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Maximizing Tennessee Gas Supplies in the PNG System

Zachary Shirk

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Overview• Objectives

• Assumptions

• Strategy

• Honesdale and Milford demand

• Low/high demand scenarios

• Calculator comparison

• Historical data comparison

• Cost Analysis

• Conclusions

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Objectives– Optimize supply from high pressure systems of

Wilkes-Barre/Scranton area (Uniondale, Saylor, Hunlock)

– Use the Tennessee Swap Calculator to help supply predict the

maximum amount of Tennessee & Gibson gas in PNG (Tennessee

gas is currently the most inexpensive supply)

– Help supply make economic decisions for daily and monthly setups

based on results

– Compare to historical data to see how well the calculator is utilized

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Map of PNG Swap Area

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Assumptions• Total Tennessee demand = Uniondale + Honesdale + Milford• Total Wilkes-Barre/Scranton Demand = Uniondale + Gibson + Saylor +

Wyoming + Hunlock• UGI Hunlock Power Plant, Allegheny Power Plant, PEI Plants, and Procter

and Gamble removed from Total System Demand and calculations• High alarm limits for Saylor South System can be adjusted, pipes are able

to run at higher pressures• Low alarm limits followed• Interruptible customers kept on• Uniondale and Lackawanna always kept at MOP (282 PSIG)• Transportation customer demands are evenly distributed throughout the

system

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Strategy• Find the pressures at Uniondale, Saylor, and Hunlock that allow the

maximum possible amount of gas to be taken from Tennessee

• Two-step graph is needed to accurately model Uniondale demand vs. total PNG demand

• Low demand scenarios– Keep Hunlock and Saylor off as long as possible, Uniondale supplies the whole

WB-S area

• High demand scenarios– Saylor and/or Hunlock must be turned on, Uniondale demand increases

nonlinearly with total PNG demand

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Honesdale and Milford Demand• Total Tennessee demand = Uniondale + Honesdale + Milford• Estimates Demand for Honesdale and Milford from Historical data

relative to total system demand• Old calculator used data from 2010, updated with data from 2014

– Old equation: y=0.0201x– New equation: y=0.0174x

• Minimum historical sendout = 314 Dth• If calculated sendout is less than 314, 314 is used instead

0 50000 100000 150000 200000 250000 300000 350000 4000000

1000

2000

3000

4000

5000

6000

7000

f(x) = 0.0174436528284647 xR² = 0.974696633462065

Total PNG Demand – PEI – Auburn (Dth/d)

Hon

esda

le/M

ilfor

d D

eman

d (D

th/d

)

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Low Demand Scenario• Used for Demand under 80,376 Dth/day• Uniondale vs. total demand below line is hard to predict• Total WB-S demand = total Uniondale at low system demands

Degree Days

Total PNG Demand (Dth/d)

Uniondale Demand (Dth/d)

Uniondale Percent

0 46,080 19,553 42.4%

2.5 56,495 27,370 48.4%

5 66,910 35,188 52.6%

7.5 77,325 43,005 55.6%

10 87,740 50,822 57.9%0 10000 20000 30000 40000 50000 60000 70000 80000 90000 1000000

10000

20000

30000

40000

50000

60000

f(x) = 3.39561092095284E-06 x² + 0.288078080613093 xR² = 0.999709811676274

Uniondale Vs. Total PNG Demand

Calcula-tor (from Syn-erGEE)Polyno-mial (Calcula-tor (from Syn-erGEE))

Total PNG Demand - P&G - PEI - Allegheny (Dth/d)

Unio

ndal

e M

axim

um D

eman

d (D

th/d

)

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Accuracy of Calculators for Low Demands

• July 4, 2014 – Total PNG Demand: 28,358 Dth– Historical Uniondale: 10,055 Dth– Historical WB-S Demand: 14,505 Dth– Old: 11,241 Dth (22.5% under WB-S demand)– New: 10,904 Dth (24.8% under WB-S demand)

• July 26, 2014 – Total PNG Demand: 31,899 Dth– Historical Uniondale: 13,751 Dth– Historical WB-S Demand: 14,987 Dth– Old: 12,972 Dth (13.4% under WB-S demand)– New: 12,649 Dth (15.6% under WB-S demand)

• Large margin for improvement of accuracy on lower end of calculator, find a better equation to fit data

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Better Fit for Low Demands• Replace equation with 3rd order polynomial fit for WB-S Data• Uniondale demand should equal WB-S demand• New equation intercept: 82,583 Dth

Degree Days

Total PNG Demand (Dth/d)

Uniondale Demand (Dth/d)

Uniondale Percent

0 46,080

23,803 51.7%

2.5 56,495

29,977 53.1%

5 66,910

36,385 54.4%

7.5 77,325

43,001 55.6%

10 87,740

49,301 56.2%0

1000

020

00030

000

4000

050

000

60000

7000

080

000

9000

0

1000

000

10000

20000

30000

40000

50000

60000

70000

80000

f(x) = − 3.98507733229606E-12 x³ + 1.75764417806089E-06 x² + 0.444027748813349 x + 1R² = 0.991957633910871

WB-S Demand Compared to Calculator

Cal-cu-lator (from SynerGEE)

Total PNG Demand - P&G - Allegheny - PEI (Dth/d)

Unio

ndal

e/W

B-S

Dem

and

(Dth

/d)

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Re-evaluating Accuracy at Low Demands

• July 4, 2014 – Total PNG Demand: 28358 Dth– Actual Uniondale Sendout: 10,055 Dth– WB-S Demand: 14,505 Dth– Calculator’s Prediction: 14,365 Dth (1% below WB-S demand)

• July 26, 2014 – Total PNG Demand: 31,899 Dth– Actual Uniondale Sendout: 13,751 Dth– WB-S Demand: 14,987 Dth– Calculator’s Prediction: 15,823 Dth (5.6% above WB-S demand)

• New fit significantly improves calculator’s prediction for Uniondale/Gibson sendout

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High Demand Fit• For any total system demand over intercept at 82,583 Dth/day• As total PNG demand gets higher, more supply has to come from Saylor

Degree Days

Total Demand (Dth/d)

Uniondale Demand (Dth/d)

Uniondale Percent

15 108,569 59,463 54.7%

20 129,399 67,387 52.1%

25 150,229 74,126 49.3%

30 171,058 80,551 47.1%

35 191,888 86,289 45.0%

40 212,718 91,831 43.2%

45 233,547 95,562 40.9%

50 254,377 99,800 39.2%

55 275,207 103,908 37.8%

60 296,036 107,675 36.4%

65 316,866 110,932 35.0%

66 321,032 111,666 34.8%

0 50000 100000 150000 200000 250000 300000 3500000

50000

100000

150000

200000

250000

f(x) = − 3.98507733229606E-12 x³ + 1.75764417806089E-06 x² + 0.444027748813349 x + 1R² = 0.991957633910871

f(x) = NaN ln(x) NaNR² = NaN WB-S Demand Compared to Calculator

Calcu-lator (from Syn-erGEE)

Total PNG Demand - P&G - Allegheny - PEI (Dth/d)

Unio

ndal

e/W

B-S

Dem

and

(Dth

/d)

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Calculator Comparison• Final TGP value given by calculator dependent on specific user inputs,

rather compare Calculated Uniondale Demand

0 50000 100000 150000 200000 250000 300000 3500000

20000

40000

60000

80000

100000

120000

New Vs. Old Calculator Uniondale Demands

New CalculatorOld Calculator

Total PNG Demand - PEI - Allegheny -P&G (Dth/day)

Calcu

late

d Un

iond

ale

Dem

and

(Dth

/day

)

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Historical Comparison• Historical data from before mid 2013 neglected due to change in Uniondale

line pressure• Data from introduction of Gibson line (November 2014) to present

compared• February 1, 2015 was best optimized day (2.2% below calculator

prediction)

0 50000 100000 150000 200000 250000 300000 3500000

20,000

40,000

60,000

80,000

100,000

120,000

Calculator Vs. Historical Data

HistoricalLinear (Histor-ical)CalculatorLoga-rithmic (Calcula-tor)Most Op-timized Historical

Total PNG Demand - PP (Dth/day)

Unio

ndal

e De

man

d (D

th/d

ay)

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Comparing Calculators and Historical Data

• Comparing Uniondale+Gibson-PEI sendout valuesJuly 4, 2014 April 10,

2015February 4,

2015February 19, 2015

Total PNG Demand

(Dth)

28,358 104,767 202,287 316,247

Historical (Dth)

10,055 38,998 80,854 99,413

Old Calculator

(Dth)

11,241 52,397 86,174 110,876

New Calculator

(Dth)

13,914 57,761 89,144 110,457

% Difference 38.4% increase over historical, 23.8% increase

over old

48.1% increase over historical, 12.7% increase

over old

10.3% increase over historical, 3.4% increase

over old

11.1% increase over historical,

0.38% decrease over

old

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Future Cost Analysis• (Difference in price of Transco and Tennessee) x (difference in sendout of Calculator

and Historical) = lost revenueTenn Price

Transco Price

Price Difference

Historical Uniondale (Dth/d)

Calculator Output (Dth/d)

Lost Revenue Per Day

Monthly Revenue Lost

Sep-15

$1.089

$2.700

$1.611 14,935 23,413 $13,658

$409,742

Oct-15

$1.214

$2.735

$1.521 24,213 36,504 $18,695

$579,533

Nov-15

$1.315

$2.823

$1.472 51,087 70,389 $28,413

$852,376

Dec-15

$1.681

$2.978

$1.297 48,232 78,200 $38,868

$1,204,923

Jan-16 $1.806

$3.073

$1.267 71,972 92,949 $26,578

$823,914

Feb-16

$1.932

$3.074

$1.142 87,881 98,299 $11,897

$333,126

Mar-16

$1.850

$3.041

$1.191 68,957 82,521 $16,155

$500,796

Apr-16 $1.728

$2.902

$1.174 40,273 51,931 $13,686

$410,595

May-16

$1.506

$2.904

$1.398 20,262 28,431 $11,420

$354,028

Jun-16 $1.506

$2.933

$1.427 16,565 21,394 $6,891 $206,729

Jul-16 $1.553

$2.968

$1.415 14,610 19,774 $7,307 $226,519

Aug-16

$1.478

$2.982

$1.504 15,158 21,408 $9,400 $291,400

Total:$6,193,682

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Conclusions• Using historical data and SynerGEE, found a much better fit line for

Uniondale demand to help meet goal of maximization

• Opportunity for improving system optimization – Sendout is optimized when Uniondale and Lackawanna running at MOP,

Saylor and Hunlock running at suggested pressures dependent on system demand

• Test system with new pressures to see how close to optimum level can be reached– Gas Control communicates to Gas Supply if we are fully maximizing

Uniondale– Gas Supply will adjust estimates based on the feedback