In this article we identify the 5 most critical factors in the design of every Biogas Plant.
Read on for our list and discussion of the 5 most vital design factors which it is essential for every AD Plant designer to get right, for successful stable AD plant operation.
For the benefit of our readers. We recommend that all of our readers note each point carefully.
Watch our video below on the Biogas – Top Design Success Factors:
Design of Every Biogas Plant – Key Takeaways
1. Flexibility in Design
- Adaptability: Biogas plants must be designed with the flexibility to handle changes in feedstock and output requirements over their lifespan.
- Customization: Configurations should support site-specific and client-specific adjustments while maintaining efficiency.
- Future-Proofing: Accommodate evolving technological developments and market demands.
2. Accurate Feedstock Dosing
- Automated Dosing: Ensure precise control over biomass inputs, pH levels, and micronutrient additions with automated systems.
- Efficiency: Maintain optimal digester performance by balancing volatile solids reduction and chemical oxygen demand (COD) metrics.
- SCADA Integration: Supervisory Control and Data Acquisition (SCADA) systems should monitor and interlock processes for maximum reliability.
3. Optimal Process Temperature
- High-Temperature Operation: Design systems to operate at the highest feasible temperature to enhance biogas production.
- Stability: Maintain digester temperature within +/- 2°C of the set point to ensure stable microbial activity.
- Parameter Monitoring: Regularly assess temperature and gas pressure to ensure process efficiency.
4. Energy-Efficient Mixing
- Low Energy Agitation: Implement stirring systems that optimize energy consumption while achieving complete mixing.
- Energy Management: Develop a comprehensive energy efficiency plan with key performance indicators and periodic improvement targets.
- Energy Balance: Track and report on energy usage and production, including exports.
5. User-Friendly Remote Control
- SCADA Systems: Enable remote monitoring and adjustments of biogas plant operations through smartphone apps.
- Continuous Monitoring: Record operational parameters, emissions, and system performance to ensure stability.
- Safety Features: Equip plants with pressure and vacuum relief systems, integrated with SCADA, to monitor and document events.
List of the The 5 Most Critical Factors in the Design of Every Biogas Plant
1. Design Must Incorporate a High Degree of Flexibility
If there is one thing for certain about biogas plants it is that the customer's requirements will continuously evolve throughout the life of any biogas plant. It is difficult, if not impossible to anticipate many of those changes, so the flexibility to alter biogas plant configuration to suit feedstocks as needed and in a manner that suits the client's particular site requirements, is essential.
Even though the set-up for each client is carefully customized for each project, the design must incorporate a level of versatility that will ensure that the configuration of the equipment can be changed to maintain efficient operation.
This must allow both for biomass inputs which continually vary, and as the marketable output products also change according to demand and new technological developments come available.
This is defined as: “Decomposition and stabilisation of biodegradable waste.”
In the design of every biogas plant which complies with good practice guidelines, the process takes place in a controlled environment, resulting in a stable, sanitised fertiliser and soil structure improver material (digestate) that can be applied to the land for agricultural purposes, to improve the soil structure or add needed nutrients.
2. Accurate Controllable Dosing Equipment to Aid Balancing Feedstock Input is Essential
We consider this so important that we recommend that every biogas plant includes an automatic dosing module within their biogas plant that ensures that all the biomass constituents will be adequately controlled, including the feedstock input rate, and pH adjustment dosing and any micronutrient addition, to match the requirements of continually varying feedstock sources and composition.
The module has to be able to provide a high degree of control, in order to achieve a high level of process efficiency, without unnecessarily limiting the plant operator's choice of biomass source/ type.
When a gas pressure alert situation is detected, you must implement an interlocked alarm device that causes reactor feeding to halt automatically.
To monitor, record, and display data for continuously monitored parameters, you must employ Supervisory Control and Data Acquisition Equipment (SCADA).
3. Ideal Process Temperature
Apply a design philosophy, which involves plants running at the highest feasible process temperature. By doing so, it makes it possible to take the fullest advantage of the natural ability of the micro-oganisms to digest the substrate within their digesters at the highest possible biogas (methane) producing potential.
Depending on the environment used and the system architecture, you must determine the optimal operating temperature.
The temperature of the digester must be kept within +/- 2 degrees Celsius of the working temperature.
4. Mixing Completely with the Lowest Energy Consumption
Reactor design needs to include a stirring and agitation system that gets as close as possible to providing a completely stirred reactor. Nature Biogas, for example, has developed its own technology for this. It is optimized for low energy use to minimize the draw on the plant's own electricity generation. The importance of this lies in keeping operating costs low while producing high gas production rates for the feed material utilized must never be underestimated.
- defining and calculating the site's energy consumption of the task (or tasks) you conduct and the waste stream(s) you accept, as well as
- setting annual key performance indicators, such as specific energy consumption (expressed in kWh/tonne of waste processed) and
- planning periodic improvement targets and actions.
As part of your facility's EMS, you'll be asked to examine and update your energy efficiency strategy on a regular basis.
You should keep track of your energy balance. This must include a breakdown of your energy usage and creation (including any energy or heat exportation) by source type (electricity, gas, conventional solid fuels, conventional liquid fuels, and waste).
5. User-Friendly Remote Control of Operating Systems to Enable Quick and Appropriate Operational Adjustments to be Made
Use a remote-controlled SCADA monitoring and operating system at all their anaerobic digestion plants.
All indications of plant status are viewable, and access to all operating system adjustments are available, via a smartphone app.
This is important to ensure that the gas production process is kept within stable (high efficiency) reactor conditions. And, can be accessed at any time to ensure the smooth running of their plants, which normally run day and night 365 days a year.
Any methane emission occurrences must be recorded using SCADA data logging. The date, time, and length of the release must all be documented. (To identify releases, a temperature sensor can be installed within the release pipe.)
Your SCADA system must be used for monitoring and interlocking.
Pressure and vacuum relief valves (PVRV) must be installed on all vessels where there is a possibility of pressurisation. The date, time, and duration of pressure relief events must all be recorded. (Release events must be identified by SCADA systems.)
FAQs for the Design of Every Biogas Plant
What makes flexibility in biogas plant design so important?
Flexibility ensures that the plant can adapt to changing feedstocks, outputs, and evolving client needs, making the system more resilient and future-proof.
Why is automated dosing essential in biogas plants?
Automated dosing provides precise control over feedstock and additives, ensuring efficient digestion and minimizing operational disruptions.
How does temperature impact biogas production?
Maintaining an optimal and stable temperature maximizes microbial activity, leading to higher methane yields and process stability.
What role does energy efficiency play in biogas plant operations?
Energy-efficient mixing and operations reduce costs and improve overall plant sustainability by lowering the energy required for processing.
How does SCADA enhance biogas plant operations?
SCADA systems allow for real-time monitoring, remote control, and precise adjustments, ensuring stable operations and quick response to issues.
What safety measures should be incorporated into biogas plant designs?
Pressure and vacuum relief systems, coupled with SCADA for monitoring and documentation, are critical for handling pressurization and emission events safely.
[First published October 2014. Updated July 2021. Latest update with Key Takeaways and FAQs added: November 2024.]
