Advances in (Bio)Energy Conversion and Waste Treatment

Dear Colleagues,

The urgent need for sustainable energy, climate mitigation, and efficient waste management is reshaping global research agendas. This Special Issue invites cutting‑edge contributions that deepen scientific understanding and catalyze real‑world impact in (bio)energy conversion, waste valorization, and circular (bio)economy solutions. High‑quality theoretical, experimental, computational, and system‑level studies are welcome, especially those that bridge disciplines (i.e., encompassing energy/feedstock supplies and logistics, conversion, waste treatment processes, disposal/final use, and engineering policy/management), demonstrate innovation, and bear relevance to current and emerging trends in the field of energy.

1. Transformative Feedstocks and Smart Pretreatment Strategies

Innovation in feedstock development and pretreatment is foundational for efficient (bio)energy systems, waste valorization, and circular resource networks:

• Next‑Generation Biomass Feedstocks—Diversification beyond conventional lignocellulosic residues to include urban organic waste, agro‑industrial byproducts, municipal solid wastes, wastewater-derived resources, and plastic co‑processing.
• Microalgae and Bioresource Integration—Harnessing micro‑ and macroalgae for integrated energy and bioproducts generation, carbon capture, nutrient recycling, and energy – efficient waste treatment.
• Advanced Pretreatments—Emerging solvent systems, enzymatic enhancements, and integrated physical–chemical methods to overcome biomass recalcitrance and optimize downstream conversion.

2. Cutting‑Edge Thermochemical and Hybrid Conversion Platforms

Elevating conventional thermochemical routes with enhanced performance and broader resource utilization:

• Gasification, Co‑pyrolysis, and Bio‑Oil Upgrading—High‑efficiency thermochemical pathways including syngas/bio‑oil processes, catalytic and plasma‑assisted systems for fuels and energy precursors.
• Hydrothermal Technologies—Hydrothermal carbonization (HTC), liquefaction (HTL), wet oxidation pathways and related processes for wet organic waste conversion.
• Biochar and Functional Carbon Materials—Production and application of biochar as catalyst support for energy conversion, as energy carrier/storage, and for other sustainable energy uses.

3. Bioelectrochemical, Biochemical, and Hybrid Biological Systems

Biological processes are rapidly evolving as key drivers of effective waste treatment with energy recovery:

• Enhanced Anaerobic Digestion and Co‑digestion—Novel microbial consortia, bioaugmentation strategies, and process engineering to maximize methane and biogas output.
• Hydrogen and Advanced Biofuels—Dark fermentation, integrated hybrid systems, and advanced microbial pathways for green hydrogen and bioethanol generation.
• Bioelectrochemical Systems and Microbial Fuel Cells (MFCs)—Dual‑purpose platforms for energy-efficient wastewater treatment and bioelectricity, including scale‑up studies.

4. Digital Innovation and Advanced Materials for (Bio)energy Optimization

Digital tools and functional materials are accelerating efficiency, resilience, and integration of (bio)energy systems:

• AI, IoT, Digital Twins, and Big Data Analytics—Data‑driven process optimization, real‑time control, predictive modeling, and autonomous biorefineries that improve stability and sustainability.
• Nanostructured Catalysts and Functional Interfaces—Nanotechnologies that enhance reaction kinetics, carbon capture, electron transfer, and microbial stimulation.
• Sensor Integration and Smart Monitoring—Sensor-integrated systems enabling real-time monitoring, adaptive process control, and intelligent reactor management.

5. Sustainability, Circular (Bio)economy, and Policy Frameworks

To translate energy-related technological advancements into sustainable impact, research must be anchored in robust sustainability evaluation and strategic frameworks:

• Techno‑Economic Analysis (TEA) and Life Cycle Assessment (LCA)—Methodologies that rigorously assess environmental impact, cost efficiency, energy efficiency, and scalability.
• Circular (Bio)economy Models and Resource Recovery—Valuation of by‑products (digestate, biochar, fertilizers, chemicals) within integrated (bio)energy supply chains and circular systems.
• Policy, Regulations, and Market Trends—Insightful analysis of climate commitments, carbon pricing, renewable mandates, and economic incentives shaping adoption of (bio)energy technologies.

Given that this special issue will cover interdisciplinary content, we would like to clarify proactively that all submitted manuscripts must centre on energy as their core research focus, even if they relate to the special issue’s subtopics. Should any manuscript’s primary focus demonstrate limited relevance to energy, we will recommend it for publication in other, more suitable MDPI journals.

Dr. Emmanuel Revellame
Guest Editor

Dr. Kristel M. Gatdula
Guest Editor Assistant

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-anonymized peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• biochemical conversion
• bioenergy
• thermochemical conversion
• electrochemical conversion
• waste-to-energy conversion
• sustainability