Baker Hughes Inc. is reporting positive results from a program to convert a fleet of its North American hydraulic fracturing (fracking) units to bifuel pumps that use a mix of natural gas and diesel, the oilfield services operator said Monday.

Subsidiary Baker Hughes Oilfield Operations converted a fleet of its Rhino fracking units to improve operational efficiency, lower costs and reduce health, safety and environmental impacts, the Houston-based operator said.

“Baker Hughes has seen excellent results with this initiative,” said Mike Davis, president of pressure pumping for U.S. Land. “The environmental benefits are significant. We’re reducing emissions from the engines driving the stimulation pumps and less fuel is needed to keep our pumps going. In addition, this has the added value of improving job site safety by eliminating re-fueling demands during operations.”

The new pumps reduce diesel use by up to 65% with no loss of hydraulic horsepower, according to the company. The converted fleet, which meets U.S. Environmental Protection Agency emissions standards, also may reduce the number of emissions that include nitrogen oxides, carbon dioxide and particulate matter.

Baker first converted a small fleet of its Rhino units in Canada, and when results there were successful, the decision was made to convert an entire fleet in the United States. The oilfield services company now is in the process of converting several more fleets of Rhino trucks to bifuel equipment. Additionally, Baker has a test program in Oklahoma, where several light-duty vehicles have been converted to natural gas.

Using the converted units, Baker recently completed a fracking job in the Eagle Ford Shale for Cheyenne Petroleum Co., which was interested in using some of the converted units given the potential savings by cutting diesel consumption, as well as the long-term reduction in emissions.

Baker was “able to pump 35 stages using three of the converted Rhinos during each stage. Throughout the job, Baker reported a 65% substitution rate (diesel fuel replaced with liquefied natural gas) with no loss of horsepower. By substituting natural gas into the converted diesel engine, the bifuel alternative can operate twice as long as engines running solely with the on-board diesel.”

Cheyenne’s Greg Presley, a senior operations engineer, said using the converted units “was transparent during the job,” which “pumped the same as a 100% diesel job with many environmental benefits.”