Three Main Feedstock Challenges
1. Feedstock evaluation and selection
The type of feedstock processed in a biogas plant has a great influence on both the plant performance and economics. Several types of ‘waste’ materials generate revenue for the plant via their “tipping fees”, while other more attractive materials, or energy crops, have to be purchased.
These substrates can significantly differ when it comes to their characteristics. Some produce a large amount of gas but are priced too high. Others have high tipping fees, but have a negative impact on the process.
2. Variations in feedstock quality
Feedstock characteristics might vary significantly over time. Factors such as the weather, seasonality, or how the material is collected and stored for instance. Those factors and many others influence the concentration and condition of the material. These variations will affect the biodegradability, the methane potential and, in turn, the performance of the process.
3. Slow degradable and toxic feedstock
Some types of feedstock might be difficult to degrade, contain toxic substances or lack certain essential nutrients for the microorganisms. The use of these substrates could lead to inefficient and unstable processes , creating a negative financial impact, and, in the worst-case scenario, could even lead to a process failure that could severely hurt the plant.
To tackle all three challenges, we need to be able to find the best and most profitable feedstock available, and foresee any variations in quality. This means gaining access to more information. With reliable smart instruments, we can produce a large amount of high-quality process data, with minimal amount of skill and manpower.
Three Solutions for your Feedstock:
1. Choose the best feedstock
By using modern & automatic instruments for your standardised batch fermentation tests, you can anticipate the methane potential, the degradation characteristics and how well the microbes will adapt to this specific feedstock. Combined with a proper analysis of availability, price, transportation cost and handling requirements, this information will give you solid foundations for your feedstocks selection.
2. Handling variations within the feedstock
Regular batch tests of the feedstock will tell you how its quality varies. It is essential to use feedstock samples that are representative, and to start the testing phase quickly, in order to get accurate results. These results can be used to adjust the feeding of the plant and possibly to negotiate the feedstock price.
3. Ensure good feedstock quality
When working with slow-degrading, toxic or nutrient-limited feedstocks, optimisation is needed. It can be for instance pre-treatment, co-digestion or additive supplementation. These kinds of process amendments can sometimes be expensive so you need to carefully analyse what is needed. Again, the use of smart and automatic instruments for both batch and continuous tests will help you investigate and find the best solution for your feedstock optimisation.
Your feedstock is an essential part of the biogas plant and strongly influences its overall performance and profitability. Smart instruments can help you optimise feedstock management and facililtate feedstock selection.
But what about other common process-related challenges?
In Lesson 3 we discuss how smart instruments can also help with operational challenges in the biogas plant.