Cleaning Up Diesel in the Bay Area

What Are the Sources? What are the Clean-Up Opportunities?

Patricia Monahan

Senior Analyst, Clean Vehicles Program

Bay Area’s Diesel Pollution Inventory

• In 2002, B.A. diesel engines released– 5,000 tons of fine soot– 117 thousand tons of smog-forming NOx & ROG

• As a share of mobile source pollution, B.A. diesel engines are responsible for– Three-quarters of fine particles – 44% of smog-forming NOx and ROG

Source: CARB Emission Inventory for the Bay Area. Available online at http://www.arb.ca.gov/emisinv/maps/statemap/abmap.htm

Bay Area Pollution from Mobile Sources: Fine Soot (PM 2.5)

Planes - Dsl

13%

Offroad -Gas6%

Offroad -Dsl

39%

Big Rigs - Dsl

16%

Cars - Gas18%

Ships - Dsl8%

Bay Area Pollution from Mobile Sources: Smog-forming (NOx & ROG)

Ships - Dsl3%

Cars - Gas46%

Big rigs - Dsl

20%

Offroad -Dsl

17%

Offroad -Gas10%

Planes - Dsl4%

Bay Area Pollution from Diesel Mobile Sources: Fine Soot (PM 2.5)

Planes17%

Trains1%

Off-road50%

Big Rigs22%

Ships10%

2002 Bay Area Pollution Diesel Mobile Sources:Smog-forming (NOx & ROG)

Planes10%

Trains3%

Off-road37%

Ships6%

Big Rigs44%

2002 Bay Area PollutionNonroad Diesel Engines:Fine Soot (PM 2.5)

Construct75%

Industrial7%

Commer-cial8%

Transp. Refrig

7%

Lawn & Garden

1%

Airport Support

2%

• Diesel engines have been under-regulated by EPA• Highway trucks and buses built before 1988 did

not have to meet ANY soot standard

Why Are Diesel Engines Such Major Polluters? Weak Pollution Standards!

Why Are Off-road Engines the Largest Single Source of B.A. Soot? Even Weaker Pollution Standards!• Off-road engines, like cranes and bulldozers, did not

have to start meeting any pollution standards until 1996– The pollution standards for off-road diesel engines are

about 10 times weaker than highway standards

• Despite the downturn in the economy, construction has continued

• As a share of pollution from off-road engines, construction equipment accounts for – 75% of fine soot– Over 80% of smog-forming pollutants

Reducing Diesel Pollution from New Engines

• New standards– Heavy-duty standards for new vehicles and ultra-low

sulfur diesel fuel• (90% less PM per vehicle in 2007)• (95% less NOx per vehicle -- 2007/2010 phase in)

– Proposed non-road diesel standards match onroad

• Limitations:– Requirements phased in over next decade– Full benefits are thirty years away– No new standards for trains, planes and ships

• Diesel engines last a long time– Existing engines may last another 20-35 years

• CARB’s Diesel Risk Reduction Program– Retrofit regs stalled– Incentive programs out of funding

• CARB’s School Bus Program– Nearly out of funding

• The Bay Area needs more local clean up The Bay Area needs more local clean up effortsefforts

What About Trucks and Buses on the Road Today?

• Replace – Use a cleaner engine powered by alternative fuels,

like electricity or natural gas

• Retrofit – PM control: Particulate matter trap– PM control: Oxidation catalyst (oxy cat)– NOx & PM control: Lean NOx catalyst in

conjunction with PM trap or oxy cat

• Fuel switching– Biodiesel– Emulsified diesel

Diesel Clean Up

Cleaner Alternative Fuels, like Natural Gas

• Pros– 1/3 reduction in NOx and 90% reduction in PM

compared with new conventional diesel– NG has pushed diesel to become cleaner– Moves transportation system towards hydrogen– Potential for reduced maintenance costs

• Cons– Engines cost $10s of thousands more than diesel– Additional infrastructure costs– NG price fluctuations– Different maintenance procedures

PM Control: Diesel Particulate Matter Filter (PM trap)

• Pros:– 85% or greater PM & toxics reduction– Soot emissions comparable to NG with oxy cat– Modest cost: around $5K

• Cons:– Can only be used on certain 1994 and newer engines– Must be used in conjunction with low sulfur diesel fuel– Some maintenance costs

PM Control: Oxidation Catalyst (oxy cat)

• Pros:– 20-30% PM reduction– Inexpensive: $1-2K– Can be used to clean up older engines

• Cons– PM remains high

PM & NOx Control: Lean NOx Catalyst + Trap

• Pros:– 85% PM, 25% NOx

control

– Only NOx aftertreatment available

• Cons:– 94 and newer engines

only

– Cost >$15K

Fuel Switching

• BIODIESEL– Pros

• B20 offers 10% reduction in PM/toxics

• Modest cost increase of about 10%

• No engine modification

– Cons• Slight NOx increase• Easy to switch back to

diesel

• EMULSIFIED DIESEL– Pros

• 15% reduction in NOx; 58% reduction in PM

– Cons• Limited to specific

applications• Limited shelf life, some

performance drawbacks (eg, power, torque)

• Cost??

Models for Diesel Clean-Up

• Boston’s Big Dig

• World Trade Center Clean-Up

• NY Ferries

Conclusions: Which Sources Should be Targeted for Clean-up?

• Emission inventories can help provide direction– Nonroad diesel (particularly construction) is major

source of diesel PM

• Other factors (eg, children’s health, local “hot spots”) must play a role

• Clean-up technologies/fuels must be tailored to the age and type of equipment, as well as the amount of funding available.