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Researchers Target Advances in NGV Fueling

As part of the U.S. Department of Energy's recent distribution of $30 million aimed at advancing the natural gas vehicles (NGV), two separate projects are examining breakthroughs in fueling to make the vehicle operator more independent of public refueling stations.

A home or office-based fueling device that would dramatically speed up the fueling time and lower the cost is being pursued jointly by a unit of General Electric Corp. (GE), Chart Industries and researchers at the University of Missouri. Separately, engineering researchers at Oregon and Colorado universities are developing a NGV that can provide its own onboard compression for fueling using a $700,000 grant from DOE's advanced research projects agency (ARPA-E).

The GE-Chart-Missouri effort and a separate project by Oregon State University (OSU) and Colorado State University (CSU) offer fueling innovations as part of projects in nine states, all looking at creating ways to make NGV fuel tanks more affordable and/or compressors more efficient for creating CNG (see NGI, July 16).

GE, Chart and the university engineering researchers have set ambitious goals of reducing the cost of small refueling equipment by 10 times while cutting refueling time from the current five to eight hours to one hour. A typical at-home unit today costs about $5,000, while this DOE-funded research seeks to develop equipment priced at around $500. The project, slated to run for about 28 months, is estimated at $2.3 million, which would be split between the GE unit and DOE's Advanced Research Projects Agency-Energy (ARPA-E). GE researchers would focus on overall system design integration; Chart and Missouri personnel are to address detailed engineering, cost and manufacturing aspects of key system components.

"The goal is to deliver and demonstrate a fully functioning at-home refueling station unit," said a GE spokesperson, who added that GE recently introduced a "Compressed natural gas (CNG)-in-a-Box" for industrial and traditional fueling station installations in which pipeline natural gas from a service line is compressed onsite into CNG. The latter is "making it faster, easier and less expensive for users to fuel up" with natural gas, he said.

For OSU/CSU engineers the goal by the end of next year is to build a compressed natural gas (CNG) truck that doesn't need a fueling station because it will carry the capability of compressing its own fuel onboard by tapping into a normal low-pressure household or small business natural gas supply.

OSU engineering professor Chris Hagen originated the idea with a plug-in electric vehicle that used CNG as its back-up fuel, but DOE asked him to concentrate on creating a CNG-powered truck instead. He is joined by CSU engineering professor Tom Bradley, who has also brought in some help from Encana Corp.'s NGV experts.

ARPA-E officials wanted to go for a light-duty pickup truck because they feel it has the potential for much greater market acceptance, Hagen told NGI last week in outlining how in either case the concept is to have one cylinder in an internal combustion engine (ICE) also dedicated to provide compression when the vehicle is parked. "So this vehicle should be able to refill itself using only the ICE," he said.

While running the CNG-powered engine as it is parked and connected to a low-pressure natural gas source, one of the cylinders will be compressing gas and refilling the vehicle's supply. Up to 96% of the CNG being produced will fill up the tank, with about 4% being consumed for the compression cycle, Hagen said. A light-duty truck like this could be attractive to various gas utility and other operators, he said.

GE is touting the personalized fueling station concept being pursued as "fundamentally different" than traditional compressor technologies used with NGVs. Researchers are devising a system that "chills, densifies and transfers CNG more efficiently," according to the spokesperson. "It will be much simpler in design with fewer moving parts, and it will operate quietly and be virtually maintenance-free."

The research project aims at some of the barriers that continue to hold back a wide spread transition to CNG for transportation despite historic low natural gas prices in North America today. Those barriers include the inconvenience and low availability of refueling stations and limited driving ranges for most NGVs. Fleet operators can more easily overcome the barriers; individual vehicle owners cannot, and it is the latter who are the focus of this research, the project partners said in accepting the DOE funding.

GE Global Research's Anna Lis Laursen, the project leader, said that "new technologies to reduce the cost of NGV fueling and continued improvements in battery technology" can help break the historic reliance on diesel and gasoline products for transportation and allow the use of alternative fuels, such as CNG, to grow.

"The goal of our project is to design an at-home refueling station that is much simpler in design, more cost effective and reduces refueling times to under an hour. If we can meet our cost targets, the price of a home refueling station would be less than typical appliances in a home, such as a dishwasher or stove."

For the self-containd compression component on trucks there obviously are some added weight and cost considerations for a CNG sector that is already sensitive to both, particularly in passenger vehicles. OSU's Hagen said that isn't a problem. "The design, as such, has kept the number of added components to a minimum," he said. "We're going to be using some engine valve deactivation technology and other things."

The only added component to the engine is the equipment needed to have one cylinder capable of compressing gas at low pressures, Hagen said. "One cylinder will have a heavier-duty liner, but other than that, the ICE is the same." He said the added cost is something less than $500 as far as the target for the DOE-funded project.

Current home fueling systems for CNG are generally costly and slow, according to Hagen. "By using the ICE for the compression, we're going to have a pretty robust compressor that should be able to fill the vehicle pretty quickly."

"With this innovation, we can refuel NGVs without having to have a dedicated high-pressure natural gas compression station," Bradley said. How the vehicle will interconnect with a household gas pipeline is still to be worked out. "Actually how you would refuel at home is still a work in progress," Hagen said.

The project has access to an Encana team of experts on NGV economics. "They are going to help us identify all of the [customer interface] issues and how we might address them," Hagen said.

In related news a delegation led by Oklahoma Gov. Mary Fallin and Colorado Gov. John Hickenlooper traveled to Detroit last week to urge U.S. auto manufacturers to get behind a "multi-state, bipartisan" CNG initiative to get more NGVs on the road. The state officials said are ready to buy more NGVs, but they need commitments from the automakers to produce them. In April 13 governors sent letters to automakers to express their commitment to "explore ways to purchase more CNG vehicles" for their respective state fleets. In 2011 the governors of Colorado, Oklahoma, Wyoming and Pennsylvania signed a memorandum of understanding calling for the states to aggregate fleet vehicle procurements with the intent of creating a demand base sufficient to support the design, manufacture and sale of NGVs by U.S. manufacturers.

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