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 Lisa Biddle, EPA

FROM: John Sunda, Tetra Tech

DATE: November 13, 2013

SUBJECT: Analysis of Manufacturing Facility Cooling Water Use for Electricity Generation

Tetra Tech was tasked with identifying the proportion of manufacturing facilities that use 

cooling water predominantly for generating electricity similar to generating facilities. A review 

of the flow data analysis1used to estimate the proportion of non-contact cooling water used at 

manufacturing facilities revealed that this data was not suitable for this analysis since the 

analysis focused on data from larger facilities (DIF >100 mgd). This analysis includes all 

facilities that completed a detailed survey and focuses 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 structure (CWIS) 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) contact and/or non-contact cooling (other than electricity 

generation or air conditioning);

5. Other.

Since this data was reported on an intake basis, the results of this analysis are reported on an 

intake basis since reporting this data on a facility basis would require a much more in-depth 

flow-weighted analysis. 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 master 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 used 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 water 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) 

Thresholda

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 “electricity 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 particularly 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. There was a significant portion (>10%) of cooling water reported as being used for nonEG purposes (Items 3 through 5 above)2

or;

 

2 This included intakes where sum of percentages exceeded 100%.
3

2. If 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 types of intakes were 

excluded. Note that this column stops at >90% cooling water used for EG since this evaluation 

was intended to identify the proportion 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 analysis indicates that an estimated 5% of intakes at manufacturing facilities are associated 

with facilities where cooling water was predominantly used for EG. The analysis 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 Section 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 analysis measures “percent intakes (47%)” while the other measures “percent 

facilities (60%).” Since many manufacturing facilities may use only 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 

system is used where all of the turbine exhaust steam is used for process purposes).