Fugitive on the loose

June 1, 2007 By    

A Confidential Study of fugitive emissions in California says that the propane industry should find ways to reduce the amount of fuel released into the atmosphere during and after product transfer – or risk losing the exemptions it has long enjoyed with state air pollution authorities.

Fugitive emissions are the liquid or vapor propane vented into the atmosphere during fuel transfer, tank purging and the changing of tank valves. Propane is released each time a fixed liquid level gauge is opened and when a hose nozzle is disconnected from a tank after fueling. The volume released through the valve depends on the length of time it was open; the amount at disconnection depends on the length and diameter of the hose or pipe evacuated and the types of valves and nozzles in use.

Beyond environmental concerns as a contributor to smog, emissions pose safety concerns if the fuel were to find a source of ignition. They also can cause freeze burns to the unexposed skin of workers making deliveries.

It is likely that the propane industry’s emissions have become a much larger target for new regulations on the West Coast as the California Air Resources Board presses its quest to improve air quality in the nation’s most populous state, the report says.

Sources of Emissions by Transfer Point Percent of total
Sources of Emissions by Transfer Point Percent of total

Other fuels have been substantially regulated for years with requirements for double-walled underground tanks, soil cleanup, vapor recovery nozzles or gas dispensing equipment. Propane emissions are not currently regulated in California, which sells the third-largest volume of retail propane in the nation. LPG is exempted from the state rules that control emissions of volatile organic compounds.

The 2004 study was conducted for the Western Propane Gas Association, which represents more than 100 propane marketers throughout California. The final report, prepared by James J. Keatley of The Adept Group Inc., breaks out emission volumes by product transfer types, but provides no cumulative statewide totals.

The project was done to head off a study by CARB, which in 2004 told the association that it would soon perform its own assessment. Historically, actions taken by that ultra-aggressive regulatory body set precedent for regulations of other state and federal agencies.

The Propane Education & Research Council gave WPGA $45,500 for a Fugitive Emissions Prevention and Awareness Pilot Program. Its goals were to reduce fugitive emissions, improve safety and demonstrate to regulatory agencies that the propane industry is responsive to air quality concerns.

Specifically, the program was to:

  • Estimate current levels of emissions and suggest ways to mitigate them.
  • Develop a list of nozzles and valves offering low-bleed or reduced-emissions capability.
  • Develop a list of procedures or improved practices that industry workers could adopt to cut emissions.

About 135 WPGA members were briefed on the project’s findings in a series of eight district meetings in early 2005. Almost unanimously, attendees said they recognized the gravity of the issue given their experience with CARB. Nobody challenged the accuracy of the presentation or the industry practices that were discussed. The only comments about emission estimates were that they probably were low.

In surveys conducted immediately after the meetings, participants expressed a near-unanimous opinion that the presentation was helpful, and some practical suggestions were made that members could – and would – take to address the problem.

Sources of FLLG Emissions at Point of Transfer Percent of total FLLG emissions
Sources of FLLG Emissions at Point of Transfer Percent of total FLLG emissions

The report’s recommendations for curbing emissions have found little traction since those discussions, however.

How it happens

In the transfer of propane from one storage vessel to another during delivery, there are two sources of emissions – one during the transfer and the second at its completion. Propane typically is released as a gas, as a liquid, and as a mix of the two through a fixed liquid level gauge – also commonly known as a “spitter” or “bleeder” valve – used to verify liquid level of a tank as it is being filled by volume. A white vapor cloud emitted through the gauge indicates the tank is full (i.e., fluid reaches 80 percent level).

At the completion of the transfer, trapped liquid in the transport hose connection is vented to the atmosphere when the connection is broken. This can be liquid or vapor, depending on whether a compressor or pump was used for the transfer.

Emissions per single transfer
Emissions per single transfer

Common product transfer points that produce emissions are:

  • From a railcar or transport to retail storage or a wholesale customer with storage;
  • From storage to a bobtail for delivery to retail customers;
  • From bobtail to customer tanks;
  • From a dispenser to cylinders, engine fuel tanks or other small tanks.

The numbers

Although the report says no attempt was made to estimate total propane fugitive emissions, volumes are provided for each release type. The study used average propane sales by market sector from 2001-02 to estimate the number and types of deliveries made annually in the state. Based on 2004-05 data, total sales volumes in California have since grown more than 53 percent.

Emission volumes vary at different points of transfer. According to the study, transports with liquid pumps release the greatest volume per transfer at 14,000 liquid cubic centimeters (cc). A cc is a unit of volume equal to one-thousandth of a liter.

Emissions per single transfer
Emissions per single transfer

Volumes from other transfer points are: 1,082 cc’s for storage to bobtail, 475 cc’s for railcar to tank, 250 cc’s for other engine fuel, 208 cc’s for bobtail to customer tank, 200 cc’s for transports to tank using a compressor, 199 cc’s for forklift cylinders, and 199 cc’s for 20-pound cylinders.

Not all fuel transfer points occur with the same frequency, of course. For example, the high-output for transports with liquid pumps occurs relatively infrequently.

To calculate the total release, the study took the emissions per single transfer and multiplied it by the estimated times each transfer occurs per year. That formula indicates that 20-pound cylinders contribute the biggest share of total emissions (36 percent). The others stacked up this way: Other engine fuel (23 percent), forklift cylinders (22 percent), bobtail to customer tank (13 percent), storage to bobtail (5 percent), transport to tank using liquid pump (1 percent), rail car to tank (less than 1 percent), and transport to tank using compressor (less than 1 percent).

The report estimates that 85 percent of all propane fugitive emissions result from the use of fixed liquid level gauges. Of that total, 20-pound cylinder fills account for the largest percentage of emissions from spit valves at 36 percent. Other engine fuels (25 percent), forklift cylinders (22 percent), bobtail to customer tank (13 percent) and storage to bobtail (4 percent) make up the balance.

Possible solutions

Since 85 percent of propane fugitive emissions result from the use of fixed liquid level gauges, the study suggests that the industry consider further research to address several questions:

  • Can the size of the tank orifice, which has no governing standard for size, be reduced in a manner consistent with safety requirements? Changing the drill size from #54 to #66, for example, could cut spit valve emissions by 65 percent, the study says.
  • Should CETP training procedures regarding the gauges be changed? The industry’s primary employee training tool now teaches that the gauge should be open during the entire tank-filling process.
  • Can an alternative means of measuring the filling process be developed? If an alternative could be developed, emissions could be reduced by about 85 percent.

PERC President Roy Willis says those issues are being pursued.

“PERC did undertake some work to find an alternative method to measure tank fills. Essentially, the conclusion is there is nothing commercially available right now short of sonar or ultrasound. But we will continue to look at ways to address that need,” Willis says.

The CETP curriculum is designed for consistency with code requirements, and bleeder valves are required by code. Willis says the suggestion to reduce the time the gauge remains open has been shared with committee members to consider as a best practice.

He also says at least two companies already have demonstrated available technology to reduce the size of the tank orifice.

“From our perspective, it appears the private sector is capable of providing answers to any regulatory mandates that may be forthcoming. The industry has the capability to respond if it is required to do so, but it will have an economic impact on the industry and, therefore, on the price of fuel to consumers,” Willis says.

New nozzle and valve products that greatly reduce emissions also are available and slowly being put to work in the field. As part of the WPGA study, RegO, Fisher Controls, Squibb-Taylor and TODO provided lists of “low bleed” equipment now available and under development.

The cost of the new technology ranges from about $200 to $1,000. There has been discussion with several manufacturers about products in the works that would cost substantially less than that, however.

WPGA Vice President Lesley Garland says new items continue to be added to that list, which the association shares with its members. The association put up $50,000 in a rebate program to encourage propane companies to install replacement equipment the last two years. The response so far has been underwhelming.

In 2005, the association issued $14,173 in rebates to 15 different companies to pay half the cost of replacement equipment purchased. Last year, another $14,605 of the budgeted $50,000 was awarded to 20 companies. Through mid-May of 2007, just $3,189 had been distributed to five companies.

In an effort to goose participation, the state PERC recently announced that the next $10,000 in would be funded at a full 100 percent rebate rate.

Garland knows it won’t be easy to get marketers to invest in equipment that may not meet the grade of a CARB mandate down the road. But she continues to preach the importance of the issue knowing that state regulators won’t stay on the sidelines forever.

“We are doing our best to solve the situation without the government coming and telling us how to solve the problem. The more out front we can be the better off we are and the less likely they will come in and mandate something that is expensive and hard to comply with,” Garland says.

“The majority of propane companies understand that this is going to be a major issue, especially once the regulators get involved. It’s not something that is just going to go away. We talk about this issue at every board meeting and every district meeting and emphasize the importance of taking action now. This isn’t something new to them; they have been hearing about it for years.”

Political dilemma

What action, if any, should the industry as a whole take regarding fugitive emissions? The question has National Propane Gas Association officials in a delicate political posture that has stunted aggressive action.

While the outcome of the California issue could well set the stage for the rest of the nation, many marketers outside the Golden State are vocal in their opposition to making costly changes until the mandates catch up with them.

“I believe that fugitive emissions is an issue that is going to evolve in importance as more and more regulators focus on it. States that have the most aggressive regulators are aware of that issue. We are not only on the radar screen, we are in their cross-hairs,” NPGA President Rick Roldan acknowledged in a wide-ranging interview last January.

“What I fear the most is the slippery slope syndrome. We can easily talk about bulk storage. It’s a very slippery slope from remediation technology that applies to bulk storage, then pretty soon you start getting to commercial tanks, then you get to residential tanks, and before you know it, we are down to a 20-pound cylinder. That is a lot of retrofitting,” he said.

Unlike California’s rebate program, however, NPGA is not planning any kind of pre-emptive strike to head off the controversy. Roldan says he is not convinced that the best strategy is to engage the issue before CARB decides its direction. Nor is he anxious to revisit the backlash he got a few years ago over the DOT cargo tank remote shutoff issue that he tried to proactively address.

“Knowledge is knowing that fire burns; wisdom is remembering the blister. (Fugitive emissions) is an issue I might just be a little too wise on,” he admitted.

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