Conference Agenda

Abstract. Biomethane has the potential to substitute natural gas and diesel fuel in various applications and can significantly contribute to reducing greenhouse gas emissions. In the future, new opportunities are opening for the introduction of tractors and other agricultural machines powered by biomethane. We present various options for upgrading biogas to the biomethane for fuel for tractors and agricultural machinery in terms of energy consumption and carbon footprint. In addition, we have developed three possible scenarios regarding the introduction of tractors powered by biomethane and possible upgrading of existing tractors in the future in Slovenia. A certain number of tractors in use could be upgraded to a system for using biomethane and diesel fuel for igniting biomethane (dual-fuel engines). Converting existing tractor engines to dual fuels offers several advantages: the original engine design remains largely unaffected, the conversion process is relatively simple, investment costs are lower compared to purchasing new tractors, and in the event of biomethane shortages, the engine can continue operating fully on diesel fuel. We found that introducing biomethane powered tractors on larger scale could significantly reduce diesel fuel consumption and their carbon footprint.

Keywords: biomethane, dual fuel engines, tractors, self-propelled agricultural machinery

The effects of ultrasound pretreatment on the drying behavior of Sour sop during microwave drying was investigated in this work. Probe-type ultra sound having frequency of 20kHz and power of 600W was employed for the study. The soursop slices were treated with ultrasound inside the distilled water for 0 min (UM0), 5 min (UM5), 10 min (UM10) and 15 min (UM15) prior to microwave drying. The microwave power of 800W was used in this experiment. The results showed that UM10 samples had the highest reduction in drying time (41.67%) of Soursop compared to UM0 and other treated samples. Also, the ef fective moisture diffusivity was significantly (p<0.05) the highest in UM10 sam ples (1.67 X 10-9 m2/s) compared to other treated and untreated samples. Page model was found to fit best to the microwave drying of both the untreated and treated soursop samples. Therefore, this work showed that incorporation of ultra sound in the microwave drying of soursop can significantly improve its drying behavior.

Composting represents a key technological approach for managing livestock manure in Japan, and closed vertical composting facilities (CVCFs) are among the most widely adopted systems for this purpose. However, the effective operation of CVCFs is often hindered by poor fermentation performance. These operational challenges complicate day‑to‑day management, frequently necessitating skilled labor and extended recovery periods to re‑establish optimal fermentation conditions. In response to these issues, the present study aimed to generate long‑term fermentation data under varying CVCF conditions and to develop automated recovery strategies capable of maintaining stable, optimal fermentation.

The study utilized an 18 m³ CVCF located at the Institute of Livestock and Grassland Science, NARO (Tsukuba, Japan), which was operated using livestock sewage sludge as the primary input material. Initial recovery interventions for poor fermentation were performed manually by adjusting aeration rates based on internal temperature profiles within the CVCF. After identifying characteristic patterns in the data collected during manual operation, programming models were developed to enable IoT‑based, data‑driven control of the CVCF. Using this system, the facility was successfully maintained under optimal fermentation conditions (compost moisture < 50%, pH > 7.5, and an average temperature of approximately 50 °C) for a continuous 43‑day period.

Closed Vertical Composting Facilities (CVCF) are widely used in Japan to treat organic wastes such as livestock manure and food waste. Different from traditional composting, CVCF systems operate in sealed containers, creating complex enclosed fermentation environments. This study investigated the relationship between fermentation conditions and microbial community dynamics through year-round monitoring of an 18 m³ CVCF.

Fresh chicken manure, swine manure, sludge, and cattle manure were introduced in rotation as raw materials. Compost discharge was sampled twice weekly, and raw materials monthly. Microbial populations were identified by abundance measurements, while daily monitoring included temperature, pH, moisture content, volatile fatty acids, and generation tests.

Results showed strong interactions among temperature, moisture content, and microbial populations. During colder seasons, chicken and swine manure helped maintain temperatures around 65 degrees Celsius. In contrast, large amounts of sludge and cattle manure reduced temperature. Lower temperatures increased moisture content, likely affecting oxygen availability and altering microbial communities. These changes could deteriorate internal composting conditions and lead to incomplete decomposition.