• Energy Research

Bioplastics are alternatives of conventional petroleum-based plastics. Bioplastics are polymers processed from renewable sources and are biodegradable. This study aims at conducting an environmental impact assessment of the bioprocessing of agricultural wastes into bioplastics compared to petro-plastics using an LCA approach. Bioplastics were produced from potato peels in laboratory. In a biochemical reaction under heating, starch was extracted from peels and glycerin, vinegar and water were added with a range of different ratios, which resulted in producing different samples of bio-based plastics. Nevertheless, the environmental impact of the bioplastics production process was evaluated and compared to petro-plastics. A life cycle analysis of bioplastics produced in laboratory and petro-plastics was conducted. The results are presented in the form of global warming potential, and other environmental impacts including acidification potential, eutrophication potential, freshwater ecotoxicity potential, human toxicity potential, and ozone layer depletion of producing bioplastics are compared to petro-plastics. The results show that the greenhouse gases (GHG) emissions, through the different experiments to produce bioplastics, range between 0.354 and 0.623 kg CO2 eq. per kg bioplastic compared to 2.37 kg CO2 eq. per kg polypropylene as a petro-plastic. The results also showed that there are no significant potential effects for the bioplastics produced from potato peels on different environmental impacts in comparison with poly-β-hydroxybutyric acid and polypropylene. Thus, the bioplastics produced from agricultural wastes can be manufactured in industrial scale to reduce the dependence on petroleum-based plastics. This in turn will mitigate GHG emissions and reduce the negative environmental impacts on climate change.

Harnessing solar energy is one of the most important practical insights highlighted to mitigate the severe climate change (CC) phenomenon. Therefore, this study aims to focus on the use of hybrid solar dryers (HSDs) within an environmentally friendly framework, which is one of the promising applications of solar thermal technology to replace traditional thermal technology that contributes to increasing the severity of the CC phenomenon. The HSD, based on a traditional electrical energy source (HSTEE) and electrical energy from photovoltaic panels (HSPVSE), was evaluated compared to a traditional electrical (TE) dryer for drying some medicinal and aromatic plants (MAPs). This is done by evaluating some of the drying outputs, energy consumed, carbon footprint, and financial return at 30, 40, and 50°C. The best quality of dried MAP samples in terms of essential oil (EO, %) and microbial load was achieved at 40°C. The HSTEE dryer has reduced energy consumption compared to the TE dryer by a percentage ranging from 37% to 54%. The highest CO2 mitigated ratio using the HSTEE dryer was recorded in lavender, thyme, basil, lemongrass, and sage samples with values ranging from 45% to 54% at 30, and 50°C. The highest financial return obtained from energy consumption reduction and carbon credit footprint was achieved at 50°C, with values ranging from 5,313.69 to 6,763.03 EGP/year (EGP ≈ 0.0352 USD) when coal was used as a fuel source for the generation of electricity. Moreover, the HSPVSE dryer achieved a 100% reduction in traditional energy consumption and then reduced CO2 emissions by 100%, which led to a 100% financial return from both energy reduction and carbon credit. The highest financial returns were observed at 50°C, with values ranging from 13,872.56 to 15,007.02, 12,927.28 to 13,984.43, and 11,981.99 to 12,961.85 EGP/year (EGP ≈ 0.0352 USD) for coal, oil, and natural gas, respectively. The HS dryers show potential for environmental conservation contribution; furthermore, earning money from energy savings and carbon credit could help improve the living standards and maximize benefits for stakeholders.

Abstract Background During the mushroom production process, about one-fifth of the mushroom gets lost. The mushroom residues (MR) are rich in nutrients and can be utilized in diverse applications. Therefore, the goal of this research was to modify a local hammermill to improve the performance of chopping mushroom residues to be efficient used as a by-product. Results The experiments were conducted on a hammermill without and with six screen diameters, three drum rotational speeds, three feed rates, two average moisture content and two hammer rotation tracks (long–short). Then, chopper experiments were carried out with a focus on a specified size, power consumption and energy required. The findings of using any size screen offered little productivity since after a short time, the chopping MR was built blocks around the drum and blades. But using no screen gives these phenomena disappear. The chopping MR performed well in long track conditions, with a feeding rate of 700 kg/h, a drum speed of 300 rpm and moisture content of 43% . Conclusions The chopping operation had the best at feed rate of 700 kg/h, drum speed of 3000 rpm and 43% moisture content of which gave the appropriate MWD of 5.54 and 5.32 mm, consumed power of 1114.35 and 1189.125 W and required specific energy of 1.59 and 1.7 kW h/Mg for short and long tracks, respectively, and also largest mean weight diameter under such conditions due to a decrease in the amount of mushroom residues and an increase in their dryness, which increases the fragmentation impact of hammers on mushroom remnants.

Recently, dry anaerobic co-digestion is one of the mechanisms which have been increasingly used to improve the reactor’s performance for treating livestock manure with agricultural crop residues. Due to carbohydrate, protein and lipid existing in agricultural wastes, biogas yield decreased with higher reactor volume when using wet anaerobic digestion. In this regard, the aim of this work was to achieve the production of biogas using the dry anaerobic technology through livestock manure co-digestion with agricultural waste (AW) such as potato peels, lettuce leaves and peas peels. The manure and AW were mixed at a ratio of 2:1 for 15 min before being introduced into the batch anaerobic system. The results indicated that the co-digestion of lettuce leaves and manure yielded the highest production of methane and biogas which were 6610.2 and 12756.7 ml, respectively, compared to the control (manure) that yielded 4689.9 ml and 11606.7 ml, respectively. Additionally, the results indicated that the co-digestion of lettuce leaves and manure yielded the highest specific production of methane and biogas which were 405.5 ml CH4 g−1 VS and 782.6 ml biogas g−1 VS, respectively, compared to the mono-digestion of manure (control) that yielded 328 ml CH4 g−1 VS and 633 ml biogas g−1 VS, respectively. Eventually, dry anaerobic co-digestion process is an effective approach to waste treatment.