During recent years, gasification technology has gained a high potential and attractiveness to convert biomass and other solid wastes into a valuable syngas for energy production or synthesis of new biofuels. The implementation of real gasification facilities implies a good insight of all expenses that are involved, namely investments required in equipment during the project and construction phases (capital expenditures, CapEx) and costs linked to the operation of the plant, or periodic maintenance interventions (operational expenditures, OpEx) or costs related to operations required for an efficient and sustainable performance of a gasification plant (e.g., feedstock pre-treatment and management of by-products). Knowledge of these economic parameters and their corresponding trends over time may help decision-makers to make adequate choices regarding the eligible technologies and to perform comparisons with other conventional scenarios. The present work aims to provide an overview on CapEx associated with gasification technologies devoted to convert biomass or solid waste sources, with a view of reducing the carbon footprint during energy generation or production of new energy carriers. In addition, an analysis of technology cost trends over time using regression methods is also presented, as well as an evaluation of specific capital investments according to the amount of output products generated for different gasification facilities. The novelty of this work is focused on an analysis of CapEx of existing gasification technologies to obtain distinct products (energy and fuels), and to determine mathematical correlations relating technology costs with time and product output. For these purposes, a survey of data and categorization of gasification plants based on the final products was made, and mathematical regression methods were used to obtain the correlations, with a statistical analysis (coefficient of determination) for validation. Specific investments on liquid biofuel production plants exhibited the highest decreasing trend over time, while electricity production became the least attractive solution. Linear correlations of specific investment versus time fitted better for electricity production plants (R² = 0.67), while those relating the product output were better for liquid biofuel plants through exponential regressions (R² = 0.65).

Biochar produced during the thermochemical decomposition of biomass is an environmentally friendly replacement for different carbon materials and can be used for carbon sequestration to mitigate climate change. In this paper, current biochar production processes and top market applications are reviewed, as well as emerging biochar uses gaining momentum in the market. Various application fields of biochar, including agricultural applications (e.g., soil conditioning), adsorption (for soil and water pollutants), carbon sequestration, catalysis, or incorporation into composites or construction materials, are also presented and discussed. According to this literature overview, slow pyrolysis is the preferred process for biochar production, whereas agricultural applications (for soil conditioning and fertilization) are the most studied and market-ready solutions for biochar use. The Alentejo region (Portugal) shows tremendous potential to be a major player in the developing biochar market considering feedstock availability and large areas for biochar agricultural application. Biochar’s production potential and possible benefits were also estimated for this Portuguese region, proving that agricultural application can effectively lead to many environmental, economic, and social gains.

Fossil fuels drive global warming, necessitating renewable alternatives such as biomethane (or renewable natural gas). Biomethane, primarily produced through anaerobic digestion (AD), offers a cleaner energy solution but is limited by the slow AD process. Biomass gasification followed by syngas methanation has emerged as a faster alternative. This review examines advancements in these processes over the last decade (2015–2024), focusing on techno-economic and life cycle assessment (LCA) studies. Techno-economic analyses reveal that biomethane production costs are influenced by several factors, including process complexity, feedstock type and the scale of production. Smaller gasification units tend to exhibit higher capital costs (CAPEX) per MW capacity, while feedstock choice and process efficiency play significant roles in determining overall production costs. LCA studies highlight higher impacts for gasification and methanation due to energy demands and associated emissions. However, integrating renewable hydrogen production through electrolysis, along with innovations such as sorption-enhanced gasification (SEG), can enhance overall system efficiency and reduce environmental impacts. This review critically evaluates the technical and economic challenges, along with the opportunities for optimizing biomethane production, and discusses the potential for these technologies to contribute to sustainable bioenergy solutions in the transition to a low-carbon economy.

The water-and-waste sector has shown a marked interest in innovative management practices for dewatered sludge. The need to manage increased sludge volumes at rising disposal costs, coupled with the recognition of the potential for on-site energy production, have been the key drivers for this recent appeal. With the current political view supporting the development of a renewable-gas industry in Portugal, renewable gases are considered an attractive solution for dewatered-sludge valorization. Moreover, investment in renewable-gas supply chains would help the industry to mature to a level at which the technology and market are rapidly established. Recognizing this interest, dewatered-sludge gasification was selected as a possible valorization pathway, with the potential for hydrogen and bio-SNG production, as well as decentralized heat and power. This document identifies the market opportunities for the establishment of sewage-sludge gasification in Portugal. The analysis starts with a brief overview of the Portuguese water-and-waste sector, and a description of the current status of the renewable-gas markets. Finally, the dewatered-sludge amounts are quantified, and the potential for energy and renewable-gas production is estimated to support the interest in wastewater management in advanced processes, and to pave the way for future feasibility studies.

Rural areas can benefit from the development of biorefineries for the valorization of endogenous feedstocks. In this study, a pre-feasibility assessment of an integrated multi-product biorefinery to produce essential oils and biomethane is carried out considering current technical and economic conditions. The proposed concept is based on the steam distillation of forestry biomass for the extraction of essential oils (2900 L/y) followed by biomethane production via syngas methanation using the spent biomass as feedstock (30.4 kg/h). In parallel, the anaerobic treatment of WWTP sludge (5.3 kg/h) is used to produce additional biomethane for mobile applications. The results show that the intended multi-product biorefinery delivers attractive benefits for investors as described by the calculated financial indicators: NPV of EUR 4342.6, IRR of 18.1%, and PB of 6 years. Overall, the pre-feasibility analysis performed in this study demonstrates that the proposed biorefinery concept is promising and warrants further investment consideration via cost and benefit analysis, ultimately promoting the implementation of multi-product biorefineries across Europe.