Biomethane. Renewable gas in natural gas transportation pipeline.

AGF carries out the first injection of renewable gas by a private company in gas transportation pipeline.

AGF has accomplished the test period for biomethane production and injection into the gas transportation pipeline. The 21st of April 2023 it was confirmed the opening of the pipeline at BIOMETAGAS LA GALERA position and normal operation for renewable gas injection was approved. On 1st of February the test period for renewable gas injection began when the pipeline was available to start the biomethane production. In contrast to a gas distribution pipeline, high-pressure injection has a higher degree of technical complexity, compositional limitations and administrative requirements.

During the fifty days that lasted the testing period the entire methane production of the biogas plant has been processed to concentrate the methane to biomethane values of valid composition. The main target parameters are the partial pressure of CO2, limited to 2% fmol, and O2 which is limited to 0,3 % fmol. That means the biggest challenge for renewable gas related with gas transportation pipeline.

The pressure is above 60 bar, which is variable depending on the pipeline situation.

Upgrading plant for La Galera compressed gas pipeline. Prepared for virtual compressed gas pipeline together with a mobile platfrom.

In the project UNUE-Biogasnalia, in which AGF is operating a plant working over a gas distribution pipeline, CO2 is limited to 2,5% (originally it was 2%, but months after the plant start up, the limitation was raised to 2,5%) and O2 to 1%, which makes the management of biogas and minority gases much easier. The O2 limitation in the high-pressure gaspipe requires a biogas with a maximum oxygen content of 0,1% in order to comply with the specifications for the outlet gas.

In order to pass the test period and to run the plant, it has been demonstrated that it is vital having one company responsible of the operation of the biogas and biomethane plant together.

Biometagás LA GALERA. Planta NDN.

The commissioning of compressed biomethane was carried out by the AGF team during February and March 2022, having very good results and feelings with the plant. It has been waiting for the completion of the gaspipe work and the opening to start its normal operation.

The good results of the 2022 commissioning have been corroborated during the new start up. As can be seen, a gas with a high methane content and very low CO2 concentration is being produced. The graph shows several hours of operation of the plant with a methane content of more than 99% in the output gas.

Operation Graph of the Biometane plant.

AGF was the first company to inject renewable gas into a gas distribution pipeline in Burgos, Spain. It has been also the first company to inject into the high-pressure gas pipeline from a private biogas plant. Considering the unique precedent of  Valdemingomez Waste Treatment Plant, which also injects into high-pressure, the injection at La Galera has been a huge challenge.

The biomethane plant was ordered by BIOMETAGAS LA GALERA to AGF to feed a Virtual Gas Pipeline (VP) for a final discharge into a gas distribution pipe, so the entire design was done to take out the gas by means of the VP Filling Terminal, already built on site, at about 250 bar. AGF has designed the necessary terminals for VP, the Filling Terminal and the Discharge Terminal, which is the element that allows the injection from the mobile platform to the pipeline. It was during the construction phase of the biomethane plant when the possibility of injection into the transport pipeline came up, as it has finally happened.

Satellite image of BIOMETAGAS LA GALERA.

AGF has currently two biogas and biomethane plants in operation injecting into two different gas pipelines. UNUE has been in operation for almost two years and La Galera has been injecting since February 2023. AGF operates the biogas and biomethane plants, both projects were executed by using its proprietary technology for biogas and biomethane production.

The experience gained in both projects is very significant, in terms of operation and design. The CO2 separation and biomethane production technology that AGF decided to develop in 2018 was water absorption, discarding all other alternatives after an extensive and deep technical and economic study, despite of the commercial trends in the sector, based more on the upgrader supplier interest than on the biomethane producers. After the commissioning of BIOMETAGAS LA GALERA and the years of operation of UNUE, it can be concluded that this choice of the separation technology could not have been more appropriate. Episodes experienced in both plants would have forced a complete change of the separation means (membranes, amine solutions or adsorbents), being impossible to compete with the versatility derived from the direct use of water.

The Compressed Biomethane Plant that AGF has built at BIOMETAGAS LA GALERA SL is not a common product in the biomethane and upgrading plants industry where normally the final compression has to be purchased as a separate module, being independent from the CO2 separation plant. Continuing with the philosophy of integral design that AGF has always followed, the final compression phase has been integrated, which allows the production of compressed gas up to 300 bar output pressure without the need of any external element.

BIOMETAGAS’s biogas plant has been in operation since 2020. With the start of the gas injection, it can be said that the real project begins now, where economic forecast and expectations must be turned into reality, to become projections into history. Previous experiences in the renewable gas industry show that the real relationship between engineering and owner begins when the construction is over. In contrast to other renewable sectors where there is more certainty, in renewable gas, plant operation is very complex and requires continuous adjustments of processes, operations and functioning, making essential to integrate the plant operation with the design and construction of the plant.

As it deserves, BIOMETAGAS LA GALERA has raised a lot of expectation, due to both for the owner company configuration, since is made up by small investors, and the difficulty of what has been achieved. The awards received in recent months are fairly deserved.

1. Bioenergy Cluster Award. 2. Biogas Award. AEE Energy Awards. Best Biomethane project of the year.

For more technical information about the upgrading plant, click on this link.

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