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Pinedale Online > News > March 2011 > Ozone and SCRs

SCR System. Photo by Johnson Matthey.
SCR System
This photo shows three Johnson Matthey emissions control systems installed on top of three caterpillar diesel engines on a Shell drill rig in the Pinedale Anticline. The diesel engines are in the white boxes. The gray devices on top are the SCR systems, one on top of each diesel engine. Photo courtesy Johnson Matthey

Ozone Alert days. Photo by Pinedale Online.
Ozone Alert days
Between February 28 and March 18th, Wyoming DEQ issued 10 Ozone Advisories for the Upper Green River Valley.

Sublette Ozone 2005-2010. Photo by EPA.
Sublette Ozone 2005-2010
Sublette Monthly Ozone 2005-2010 (Editor's Note 3/24/11: This graphic has been replaced. The graphic in our original story had an incorrect graphic for the 2008 year data. We have corrected this graphic with the correct 2008 plot. We apologize for the error.) Source: Individual data charts compiled by Pinedale Online into a composite display for Sublette County.
Ozone and SCRs
by Dawn Ballou, Pinedale Online!
Original post March 19, 2011 | Modified March 24, 2011

Editor's Note, 3/20/11: We have modified this article to add reader's comments. Scroll to the end of the article to read these comments. Editor's Update 3/24/11: We have modifed this story to replace the EPA AQI data graphic which had an incorrect chart for 2008. The graphics accompanying this story were added by Pinedale Online and were not a part of the original DEQ media release. We apologize for the error. - Dawn Ballou, Editor, Pinedale Online!

3/19/11 - Original article

Recently, questions have been asked about elevated ozone episodes in the Upper Green River Valley and why SCR devices aren’t required on all the natural gas drill rigs operating in the natural gas fields south of Pinedale.

SCR devices (Selective Catalytic Reduction) use a process which can reduce nitrogen oxides from diesel engines from 70 to 95%. Currently some, but not all, of the rigs operating in the Pinedale Anticline and Jonah Field are outfitted with these devices, which has caused questions of why rigs are being allowed to operate without these devices in light of the repeated occurrences of high ozone levels in the Upper Green River Valley.

Pinedale Online asked the Wyoming Department of Environmental Quality and Pinedale Bureau of Management office for clarification on this topic.

Below is the response from the Air Quality Division of the Wyoming Department of Environmental Quality.

"While SCR is an applicable control technology for lean burn natural gas fired engines, the drill rigs that are powered by natural gas fired engines already incorporate low NOx emitting technology.

EnCana is the only company currently using natural gas fired engines to power their drill rigs. These engines NOx controls meet current best available control technology (BACT) requirements.

First a little background on diesel engines. These engines are regulated by the EPA under the Non-road Diesel rule. Basically, these engines move around and are not considered stationary sources. The Wyoming Air Quality Standards and Regulations apply to stationary sources only. Therefore, unless a non-road engine changes its method of operation to become a stationary source, the Air Quality Division has very limited authority to regulate these engines. The Division has reviewed how the drill rig engines are used and, to date, they are not considered a stationary source.

However, the Division has worked cooperatively with industry to issue drill rig permits for companies operating in the Jonah Pinedale Development Area (JPDA). Given our limited authority, we did not have the ability to dictate when the controls will be installed. We worked with each company to develop a schedule that meets their business needs. By January 1, 2012, all diesel rigs operating in the JPDA will be equipped with SCR or limited in use. It is our understanding that there are drill rigs powered by diesel engines operating in the February/March 2011 timeframe without SCR control. We won’t know the exact count until we get the winter inventory, which is due in June.

Right now, the permitting requirements only apply to the JPDA. Control requirements for new drill rigs in the JPDA will be evaluated on a case-by-case basis."

Here is the response from Shelley Gregory, Public Affairs with the BLM Wyoming High Desert District:
Question: Considering the issues with elevated ozone levels in the Upper Green River Valley for several years now, and BLM controls the contractual stipulations in the leases these companies bid on, I am wondering why the BLM does not require that SCR devices be placed on all drill rigs operating in the Upper Green River Valley before allowing them to go into operation?

BLM Answer: "Lease stipulations cannot be modified after the fact except through the waiver, modification or exception process. This process however, does not allow the addition of new stipulations to the lease contract. Regarding your question about future stipulation of SCR devices on all drill rigs, you have posed a very good question and it is one that we will evaluate in our continuing conversations with DEQ."

Question: Would you please confirm if there are/were natural gas drilling rigs operating in the Pinedale Anticline in February/March 2011 timeframe that do NOT have SCR devices on them to reduce ozone emissions, and if so how many, compared to the total rigs operating then and the ones that are outfitted with SCRs?

BLM Answer: There are currently 16 diesel fired rigs operating on the Pinedale Anticline, 11 of these do not currently have SCRs installed on the diesel engines."

Question: Which companies were allowed to put up rigs without these devices and why did the BLM and DEQ give the OK to them to operate without them?

BLM Answer: "Two of three companies currently drilling are operating diesel fired rigs which do not have SCR installed on all rigs in their fleet. When the Operators engaged DEQ regarding a permitting process to manage emissions from the rigs, a schedule was put in place for installation of SCR. The majority of these diesel fired rig permits have a January 1, 2012 deadline. It is our understanding that this was allowed due to the limited availability of the SCR technology. However, for specifics regarding the permits we must refer you to DEQ who has regulatory oversight for these permits."

Question: For the future, will the BLM and DEQ be allowing any new natural gas drilling rigs to operate in the Pinedale Anticline/Upper Green River Valley without being outfitted from the start with SCR devices to reduce ozone producing emissions? If so, why?

BLM Answer: "It's uncertain whether we can answer this question at this point. A commitment of the SEIS proponents (USQ) was that at a minimum Tier II diesel engines would be used in developing the resources of the Anticline. If an Operator who was not a proponent of the SEIS were to submit APD’s, their application would be evaluated through the NEPA process and the additional air quality mitigation identified in the ROD would be evaluated. It is our understanding that any Operator within the Jonah and/or Anticline is required to obtain a drilling rig permit from DEQ so this would also be addressed at that time.

As it stands now, 15 diesel engines on 5 rigs are outfitted with SCR. All of the remaining engines on the eleven rigs are Tier II as required by the ROD. These remaining engines will be outfitted with SCR no later than January 1, 2012 as required by their DEQ permits. The SCR technology has been purchased by the Operators but delivery is pending completion of the manufacturing of the required components."

We understand the concern of the public as it relates to the recent exceedances and we share these same concerns. Furthermore, the issue is, as you indicated, very complex. In 2005 when the initial exceedances occurred, there were over 60 uncontrolled (Tier 0) rigs operating in the basin, and produced liquids and condensate were being transported from individual well locations. The exceedence events we have seen of late are in spite of fact there are only 21 rigs operating in the basin, all of the rigs employ Tier II or higher emission reduction technology, and the emissions from production related facilities and associated truck traffic in the Jonah and the Anticline are significantly reduced as the Liquids Gathering System on the Anticline and centralization of production facilities in Jonah have come online.

As a result of these and other measures, the operators on the Anticline have reduced their NOx and VOC emissions to below 2005 levels and Jonah operators have achieved similar reductions. With this in mind, we are trying to understand these latest exceedances in light of this information and the fact that we have had "normal" winter conditions which have not been seen in the last couple of years. We are in discussions with both the DEQ and EPA regarding the exceedances experienced recently.

Ozone modeling, as required by the SEIS ROD, is progressing in concert with our discussions with EPA and DEQ. The intent of the modeling is to determine the sensitivity of ozone formation to NOx and VOCs. This sensitivity analysis will inform the agencies as to which constituent we should target for additional mitigation.

While we are trying to determine whether or not, and to what extent, there is a direct one to one correlation with recent events and Jonah and Anticline operations, we are committed to working to achieve additional emission reductions from our federally regulated operations within the entire UGRB."

Reader Comments

Sunday, March 20, 2011: "Nice write up on rig engines, but that issue has always been a red herring. Seems like the smog issue is becoming really bad after a few better years following the bad 2008 season. As was pointed out by your interviewees, Encana uses gas fired rig engines considered to be the Best Available Tecnology (BACT) and there aren't the number of rigs there have been anyway. If you may recall from the DEQ meeting at Rendezvous Pointe in April 2008, one DEQ presenter stated that he found it "interesting" that they had detected several of these types of VOC molecules. I asked him about that later individually and it was my understanding that these VOC precursors to ozone cannot possibly be emitted from internal combustion engines. Basically, there are complex hydrocarbons (VOC's) that are much more powerful in forming ozone the same way that methane is a much more powerful greenhouse gas than carbon dioxide. In other words these compounds are being emitted from the Operators' completions and production locations, whether from a flowback tank, a reserve pit, or are otherwise vented off without being flared or combusted. You may recall that Encana has spent $$ installing combustion units on production locations. Anyhow, the real common denominator between the earlier smog events (2008 for example) and now is the price of energy. Look it up. Anyone can tell you things really slowed down out in the patch after the recession hit, do you really think $3.50 gas and smog are unrelated, that they are a coincidence? The bottom line seems to be that despite good DEQ forecasts and despite implementing all their mitigation measures for ozone, we have seen readings in excess of 120 ppb for 8 hour ozone. Keep in mind that in all their NEPA planning documents the BLM and the Operators stated they anticipated NO violations of applicable air quality standards. The reprehensible part is that it is the price of energy, and not the Operators' mitigation measures or the BLM or DEQ, that TRULY determine whether we have a really bad smog season or not. " – Pinedale resident

Sunday, March 20, 2011: " ...gasoline prices ... are a good indicator of how the larger energy markets are running. The scary part is that they really haven't got those two fields close to completed (remember the Anticline SEIS was another 4,400 wells) and we're STILL having huge problems! Put another way, energy prices and pipeline capacity are NOT at optimum levels for production, current projects aren't even close to completion and we have other major fields in the Upper Green that are contemplated but not approved yet, DEQ can predict events, Operators say they are mitigating and yet....... 8 hour readings close to DOUBLE the limit and day after day of warnings. The big thing with natural gas from here is that its price is also largely a function of pipeline capacity, and that is changing rapidly. Remember that atmospheric inversion is the meteorological key to what is happening here, so it would be like trying pouring water into a pot but the lid is already on." – Pinedale resident

Sunday, March 20, 2011: "If BLM were to require SCR on rigs (or equipment to eliminate blowdown venting to atmosphere etc.), it would probably be as a Best Management Practice / Condition of Approval to an APD. They could even use their Adaptive Management powers to add such requirement to the PAPA ROD. If they wanted to :) SCR is good for lots of gas and diesel engines -- the big compressor stations, the Schlumberger frac units. Evolution is slow." Pinedale resident

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Related Links
  • Sublette County Ozone Discussion March 22 - March 18, 2011
  • What kind of conditions contribute to an ozone advisory? - March 16, 2011
  • Sublette County Commission responds to ozone concerns - March 16, 2011
  • Ozone readings hit 153PPB in Boulder March 1st - March 2, 2011
  • Ultra, Shell and QEP Energy implement ozone contingency plans - February 28, 2011
  • Screening Health Risk Assessment for Sublette County available - February 23, 2011
  • New system helps control NOx for Shell drill rigs - October 28, 2008
  • Pinedale Online > News > March 2011 > Ozone and SCRs

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