To claim carbon credits for flaring landfill gas, you must prove how much gas was destroyed. Under the Clean Development Mechanism (CDM) methodology cited in a Middle East landfill proposal, that means measuring gas flow, methane concentration, flare temperature and flame presence, and logging them every minute. This article explains the three compliance options and the gas train around them.
The challenge: engines, a flare and a revenue stream
The scheme combined three jobs: pressurise and condition landfill gas for engines, burn surplus in a standby flare, and generate evidence for carbon credits. The equipment was scaled in three sizes, 2,000, 2,500 and 3,000 Nm³/h, so the design could follow how much gas the site proved to produce.
The three CDM options
- Default efficiency of 90%. Assume 90% destruction and prove the flare operated. The proposal judged this the most economical route.
- Annual test. Measure flare efficiency once a year with an accredited laboratory.
- Continuous measurement. Measure efficiency continuously by the method in the CDM annex.
All three need the same instruments. A higher claim, theoretically up to 99% of credits, needs the more demanding methodology. The exact rules must come from the CDM document itself, so confirm the current version before designing.
The four logged parameters
- Gas flow rate into the flare.
- Methane concentration.
- Combustion chamber temperature.
- Presence of a flame.
The credit claim stands on this data, so instrument calibration and uptime matter as much as the flare.
The gas train
| Item | Design |
|---|---|
| Gas flow | Three size options: 2,000, 2,500 or 3,000 Nm³/h maximum, with 5:1 turndown (400, 500 or 600 Nm³/h minimum) |
| Blower | Multi-stage centrifugal, 300 mbar, single blower with duty-standby option |
| Dewatering | Stainless steel condenser cooled by a chiller to about 20°C; blower heat then reduces relative humidity below 80% |
| Exit cooler | Air blast cooler keeps gas below 40°C |
| Filter | F9 class, 175 Pa initial resistance |
| Standby flare | Enclosed, 5:1 turndown, 310 stainless steel shroud, residence time over 0.3 seconds |
The flare is sized for peak gas, up to about 16 MW thermal at the largest size. No H₂S bioscrubber was needed in this scope. The proposal also offered containerisation of the plant as an option.
What to consider for your own project
- Choose the CDM route first. It sets the instrument list.
- Specify data logging and storage. A minute-by-minute record must be secure and tamper-evident.
- Calibrate regularly. Instrument drift can invalidate credits.
- Plan for gas growth. Pick a train that scales.
- Check local rules. UK sites follow the Environment Agency’s LFTGN05 and LFTGN03.
FAQ
What is CDM?
The Clean Development Mechanism, an international scheme that issued tradable credits for verified emission reductions.
Why 90% by default?
It is a conservative default efficiency in the methodology that requires only monitoring of operation.
Do I need a flare if I have engines?
Yes, for when engines are down or gas exceeds their capacity.
Claiming credits?
Tell us your CDM methodology and we will specify the instrumentation.