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Frequently Asked Questions

Question 1: What is a diesel retrofit?

Question 2: What are the benefits of DPF and DOC retrofits?

Question 3: What is the cost of a diesel retrofit?

Question 4: Which products are EPA verified/CARB certified?

Question 5: How does a Diesel Oxidation Catalyst (DOC) work?

Question 6: How does a Diesel Particulate Filter (DPF) work?

Question 7: How does a Closed Crank Ventilation Systems work (on-road vehicles only)?

Question 8: What are the maintenance requirements for each type of device (DOC, DPF, and CCV)?

Question 9: Is an idle reduction policy required?

Question 10: What is idling?

Question 11: What are common anti-idling strategies?

Question 12: How to Participate in the National Idle-Reduction Campaign?

Question 13: Is replacing gasoline powered school buses with new diesel powered school buses eligible?

Question 14: How much does ODEQ match to reimburse if a diesel school bus is replaced with a new diesel or hybrid school bus?

Question 15: What constitutes the "scrappage" of a vehicle after it is replaced? Are we allowed to sell it?

For more information on funding for Clean Diesel visit the EPA's FAQ page at: http://www.epa.gov/otaq/eparecovery/documents/faq-national-rfa.pdf

A diesel particulate filter (DPF) is a ceramic device that collects particulate matter in the exhaust stream. The high temperature of the exhaust heats up the ceramic device which allows the particles in the exhaust to break down, or oxidize, into less harmful components.

A diesel oxidation catalyst (DOC) is a device that uses chemical processes to breakdown pollutants in the exhaust stream into less harmful components. The device is made of a porous ceramic honeycomb-like structure that is coated with materials which catalyze a chemical reaction reducing harmful pollution.

A closed crank ventilation system (CCVS) is designed to capture and return the crankcase gases that have leaked through the engine piston rings. These crankcase emissions can be substantial, thus a CCV is used to control gases flow and return the emissions to the engine for combustion. This effectively prevents the crankcase emissions from entering the atmosphere.

Question 2: What are the benefits of DPF and DOC retrofits?

DPFs reduce emissions of particulate matter 2.5 (PM2.5), hydrocarbons (HCs), and carbon monoxide (CO) by 60-90%. DPFs require the use of ultra low sulfur diesel fuel (ULSD).

DOCs reduce PM2.5 emissions by about 30% as well as reduce emissions of HCs by 50% and CO by 40%. DOCs do not require the use of ULSD.

CCVs reduce PM2.5 by 10-15%, HCs by 30-40%, and CO by 50-90%.

Question 3: What is the cost of a diesel retrofit?

DPFs cost between $4,000 and $7,500. The cost is dependent on the specific engine and operating characteristics, such as exhaust temperature.

DOCs cost between $1,000 and $2,000.

CCVs cost between $1,200 and $2,000.

Question 4: Which products are EPA verified/CARB certified?

For the Clean Diesel Grant Program, the Oklahoma Department of Environmental Quality, Air Quality Division (DEQ), requires products that have been verified/certified by the US Environmental Protection Agency (EPA) and the California Air Resource Board (CARB). For a complete list please check the EPA Verified Retrofits Technologies List or the CARB Diesel Reduction Program, verified technology at:
http://www.epa.gov/otaq/retrofit/verif-list.htm
http://www.arb.ca.gov/diesel/verdev/verdev.htm

Question 5: How does a Diesel Oxidation Catalyst (DOC) work?

A DOC is a form of "bolt on" technology that uses a chemical process to reduce pollutants in the diesel exhaust into decreased concentrations. They replace mufflers on vehicles, and require no modifications. More specifically, this is a honeycomb type structure that has a large area coated with an active catalyst layer. As carbon monoxide and other gaseous hydrocarbon particles travel along the catalyst, they are oxidized thus reducing pollution.

Question 6: How does a Diesel Particulate Filter (DPF) work?

DPFs are the most effective at reducing emissions, but are also the most sensitive. These have a yearly maintenance cycle, and the filter periodically needs to be cleaned out due to accumulation of particulates. The filter is typically placed inline of the diesel exhaust flow to collect particulates. These systems are on average heavier and larger than your standard muffler, thus some modifications may need to be made for proper installation. The exhaust gas must be high enough to regenerate the filter however. This can be done by either an active control system or a passive control system. Some examples of this for school buses include longer bus routes and wrapping the exhaust pipe in insulated material to retain as much heat as possible.

Question 7: How does a Closed Crank Ventilation Systems work (on-road vehicles only)?

During the engine combustion process crank emissions are created. These emissions are typically composed of PM, unburned fuel, and hydrocarbon vapor. Crank systems effectively close off this crankcase, thus eliminating the emissions without impacting engine performance. The general maintenance of the CCV system involves replacing the filter which is similar to changing the engine oil. Higher mileage on-road engines will typically need maintenance every 25,000 miles, while low-mileage vehicles are recommended to be maintenance annually.

Question 8: What are the maintenance requirements for each type of device (DOC, DPF, and CCV)?

DOCs essentially require no maintenance except for a periodic visual inspection of brackets and hangers. DPFs, due to their reliance of wall flow filters, will capture all of the lube oil ash that would normally go out the tailpipe as lube oil is consumed. As such, a periodic cleaning of the filter is necessary as the backpressure of the system increases. Visual inspections of hangers, bolts, backpressure monitors are also recommended. CCVs require periodic filter replacement.

Question 9: Is an idle reduction policy required?

All sub grant recipients must agree to implement a fleet-wide idle reduction policy. Unnecessary vehicle idling pollutes the air, wastes fuel, and causes excess engine wear. Reducing idling saves fleets’ money. Idling should be limited to the engine manufacturer recommendation (generally no more than five minutes). Sub grantees will be required to specify the policy to be implemented including (but not limited to) idling time limits, idling exceptions, expected fuel savings, etc.

Question 10: What is idling?

An idling vehicle is one whose engine is running when it is parked or not in use.
Common reasons for engine idling are:

These examples are NOT considered idling:

Question 11: What are common anti-idling strategies?

Question 12: How to Participate in the National Idle-Reduction Campaign?

Information on how to implement your idling-reduction program, and a Do-it-Yourself Kit can be found at http://epa.gov/cleanschoolbus/antiidling.htm

Question 13: Is replacing gasoline powered school buses with new diesel powered school buses eligible?

No, only heavy duty diesel vehicles and engines are eligible for funding. The replacement of gasoline-powered vehicles is not allowable under this RFA. However, replacement of diesel vehicles with newer, cleaner diesel or hybrid or alternative fuel vehicles is eligible for funding.

Question 14: How much does ODEQ match to reimburse if a diesel school bus is replaced with a new diesel or hybrid school bus?

ODEQ's match to reimburse is up to 25% for school buses that meet 2007 emissions standards and a match to reimburse of up to 50% for school buses meeting the 2010 emissions standards.

Question 15: What constitutes the "scrappage" of a vehicle after it is replaced? Are we allowed to sell it?

The vehicle/equipment being replaced will be scrapped or rendered permanently disabled or returned to the original engine manufacturer for remanufacturing to a certified cleaner emission standard. Drilling a hole in the engine block and manifold and disabling the chassis while retaining possession of the vehicle/equipment is an acceptable scrapping method. Other methods may be considered and will require prior EPA approval. Equipment and vehicle components that are not part of the engine or chassis may be salvaged from the unit being replaced (e.g. plow blades, shovels, seats, tires, etc.) If scrapped or salvaged vehicles/parts are to be sold, program income requirements apply and must be accounted for in the project.

Evidence of appropriate disposal, including engine serial number and vehicle identification number (VIN), is required in a final assistance agreement report submitted to EPA.

To be able to apply for this funding opportunity for replacement of a vehicle, engine, or equipment, the following requirements apply:

1. The vehicle, engine, or equipment being replaced will be scrapped, or the replaced engine would be returned to the original engine manufacturer for remanufacturing to a cleaner standard.

2. The replacement vehicle or engine will be of the same type and similar gross vehicle weight rating or horsepower as the vehicle or engine being replaced. The replacement vehicle/equipment must be of the same type and similar gross vehicle weight rating or horsepower as the vehicle/equipment being replaced (e.g., a 300 horsepower bulldozer is replaced by a bulldozer of similar horsepower). The replacement vehicle/equipment must perform the same function as the vehicle/equipment that is being replaced (e.g., an excavator used to dig pipelines would be replaced by an excavator that continues to dig pipelines). These projects can also include the replacement of nonroad vehicles/equipment with highway models if the highway models are capable of performing the same functions as the nonroad models.

Page last updated: March 19, 2013