A critical review on sustainable biochar system through gasification: Energy and environmental applications.

The acid pretreatment process is the most employed technique used to disrupt the lignocellulosic matrix. Thus, this paper provides an overview of the acid pretreatment considering important aspects related to the operation conditions, yields, future improvements and the potential use to upgrade lignocellulosic biomass in energy vectors. Moreover, this paper is focused on technical and economic aspects of the use of the acid pretreatment in bioethanol production using olive tree biomass as a case study. This review will provide the framework of the acid pretreatment based on reported applications, experimental and theoretical data. The most well-studied applications of the acid pretreatment are in bioethanol and biogas production. Furthermore, this pretreatment has been improved using solid catalysts and by increasing the solids loading. These options have advantages compared to the traditional way. Even so, improvements in the technical and energy aspects must be performed to make the implementation of this process viable from an economic and environmental perspective. Instead, the kinetic modelling and statistical analysis of the acid pretreatment can be postulated as strong tools to predict the behaviour of different feedstocks under acidic conditions. Moreover, new alternatives to increase the mass and heat transfer in this process related to reactor design conform a new research field. Regarding the case study, the acid pretreatment is one of the most energy-consuming stages of bioethanol production. Low solids loadings are recommended to obtain production costs that are comparable with those reported on the industrial level. In contrast, a high solids loading allows the environmental impact of the process to be reduced in terms of liquid waste generation and carbon dioxide emissions. Finally, the acid pretreatment should be included as an effective method for the biotechnological conversion of lignocellulosic biomass to produce energy vectors once the technical, economic and environmental drawbacks have been overcome.

Acid pretreatment of lignocellulosic biomass for energy vectors production: A review focused on operational conditions and techno-economic assessment for bioethanol production

A systematic review of bioenergy life cycle assessments

Biofuels are being promoted as a low-carbon alternative to fossil fuels as they could help to reduce greenhouse gas (GHG) emissions and the related climate change impact from transport. However, there are also concerns that their wider deployment could lead to unintended environmental consequences. Numerous life cycle assessment (LCA) studies have considered the climate change and other environmental impacts of biofuels. However, their findings are often conflicting, with a wide variation in the estimates. Thus, the aim of this paper is to review and analyse the latest available evidence to provide a greater clarity and understanding of the environmental impacts of different liquid biofuels. It is evident from the review that the outcomes of LCA studies are highly situational and dependent on many factors, including the type of feedstock, production routes, data variations and methodological choices. Despite this, the existing evidence suggests that, if no land-use change (LUC) is involved, first-generation biofuels can-on average-have lower GHG emissions than fossil fuels, but the reductions for most feedstocks are insufficient to meet the GHG savings required by the EU Renewable Energy Directive (RED). However, second-generation biofuels have, in general, a greater potential to reduce the emissions, provided there is no LUC. Third-generation biofuels do not represent a feasible option at present state of development as their GHG emissions are higher than those from fossil fuels. As also discussed in the paper, several studies show that reductions in GHG emissions from biofuels are achieved at the expense of other impacts, such as acidification, eutrophication, water footprint and biodiversity loss. The paper also investigates the key methodological aspects and sources of uncertainty in the LCA of biofuels and provides recommendations to address these issues.

https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.2020.0351

Environmental sustainability of biofuels: a review

https://www.tandfonline.com/doi/pdf/10.1080/21870764.2018.1539210

Rice husk/rice husk ash as an alternative source of silica in ceramics: A review

Sustainable utilization of rice husk ash from power plants: A review

Recently, the Thai government has been advancing the expanded use of biomass as an alternative source of energy substituting it for the fossil fuels that have been shown to be harmful to the environment. Rice husk, one of the main sources of biomass in Thailand, has already been used as an energy source in many different applications and has been successful in reducing the consumption of fossil fuels. At present (2011), the main use of rice husk in Thailand is as fuel to generate electricity. However, rice husk can potentially be used to produce other forms of energy such as cellulosic ethanol. This paper compares the environmental performance of the current main use of rice husk for energy purposes in the Thai context, i.e., for electricity generation with the prospective use, i.e., for cellulosic ethanol production. The results from this study will identify the more environmentally friendly option for use of rice husk for energy purposes. To determine the more environmentally friendly rice husk use option, that being the option that showed the greatest reduction of environmental impacts, the environmental impacts of the two selected rice husk use options were compared with the environmental impacts of their conventional energy production processes using the life cycle assessment (LCA). The LCA software package SimaPro 7.1.6 was used to assist in the analysis of the environmental impacts, with the impact assessment method ReCiPe 2008. The system boundary of the study was expanded to take into consideration the effects caused by the consumption of coproducts generated within the two rice husk options. To make the options comparable, the functional units defined for both options were based on processing 1,000 tonnes of rice husk in both rice husk use systems studied. Based on the available data and assumptions made for this study, the results show that the use of rice husk in both electricity and cellulosic ethanol options had a significant effect in reducing the impacts on fossil fuel depletion and climate change, when compared with the conventional processes. However, the use of rice husk in both options caused a slightly higher impact on particulate matter formation than the conventional processes. The option of using rice husk to generate electricity was preferred over the option of using rice husk as a feedstock to produce cellulosic ethanol for all other impact categories analysed, except particulate matter formation, marine eutrophication, photochemical oxidant formation and freshwater ecotoxicity. In addition, it was found that using rice husk to produce cellulosic ethanol caused a considerably greater impact on human toxicity than its conventional product. The environmental benefits gained by using rice husk depend on the materials that rice husk is replacing. This means that the reduction of environmental impact depends upon the use of the rice husk. Overall, the option of using rice husk to generate electricity shows benefits over the option of using rice husk to produce cellulosic ethanol for most impact categories analysed. However, the cellulosic ethanol option is better than the electricity option in terms of particulate matter formation, marine eutrophication, photochemical oxidant formation and freshwater ecotoxicity. In the short run, the option of using rice husk to generate electricity is more environmentally friendly than the option of using rice husk to produce cellulosic ethanol. However, if rice husk is to be used for electricity generation, the ash generated in power plants should be sent out to be used in other industries. It should not be disposed of in landfills as it causes greater impacts than other ash use options. In the time of oil shortages, rice husk should be considered for use as a feedstock to produce cellulosic ethanol for use as a substitute for petrol to help reduce the dependency of oil importation for Thailand. However, the production process of cellulosic ethanol should be improved to help increase efficiency in reducing the environmental impacts in other impact categories.

Comparative life cycle assessment of uses of rice husk for energy purposes

Sustainability of sugarcane cultivation: case study of selected sites in north-eastern Thailand

This paper aims to identify the environmental, socioeconomic, and social hot spots and to find ways to enhance the sustainability of selected food, fuel, and fiber products from sugarcane, i.e., sugarcane, sugar, electricity from bagasse, and molasses-based ethanol. Life cycle assessment (LCA) and social life cycle assessment (S-LCA) were used to examine the environmental, socioeconomic, and social performances of the various sugarcane-based products. All data from the field were collected during the production year 2014/2015. The environmental data were analyzed using the ReCiPe life cycle impact assessment method. Social data were analyzed using performance reference points method, using social indicators from relevant standards/guidelines. Interesting results from the study are that some problems such as cane trash burning and overuse of chemical fertilizers and agrochemicals are the main causes not only of negative environmental performance, but also of negative socioeconomic and social performances. Moreover, recommendations to help increase the sustainability of the Thai sugar industry for each stakeholder group have been provided. These include, for example, using demonstration farms in the same areas, zoning of agricultural crops, implementing large area-based agriculture policy, and making local regulation to prohibit cane trash burning.

Jittima Prasara-A

Papers

Sustainable utilization of rice husk ash from power plants: A review

Comparative life cycle assessment of uses of rice husk for energy purposes

Sustainability of sugarcane cultivation: case study of selected sites in north-eastern Thailand

Environmental and social life cycle assessment to enhance sustainability of sugarcane-based products in Thailand

Applying Social Life Cycle Assessment in the Thai Sugar Industry: Challenges from the field