Results

Adams, T., Hart, M., & Schwartz, A. (2013). Transportation impacts of frac sand mining in the MAFC Region: Chippewa County case study. National Center for Freight & Infrastructure Research & Education. Chase, T. (2014, July 13). As rail moves frac sand across Wisconsin landscape, new conflicts emerge. WisconsinWatch.org. EPA. (2004).Unit conversions, emissions factors, and other reference data. [Brochure]. http://www.epa.gov/cpd/pdf/brochure.pdf. Griffin, M., Hendrickson, M., Jaramillo, P., & Venkatesh, A. (2011, August 5). Life cycle greenhouse gas emissions of Marcellus Shale gas. Environmental Research Letters, 6. doi: 10.1088/1748-9326/6/3/034014. MacKay, D.J.C., & Stone, T.J. (2013, September 9). Potential greenhouse gas emissions associated with shale gas extraction and use. UK Dept. of Energy and Climate Change. Northern Industrial Sands. (2012). Permit Application and Supplemental Document. O’Sullivan, F., & Paltsev, S. (2012, November 26). Shale gas Production: Potential vs. actual greenhouse gas emissions. Environmental Research Letters, 7, 1-5. DOI: 10.1088/1748-9326/7/4/044030. U.S. Silica. (2013). U.S. Silica 2012 Sustainability Report. http://www.ussilicasustain.com/US_Silica_2012_Sustainability_Report.pdf Wisconsin Department of Natural Resources. (2012,). Silica Sand Mining in Wisconsin.

Introduction / Background Hydraulic fracturing is a method of oil and gas extraction that is rapidly emerging as one of the largest sources of energy around the globe. It involves the use of a highly pressurized

Methods The life-cycle of silica sand was divided into two parts: Production (mining & processing) and Distribution (transportation from Wisconsin to wells across the nation.) This research did not include any emissions that occur after the delivery of silica sand to the well. I. Production The permits of the 143 active silica sand facilities in Wisconsin were searched for GHG data. It was noted that the facilities that provided some emissions data only provided data from two processes: sand blasting and sand drying. Since there are dozens of other processes that occur on-site, the facility-reported emissions data was adjusted based on an extensive document from Northern Industrial Sands (NIS) that provided hard data on the hours of equipment used annually (bull- dozers, backhoes, etc.) and the annual mileage traveled (haul trucks, water tanks, etc.) CO2e emissions per year were calculated (Equations 1 & 2). A percent increase between what NIS reported in their permit and what was calculated from their separate raw data was applied to the other facilities’ data and extrapolated statewide. Low and high estimations were used wherever possible. II. Distribution The CO2e emissions from distribution were calculated using two widely cited values of silica sand output from Wisconsin: 26 million tons (Chase, 2014) and 40 million tons (Adams et al., 2013). It was assumed that these silica sand tonnage values were distributed equally to the top five silica sand consuming states: Texas, Louisiana, states: Texas, Louisiana, Colorado, Ohio, and North Dakota (National Center for Freight & Infrastructure, 2014). It was assumed that transportation was carried out by rail (70%) and truck (30%) (U.S. Silica, 2013). Rail and truck specific CO2e rates with a fuel emissions factor of 0.011185 ton CO2 / gal (EPA, 2004) were used to calculate total emissions from distribution (Equations 3 & 4).

Conclusions The answers to the research questions are as follows: 1. Calculated GHG emissions from the proppant life-cycle totaled 4.5

million TPY, which is equivalent to the annual emissions of over 860,000 passenger vehicles.

Acknowledgements

References

I would like to profoundly thank University of California, Santa Barbara, for providing me with the skills necessary to complete this project, as well as NASA for giving students the exciting opportunity to present their research in a professional setting.

Climate Change and Hydraulic Fracturing Proppants: Calculating the CO2e Emissions from Silica Sand Production in Wisconsin

Natalia Nelson

Research Questions 1. What numerical quantity of carbon dioxide equivalent (CO2e) emissions is released from

the production and distribution of silica sand proppant? 2. How do these emissions compare to life-cycle CO2e emissions of hydraulic fracturing? 3. Should proppant production be included in future CO2e life-cycle assessments of

hydraulic fracturing?

mixture of water, proppants, and chemicals to fracture deep underground rock formations and release oil or natural gas. Each well requires thousands of tons of proppants, most commonly silica sand, to “prop” open the induced fractures. In the past decade, the production of silica sand has grown into a massive industry, with Wisconsin leading the production boom due to its ancient quartz geological formations. Silica sand is mined, processed, and distributed from Wisconsin to hydraulic fracturing wells across the nation. Numerous life-cycle assessments have been conducted on hydraulic fracturing greenhouse gas (GHG) emissions, but life-cycle emissions from proppant production are absent from scholarship. This research aims to fill this unstudied gap in the relationship between hydraulic fracturing and climate change, as GHG emissions from energy-intensive processes must be drastically reduced in order to sustain a healthy planet.

Mining Processing Transportation

Equation 1: NIS Hourly Data CO2e Emissions

ℎ𝑜𝑢𝑟𝑠 𝑜𝑓 𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝑢𝑠𝑒

𝑦𝑒𝑎𝑟 𝑥

𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑔𝑟𝑎𝑚𝑠 𝐶𝑂2𝑒

ℎ𝑜𝑢𝑟𝑥

𝑡𝑜𝑛

𝑔𝑟𝑎𝑚=

𝑡𝑜𝑛 𝐶𝑂2𝑒

𝑦𝑒𝑎𝑟

Equation 2: NIS Mileage Data CO2e Emissions

𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝑡𝑟𝑖𝑝𝑠

𝑦𝑒𝑎𝑟𝑥

𝑓𝑒𝑒𝑡

𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝑡𝑟𝑖𝑝𝑠 𝑥

𝑚𝑖𝑙𝑒

𝑓𝑒𝑒𝑡𝑥

𝑔𝑎𝑙𝑙𝑜𝑛𝑠 𝑓𝑢𝑒𝑙 𝑢𝑠𝑒𝑑

𝑚𝑖𝑙𝑒𝑥

𝑡𝑜𝑛 𝐶𝑂2𝑒

𝑔𝑎𝑙𝑙𝑜𝑛 𝑓𝑢𝑒𝑙 𝑢𝑠𝑒𝑑=

𝑡𝑜𝑛 𝐶𝑂2𝑒

𝑦𝑒𝑎𝑟

CO2e Emissions from Silica Sand Production & Transportation in Wisconsin

(1) Production

Facility Reported Emissions

NIS Case Study Calculated Emissions

Hourly Data

Percent Increase in Emissions

Adjusted Facility Emissions

Total CO2e Emissions

Traffic Data

(2) Distribution

Rail

Combined Rail & Truck Distribution Emissions

Truck

Methods Continued Equation 3: Rail Transportation CO2e Emissions

𝑚𝑖𝑙𝑒𝑠 𝑡𝑜 𝑑𝑒𝑠𝑡𝑖𝑛𝑎𝑡𝑖𝑜𝑛 𝑥𝑔𝑎𝑙𝑙𝑜𝑛𝑠 𝑑𝑖𝑒𝑠𝑒𝑙 𝑓𝑢𝑒𝑙 𝑢𝑠𝑒𝑑

𝑚𝑖𝑙𝑒 𝑥 𝑡𝑜𝑛 𝐶𝑂2𝑒 = 𝑡𝑜𝑛 𝐶𝑂2𝑒

Equation 4: Truck Transportation CO2e Emissions

The flowchart at right is a graphic summary of the steps used to calculate total CO2e emissions from the production and distribution of silica sand proppant in Wisconsin. III. Total Calculated GHG emissions from production and distribution were added together. The total tonnage was converted to emissions per ton of silica sand produced. This value was compared to three previously conducted life-cycle assessments of hydraulic fracturing GHG emissions: Griffin et al. (2011), MacKay & Stone (2013), and O’Sullivan & Paltsev (2011). Assuming the average well requires 2,500 tons of proppant (U.S. Silica, 2013; Wisconsin Dept. of Natural Resources, 2012), the calculated life-cycle CO2e emissions per ton of silica sand produced was compared to the three studies to estimate the percent increase that would occur if proppant production was included in future hydraulic fracturing life-cycle assessments.

I. Production Out of the 143 active silica sand facilities in Wisconsin, only 28 (20%) provided CO2e emissions data in their permits (Graph 1), which illustrated the lack of facility GHG data publicly available. It was calculated that facilities’ emissions data were approximately 5 – 11% higher than reported (Table 1), as NIS reported a value of 27,460 ton CO2e emissions per year (TPY) in their permit but low and high values of 28,880 TPY and 30,465 TPY were calculated based on the data they provided in their document. This corresponded to adjusted facility average emissions value of 33,410 TPY -35,318 TPY. Statewide, it was found that the silica sand industry in Wisconsin emits approximately 3.3 million TPY. II. Distribution It was calculated that distribution of silica sand from Wisconsin to hydraulic fracturing wells across the nation emitted 936,356 TPY – 1,440,349 TPY. It was found that rail transportation is 3 times more efficient.

Results Continued III. Total It was calculated the CO2e emissions from Production (75% of total) and Distribution (25% of total) statewide totaled ~4.5 million TPY (Table 2), which corresponded to a value of 0.10-0.19 tons CO2e released in the life-cycle of one ton of silica sand proppant. When compared to the three previously conducted assessments of the hydraulic fracturing life-cycle, it was found that proppant CO2e emissions compose 5-34% of total hydraulic fracturing CO2e emissions (Table 3).

Table 2: Summary of Silica Sand Proppant Production and Distribution CO2e Emissions in Wisconsin (TPY)

Lower Estimate Upper Estimate

Production 3,247,452 3,432,910

Transportation 936,356 1,440,349

Total 4,183,808 4,873,259

𝑡𝑜𝑛𝑠 𝑠𝑎𝑛𝑑 ℎ𝑎𝑢𝑙𝑒𝑑 𝑥 𝑚𝑖𝑙𝑒𝑠 𝑡𝑜 𝑑𝑒𝑠𝑡𝑖𝑛𝑎𝑡𝑖𝑜𝑛 𝑥𝑔𝑎𝑙𝑙𝑜𝑛𝑠 𝑑𝑖𝑒𝑠𝑒𝑙 𝑓𝑢𝑒𝑙 𝑢𝑠𝑒𝑑

𝑡𝑜𝑛 𝑚𝑖𝑙𝑒𝑠 𝑥

𝑡𝑜𝑛 𝐶𝑂2𝑒

𝑔𝑎𝑙𝑙𝑜𝑛𝑠 𝑑𝑖𝑒𝑠𝑒𝑙 𝑓𝑢𝑒𝑙 𝑢𝑠𝑒𝑑= 𝑡𝑜𝑛 𝐶𝑂2𝑒

Table 1: Summary of Calculated CO2 Emissions Data and NIS Provided Data (TPY)

Facility-Reported Data Calculated Estimate

Blasting 149

Sand Dryer 27,311

Total 27,460

Calculated Emissions Data Lower Estimate Upper Estimate

Calculated Hourly Data Totals 345 494

Calculated Traffic Data Totals 1074 2510

Total Additional Emissions 1419 3004

Total Estimated Emissions (Facility-Reported + Calculated)

28,880 30,465

Percent of Total Emissions Added 5% 11%

Table 3: Summary of Percent Increase in Overall Hydraulic Fracturing Emissions due to Silica Sand Production

Authors Scope Finding (t CO2e per well)

Percent Increase in Emissions of Silica Sand Production (Lower and Upper Estimates)

O’Sullivan & Paltsev (2011)

Least extensive 1,378 19% 34%

Griffith et al. (2011)

Extensive 5,500 15% 27%

MacKay & Stone (2013)

Most extensive 4,887 5% 10%

27

53

108

28

Graph 1: 143 Facilities' GHG Data from Permits

Unidentified by AirPermit Search ToolIdentified; No records

Identified; Records; NoCO2e Emissions DataIdentified; Records;CO2e Emissions Data

2. If proppant CO2e emissions were included in life-cycle analyses of total hydraulic fracturing emissions, findings would increase by 5-34%.

3. GHG emissions from proppant production should absolutely be included in future life-cycle assessments of hydraulic fracturing. A 5-34% increase is extremely significant for scientists, policy-makers, and the public to make crucial decisions about energy production.

Suggestions for emissions reduction include: decrease the distance between the mining and processing sites, upgrade equipment efficiency, switch transportation from truck to, and research the feasibility of recycling proppants after well injection. Additionally, there is a lack of data surrounding proppants and GHG emissions and it is recommended that long-term CO2e monitoring systems be set in place in order for scientists to have access to quantitative data. Climate change is one of the greatest challenges faced by the human race, and with carbon-intensive hydraulic fracturing and subsequent proppant production rapidly expanding, this research is only one of many future studies that should be conducted to fully quantify and ultimately reduce the GHG emissions for the benefit of the planet and its inhabitants.