Depleting fossil fuel resources, increasing energy prices and the rapid addition of greenhouse gases into the atmosphere all stress the importance of renewable energy sources. Biogas technology is a very attractive way to utilize biomass sources and recycle nutrients.
Anaerobic Digestion (AD) is an ideal technology to create biogas from organic waste which can be converted into renewable heat and power. Alternatively, by implementing and using a biogas upgrading system, the biogas can be turned into biomethane capable of fueling vehicles or to be injected into the Natural Gas grid to render Renewable Natural Gas (RNG).
How is Biogas Produced
Biogas is produced after organic materials, such as solid animal manure, biowaste and food waste, are broken down by bacteria in an oxygen-free environment, a process called anaerobic digestion. Biogas systems use anaerobic digestion to recycle these organic materials, turning them into biogas, which contains both energy (gas) and valuable soil products (liquids and solids).
Benefits of Biogas
100% Renewable
(No new carbon)
Permanently
Available
Ability to
Transport
Easily
Storable
UPCYCLING
Turn low-grade organic
waste into a high-value
energy sources
Anaerobic Digestion
Anaerobic Digestion for biogas production is done in gassealed units called digesters, which are designed and build in different forms and sized, depending on the type of feedstock and loading amount. The digester units contain bacterial cultures that break down the waste to produce biogas and digestate, which can be converted into other valuable soil products.
Optimized Process
WTT specializes in engineering AD facilities using the latest technology. WTT’s AD tunnels are equipped with an aeration floor to allow the aerobic start-up of the process to quickly reach the mesophilic temperature, after which the process becomes anaerobic. Also, this allows the complete flushing of the biogas at the end of the process, not only in the upper part of the tunnels, but also in the material. Furthermore, WTT’s system is inoculated via extensive irrigation with percolate, therefore avoiding material recirculation in the tunnels, which results in higher throughput.
Key Advantages
- Reliable and continual operation
- Stable quantity and quality of biogas
- Easy maintenance
- Low operational costs
- High net energy production
“Having realized over 130 complete waste processing and recycling projects worldwide, comprising more than 1300 tunnels, all to full satisfaction of our clients, we believe that WTT is the ideal partner for designing and building a high-tech solution for AD.”
Alexander Horvath
Managing Director WTT
Converting Waste to Energy
Biogas requires pre-treatment to reduce the H¬2S content, the treatment requires active carbon and/or scrubbers. In addition, the biogas requires cooling to 3-5 °C to reduce the water content. After pre-treatment the biogas can be used in a Combined Heat and Power (CHP) unit for the co-generation of electric and thermal energy, or it can be upgraded to natural gas.
Biogas for heat and electricity
When biogas is used directly in a combined heat and power (CHP) unit, electric and thermal energy are available in similar amounts. The electrical energy can be used directly on site, to e.g. power the fans and other related equipment. This allows a site to be self-sufficient. The thermal energy for your site can be used for:
- Heating the fermentation tank liquid to optimize the activity of mesophilic bacteria.
- Heating the percolate before irrigation to promote a quick rise of the temperature of a fresh batch of waste.
- Heating of the technical AD corridor, to reduce heat losses from process related equipment.
- Heating the air inlet from aerobic tunnels to optimize the drying process and reduce moisture content.
Upgrade to natural gas
Biogas can be upgraded to natural gas by separating the methane (CH4) from the other gases. As natural gas it can be injected into the local grid (dependent on local regulations), or it can be used as LNG for fueling trucks.
In addition to methane, CO2 is also an important component in biogas, about 35-45% of the total volume. This can be extracted and used for:
- Flushing of the AD tunnels at the end of the process, before emptying the tunnels, to prevent entering LEL-zones.
- Nearby greenhouses or other local businesses to optimize plant growth.
- Parties that use it in liqui
View Past Client Projects
BIOFUEL PROCESSING FACILITY
The Surrey Biofuels Processing Facility processes 115,000 t/a of residual kitchen and garden waste (ICI) from the City of Surrey and is processing the waste by means of dry anaerobic digestion, hybrid, and composting tunnels. To keep the odour emission as low as possible the facility is equipped with an odour abatement system including a scrubber and a biofilter. Renewable natural gas (RNG) is created by this process which is used to power the city’s natural gas waste collection trucks. The facility produces a compost product suitable for landscaping and agricultural applications. The facility of the City of Surrey is operational since 2018 and is the first closed loop fully-integrated organics waste management system in North America, with a capacity to process 100% of the city’s organic waste, along with commercial organic waste, helping Metro Vancouver achieve its regional 70% waste diversion target. Waste Treatment Technologies (WTT) took care of the complete design, supply, installation, and startup of all the process-related equipment, instruments, and automation system.
KEY EQUIPMENT:
6 dry anaerobic tunnels, 4 hybrid tunnels, 7 composting tunnels, air and water treatment