The main waste of starch plants is mash. It can be and should be processed into biogas.
There are two alternative ways to process mash: dry fodder and biogas.
It was previously believed that investment into mash drying is lower than the one into a biogas plant. Dry fodder competes with grain. During a period of grain overproduction, dry fodder has a low market value and is difficult to sell.
Mash can be converted into biogas to replace natural gas in the boilers of starch mills or to produce electric energy.
Mash has 20-25% of solids and can be processed using high-load reactor technology. With the direct replacement of natural gas by biogas in boilers the capital costs are lower because there is no need to buy a generator. These two factors (high-load reactors and generator savings) lead to an investment in a biogas plant over an investment in mash drying.
Biogas plants are preferable to drying. The payback is 3 years.
Unlike drying, a biogas plant does not consume energy but produces. When comparing the payback periods of drying and a biogas plant, it is correct not only to take into account the direct benefit of the produced biogas but also to consider the savings on natural gas from not drying mash.
NGE Biogas has built biogas plants processing a wide variety of raw materials similar to mash: distillery wastewater, carrot pulp, pumpkin pulp, sugar beet pulp, corn silage.
Accordingly, we are able to implement a starch pulp biogas plant.