1. Uncertainty vs. Action
Our understanding of the winter ozone issue has many gaps. These gaps hinder our ability to solve the problem efficiently and effectively. Research is the key to overcoming this challenge. More research is needed and will be needed for many years.
BUT, we have enough information right now to make some decisions that will reduce winter ozone with little risk of wasting time and money. 1

2. What We Know and What We Don’t Know
The basic drivers that lead to wintertime ozone are known with certainty. 2

3. What We Know and What We Don’t Know
We know with certainty that almost all local organic compound emissions and a strong majority of NOx emissions are from oil and gas. 3

4. What We Know and What We Don’t Know
We know a lot about WHERE high ozone occurs and WHY it has the distribution it does (though the spatial distribution may be changing) 4

5. What We Know and What We Don’t Know
2014 Air Agencies Oil and Gas Emissions Inventory Participation
A collaboration between UDAQ, Ute Tribe, and EPA
Approximately 60 companies contacted (some letters returned, other companies no longer operating)
31 Workbooks received
Covers approximately 96% of 2014 producing or shut- in APIs in Uintah and Duchesne counties 5

6. What We Know and What We Don’t Know
We have a basic understanding of the SOURCES of oil and gas emissions.
For non-road and on-road :2014 NEI Summary (EPA website) * Couldn't find non-Winter UDAQ estimates, but within range of 2014 UDAQ Workbook estimates 6

7. What We Know and What We Don’t Know
We have a basic understanding of the SOURCES of oil and gas emissions. 7

8. What We Know and What We Don’t Know8

9. What We Know and What We Don’t Know9

10. What We Know and What We Don’t Know
Inventory Information Gaps
Reliance on national emission factors (EFs) – e.g. AP-42
Impact of composition on emission estimates
Hard to quantify categories like fugitive emissions
% Control vs. Control Efficiency
Ideal operating vs. real world operating
Equipment Types Still Absent in Inventory – Reciprocating Compressor Venting, Centrifugal Compressor venting, well testing venting and flaring, associated gas venting and flaring from prod. Hydrocarbons, EOR Injection Pump Blowdown, Gathering Pipeline Equipment Leaks, Pipeline Blowdowns, Methanol Tanks, Pigging Pipelines 10

11. What We Know and What We Don’t Know
The 2014 Air Agencies Oil and Gas Emissions Inventory is the most comprehensive oil and gas inventory for the basin to date.
But….
We still see discrepancies between bottom up inventories like ours and top-down inventories.
The reasons for the discrepancies between the two inventory approaches are not clear in many cases.
We are still unable to model high ozone levels using bottom up inventoried values. 11

12. What We Know and What We Don’t Know
We have a basic understanding of the COMPOSITION of emissions from different oil and gas sources.
Key areas of poor understanding:
Composition information is generalized and not tested against field measurements
Composition information about carbonyls (e.g., formaldehyde) and methanol is very poorly understood, even though these are very important ozone precursors 12

13. What We Know and What We Don’t Know
We don’t have a good understanding of whether inventoried NOx emissions are too high or too low.
Competing modeling studies make both claims. 13

14. What We Know and What We Don’t Know
The best estimates made so far indicate that reducing emissions of NOx and organics would both be effective, but this has never been done basin-wide.
Edwards et al., 2014 14

15. What We are Learning About Right Now
Emissions
Investigations of several different source types
Produced water
Subsurface leaks
Well sites (detailed emiss. composition)
Fugitive emissions from tanks
(particular focus on methanol and aldehydes)
High-density organic compound measurements—coupled with modeling—to verify inventory at fine scale
Investigating inter-annual changes in ambient NOx and organics
Investigating snowpack processing of organics 15

16. What We are Digging Into Right Now
Modeling
Improving accuracy of meteorological and chemical models with data assimilation (ground-based and satellite data)
Incorporating new measurement data into inventory and model (including composition)
Verifying models using ground-based and satellite measurement data
Developing methods for ozone forecasting 16

17. Links
DAQ
All of UDAQ’s research products to date:
Summary of all of the Uinta Basin Winter Ozone Studies (UBWOS) completed in the Basin from
UDAQ’s main Uinta Basin page, including links to the oil and gas emissions inventory
Ulend camera lending program page:
USU
All of USU’s research products to date:
Cumulative summary of all UB air quality research to date (including other institutions):
Ozone Alert sign-up page:
Map view of all available real-time air quality data in UB: 17