It doesn't take a genius to comprehend why Caterpillar engineers burn the midnight oil developing alternative fuel marine diesels. Over the past few years fuel prices have skyrocketed, with the cost per liter in Europe doubling between 2003 and 2005. The good news is that salvation may be found by burning alternative fuels like B30 Biodiesel, a blend of 30 percent biodiesel and 70 percent regular mineral diesel.

Compared to conventional mineral diesel fuel refined from Brent light or Arabian sweet crude, biodiesel boasts a higher cetane rating. Cetane is to diesel what octane is to gas. Biodiesel burns cleaner. As a result an engine runs more smoothly and without that characteristic loud clatter of a diesel motor. Cold weather performance, no problem.

On the environmental side of the balance sheet burning biodiesel substantially reduces toxic exhaust emissions: nasty things like unburned hydrocarbons, carbon monoxide and particulate matter. And because it contains naturally occurring oxygen, biodiesel burns more completely, all but eliminating the cloud of black smoke associated with diesel engines. Because biodiesel is produced from vegetable oil, greenhouse gas emissions created in the combustion chamber are balanced by the amount of greenhouse gas absorbed from the air above the cultivated fields where the vegetables were grown. With all these things going for it, it should come as no surprise to learn experts agree biodiesel blends are better for the environment.

Then are also certain financial benefits. Depending on when and where, boaters could potentially save up 50 percent of their fuel bill with B30. After the 2008 tax increases on regular diesel in the U.K., biodiesel is expected to be available at the price of regular diesel.

That's the theory. To test the hypothesis Caterpillar Marine and Horizon powered a 65-foot motor yacht with twin CAT C18 engines running on, you guessed it: B30 Biodiesel. Neither the boat nor the engine received any modifications. For the record, the electronically-controlled C18s displace 18.1 liters and are rated 1,000 horsepower at 2300 rpm. Also important to note, this six-cylinder heavy-duty block boasts an enviable reputation for durability and low emissions even with mineral based diesel fuel.

Fuel was pre-blended before topping off the Horizon tanks. Pre-blending insured fuel flowing to the twin engines was B30 at all times. Consistency matters when trying to prove a point by scientific method. After logging considerable hours touring the coast of Southern England, test results showed the C18 Biodiesel engines performed identically with conventional mineral diesel. Which is to say the motors ran reliably, were fuel efficient and the exhaust was virtually smokeless (nor was smoke visible when starting cold). Best top speed with both the conventional and the B30 biodiesel fuels was 24.4 knots.

According to a Caterpillar Marine spokesperson, most of its existing marine diesel engines are capable of burning up to 30 percent biodiesel without modification, although seals and hoses made of elastomers on older engines should be monitored regularly (some of the fuel additives can cause damage). Newer components don't suffer that malady.

When burning B30, the Cat C18s require the same maintenance intervals as engines burning regularmarine diesel. In other words, standard maintenance procedures are required either once per year, every 250 service hours or about every 3,500 gallons of fuel consumed, whichever comes first. Other biodiesel blends exist, such as B20 which is popular in the United States. Depending on the particular biodiesel blend, Cat marine diesel engines may require shorter oil change intervals and shorter fuel filter change intervals. Consult your local dealership for guidance.

Both Horizon Motor Yachts UK and Caterpillar Marine Power Systems predict growing demand in biodiesel, and naturally it follows a growing demand in motor yachts capable of burning biodiesel. For that reason every new marine Caterpillar engine model will be compatible with biodiesel blends. Existing Caterpillar engines are both U.S. EPA- and EU-certified running on commercially available fuels, which includes biodiesel. With its headquarters located in Hamburg, Germany and a service network numbering more than 2,100 dealer locations worldwide, the Cat product line offers main propulsion engines from 93 to 7,200 kW, auxiliary engines from 162 to 5,420 kWe, and generator sets from 11 to 5,200 kWe.