Mara Zantedeschi - Microbioenergy: heat and biogas biomass plant for domestic use
Design, construction and monitoring of Microbioenergy prototype in Lozzo Atestino, Padua, Italy.
The objective was to create a sustainable energy solution for rural area’s.
Generally an anaerobic (biogas) digester needs very specific controlled conditions. A biomeiler has the correct specific conditions, but needs to be rebuild every two years. The plan was to feed the biomeiler with the digestate from the anaerobic digester to extend it’s lifespan.
The digester would be filled with grass, but in the end it was also used for kitchen scraps. An power production forecast was made based on Native Power data. Since part of the volume would be used for the digester they hoped to at least create enough power as with a normal solid biomeiler.
They tried to calculate from literature how much energy could be obtained from woodchips in anaerobic conditions by burning the methane gas versus aerobic composting and direct heat gain in a normal biomeiler. The power houtput was very similar, but the expectation for a normal biomeiler was a little higher.
The average thermal output was according to the expectations. These calculations were projected towards a year running time although the test was only done for 6 months.
In the temperature data are some small dips visible, this is probably because of the power output and some tries to find the maximum power output.
Looking at the profitability the return of investment time for both systems is similar, about three years, however the possible future profit for the microbioenergy plant is higher with also higher start investment costs as compared to the classic biomeiler setup.
All data is based on assumptions about the biogas production, because it was not possible to measure the gas production. However, the measured conditions inside the digester where hot enough for an ideal production.
This project also gave them the suggestion to actually use the water draining from the biomeiler as a heat source itself. This could also be tested with the large turbomeiler in The Netherlands.