NATURAL GAS ENGINES FOR SHALE GAS OPERATIONS Presenter: Nigel N. Clark Center for Alternative Fuels, Engines and Emissions Department of Mechanical and Aerospace Engineering West Virginia University Morgantown, WV 26506-6106 Acknowledging CAFEE and Director Dan Carder
HISTORY Natural gas / Petroleum cost driver Capital cost, incentives and mandates California bus & refuse rules Large stationary engines Efficiency consideration Chicken and Egg issue Photographs: http://blog.westport.com/2012/04/first-natural-gasvehicles.html Chart:EIA
Natural Gas Engine Types Lean burn spark ignited Slightly lean = high NOx Very lean = poor combustion efficiency = methane loss Throttling losses reduce CNG engine efficiency - more so at light load Older truck, bus and stationary use 3
Natural Gas Engine Types Stoichiometric spark ignited Uses 3-way catalyst NOx and methane low when catalyst hot Turbocharged or naturally aspirated Throttling losses reduce CNG engine efficiency - more so at light load Truck and bus use since 2007, stationary use 4
Natural Gas Engine Types High Pressure Direct Injection (HPDI) Westport Innovations technology Small diesel usage Direct injection of natural gas into the cylinder http://www.westport.com/is/core-technologies/fuel-injectors/hpdi 5
Natural Gas Engine Types Dual fuel engines Truck and stationary use Diesel replacement fraction Always need some diesel to ignite Recent work by Hailin Li & co-workers on hydrogen dual fuel - similarity Better natural gas combustion at heavy load Better replacement opportunity at heavier load Concerns with knock (at boosted conditions) Requires careful control 6
STATIONARY AND OFF-ROAD ENGINE TECHNOLOGY Long tradition of high horsepower stationary engines Previously lean-burn technology Dual fuel diesel pilot also used Latest technology is stoichiometric ( Rich-Burn ) High horsepower fracturing Image Source: Caterpillar Image Source: GE-Energy
Stoichiometric CNG Research 2008 Model Year NABI 60-Foot Articulated Conventional Powertrain Cummins ISL-G 320 Stoichiometric CNG Three-way Exhaust Catalyst This research was conducted by CAFEE and Reported at a CRC workshop DOE Contracts DE-FC26-08NT01920 DE-FC26-09NT01920 8
Diesel Hybrid-Electric (Comparison) 2009 Model Year New Flyer 60-Foot Articulated Allison Hybrid Powertrain Cummins ISL-07 330 Exhaust DPF 9
Driving Schedules Employed Orange County Bus (OCTA) Braunschweig City New York Paris Manhattan UDDS 45 40 Braunschweig City driving schedule Speed - (mph) 35 30 25 20 15 10 5 0 0 200 400 600 800 1000 1200 1400 1600 1800 Time (s) 10
Distance specific CO 2 emissions 9000 8000 7000 Hybrid 60 (5452) Hybrid 60 (5451) CNG 60 (5410) CNG 60 (5420) CO 2 (g/mile) 6000 5000 4000 3000 2000 1000 0 OCTA 1 Braunschweig Manhattan NY Bus PARIS UDDS 11
Fuel Combustion and CO 2 Hydrogen to Carbon Ratio CNG: 0.0150 kg/mj Carbon, 0.0050 kg/mj Hydrogen Diesel: 0.0205 kg/mj Carbon, 0.0033 kg/mj Hydrogen Combustion of CNG less complete than for diesel & compression ratio lower. Throttling losses reduce CNG engine efficiency - more so at light load. Diesel engine efficiency is reduced by emissions compliance - complex in comparison to CNG three-way catalyst. 12
Effect of cycle speed on CO 2 emissions 7000 Carbon Dioxide (grams / test) 6000 5000 4000 3000 2000 1000 Diesel Hybrid CNG 0 0 5 10 15 20 25 30 35 40 45 Average Speed (mph) 13
Distance specific NOx emissions Oxides of Nitrogen (g/mile) 35 30 25 20 15 10 Current diesel NOx Emissions are far lower Hybrid 60 (5452) Hybrid 60 (5451) CNG 60 (5410) CNG 60 (5420) 5 0 OCTA 1 Braunschweig Manhattan NY Bus PARIS UDDS 14
Conclusions and Findings Distance specific CO 2 emissions Substantially higher CO 2 emissions from CNG bus (5410) than CNG bus (5420) and the diesel hybrid-electrics. Higher from CNG buses than from hybrid-electric buses excepting the UDDS (CNG 9% lower than diesel hybrid-electric buses). CO 2 averaged over the non UDDS driving schedules from the CNG buses was 15.3% higher than from the hybrid-electric buses. CO 2 emissions dependent on average cycle speed for both CNG and diesel hybrid bus emissions. 15
Conclusions and Findings Distance specific NOx Higher NOx emissions from CNG bus (5410) than from CNG bus (5420). Substantially lower from CNG buses than from hybridelectric buses. 92% lower from CNG buses than from hybrid buses (excluding UDDS, 82% lower including UDDS). 16
Assessing Fugitive Methane Emissions Impact Using Natural Gas Engines in Unconventional Resource Development West Virginia University Center for Alternative Fuels, Engines and Emissions Department of Mechanical and Aerospace Engineering DE-FE0013689 Project Kickoff Meeting November 26, 2013 CAFEE Center for Alternative Fuels, Engines, and Emissions 17 NETL FY2013 Unconventional Gas and Oil Technologies DE-FE0013689 Dr. Andrew Nix, West Virginia University Dan Carder, Dr. Derek Johnson
Project Introduction Project Awarded under DE-FOA-0000894 FY2013 Unconventional Gas and Oil Technologies - Topic Area 2 Assuring, Monitoring, and Mitigating Issues Related to Methane Emissions, Wellbore Integrity, and Zonal Isolation (protecting shallow groundwater resources) This program supports efforts to develop improved technologies and engineering practices to ensure that unconventional resources are developed safely and with minimal environmental impact. Opportunities or technologies that can reduce emissions while reducing the diesel fuel consumption, or overall production costs, are very attractive for the following reasons: Reduction of emissions - The GHG potential of CH 4 is 21 times that of equivalent mass of CO 2 and as a result classified as a potent GHG component Expense - The cost of diesel fuel powering the diesel engines of the drilling rig, fracturing pumps, and diesel trucks accounts for about 30% of the total cost of Shale gas well development CAFEE Center for Alternative Fuels, Engines, and Emissions 18 NETL FY2013 Unconventional Gas and Oil Technologies DE-FE0013689 Dr. Andrew Nix, West Virginia University Dan Carder, Dr. Derek Johnson
Project Introduction (cont.) Effort will investigate fugitive methane emissions related to the prime movers and transportation systems at unconventional well site locations including: On-site supply pipeline Compression systems Storage tanks Engine fuel lines Crank case vents Unburned fuel in engine exhaust Through this characterization, our objective is to provide industry the data, assessment, conclusions and mitigation strategies about fugitive methane emissions through the utilization of natural gas for the prime movers and transportation used in unconventional gas production. CAFEE Center for Alternative Fuels, Engines, and Emissions 19 NETL FY2013 Unconventional Gas and Oil Technologies DE-FE0013689 Dr. Andrew Nix, West Virginia University Dan Carder, Dr. Derek Johnson
Project Background CAFEE has reported that dual-fuel and natural gas engines show reductions in NO X, PM, and CO 2 CH 4 slip in the exhaust and that lost through crankcase venting will add to the greenhouse gas inventory of a given well Dual-fuel conversion systems are currently not regulated on CH 4 emissions or emissions of other toxic pollutants Natural gas used on dual-fuel or dedicated natural gas engines typically comes from three sources: Nearby wells (field gas) CNG or LNG stored on site Field gas composition can vary from well-to-well and specifically from the different Shale plays across the U.S. as shown below. C1 Methane (CH 4 ) C2 Ethane (C 2 H 6 ) C3 Propane (C 3 H 8 ) CAFEE Center for Alternative Fuels, Engines, and Emissions 20 NETL FY2013 Unconventional Gas and Oil Technologies DE-FE0013689 Dr. Andrew Nix, West Virginia University Dan Carder, Dr. Derek Johnson
Primary Technical Objectives 1. To create an inventory of diesel engines, their use, and emissions incurred during unconventional well development 2. 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 3. To examine and determine operating and fugitive CH 4 emissions effects based on the operation of current technologies on variety of natural gas compositions 4. To examine new catalyst formulations that can be used in conjunction with these developing technologies to minimize these new sources of fugitive CH 4 emissions associated with unconventional well development CAFEE Center for Alternative Fuels, Engines, and Emissions 21 NETL FY2013 Unconventional Gas and Oil Technologies DE-FE0013689 Dr. Andrew Nix, West Virginia University Dan Carder, Dr. Derek Johnson