Partner Reported Opportunities (PROs) PRO Fact Sheet No. 201 for Reducing Methane Emissions 

Reroute Glycol Skimmer Gas 

Technology/Practice Overview 

Description 

In the glycol dehydration process, rich

glycol is circulated through a 

regenerator where the dissolved water,

methane, volatile organic compounds 

(VOCs), and Hazardous Air Pollutants 

(HAPs) are vaporized and vented to the 

atmosphere. Some glycol dehydrators 

have glycol vent condensers and 

condensate separators to recover natural 

gas liquids and reduce VOC and HAP 

emissions. The non-condensable gas

from the condensate separator, which 

contains mostly methane, is vented to 

the atmosphere. 

A Partner reported rerouting the 

condensate separator gas, called 

skimmer gas, to the reboiler firebox or 

other low pressure fuel gas systems for 

fuel use. In addition to reducing

methane emissions, this practice further 

reduces VOC and HAP emissions, and 

increases product revenue. 

Operating Requirements 

The condensate separator must operate 

at a higher pressure than the 

destination to which the skimmer gas is 

routed. 

Applicability 

This practice can be employed on all 

dehydrators with vent condensers but is 

based on the assumption that fuel gas

consumption levels can accommodate the

volume of re-routed skimmer gas. 

Methane Emissions 

The methane emissions savings are 

based on the dehydrator having a gas

entrainment rate of 3 scf per gallon of 

TEG, and vent gas containing 95 percent

methane. 

Estimated 

Gas Price 

Annual 

Methane 

Savings 

Value of 

Annual

 Gas Savings* 

Estimated 

Implementation 

Cost 

Incremental 

Operating Cost 

Payback 

(months) 

$7.00/Mcf 790 Mcf $5,900 $2,000 $100—$1,000 4 - 7 

$5.00/Mcf 790 Mcf $4,200 $2,000 $100—$1,000 6 - 9 

$3.00/Mcf 790 Mcf $2,520 $2,000 $100—$1,000 10 - 15 

Economic and Environmental Benefits 

Economic Evaluation 

Additional Benefits 

 Fuel gas savings 

Estimated annual methane emission reductions 790 Mcf per dehydrator unit 

Methane Savings 

* Whole gas savings are calculated using a conversion factor of 94% methane in pipeline quality natural gas. 

Compressors/Engines 

Dehydrators 

Directed Inspection & 

Maintenance 

Pipelines 

Pneumatics/Controls 

Tanks 

Valves 

Wells 

Other 

Applicable Sector(s) 

Production 

Processing 

Transmission 

Distribution 

Other Related Documents: 

Pipe Glycol Dehydrator to Vapor 

Recovery Unit, PRO No. 203 
 

 

 

 

PRO Fact Sheet No. 201 Continued 

Reroute Glycol Skimmer Gas (Cont’d) 

Methane emissions reductions of 7,600 Mcf per year can 

be achieved for a 20 MMcf per day dehydrator having a 

vent condenser, without a flash tank separator, 

circulating 300 gallons of glycol per hour with an energy

exchange pump. The absence of a flash tank separator

(as is common with some International Natural Gas 

STAR Partners) would result in greater emissions and, 

by extension, a greater amount of gas possibly being 

recovered through this practice. 

One Partner reported methane savings of 24 Mcf per day

per unit (8,760 Mcf per year per unit). Methane savings 

may be limited by the amount of low-pressure fuel gas 

consumption at the site. 

Economic Analysis 

Basis for Costs and Savings 

Methane emissions reductions of 790 Mcf per year apply 

to a 20 MMcf per day dehydrator with a vent condenser 

and a flash tank separator, circulating 300 gallons of 

glycol per hour with an energy exchange pump. 

The cost of this project would include planning, design, 

and implementation by an engineer and installation of 

additional 

rudimentary

installation

estimated to 

piping. Using expert judgment

 estimates of equipment capital 

costs, the implementation costs 

be approximately $2,000. 

and 

and 

are 

Discussion 

This technology pays back quickly. Using glycol skimmer 

gas as a fuel directly offsets use of saleable natural gas,

increasing product revenues. The significant gas savings 

from rerouting glycol skimmer gas to a fuel gas system 

will offset the low capital, operating, and maintenance 

costs. This practice is more cost effective for dehydrators

without flash tank separators. 

The average methane content of natural gas varies by natural gas 

industry sector. The Natural Gas STAR Program assumes the 

following methane content of natural gas when estimating 

methane savings for Partner Reported Opportunities. 

Production 79 % 

Processing 87 % 

Transmission and Distribution 94 % 

Methane Content of Natural Gas 

EPA provides the suggested methane emissions estimating methods contained 

in this document as a tool to develop basic methane emissions estimates only. 

As regulatory reporting demands a higher-level of accuracy, the methane emission estimating methods and terminology contained in this document may not 

conform to the Greenhouse Gas Reporting Rule, 40 CFR Part 98, Subpart W 

methods or those in other EPA regulations. 

2011 2