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A Better Way to Estimate Emissions from Oil and Gas Operations Dr. Susan Stuver Research Scientist 10/10/2013 Energy, Air & Water A Comprehensive Study of the Issues of Today UNIVERSITIES HEALTH SCIENCES AGENCIES Problem Statement Solution Policy without Data Conservative data assumptions leads to over estimation – assume 100% engine load and 24/7 operation times Measure Equipment Emissions Engine load data and activity times would make estimates more realistic Calculations Based on Outdated Standards US Regulators use the USEPA AP-42 Standards that assume worst possible emissions Use Engine Emission Factors Use EPA certified tiered engine emission factor data from engine manufacturers 3 Max Regional 8-hr Ozone Impact derived from worst case estimates Wind Direction from Eagle Ford into San Antonio Texas 4 CALCULATION – the old fashioned way… So, 2,250 hp Pump truck deck engine and 12 pump trucks engines are used for the hydraulic fracturing process 2,250 hp/pump truck engines x 12 pump truck engines = 27,000 hp ENOx = 2.4 x 10-02 lb NOx/hp-hr x 27,000 hp x 1 = 648 lb NOx/hr Hey – who messed up the math? ENOx = EF x HP x LF Where, ENOx = NOx Emissions (lb/hr) EFNOx = NOx Emission Factor (lb NOx/hp-hr)No Emission Controls are assumed HP = Total power output (hp) LF = Load factor-100% assumed 5 Vehicles Mobile Command Center Crane (large) - Operating Engine Pickup Trucks Equipment Light Tower (mobile) Bulldozer Backhoe Generator - Cooling Room Make/Model SMT 503 Mobile Monitoring Unit ATC3200 GMC 2500 HD Make/Model RL4000 TR95 w/Engine 420D Model QAS25 Fuel Diesel Diesel Gasoline Rating 210 hp 517 hp 360 hp Fuel Diesel Diesel Diesel Diesel Number 1 1 2 Rating 13.6 hp 99 hp 88 hp 29.6 hp Number 6 1 1 1 6 EMISSION GROUP RANKING SYSTEM RANK 1 Largest Sources - EX: Pump Trucks (Fracturing/Perfing) RANK 2 Medium Sources - EX: Fracturing Water Pumps RANK 3 Small Sources - EX: Light Carts 7 There are 7 of them - Using worst case can cause huge variation 8 GPSA Engineering Data Book (2004)6 and Carl Branan’s Process Engineer’s Pocket Handbook (1984)7 provides the equation BHp = Q x ∆P/1714(e) Where, BHp Q ∆P 1714 (e) = Required brake horsepower = Fracturing fluid flowrate (gal/min) = Pump discharge – Pump suction (inlet pressure) (psi) = Conversion factor (convert to BHp) = Pump efficiency = 90% (see Note) Note 1 – Inlet pressure was not recorded so it is conservatively assumed to be zero (psi) Note 2 - The combination of mechanical and volumetric efficiency is normally 90% or higher for non-compressible fluids (GPSA Engineering Data Book, 2004)8 9 BHp = Q x ∆P/1714(e) BHp = ((65 bbl/min x 42 gal/bbl x (6000 psi – 0 psi))/1714)/(0.90)=10,618 Bhp LF= BHp and divide it by full horsepower. Full horsepower is obtained by the engine HP times the number of engines. LF = 10,618 Bhp/(2250 hp x 12 engines = 27,000 hp) = 39.2% while the engine was under load. 10 2,250 hp Pump truck deck engine and 12 trucks Epoll = EF x P x N x LFA Where, Epoll = Emissions for pollutant EF = Emission factor in lb/hp-hr P = Brake horsepower in hp N = Number of units LFA = Load factor Average (39% for 7.5hr and 15% for 4.5hr) So, Nox = 108.5 lb Nox/hr AP-42 factors with 100% estimated load = 648 lb Nox/hr that’s 539 pounds per hour difference. 539 lb/hr x 12 hour day = 6,468 pounds (3.2 tons) per day for 1 frac job ENOx = (1.34 x 10-02lb/hp-hr x 2250hp/eng x 12 eng) x 39% x 7.5 hr/day + 15% x 4.5 hr/day 12 hr/day 11 Lets compare the results • Nox AP42 100% LF = 648 lb/hr • Nox Tier Eng LF Avg = 108.5 lb/hr • VOC AP42 100% LF = 19 lb/hr • VOC Tier Eng LF Avg = 5.7 lb/hr • CO AP42 100% LF = 149 lb/hr • CO Tier Eng LF Avg = 20 lb/hr • PM/PM10 100% LF = 19 lb/hr • PM/PM10 LF Avg = 1.6 lb/hr • 539 lb/hr • 12 hour day = 6,468 pounds (3.2 tons) per day for 1 frac job • 2000 frac jobs = 6,400 tons of emissions that are not really there. 12 Tier IV engines would be much lower Are actually measured in grams (not pounds) per hour 13 14 ENOx = EF x HP x LF Using engine load is not realistic Too much variance – need an entirely new way to estimate Conceivable to use • • • • total fuel consumption, brake specific fuel consumption diesel density tier rated emissions to estimate emissions from a job 15 Assume a drilling operation uses 5,000 gallons of diesel per day for 5 days And Assume we know the BSFC is 0.35 lb/bhp-hr And Assume we know that diesel density is 7 lb/gallon And Assume we know the engines are Tier 1 – 6.9 g/hp-hr for Nox And we want to estimate NOx Emissions Note: numbers aren't actual Calculating Hp-hr/job = (fuel for job, gallons) X 7 lb/gal = 500,000 Hp-hr/job 0.35 lb/bhp-hr Tons = Hp-hr/job x tier rated emissions g/hp-hr x 1/454 g/lb x 1/2000 lb/ton Nox Tons = 500,000 hp-hr/job x 6.9 g/hp-hr x 1/454 g/lb x 1/2000 lb/ton = 3.8 tons This will be compared to the traditional method: ENOx = EF from AP42 x total HP x 100% LF X 100% activity And backed up with measurements to validate 16 No engine certification for emission factors Emission Reduction Potential Not Recognized engines are currently being loaded into the regional air shed model as diesel Measurement of emission reduction is needed. We are securing study sites to quantify the emissions reduced by switching to bifuels, dual fuels and /or NG 17 Remote Monitoring with Low Cost Sensors 18 Wireless Data Networking 19 Advanced Analytics for Fugitive Sampling There's no protocol for the use of relatively new technology in oil and gas operations 20 Water Screening Kits Education and Outreach Temporary Roads Fugitive Emissions Invasive Species Adv. Analytics Produced Water Trmt Stray Gas Livestock Impacts Soil Impacts Managing Misinformation Wireless Data Loggers Aggie Pigeon 22