Utilisation of biomass gasification by-products for onsite energy production

The role of soils in provision of energy

Soils have both direct and indirect impacts on available energy, but energy provision, in itself, has direct and indirect impacts on soils. Burning peats provides only approximately 0.02% of global energy supply yet emits approximately 0.7-0.8% of carbon losses from land-use change and forestry (LUCF). Bioenergy crops provide approximately 0.3% of energy supply and occupy approximately 0.2-0.6% of harvested area. Increased bioenergy demand is likely to encourage switching from forests and pastures to rotational energy cropping, resulting in soil carbon loss. However, with protective policies, incorporation of residues from energy provision could sequester approximately 0.4% of LUCF carbon losses. All organic wastes available in 2018 could provide approximately 10% of global energy supply, but at a cost to soils of approximately 5% of LUCF carbon losses; not using manures avoids soil degradation but reduces energy provision to approximately 9%. Wind farms, hydroelectric solar and geothermal schemes provide approximately 3.66% of energy supply and occupy less than approximately 0.3% of harvested area, but if sited on peatlands could result in carbon losses that exceed reductions in fossil fuel emissions. To ensure renewable energy provision does not damage our soils, comprehensive policies and management guidelines are needed that (i) avoid peats, (ii) avoid converting permanent land uses (such as perennial grassland or forestry) to energy cropping, and (iii) return residues remaining from energy conversion processes to the soil. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.

Decentralized Renewable Hybrid Mini-Grids for Rural Communities: Culmination of the IREP Framework and Scale up to Urban Communities

The Integrated Rural Energy Planning (IREP) framework offers a unified road map for locating, planning and operating decentralized renewable hybrid off-grid energy systems for localized (rural) applications in low-income countries. This paper presents the culmination of the IREP framework and aims to illustrate the final step of the IREP framework for two communities in Nigeria. It is focused on two aspects. Firstly, the techno-economic modeling (investment and operation optimization) of a hybrid mini-grid system using HOMER Pro, a techno-economic evaluation tool; and evaluating the benefits of demand side management (DSM) based on energy efficiency on the overall system economics using a scenario-based approach. Secondly, the conceptualization of a sustainable business model using the business model canvas scheme to deliver measurable socio-economic impacts in these communities. The results provide valuable insights into rural electrification via renewable hybrid mini-grids powered primarily with solar photovoltaic technology. Transcending mere electricity access, electricity is provided for productive uses (considering disaggregated end-uses) by harnessing other dispatchable renewable energy resources such as waste biomass. Given high share of rural population in developing countries, these insights are applicable in these regions and further the realization of the United Nations’ goal of sustainable energy (SDG7) and sustainable cities and communities (SDG11).

Techno-economic assessment of turning gasification-based waste char into energy: A case study in South-Tyrol

In the South-Tyrol region (Italy), 46 gasifiers are currently operating and €200,000 are annually paid to dispose of as a waste 1300 tons of char. Therefore, there is a considerable interest in finding alternatives for the valorization of this solid by-product. The aim of this work is to assess the potential of char as energy source and to compare two scenarios. The first scenario considers the possibility of exploiting char in a dedicated burner integrated in the gasification plant. The second scenario assumes that all the char is collected from South-Tyrol and co-fired with biomass in an existing combustion-ORC plant. An economic analysis was performed evaluating the discounted payback time and both scenarios were modeled using Aspen Plus®. The results reveal that substantial savings in the operating costs of the plants can be achieved. In the first scenario the owners of the gasification plants could save from 50% to 94% of the char disposal costs with a payback time ranging between 3 and 7 years. In the second scenario, the owner of the plant could save approximately €235 k per year with a payback time of approximately 7 years. The present study provides a basis for further techno-economic studies on char combustion. The results can be helpful for the owners of the gasification plants in determining the most cost-effective way to dispose char and to avoid disposing it of as a waste. Furthermore, it is demonstrated how char could be used as a renewable fuel, with better performance than raw biomass.

Multi-criteria decision analysis of waste-to-energy technologies for municipal solid waste management in Sultanate of Oman

The Sultanate of Oman faces challenges, like rapid growth of waste generation, which calls for an optimum waste management strategy. Oman has witnessed the production of 1.5m t of municipal solid waste in 2012, which is expected to elevate to 1.89m t in 2030. This rapid increase needs to be tackled to reduce the generation rates along with the environmental impacts. Currently, there are no treatment facilities in Oman other than limited recycling, and therefore dumping waste into the landfill is the only ultimate way to dispose solid waste. Hence, this study is an initiative to improve the waste managing system in Oman by proposing optimum waste-to-energy technology using an analytical hierarchy process, manually and through expect choice software as well. In the present study, the identified important parameters were considered in an analytical hierarchy process model to rank the waste-to-energy technology alternatives. Based on the survey conducted, the most important criteria were environmental and economic, with the local priority vector of 0.400 and 0.277, respectively. This research concludes that the most suitable waste-to-energy technology for Oman, on the basis of the identified criteria, is anaerobic digestion followed by fermentation and incineration, which will help to reduce the amount of waste, greenhouse gas emissions and developing and maintaining costs of landfills.

Pretreatment of Lignocellulosic Biomass with Ionic Liquids and Ionic Liquid-Based Solvent Systems

Pretreatment is very important for the efficient production of value-added products from lignocellulosic biomass. However, traditional pretreatment methods have several disadvantages, including low efficiency and high pollution. This article gives an overview on the applications of ionic liquids (ILs) and IL-based solvent systems in the pretreatment of lignocellulosic biomass. It is divided into three parts: the first deals with the dissolution of biomass in ILs and IL-based solvent systems; the second focuses on the fractionation of biomass using ILs and IL-based solvent systems as solvents; the third emphasizes the enzymatic saccharification of biomass after pretreatment with ILs and IL-based solvent systems.