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Five Key Areas to Monitor and Manage in AD operation

February 24th, 2016 | 11:43 am

It has now been over 5 years since CO2Sense has been investing Anaerobic Digestion projects. Having deployed capital into 4 projects between 250kW and 1MW+, we have built up a bank of knowledge that we are keen to share with others to help navigate the complex operational phase of their schemes.
In this article, we set out our top five areas to monitor and manage to help ensure long term project profitability.

1. Feedstock management and quality control

Feedstock is one of the most obvious but still most important factors to get right in the operation of an AD project. In addition to getting it at the right price, feedstock needs to be of the right quality. Feedstock that isn't processed correctly prior to entry into the digester tanks or is of the wrong type can lead to less than optimum biology by affecting pH balances and dry matter content. Correcting the biology can be a time consuming and costly process, both in terms of additional help needed to correct it and reduced gas yield.

Poor quality and improperly processed feedstock can also cause undue stress on mechanical components; increasing the chances of mechanical failure and more down time than was budgeted for. In many cases it can also affect your recourse in relation to your technology solution if it is not functioning as expected. It is therefore highly important that you use feedstock suited to your plant.

2. Funding source

Funding for a project has long term implications and it is important that it is given the appropriate consideration. An inflexible funding agreement or funding from a provider that is not familiar with AD projects may lock you into a relationship that is not in your best interests and that over time could look less attractive than at the beginning of the term. You should make sure that you have a strong relationship with your funder(s) and that they understand your requirements. Funding packages which allow you to refinance could help you to switch to more appropriate deals as the project matures. It is also important to consider how the timing of finance payments aligns with project cash flows; flexibility here can also support the long term financial health of the scheme.

3. Strong Contractual Arrangements

Anaerobic Digestion is a complex technology to operate correctly and you need to ensure that there are clear and robust contractual structures in place for handover of the plant and for maintenance. Regular monitoring can help you to manage issues before they become more serious, whether they are biological or mechanical. Having clear performance indicators for your project that you can use to ensure your project is operating as effectively and efficiently as possible is important and that are linked to your maintenance contracts can aid with regular accurate monitoring and performance management. Common metrics can include:

Accurate metrics which show a healthy project can also help you to attract further funding for expansion or to refinance existing funding agreements.

4. Timing of maintenance

Timing maintenance appropriately will allow you to maintain maximum uptime in the periods where you will receive the most for your output. For example, winter PPA prices are typically higher than in summer, and operating during TRiAD periods will allow you to bring in significant additional benefit. Any unnecessary maintenance carried out during these times can cause you to lose out financially. You also need to take into account the cost of labour and it will usually make more sense to carry out maintenance during the day as opposed to at night when overtime will be payable.

It is also important to note that large maintenance work carried out may be best done in summer when temperatures are higher. For example, work such as removing the roof in winter can have a much more adverse impact on biology than it would have in the summer.

5. Managing your outputs

Anaerobic digestion has the capability of producing a diverse range of outputs including electricity, heat and digestate. Structuring your AD project from the beginning to allow for these outputs to be balanced as efficiently as possible will greatly improve profitability but ongoing management of them is vitally important, as each can be a complex income stream. It can be worth securing dedicated staff to manage these outputs to ensure that:

Also, having a good understanding of how to procure and manage the feedstock so that it is of the right quality for your outputs is very important.

CO2Sense has a long track record of financing a range of environmental projects and renewable energy schemes. We offer flexible short term finance to help mobilise projects and in the case of community groups can offer pro bono support. To discuss your project and funding needs with us, please contact 0113 247 3848 or e-mail


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