Partner Reported Opportunities (PROs) PRO Fact Sheet No. 502 for Reducing Methane Emissions 

Recover Gas During Condensate 

Loading 

Technology/Practice Overview 

Description 

Lease condensate production, when 

transferred from storage into tank 

trucks, can generate significant volumes 

of methane vapor due to pressure and 

temperature changes and evaporation.

This methane is typically vented to the

atmosphere to prevent the internal tank

pressure from rising. 

One Partner reported capturing

methane that would otherwise be vented 

by connecting the tank truck vent to the 

condensate storage tank, or to a vapor 

recovery line. This has provided the

Partner with the flexibility to send the 

methane to a sales line, use the methane 

for lease fuel, or flare the methane 

vapors. 

Operating Requirements 

To avoid methane emissions, the lowpressure gas in the natural gas liquids 

storage tank must be either flared or 

recovered with a vapor recovery unit. 

Applicability 

This technology applies to all condensate 

production operations using tank trucks 

or railroad tanks. 

Methane Emissions 

Methane emissions occur when methane 

and volatile organic compounds (VOC) 

flash or evaporate into the air displaced

during the loading process. Considering

that a loading cycle may occur every 3 to 

5 days, approximately 100 loading 

transfers can occur per year. Using the 

Pipeline Rules of Thumb handbook, 

Estimated 

Gas Price 

Annual 

Methane 

Savings 

Value of 

Annual

 Gas Savings* 

Estimated 

Implementation 

Cost 

Incremental 

Operating Cost 

Payback 

(months) 

$7.00/Mcf 100 Mcf $745 $1,000 $200 20 Months 

$5.00/Mcf 100 Mcf $530 $1,000 $200 28 Months 

$3.00/Mcf 100 Mcf $320 $1,000 $200 45 Months 

Economic and Environmental Benefits 

Economic Evaluation 

Additional Benefits 

 Safer loading operations 

 Reduced VOC emissions 

Estimated annual methane emission reductions 100 Mcf per storage 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 

Connect Casing to Vapor 

Recovery Unit, PRO No. 701 
 

 

 

 

PRO Fact Sheet No. 503 Continued 

Recover Gas During Condensate Loading (Cont’d) 

Fourth Edition, p. 492, the rate of methane emissions 

from evaporation can be estimated as 50 percent of the 

total volume filled. Partners have reported reducing

methane emissions by 6,500 Mcf to 39,000 Mcf per year, 

which includes flashing loses. 

Economic Analysis 

Basis for Costs and Emissions Savings 

Methane emissions reductions of 100 Mcf per year apply 

to the use of a single vapor recovery line used to recover 

vapor during truck loading every 3 to 5 days. Flashed 

gas savings can be estimated from site-specific data using 

GRI-GLYCalc. 

The estimated costs of purchasing additional connections 

to route the tank truck vent to a useful outlet is 

approximately $1,000. The additional operating costs to 

connect the lines are estimated at $200. 

Discussion 

To implement this project, operators will need a vapor 

recovery line and the appropriate connections to attach

the line to the tank, a VRU, or flare stack. If the 

methane is recovered to a sales or fuel line, the Partner 

can largely offset the cost of this project. In addition,

operators will have a safer working environment since 

tank vents will not be a concern and the system will be

closed loop. This project can payback in two years 

depending on frequency of loading, load volumes, 

temperature and pressure changes, the value of gas, 

among others. 

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