1 **MEMORANDUM**

**Tetra Tech, Inc. 10306 Eaton Place, Suite 340**  **Fairfax, VA 22030 Phone**  **703 -**  **385 -**  **6000 Fax**  **703 -**  **385 -**  **6007** TO : Paul Shriner and L isa Biddle, EPA FROM : John Sunda, Tetra Tech DATE: November 13 , 2013 SUBJECT: Analy sis of Manufacturing Facility Cooling Water Use for Electricity Generation Tetra Tech was tasked with identifying the pro port ion of manufacturing facilities that use cooling water predominantly for generating electricity similar to generating facilit ies

. A review of the flow data anal ys is 1 used to estimate the proportion of non

- contact cooling water used at manufacturing facilities revealed that this data was not suitable for this analy sis since the anal ys is focused on data from larger facilities (DIF >100 mgd)

. This anal ysis includes all facilities that completed a detailed survey and focuse s only

on the reported percent electric generation data

. Question 4 in Section 2 of the detailed technical survey requested data for each cooling water intake str ucture (CWI S) regarding the percentage of cooling water used for each of the following purposes: 1. Electricity

generation using steam turbines; 2. Electricity

generation using prime movers other than steam; 3. Air conditioning; 4. Production line (or process) contac t and/or non

- contact cooling (other than electricity generation or air conditioning); 5. Other

. Since th is data was reported on an intake basis , the results of this anal ys is are reported on an intake basis since reporting this data on a facility basis would require a much more in

- depth flow

- weighted anal ys is

. All results are weighted using DQ facility weights.

1 As described in Technical Development Document Chapter 8.3.1, EPA evaluated all available data from both the survey responses and the schematic flow diagrams in order to estimate non

- contact cooling water use at manufacturing facilities . Schematic flow diagrams were consulted since the survey did not distinguish between contact and non

- contact cooling water

.2

Data from in

- scope facilities listed in the m aster database were sorted into manufacturers and generators. The percent reported for responses 1 and 2 from the list above were then added to represent percent cooling water u sed for electricity generation. Table 1 below shows the percentage of generating and manufacturing facility intakes (weighted) that reported a percent of cooling water used for electricity generation (EG) that was greater than the percentage thresholds shown. For example, 8% of manufacturing intakes used >95% of intake cooling w ater for electricity generation. Table 1 shows that a threshold of 90% EG included the majority (94%) of generating facility intakes and therefore is a good indicator for identifying an intake that is predominantly used for EG cooling water and is similar to intakes at generating facilities. **Table 1 Proportion of Intakes Based on Percent Use of Cooling Water**  **for Electricity Generation**

Percentage Electricity Generation (EG) Threshold a Generating

Facility Intakes Manufacturing

Facility Intakes Manufacturing Facility

Intakes at Facilities Where Total Plant Cooling Water Use was Predominantly for

EGb >99% 71% 6% 3% >95% 89% 8% 4% >90% 94% 9% 5% >75% 96% 12% >50% 96% 17% >10% 97% 29% >0% 97% 46% a Includes sum of items 1 and 2 listed above (“electricity generation using steam turbines” and “e lectricity generation using prime movers other than steam”)

. b Excludes intakes where other uses were >10% or those at facilities with other intakes with <90% electricity generation

. One inconsistency with the manufacturing facility intake data was that some intakes reported percentages for each category that when summed together exceeded 100%. In some cases , an intake would report that a high percentage was used for EG and also a high percentage was used for production line or process purposes. This was particularl y notable for paper manufacturing intakes , suggesting that these data represented situations where water was being reused for multiple purposes. Also, many manufacturing facilities had multiple intakes with some intakes used for EG and other intakes used for process or other purposes. In order to get an idea of how many intakes were associated with facilities where total plant cooling water was used predominantly

for EG purposes, manufacturing intakes with a percent EG >90% were examined to see if : 1. T here was a significant portion (>10% ) of cooling water reported as being used for non

EG purposes (Items 3 through 5 above) 2 or ;

2 This included intakes where sum of percentages exceeded 100%

.3

2. I f there was another intake at the same facility with percent EG being much less than 90%. The column on the right shows the percentage of intakes where both ty pes of intakes were excluded. Note that this column stops at >90% cooling water used for EG since this evaluation was intended to identify the pro portion of manufacturing facilities that use cooling water predominantly

for generating electricity similar to generating facilities and the exclusion criteria were based on 90% threshold. This analy sis indicates that an estimated 5% of intakes at manufacturing facilities are associated with facilities where cooling water was predominantly used for EG. The anal ys is also indicates that an estimated 46% of intakes at manufacturing facilities use at least a portion of their cooling water for EG purposes. As reported in TDD S ection 5.3, the results of separate survey question indicated that 60% of manufacturing facilities had generated electricity during 1996, 1997, or 1998

. Factors that may

contribute to this apparent inconsistency include:

 This analy sis measures “percent intakes (47%)” while the other measure s “ percent facilities (60%)

. ” S ince many m anufacturi ng facilities may use onl y one of several intakes for EG purposes, the total number of EG intakes and facilities may be similar in value but the total number of intakes will be higher than the total number of facilities resulting in a lower proportion of the total

.  Some facilities may

generate electricity without using cooling water (e.g., a cogeneration sy stem is used where all of the turbine exhaust steam is used for process purposes)

.