U.S. INDUSTRY PUSHES NATURAL GAS MOTOR FUEL

Plans are forming across the U.S. to offer more natural gas as a vehicle fuel.

Here are some samples of the latest action:

• n Texas, the Houston Metropolitan Transit Authority (HMTA) unveiled plans to add 20 full size StarShip Apollo transit buses to a field test of alternative fuel vehicles.

  Stewart & Stevenson Services Inc., Houston, will equip 10 of the 40 ft units with liquefied natural gas fuel systems. Five diesel units will be equipped with particulate traps to capture and burn exhaust emissions. Base data will be gathered from five diesel units equipped with standard turbocharged engines.

• A group of companies is studying natural gas's potential role in greater Houston's transportation fuels market. Pending positive findings by May, group members said they will form a joint venture that by yearend will open several public and private gas refueling stations and begin vehicle conversions.

• In Austin, Texas' first retail refueling station for compressed natural gas (CNG) vehicles opened to the public. Station operator Frank Sapp also has begun converting vehicles to use CNG and hopes to begin selling CNG from three other Austin sites.

• In southern California, Unocal Corp. and Southern California Gas Co. (SoCal) disclosed a joint demonstration project that will offer CNG to motorists in the smoggiest region of the U.S.

  Southern California's top air pollutant is vehicle emissions.

  The first CNG fueling unit will be installed by midsummer at a Unocal 76 service station in the Los Angeles basin. A second Unocal station will be selling CNG by December. Unocal and SoCal haven't determined specific sites.

• Pacific Gas & Electric Co. (PG&E) opened seven CNG stations in central and northern California and has filed with the California Public Utilities Commission a request to open 19 more. PG&E estimates 500,000 fleet vehicles in its service area are capable of operating on CNG.

• Two city buses operated by the city transportation department in Colorado Springs, Colo., by the end of this month will start monitoring effects of high altitude on emissions of a new CNG/diesel, dual fuel engine.

  The 2 year, $371,000 test, sponsored by the U.S. Mass Transit Administration, Colorado Springs Gas Department, Colorado Interstate Gas Co. (CIG), and Colorado Transit Management Inc., will collect air pollution and performance data needed to help transit buses comply with Environmental Protection Agency emission standards.

• In Oklahoma, Phillips 66 Co. on Apr. 15 will begin selling CNG from two retail outlets-one at Stroud, Okla., on the Turner Turnpike and the other near 1-40 highway in Oklahoma City. Oklahoma Natural Gas Co. (ONG) will deliver CNG to the two Phillips outlets. The Turner Turnpike site will be the first commercial CNG retail outlet on a U.S. turnpike.

The American Gas Association says more than 325 natural gas refueling stations for vehicles are in operation in the U.S. About one third are open to the public. Private fleets use the rest.

AGA has published a directory of the stations, which also lists more than 120 companies that are manufacturing products or providing services directed at the natural gas vehicle market.

THE TEXAS PLAN

The Texas General Office attributes gas vehicle initiatives in Texas to the Texas Plan, a law passed in June 1989 by the Texas Legislature.

The Texas Plan requires certain centrally refueled fleets to begin using alternative fuels. After Sept. 1, 1991, specified fleet operators are to purchase only alternative fuel vehicles and convert 90% of their fleets to alternative fuels by 1998.

State agencies with more than 15 vehicles, school districts with more than 50 buses, private fleets with more than 25 vehicles, and all metropolitan transit authorities in Texas are required to comply.

In preparation to meet the new requirements, several fleets are burning CNG voluntarily, including units of the Texas General Land Office, Entex, Enron Corp., HMTA, Garland School District, United Parcel Service, and Dallas County.

LNG FUEL SYSTEM

Stewart & Stevenson said HMTA could begin receiving full size LNG transit buses this spring.

All 20 test buses will be equipped with Detroit Diesel 6V92TA DDEC 11 engines. The 10 units adapted to carry LNG also will be capable of burning either gas or diesel fuel.

HMTA plans tentatively to build a central gas liquefaction plant and use tank trucks to deliver LNG to bus yards. At the yards, LNG at temperatures from -250 F. to -260 F. will be injected into cryogenic fuel tanks on the test vehicles.

Onboard fuel tanks are described as 70 gal, cryogenic thermos bottles composed of a cylindrical, stainless steel, inner vessel encased by an outer steel tank. Space in between is filled by superinsulating fiber under vacuum.

Cryogenic Services Inc., Canton, Ga., is supplying LNG tanks for the HMTA field test.

Officials say temperatures will rise slowly in the cryogenic vessels on each bus, allowing some LNG to boil into gas and building pressure in the fuel tank to about 165 psi. As long as tank pressure remains at more than 30 psi, the fuel system will siphon LNG vapor to fuel the engine.

As pressures in the cryogenic tank fall to near 30 psi, LNG boiling to gas absorbs more heat than is created. Temperatures inside the tank begin to drop, and eventually the LNG stops boiling to vapor phase.

With no way to induce heat into the cryogenic tank, at that point the fuel system draws off LNG through a valve and runs it through a two stage heating process, which warms it to vapor and pressurizes it to 300 psi for delivery to the 6V92TA DDEC 11 engine.

Stewart & Stevenson estimates the full size, dual fuel, transit buses cost about $250,000/unit, with expense of CNG-LNG conversions about $30,000-40,000.

HMTA has eight 25 ft buses operating on CNG and two on LNG.

TEXAS CNG OUTLETS

The Houston group intends to develop a CNG vehicle retail refueling strategy for Brazoria, Chambers, Fort Bend, Harris, Liberty, Montgomery, and Waller counties, Tex.

Leading the Houston group with a 50% share is Natural Fuels Corp., Denver, owned jointly by Julander Platt Nelson, Public Service Co. of Colorado, and CIG, a subsidiary of Coastal Corp. Houston's natural gas utility Entex, a division of Arkla Inc., owns 25%; Houston Pipe Line Co., a subsidiary of Enron Corp. 15%; and Vista Group Inc. investment firm, Houston, 10%.

Natural Fuels operates three public and two private CNG fueling stations in Denver and plans to open nine more this year. The company also operates a conversion and service center that can convert as many as 100 vehicles/month and plans to open two more during 1991.

The group will draw upon members' resources to complete research and develop a business plan by May 1991. Natural Fuel's CNG marketing experience in Colorado will serve as a model.

During the second phase of the plan, the group by September will form a joint venture, which could be selling CNG and converting vehicles at service centers by yearend 1991.

At the retail outlet opened last month in Austin, CNG sells for 79.9/gal equivalent of gasoline.

Natural Gas Resources (NGR), Austin, installed the compressor and pump at the Austin CNG station. NGR also trains mechanics to install its patented conversion kit.

Southern Union Gas Co. owns the CNG refueling station and leases it to Sapp.

CNG IN LOS ANGELES

The Unocal CNG stations will be self-serve units accessed by computerized cards issued to SoCal customers.

Unocal will provide daily operations through its dealers, and SoCal will provide design, engineering, general maintenance, and customer billing.

The two companies will divide equally the estimated $250,000 cost of adapting each station.

By increasing the supply of CNG to Los Angeles motorists, Unocal Chairman Richard J. Stegemeier said, the two companies hope to help remove one roadblock restricting CNG's use as a vehicle fuel.

SoCal Chairman Richard D. Farman said his company had helped allay another major restriction-limited size of the CNG user fleet-by playing a leading role in a $40 million project to develop light and medium duty trucks, disclosed late last month by General Motors.

Proponents say CNG vehicles produce 50% less pollutants and 90% less carbon monoxide than gasoline, and CNG is safer than traditional vehicle fuels.

PG&E CNG NETWORK

PG&E's public CNG refueling stations are on company sites in San Francisco, San Jose, Hayward, San Rafael, Bakersfield, Concord, and Richmond, Calif. PG&E and Shell Oil Co. plan to open a station in Sacramento in April that will dispense gasoline and CNG.

In 1973, PG&E began using CNG in its vehicle fleet and plans to have 500 company vehicles operating on CNG by yearend 1992.

PG&E estimates the cost of converting a vehicle to CNG at $2,500, but it proposes to offer financial incentives to fleet operators to encourage conversions.

The utility company aims to convert 125,000 fleet vehicles to CNG in its service area by 2000. PG&E customers operating CNG vehicles include Federal Express, United Parcel Service, U.S. Post Office in Concord, Contra Costa County, Berkeley Unified School District, Alemeda, Oakland, and Mechanics Bank of Hercules.

HIGH ALTITUDE TESTS

Colorado Springs will test the same hybrid, CNG/diesel, Detroit Diesel 6V92 engines to be tried by HMTA.

CIG said about 10% of the fuel burned will be diesel required for ignition. The other 90% will be CNG injected into combustion cylinders.

Skip Simonton, CIG manager of planning and evaluation, said Colorado Springs' field test is important because Detroit Diesel 6V92 engines power about 90% of all heavy duty transit buses in the U.S.

Data from the test also will help quantify air pollution problems unique to cities in high altitudes.

Buses burning alternate fuels are being tested in Denver and Albuquerque, N.M., where altitudes are 5,280 ft and 4,958 ft, respectively. Colorado Springs' altitude is 6,172 ft.

In previous tests, dual fuel Detroit Diesel engines have reduced particulate emissions to 0.17 g/hp-hr from 0.5 g/hp-hr and nitrous oxides to 4.5 g/hp-hr from 8 g/hp-hr, he said.

Stewart & Stevenson Power Inc., Denver, a subsidiary of Stewart & Stevenson Services, is installing CNG fuel tanks and controls for the Colorado Springs test.

Colorado Springs transit officials said part of the test cost will be recovered by lower fuel costs. The company will pay 50-60/gal for about 40,000 gal/year of CNG required by the two test vehicles.

CONVERSION FUNDING

Oklahoma legislators in 1990 passed a law that makes funds available to state agencies for converting fleet vehicles to cleaner burning fuels. CNG conversions would qualify for funding under the law.

Phillips 66 Pres. Bill Thompson said the agreement with ONG will help make the most of Oklahoma's most important natural resource.

Charles C. Hopper, ONG vice-president of marketing, said the company has received more than 600 inquiries about CNG vehicle fuel.

Copyright 1991 Oil & Gas Journal. All Rights Reserved.