|Assessing Fugitive Methane Emissions Using Natural Gas Engines in Unconventional Resource Development
||Last Reviewed 6/26/2015
The goal of this project is to create an inventory of diesel engines, their use, and their emissions incurred during unconventional well development. The first objective is to analyze the benefits of operating these or similar engines on dual fuel or dedicated natural gas to determine regulated and non-regulated emissions and fuel cost reductions. The next objective is to determine the effects of operating these or similar engines and fugitive methane emissions based on the operation of current technologies using a variety of natural gas compositions. The final objective will be to examine new catalyst formulations that can be used in conjunction with these developing technologies to minimize these new sources of fugitive methane emissions associated with unconventional well development.
West Virginia University (WVU), Morgantown, WV 26571
Production of unconventional gas wells incurs a significant cost in diesel fuel used to power the extraction equipment. The industry is moving toward substituting domestic natural gas for diesel fuel in order to reduce operating costs. Ideally, local wellhead gas would be utilized, but this solution is undermined by engine control and emissions problems in the near term. Additionally, pending and future greenhouse gas emission regulations, which include methane emissions, have the potential to slow this change.
Dual fuel retrofit strategies will be implemented in the near term to reduce the risk to unconventional gas producers; however, the strategies will evolve to include dedicated stoichiometric natural gas engines in the long term to realize the greater cost benefit of utilizing domestic natural gas. Switching from diesel to dual fuel or dedicated natural gas engines also has the potential to reduce local and regional emissions inventory loading to the atmosphere from these sites.
WVU’s Center for Alternative Fuels, Engines and Emissions (CAFEE) will collaborate with its project partners to assess fugitive methane emissions when utilizing domestic natural gas for the prime movers and transportation at unconventional gas drilling sites. Specifically, CAFEE will identify and characterize the impacts of fugitive methane emissions using dual-fuel (natural gas and diesel) and dedicated natural gas engines as replacements for the diesel-powered units that currently dominate unconventional well site operations. This effort will include assessing fugitive methane emissions at unconventional well site locations as well as for the on-site supply pipeline, compression systems, storage tanks, engine fuel lines, crank case vents, and unburned fuel in the exhaust. This effort will provide industry with the data, assessment, conclusions, and mitigation strategies for fugitive methane emissions through the utilization of natural gas for the prime movers and transportation used in unconventional gas production.
The successful completion of this project will provide the natural gas industry with information needed to implement low-cost, robust technologies that will promote production and utilization of U.S. energy resources while simultaneously mitigating risk to the public, oil and gas personnel, and the environment.
Accomplishments (most recent listed first)
- Emissions and fuel economy data were collected on common operating points of a Cummins QSK 50 engine operating as diesel only and dual fuel with two separate oxidation catalysts. This engine is used for hydrauilic stimulation of wells.
- Diesel only operation with catalysts decreased both CO and THC emissions
- Three load levels of dual fuel operation showed reductions in diesel fuel consumption of 50-56 percent
- Total efficiency of the engine over these three modes decreased by 10 percent
- Crankcase methane emissions were about one percent of exhaust methane slip
- Total methane lost was 13-26 percent of the natural gas substituted to the engine
- CO2 equivalent emissions increased compared to diesel only operation – due to efficiency and methane slip
- PM emissions were reduced by 6-43 percent with the combined effects of the catalyst and dual fuel operation
- A catalyst focused on methane mitigation showed only a modest three percent reduction in methane emissions
- Performed a comprehensive literature review of available dual-fuel and natural gas technologies, well site fueling infrastructure, diesel fuel consumption rates of the prime movers, and emissions regulations.
- The comprehensive review was summarized in a journal article published in a special edition of energy technology.
- The interim report currently being developed for the Baker-Hughes testing will likely be restructured and submitted as a formal publication.
- Updated multiple miniature stand-alone data loggers. These loggers were implemented in on-road prime movers and are collecting activity data for cycle development. On-road data collection has been completed, while off-road continues.
- A scaled dedicated natural gas engine (Cummins-Westport ISL-G 8.9L) has been obtained and installed in the WVU test cell. On-road cycles are currently being operated to establish regressions statistics for selection of the final on-road cycle.
- A Cummins ISX 15L engine is currently being outfitted with a dual fuel system.
- WVU gathered data produced during their field-related activities and prepared it for processing.
- Researchers completed a draft literature review of currently available dual-fuel and natural gas technologies, well site fueling infrastructure, diesel fuel consumption rates of the prime movers, and emissions regulations.
- Researchers updated three miniature stand-alone data loggers that were implemented in on-road prime movers to collect activity data for cycle development. Three new mechanical engineering graduate students are now gaining hands-on experience in conducting field measurements.
Current Status (June 2015)
Researchers continue to work with industry to collect off-road activity data. They are working with Baker-Hughes and other industry leaders in horizontal drilling and well stimulation to obtain additional activity data and in-use emissions and fuel consumption data. They are proactively engaged in the Marcellus Shale Energy and Environmental Laboratory project and will collect additional data at this site - operated by Northeast Natural Energy and the main subcontractor, Schlumberger.
Researchers are currently working with catalyst manufacturers to develop a methane oxidation catalyst for laboratory testing. The laboratory portion of the program will also examine the effects of various gas blends – pure methane (LNG), pipeline gas (CNG) and two to three additional shale plays. WVU has recently obtained a CNG compressor to blend all gases in their laboratory. Gas blends will contain higher levels of ethane and propane which are typical in shale plays and which could alter the performance of these new technologies.
Project Start: October 1, 2013
Project End: March 31, 2016
DOE Contribution: $1,499,830
Performer Contribution: $410,813
NETL – William Fincham (firstname.lastname@example.org or 304-285-4268)
West Virginia University – Dr. Andrew Nix (Andrew.Nix@mail.wvu.edu) or 304-293-0801)