduce carbon dioxide emissions by about 250,000 tons per year – equivalent to the carbon output of about 120,000 cars.

Other biological raw materials

Tall oil is itself a limited resource, however, and as the name Evolution Diesel implies, the composition of the fuel will be changed with time – Preem designed the biorefinery to produce diesel from other biomass. Trials are underway already using waste cooking oil and energy-rich algae. The company is also looking closely at jatropha, an inedible succulent that grows in soils unsuitable for raising food.

Article published in March 2011