ENGR 867 Rate Schedules

Ahmad R. Ganji

Professor of Mechanical Engineering

Rate Schedule

• Rate schedule is the tariff /method that the utility company charges its customers, varies greatly by utility and type of fuel.

• Rate schedule may depend on: – Type of use/customer – Energy use – Energy demand – Season – Time of use – Historical use – Primary – Secondary – transmission

Electrical Consumption and Electrical Demand

• Electrical consumption is the amount of energy consumed by a device in a given period of time. For example a 100 watt lamp, being on for 10 hours will consume:

100 W x 10 hrs = 1000 Watt-hr = 1 kWh

• Electrical demand is the draw that the device puts on the grid. In this example it is:

100 Watts = 0.1 kW

4

Demand: The measured average kilowatt during any 15-minute

metered interval.

The maximum demand in the specified time period is considered and charged for the month.

kW

Time - Minutes

0 5 10 15

average - This is the demand

Some Typical PG&E Rate Schedules

Sample Daily Interval Data

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

12

:00

AM

1:0

0 A

M

2:0

0 A

M

3:0

0 A

M

4:0

0 A

M

5:0

0 A

M

6:0

0 A

M

7:0

0 A

M

8:0

0 A

M

9:0

0 A

M

10

:00

AM

11

:00

AM

12

:00

PM

1:0

0 P

M

2:0

0 P

M

3:0

0 P

M

4:0

0 P

M

5:0

0 P

M

6:0

0 P

M

7:0

0 P

M

8:0

0 P

M

9:0

0 P

M

10

:00

PM

11

:00

PM

Time (Hour)

Dem

an

d (

kW

)

Jul-15th Tues Jan-15th Thurs

Sample Weekly Interval Data

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday

Day

Dem

an

d (

kW

)

Jul-08 Jan-09

Example of TOU Energy and Demand Data

Electrical Summary (Jan. – Dec. 2012

Month

Energy Usage (kWh/month) Demand (kW) Energy Charges ($) Demand Charges ($) Energy Tax

($)

Total Charges

($) On Peak Part Peak

Off Total

On Peak

Part Peak

Max On

Peak

Part Peak

Off Peak

Total On

Peak

Part Peak

Max Total Peak

Jan-12 - 130,752 189,150 319,902 - 1,058 1,058 - 11,205 13,229 24,435 - 265 9,903 10,167 93 34,695

Feb-12 - 232,001 271,007 503,008 - 1,070 1,070 - 19,882 18,954 38,837 - 268 9,968 10,236 118 49,191

Mar-12 - 234,339 262,336 496,675 - 1,115 1,115 - 20,230 18,513 38,744 - 279 10,436 10,715 144 49,603

Apr-12 14,627 178,481 235,651 428,759 - 1,061 1,084 1,806 15,472 17,214 34,492 - 265 10,146 10,411 124 45,027

May-12 72,317 82,766 187,208 342,291 1,088 1,088 1,088 9,471 7,457 13,157 30,086 15,26

5 3,253 10,184 28,701 99 58,886

Jun-12 76,797 88,039 205,491 370,327 1,091 1,091 1,091 9,484 7,932 14,501 31,918 15,30

7 3,262 10,212 28,781 90 60,789

Jul-12 78,565 90,386 208,572 377,523 1,096 1,096 1,096 9,618 8,079 14,613 32,309 15,37

7 3,255 10,259 28,891 109 61,309

Aug-12 76,500 89,018 197,236 362,754 1,125 1,085 1,125 9,365 7,956 13,818 31,140 15,78

4 3,222 10,530 29,536 105 60,781

Sep-12 97,518 112,279 223,744 433,541 1,104 1,071 1,104 11,938 10,035 15,676 37,649 15,48

9 3,181 10,333 29,003 126 66,779

Oct-12 71,008 88,230 188,701 347,939 1,040 1,023 1,040 8,693 7,465 12,940 29,098 14,59

1 3,038 9,734 27,364 101 56,563

Nov-12 - 147,825 212,082 359,907 - 1,032 1,032 - 12,661 15,495 28,156 - 258 9,660 9,918 104 38,177

Dec-12 - 190,052 270,453 460,505 - 1,068 1,068 - 16,278 19,759 36,037 - 267 9,996 10,263 117 46,418

Total 487,332 1,664,16

8

2,651,631

4,803,131

60,376 144,65

4

187,869

392,900

91,812

20,813 121,362 233,98

7 1,330 628,217

Monthly Average

s

69,619 256,026 407,943 564,519 1,091 1,072 1,081 5,031 12,055 15,656 32,742 7,651 1,734 10,113 19,499 111 52,351

Table 1.1– Historical Electrical Consumption and Cost Summary

Usage Max Demand Energy Cost Demand Costs Energy Tax Total Cost

Electrical Power 4,803,131 kWh

(16,388.3.1) MMBtu) 1,125 kW $392,900 $233,987 $1,330 $628,217

Average Values 400,261 kWh/month 1,084 kW $0.0818/kWh $18.05/kW $0.131/kWh

Table 1.2– Projected Electrical Consumption and Cost Summary

Usage Max Demand Energy Cost Demand Costs Other Costs*

Total Cost

Electrical Power 4,803,131 kWh

(16,388.3.1) MMBtu) 1,125 kW $396,536 $237,654 $1,330 $635,520

Average Values 400,261 kWh/month 1,084 kW $0.0826/kWh* $18.33/kW* $0.132/kWh

How to Account for Energy and Demand Savings of Equipment

• Estimate the energy and demand savings based on time of use and account for them based on the rates for each period – This can be fairly involved, and may need a great deal of book-keeping.

• Estimate the average cost of energy and demand:

oAnnually

o Seasonally

This method is much simpler but will not be very accurate

How to Account for Energy and Demand Savings of Equipment

• Example: Eliminate the use of a 10 hp pump in the process during the summer months

Net Metering

• Allows customers with eligible power generator (e.g. PV system, bio-gas) to offset the cost of their electric usage with energy they export to the grid

• May be used with any otherwise-applicable-rate schedule, or the schedule the facility would qualify for if there was not a generating facility.

Net Metering

To qualify in California:

• Generator must be less than/equal to 1 MW

• Must be an eligible renewable power source

• Not interconnected to secondary network distribution line

• Customer must pay for 2-way meter if none is installed; reprogramming fees are$0 - $288.

Example for Net Metering and the Effect of Renewables on Demand

Change in Demand Load Profile Due to Installation of a 800 kWPV System

Photovoltaic Electrical Power Generation and Demand Savings

Month Present Max

Demand (kW)

Estimated

Generated Power

(kW)

Peak Demand

Savings (kW)

Part-Peak

Demand

Savings (kW)

Demand Cost

Savings ($)

Total Cost

Savings ($)

January 479 339 - - - 4,284

February 713 339 - - - 5,401

March 845 339 - - - 7,536

April 806 339 - - - 9,456

May 550 662 206.7 65.3 5,420 19,102

June 586 662 206.7 65.3 5,420 19,250

July 586 662 206.7 65.3 5,420 20,481

August 768 662 206.7 65.3 5,420 18,736

September 636 662 206.7 65.3 5,420 16,782

October 636 662 206.7 65.3 5,420 14,089

November 828 339 - - - 4,495

December 514 339 - - - 3,824

Total 32,523 143,436

Direct Access Rate Schedules

• Are those rates schedules that the commodity is purchased from a 3rd party, and he utility charges for transmission and distribution.

• Applies to both electric and gas

• For eclectic rates, usually the 3rd party will charge for usage and the utility will charge both for usage and demand, but sometimes based on the contract the 3rd party also may charge for demand.

Direct Access Rate Schedules • An example for PG&E E20Direct Access

Electric Rate Schedule

For E20 Rate Schedule, the charges are as follows:

Gas Rate Schedules

• Gas Rate schedules may depend on:

– Type of use/customer

– Pressure

– Energy demand

– Season

– Direct Access

Gas Rate Schedules As an example if customer’s average monthly use exceeds 20,800 therms during the previous 12 months, for PG&E:

Schedule G-NR2 Gas Service to Large Commercial Customers

January 1, 2014, to Present ($/therm)

Customer Charge ($/day) $4.95518

Procurement Charge $0.558443/

Transportation Charge

Summer First 4,000 $0.33336

Excess $0.16496

Winter First 4,000 $0.40812

Excess $0.20196

Total Charge

Summer First 4,000 $0.89180

Excess $0.72340

Winter First 4,000 $0.96656

Excess $0.76040

Public Purpose Program Surcharge

2/ $0.09160