Michigan State UniversityCollege of Engineering

Fall 2007 – ME 444

Andrew BuczynskyFuels and Lubricants Department

General Motors Powertrain

Fuels for Road VehiclesBasics of Gasoline, Diesel Fuel, E85,

and Biodiesel

A. Buczynsky, GM

Petroleum

Source of fuels– Petroleum-based fuels come from crude oil– Crude oil varies depending where in the world it

comes from

A. Buczynsky, GM

Map: API, Understanding Today’s Energy Needs. Crude oil import data: EIA

Three-quarters of U.S. crude oil imports come from 5 locations: Persian Gulf (21%), Canada (17%), Mexico (16%), Venezuela (11%), Nigeria (10%).

Flow of Crude Oil

A. Buczynsky, GM

Crude Oil Refining

A. Buczynsky, GM

Regional Consumption by Fuel Type

46.5

22.328.4

30.2

47.5 36.2

3.311.4

14.8

20.0 18.8 20.5

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

US EU 25 Asia Pacific

Co

nsu

mp

tio

n d

em

an

d

Other

Hvy dist

Mid dist

Lt dist

Source: BP Statistical Review of World Energy June 2007Lt dist = Aviation and motor gasoline. Mid dist = jet fuel, kerosene, and diesel fuel.Hvy dist = Marine bunker fuel and crude oil used as fuel. Other = refinery gas, LPG, coke,lubricants, solvents, bitumen, wax.

A. Buczynsky, GM

Flow From Refinery to Pump

Pipeline, bargerailcar, truck

Supply terminal Retail station

Truck

EthanolBiodiesel

A. Buczynsky, GM

Fuel Lingo

Gasoline– Conventional gasoline– Reformulated gasoline (RFG)– California gasoline (CARB Phase 3 RFG)– Boutique fuels

Low vapor pressure gasoline (low RVP) Clean burning gasoline (CBG)

Diesel fuel– Ultra low sulfur diesel fuel (ULSD)– Low sulfur diesel fuel (LSD)– High sulfur diesel fuel (HSD)

On-road

Off- road

A. Buczynsky, GM

States Have Developed “Boutique” Fuel Recipes to Avoid RFG

A. Buczynsky, GM

U.S. Pipeline Distribution SystemGasoline, diesel fuel and jet fuel move in the same pipelines

Fuels are fungible (interchangeable) products

A. Buczynsky, GM

Pipeline Primer

Different product batches are “pushed” through the system abutting each other. The mixing zones between batches are called interfaces.

RFG reg. ULSD Jet fuel HSD Conv. ULR

RFG prem.

RFG reg.

Product flow

Interfaces

A. Buczynsky, GM

Gasoline

Defined by ASTM D 4814

– “a volatile mixture of liquid hydrocarbons, generally containing small amounts of additives, suitable for use as a fuel in spark-ignition, internal combustion engines.”

A. Buczynsky, GM

Volatility

The tendency of a fuel to vaporize– Measured by

Vapor pressure Distillation Vapor-liquid ratio

Gasoline volatility is adjusted seasonally– Winter: cold start– Summer: hot restart, evaporative emissions

A. Buczynsky, GM

Driveability

Volatility affects driveability– Driveability: the ability of a vehicle to operate

satisfactorily under normal driving conditions:Ease of startingSmooth idleSmooth acceleration and cruise

– Driveability is quantified by trained raters using a set driving protocol

Lower demerits mean better driveability

A. Buczynsky, GM

Antiknock Quality

Ability of a gasoline to resist knocking– Knock – engine noise produced by rapid pressure

rise as a result of abnormal combustion Expressed as octane number

– Two laboratory test methods measure octane number

Both use single cylinder, variable compression engines

Each uses different operation conditions

A. Buczynsky, GM

Octane Number

RON (R): Research Octane Number

MON (M): Motor Octane Number

Antiknock Index: (R+M)/2 87MINIMUM OCTANE RATING

(R+M)/2 METHOD

A. Buczynsky, GM

Octane Grades

Current offerings– Regular 87 (R+M)/2: sufficient for >90+% of vehicles– Midgrade 89 (R+M)/2: for vehicles with a higher

octane requirement– Premium 91 (R+M)/2: for performance vehicles

Regular versus premium– Octane higher than required to prevent audible

knock or knock sensor activity is a waste of money

A. Buczynsky, GM

Oxygenates

Oxygenates are fuel molecules that contain oxygen– Ethanol (EtOH) is the only oxygenate now used in

gasoline Limited to 10 volume % in gasoline About 50% of U.S. gasoline contains 10% ethanol

– Ethers were formerly used but have been banned by many states

– Biodiesel is used in diesel fuel Renewable Fuels Standard (RFS)

– Requires a certain volume of renewable fuel be used– By about 2010-2015, all U.S. gasoline will contain

10% ethanol

A. Buczynsky, GM

Effect of Ethanol on Distillation of Gasoline

100

150

200

250

300

350

400

0 10 20 30 40 50 60 70 80 90 100

Percent evaporated

Deg

rees

, F

E0 E10

A. Buczynsky, GM

Oxygenate Use in Vehicles

10% ethanol blends– Compatible with all vehicles

Flex-fuel vehicles– Can run on up to 85% ethanol– Check your owners’ manual to know if you have a FFV– Do not use more than 10% ethanol in a standard vehicle

Never put methanol into your vehicle– That includes de-icers in the winter – That includes FFVs

Solvent chemicals touted to improve fuel economy– Can be aggressive toward elastomers plastics

A. Buczynsky, GM

Engine Deposits

Negatively affect vehicle performance– Fuel injector fouling– Intake valve deposits– Combustion chamber deposits

All gasoline must contain deposit control additive

EPA requirement Provides minimum performance

TOP TIER Detergent Gasoline

A. Buczynsky, GM

Comparison of TOP TIER and EPA Additive Concentrations

Base Fuel + EPA detergent concentration

Base fuel + TOP TIER detergent concentration

After 100-hrs in Ford 2.3 L engine

A. Buczynsky, GM

Diesel Fuel

A liquid hydrocarbon mixture, for use in compression-ignition engines– ASTM D 975– Types of compression-ignition fuels

Diesel fuel – grade 2-D Kerosene – grade 1-D

A. Buczynsky, GM

Distillation Comparison of Gasoline and Diesel Fuel

100150200250300350400450500550600650

0 10 20 30 40 50 60 70 80 90 100

Percent evaporated

Deg

rees

F

E0 Diesel

A. Buczynsky, GM

Cold Flow Properties

Diesel fuel can gel at low temperatures– Diesel fuel contains wax molecules– Wax causes the fuel to become more viscous as

temperature drops– Wax also will precipitate from the fuel at low

temperatures and plug fuel filters– Remedy is to blend kerosene to improve cold

handling properties or use additives Kerosene results in a fuel economy debit Additives are expensive and their performance

depends on the base fuel

A. Buczynsky, GM

Cetane Number

A measure of how readily a fuel auto-ignites– A high cetane number is desirable

Indicates short ignition delay after injection Makes starting easier, reduces white smoke and

engine noise– Cetane number of diesel fuel in the U.S. is poor

compared to the rest of the world ASTM 975 specifies a minimum of 40 Europe specifies a minimum of 51

– Cetane index is a calculated value used to approximate cetane number

Based on density and distillation temperatures

A. Buczynsky, GM

Alternative Fuels

Any non-petroleum based fuel by legislative definition.

– Alternative fuels currently of primary interest Ethanol (E85) Biodiesel

– Others alternative fuels M85 M100 E100 LPG CNG

A. Buczynsky, GM

E85 70-83 volume % denatured ethanol blended

with hydrocarbons– Controlling specification is ASTM D 5798

Based on early 1990s vintage vehicles Currently undergoing extensive review

– Ethanol content controlled by desired volatility Ethanol has a low vapor pressure Less ethanol in winter to ensure good start-up

– Stoichiometric air/fuel ratio is 10 compared to 14.7 for gasoline

– E85 has (R+M)/2 octane value of about 96-98– Lower heating value than gasoline (12,500 BTU/lb

vs. 18,500 BTU/lb)

A. Buczynsky, GM

Benefits of E85

Reduces dependence on foreign oil Renewable fuel Reduces CO2 (greenhouse gas) emissions

A. Buczynsky, GM

Carbon Dioxide in Perspective

600 gallons gasoline per year

Creates ~12,000 lbs CO2

Requires 240 trees to extract the CO2

Source: Automotive News

A. Buczynsky, GM

Energy to Produce Ethanol vs. GasolineSource: Argonne National Laboratory

A. Buczynsky, GM

-2%

-23%

-64%

-6%

-80%

-60%

-40%

-20%

0%

E10 E10 cell. E85 E85 cell.

Ethanol Blends Significantly Reduce GHG Emissions

Source: Argonne National Laboratory

A. Buczynsky, GM

Disadvantage of E85

Only 1,252 E85 stations exist nationwide as of August 1, 2007 (some stations are for private fleet vehicles only)

– Compared to more than 150,000 for gasoline* 317 in Minnesota 151 in Illinois 49 in Michigan 5 in California

Price is still not competitive in many areas

Lower fuel economy Food versus fuel controversy

A. Buczynsky, GM

Biodiesel

Oil or Fat SoybeanCornCanolaCottonseedSunflowerBeef tallowPork lardRecycled cooking oils

CatalystSodium hydroxidePotassium hydroxide

Fatty acid methyl ester

(FAME or biodiesel)

+

Glycerin(removed)

Made by a chemical process using vegetable or used cooking oils, animal fat, or grease as starting material. Oils or fats that have not undergone the chemical process are not biodiesel.

+ Alcohol Methanol

A. Buczynsky, GM

Biodiesel

Biodiesel blends are designated B___– 5% biodiesel is B5– 20% biodiesel is B20– 100% biodiesel is B100

B100 in U.S. comes primarily from soy beans – Yellow grease is a secondary source

B100 in Europe comes primarily from rape seed– B5 is considered standard diesel fuel

Biodiesel blends are made at a supply terminal, not at a refinery

A. Buczynsky, GM

Advantages of Biodiesel

Renewable energy source Reduces CO2 life-cycle emissions by 78%

compared to diesel fuel Improves cetane and lubricity of diesel fuel Improves most regulated emissions

A. Buczynsky, GM

Disadvantages of Biodiesel

Can oxidize (become rancid)– Results in gums, deposits, and acids

Has poor cold temperature properties Entrains more water than diesel fuel May increase NOx emissions Heating value about ~10% lower compared to 2-D

– B20 users experience a 1-2% loss in fuel economy Requires tax incentives to be competitive

A. Buczynsky, GM

Hydrogenated Biodiesel

Also called ‘renewable diesel’ or ‘green diesel’

Hydrogen is used to convert fats and oils to hydrocarbons

Advantage is a product more like standard diesel fuel

Disadvantages are high capital requirement and poor lubricity

CH3(CH2)16COO CH2

CH3(CH2)16COO CH

CH3(CH2)16COO CH2

3 n-C18 + 1 C3H8 + 6 H20

+ H2

Source: OMV Refining and Marketing