What are the benefits of membrane separation technology for biogas upgrading?
For biogas upgrading into renewable natural gas (RNG), membrane separation technology yields high methane recovery and offers better system performance overall. DMT’s Carborex®MS upgrades biogas to high-quality RNG which can be injected into the natural gas pipeline or used as vehicle fuel (CNG). DMT has more than 50 operational sites worldwide and has some of the largest RNG sites in North America. With over 30 years of experience, we are global industry leaders in the renewable energy sector with an award-winning portfolio.
The highest priority for a biogas upgrading system is uptime. A simple compression step, combined with our multi-stage membrane technology, results in 20-100% flow flexibility, over 98% uptime, and a purified renewable natural gas (RNG) stream of up to 99%.
The Carborex®MS is a modular, easily transportable system designed to create a small footprint. This containerized solution is quick to start-up and requires no columns, chemicals or water to operate, allowing for low operational costs. Operation of the system is easy and can be monitored remotely 24/7.
How does membrane separation technology work?
For biogas upgrading, the Carborex®MS separates methane (CH₄) from carbon dioxide (CO₂) using hollow polymeric membranes. As compressed gas travels down the length of the fiber, carbon dioxide will permeate through the porous membrane leaving methane as the retentate.
Permeate: Gas that has traveled through the porous membrane
Retentate: Gas that is retained and collected at the end of the membrane fiber
Selectivity: Ability of a membrane to predictably meet required separation performance expectations
Your system in 6 easy steps!
Pre-Treatment and Compression
Before entering the membranes, contaminants in the biogas stream, such as hydrogen sulfide (H₂S), ammonia (NH₃), mercaptans, VOC’s and siloxanes, must be removed. Once the biogas is pre-treated, biogas is compressed to 10-20 bar. The pressure optimizes the separation of methane and carbon dioxide by increasing the permeability of the membrane.
Multi-stage Membrane Separation
Depending on the biogas inlet flow and the desired methane recovery, the amount of membranes and stages inside the Carborex®MS will vary. The two-stage methane recovery unit can reach up to 97% while the three-stage methane recovery unit can reach up to 99.5%.
Renewable Natural Gas (RNG) Applications
Renewable natural gas (RNG), also known as biomethane, is renewable energy. RNG can be injected into the natural gas pipeline or compressed for transportation fuel.
Bio-LNG Product Description
Liquefied Natural Gas (LNG)
Liquefied Natural Gas, from the liquefaction of high quality biomethane, is the only biofuel better for the environmental than its fossil counterpart. Research shows that Bio-LNG is the most cost-effective fuel available today for reduction of carbon dioxide emissions and, therefore, an ideal investment for reaching climate goals. By combining clean combustion, easy transportation, flexibility and higher security (both in terms of reserve capacity and stability of price), Bio-LNG is gaining worldwide status as the fuel of the future.
Carborex®LNG in Four Steps
Common problems associated with the liquefaction of biogas include the presence of contaminants and the freezing of components such as carbon dioxide and water. After screening established and promising new technologies, DMT has overcome these problems by developing a process comprised of four steps. First, the biogas is pre-treated to remove toxic and harmful contaminants. Pre-treatment also removes water, leaving no water at the end of the process that can be frozen during liquefaction. Second, the biogas is upgraded and polished by membranes in the Carborex®MS to remove carbon dioxide. Finally, the gas is liquefied in a Carborex®LNG and ready to be distributed to fuel stations.
Up to 30 Tons Per Day
While the technology by DMT guarantees a H₂O-free, CO₂ -poor gas stream at high pressure, the liquefaction cycle can harness these same advantages into increasing its own efficiency and eliminating quality related operational risks. The result is a low-cost flexible process, available and scalable up to 30 tons per day which offers a varying degree of integration of the upgrading and liquefaction steps.