How To Measure Flare Gas Within The EU Emissions Trading Scheme

A white paper, 'Measuring Flare Gas Within The EU Emissions Trading Scheme' from Fluid Components International (FCI), explains how the next-gen Model ST110 Air/Gas Flow Meter with its split range multiple calibration system (SR2x ™) helps better monitor greenhouse gas emissions.

The Emissions Trading Scheme (ETS) was introduced in 2005 by the European Union as a part of its climate change policy and is in its third trading period, which will run from 2013 to 2030. The basic concept is that the European commission allocates carbon credits (each credit is worth 1000 Kg of C0₂) to participating countries, which effectively limits the amount of C0₂ that can be released to atmosphere. This limit or 'cap' is then spread across the major industrial installations in each country.                      

Flow Measurement Compliance
Depending on the industry and size of the facility, the ETS stipulates different levels of accuracy for the instrumentation used to measure both fuel gas and flare gas. For the oil and gas industry, flow meters used to report emissions from flares fall within the Tier 3 accuracy level which, means they must have a degree of uncertainty (accuracy) better than ± 7.5% of the measured value. (Dir 2003/87/EC-Appendix 2- 2.1.1.3).       

Flare Gas Measurement
The main problem for operators in the offshore oil and gas industry is that measuring flare gas emissions is notoriously difficult. In fact, the EU commission recognised this and decided not to apply the same accuracy targets for flare gas as other important gas streams such as fuel gas, which, for Tier 3 is ± 2.5%. The problem is that not only can the gas be dirty and corrosive, but the variation in flow rates between the minimum and maximum flow can be enormous.                  

Thermal Flow Meter Solution
The ETS directives have completely changed the way we look at flare gas measurement and a new industry standard in flow measurement is required to address the issues of accuracy and field testing. FCI, with over 40 years of experience supplying thermal mass flow instrumentation for the oil and gas industry, has designed its future-ready ST110 Air/Gas Flow Meter specifically to meet the new challenges set down in the EU ETS.

Thermal flow meters are inherently sensitive at low flow rates, and this means they are capable of extreme turndown ratios. The ST110 Flow Meter is unique in its ability to measure gas flow rates with a turndown of 1000:1. It uses a special split range multiple calibration system (SR2x ™) developed by FCI engineers specifically for flare gas applications. It has an accuracy statement of ±0.75% of reading plus 0.5% of the calibrated full scale with a worst case accuracy of ±5% of reading. So, even at the low end of a 1000:1 turndown, the ST110 Flow Meter complies with the ETS directive and is within the target ±7.5% accuracy requirement.