Sprint 2: Producing Bioethanol out of Brewer's spent grains

Beer Brewery’s waste 

The Beer Brewery’s waste, spent grain, also known as ‘Bierborstel’ in Dutch comes from the Brewing facility at the HAS University of Applied Sciences. After the beer is brewed you are left with a solid residue consisting of exhausted grain husks, from which the carbohydrates are already used. The spent grain is rich in water and has a dry matter of 22%. Spent grain is used a lot in animal feed because it contains a high protein content. 

Brewer’s spent grain is mostly used for animal feed. But is it possible to use it for much more? Why couldn’t it be used as a biofuel? That is why we thought of producing bio ethanol from brewer’s spent grain. Bio ethanol is mostly produced by the sugar fermentation process. It is a clear colourless liquid, it is biodegradable, low in toxicity and causes little environmental pollution. 

You can name a number of benefits for bio ethanol in comparison to conventional fuels. First of all, it comes from a renewable resource, for example a crop or a bio-based waste product. Secondly, transport on roads counts for 22% of all greenhouse gas emissions. But through the use of bioethanol, some of these emissions can be lowered. Thirdly, you can mix bioethanol with petrol which creates a more environmentally friendly fuel for transport. Through this, you can slowly transform the fossil-based economy into a bio-based economy. 

Producing Bioethanol 

The last two weeks we spent a lot of time in the ‘milieuhal’, also called the lab. Within this time period, we tried to make bioethanol out of brewer’s spent grain. We used two different methods. One using enzymes and one without the use of enzymes. We chose to do one process without enzymes, because it takes less time, so that we could also distillate it. 

Within the next two vlogs we show you our processes. 

1.     Enzymatic process

Here you can find the mass balance. It shows all the inputs used for the enzymatic process to make bio ethanol. 

Here you can find the total electricity input of 108.75 kWh. Explained here under is the electricity input step per step. 

 Starch fermentation 

We chose to do two different methods so that we could also try out distillation. In the end we had bioethanol with an alcohol content of 13%! It is not that much, but if it is done in a professional way it is possible to create a higher alcohol level. 

Making bioethanol out of brewer's spent grain is not very efficient, because bioethanol is made out of sugars, and most of the sugars are already taken out of the spent grains during the beer brewing process. Still we wanted to try it out due to it's interesting process, which creates a great learning opportunity.