New Technology Diesel Engines: Eliminating NOx Emissions from Higher Biodiesel Blends in Un-modified Diesel Engines California Biodiesel & Renewable Diesel Conference February 4, 2013 Steve Howell President, MARC-IV Consulting, Inc.
New Technology Diesel Engines (NTDE) Today s (2010 and newer model year) New Technology Diesel Engines (NTDE) reduce major diesel tailpipe emissions by over 90% compared to 2004 diesel engines (PM, NOx) 95 to 98% reduction over older engines cited in recent studies NTDE are ~30% more efficient and provide ~30% better mpg than comparable gasoline or natural gas engines This means new diesel engines can be a major contributor to reducing tailpipe carbon emissions and climate change If biodiesel is used in a NTDE, the beneficial carbon effects of biodiesel adds to the carbon advantages of diesel technology New Technology Diesel Engines using biodiesel blends can be a preferred clean and green technology choice
New Technology Diesel Engines (NTDE) NTDEs employ a sophisticated combination of diesel engine and fuel system controls, ultra low sulfur diesel fuel, and exhaust after-treatment catalysts to achieve low emissions: Closed loop control systems constantly measure emissions or other parameters on the vehicle and adjusts operation in real time regardless of fuel 15 ppm sulfur or lower fuel (i.e. on-road petrodiesel, biodiesel) Oxidation catalysts and particulate traps reduce PM, HC, CO Selective catalytic reduction (SCR) reduces NOx through addition of DEF (diesel exhaust fluid)
Diesel Oxida+on Catalyst (DOC) Originally introduced to burn unburned fuel and CO Today used to burn fuel to heat DPF for regenera+on Also converts NO to NO 2 : o Important for DPF regenera1on o And high SCR ac1vity CO Toxics Unburned Fuel NO Flow through monolith with catalytic coating CO 2 H 2 O NO /NO 2 4
Diesel Par+cle Filter (DPF) Ceramic wall flow filter captures soot par+cles Required for on- highway in 2007 Periodically heated to burn off the accumulated soot Reduces soot (or par+culate maier) emissions to almost undetectable levels 5
NOx Selec+ve Cataly+c Reduc+on (SCR) Requires injec+on of urea/water solu+on in to exhaust to form ammonia Urea refill at oil change called diesel exhaust fluid (DEF) DEF usage of 1.5-2% of diesel fuel usage (10 gal of DEF for about 5,000 miles) Ammonia reacts with NOx to produce nitrogen Most common technology for mee+ng 2010 heavy- duty engine requirements Urea Injection DOC Diesel Particulate Filter Selective Catalytic Reduction NH3 Slip Cat 6
Conven+onal Emission Control System Architecture DOC=Diesel oxida+on catalyst HD Diesel Heavy Duty: focused on fuel economy, less stringent NOx limit DEF=Diesel exhaust fluid DPF=Diesel par+culate filter SCR = Selec+ve Cataly+c Reduc+on Exhaust gas DOC DPF SCR DEF LD Diesel Light Duty: +ght NOx standard requires focus on cold start NOx and high SCR efficiency SCR closer to engine Exhaust gas DOC SCR DPF DEF 7
Biodiesel Works in New Technology Diesel Engines (NTDE) The National Biodiesel Board (NBB), the Truck and Engine Manufacturers Association (EMA), and the National Renewable Energy Laboratory (NREL) have studied how biodiesel works in NTDEs Testing completed by respected independent third party laboratories (NREL, SwRI) or by EMA members themselves Over $15 million hard cash in testing since 2004 This does not include internal EMA member testing Both engine dynamometer and full vehicle chassis dynamometer B20 impacts on NTDE: Lubricity of biodiesel eliminates lubricity concerns with ULDS High cetane number and oxygen provide less particulates in trap, those collected burn easier and at lower temperatures Closed loop NOx controls reduce NOx to same engine out level as with pure petrodiesel
NREL Research on Biodiesel Impact of Diesel Emission Control Systems Aaron Williams & Bob McCormick January 28, 2011 NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
DPF Balance Point Temperature & Regeneration Rate Tests conducted on 2002 Cummins ISB retrofitted with a passive DPF system DPF regeneration rate increased with increasing biodiesel content Balance Point Temperature with B20 and B100 is lower than petroleum diesel by 45ºC and 112 ºC Regeneration Rates Balance Point Temperatures Effect of Biodiesel Blends on Diesel Particulate Filter Performance (SAE 2006-01-3280) National Renewable Energy Laboratory Innovation for Our Energy Future
Soot Characterization Soot characterization reveals why DPF performs better with biodiesel Lower combustion temperature for biodiesel soot (TGA) Higher disordered carbon for biodiesel soot Graphitic/Disorderd (G/D) Carbon Ratio G/D ULSD =.836 G/D B100 =.586 Higher oxygen content for biodiesel soot Carbon/Oxygen Ratio C/O ULSD = 25.34 C/O B100 = 20.34 N 2 Feed O 2 Feed www.pecj.or.jp/english/jcap/images/jcap18_01.gif Effect of Biodiesel Blends on Diesel Particulate Filter Performance (SAE 2006-01-3280) National Renewable Energy Laboratory Innovation for Our Energy Future
Biodiesel use in a production DPF equipped vehicle Conducted testing on International class 8 truck with Cummins ISX and DPF Operated vehicle over two drive cycles and monitored DPF soot loading and regeneration rates Central Business District Cycle Cycle creates low opportunity for regen Max Speed = 20 mph Avg Exhaust Temp = 225 C WVU Interstate Cycle Cycle creates high opportunity for regen Max Speed = 60 mph Avg Exhaust Temp = 365 C National Renewable Energy Laboratory Innovation for Our Energy Future
Biodiesel use in a production DPF equipped vehicle National Renewable Energy Laboratory Innovation for Our Energy Future
Biodiesel Impact on SCR Performance Study conducted on 2002 Cummins ISB retrofitted with a DPF + SCR system Compare SCR catalyst performance with ULSD and Soy B20 Measure relative importance of catalyst temp, exhaust chemistry and catalyst space velocity Measure B20 s impact on these system variables and on overall NOx conversion Focus on steady-state modal tests Urea Injection DOC Diesel Particulate Filter Selective Catalytic Reduction NH3 Slip Cat Effect of Biodiesel Blends on Urea SCR Catalyst Performance with Medium-Duty Engine (SAE 2008-01-2484) National Renewable Energy Laboratory Innovation for Our Energy Future
SCR catalyst NOx conversion B20 created higher NO2:NOx ratio (3% on average) B20 created lower SCR temperatures (11º C on average) B20 caused no change in catalyst space velocity No significant difference in NOx conversion with B20 Effect of Biodiesel Blends on Urea SCR Catalyst Performance with Medium-Duty Engine (SAE 2008-01-2484) National Renewable Energy Laboratory Innovation for Our Energy Future
Summary Biodiesel testing with DPF suggests that biodiesel soot will regenerate faster and at lower temperatures Biodiesel reduces engine-out soot emissions such that DPF loads more slowly Short term SCR testing shows no impact of biodiesel, perhaps some benefit in hydrocarbon inhibition Ongoing study is evaluating effect of alkali metals in biodiesel on long term durability (435,000 mi) National Renewable Energy Laboratory Innovation for Our Energy Future
SAE 2012-01-1984 Figure 10 - NOx emissions from a 2010 transit bus..
SAE 2012-01-1984 Figure 11 - NOx emissions from a 2011 transit bus.
New Technology Diesel Engines and Biodiesel Blends NTDEs are changing the way we talk about and think about biodiesel regulated emissions NTDEs emissions are so low due to after-treatment technology, it is difficult if not impossible to discern any difference between fuels whether that be EPA diesel, CARB diesel, or biodiesel blends NTDEs use closed loop controls for NOx control: constantly measuring parameters and adjusting the engine operation or DEF use so emissions limits are always met No two runs will provide the same results, even with same fuel Allows engine companies to increase engine-out NOx and optimize operation for fuel economy, torque, and horse power The question is not whether one fuel is different than another, it is whether the engine will continue to meet vehicle/engine emissions specifications with fuel being used
New Technology Diesel Engines and Biodiesel Blends--Summary Short term emissions tests show that NTDE with B20 meet or exceed the significantly lower (~90% lower) engine/vehicle emissions standards for NOx and PM from NTDE Potentially even B100, although very few data points with B100 Additional work is on-going to confirm that the biodiesel specifications are set so: Long term durability of the after treatment systems on NTDEs Catalyst long term effectiveness is the same as petrodiesel NTDEs resolve potential NOx concerns with B20 blends, even when using CARB like diesel fuel New emissions after-treatment technology or use of blend level sensors and modifying timing slightly provides a path forward for retro-fits for NOx reductions with biodiesel blends