Energy and environmental assessment of hydrogen from biomass sources: Challenges and perspectives

Hydrogen is considered as one of the pillars of the European decarbonisation strategy, boosting a novel concept of the energy system in line with the EU's commitment to achieve clean energy transition and reach the European Green Deal carbon neutrality goals by 2050. Hydrogen from biomass sources can significantly contribute to integrate the renewable hydrogen supply through electrolysis at large-scale production. Specifically, it can cover the non-continuous production of green hydrogen coming from solar and wind energy, to offer an alternative solution to such industrial sectors necessitating of stable supply. Biomass-derived hydrogen can be produced either from thermochemical pathways (i.e., pyrolysis, liquefaction, and gasification) or from biological routes (i.e., direct or indirect-biophotolysis, biological water–gas shift reaction, photo- and dark-fermentation). The paper reviews several production pathways to produce hydrogen from biomass or biomass-derived sources (biogas, liquid bio-intermediates, sugars) and provides an exhaustive review of the most promising technologies towards commercialisation. While some pathways are still at low technology readiness level, others such as the steam bio-methane reforming and biomass gasification are ready for an immediate market uptake. The various production pathways are evaluated in terms of energy and environmental performances, highlighting the limits and barriers of the available LCA studies. The paper shows that hydrogen production technologies from biomass appears today to be an interesting option, almost ready to constitute a complementing option to electrolysis

Quantification of the carbon intensity of electricity produced and used in Europe

The EU has a comprehensive legislation to facilitate the energy transition towards a low carbon energy system and achieve the EU's Paris Agreement commitments for reducing greenhouse gas emissions. The European Green Deal is an integral part of the EU strategy for a sustainable and climate neutral economy by 2050. The decarbonisation of the power generation is essential to achieve the goal of decarbonising the energy and transport sectors. This paper presents a study conducted to quantify the carbon emissions associated to the production of electricity produced and used in European countries, based on a comprehensive methodology developed for this purpose. A spreadsheet model has been developed that considers the various sources for electricity generation, the type of plants, conversion efficiencies, upstream emissions and emissions from power plant construction, as well as the electricity trade. The results show the greenhouse gas emissions from the production and use of electricity in all European countries, revealing significant variations between countries. The carbon intensity of electricity shows a clear reduction trend since 1990, for most of the European countries. In the European Union, carbon intensity of electricity used at low voltage degreased from 641 gCO2eq/kWh in 1990 to 334 gCO2eq/kWh in 2019, and this trend is expected to continue in the coming years

What is still limiting the deployment of cellulosic ethanol? Analysis of the current status of the sector

Ethanol production from cellulosic material is considered one of the most promising options for future biofuel production contributing to both the energy diversification and decarbonization of the transport sector, especially where electricity is not a viable option (e.g., aviation). Compared to conventional (or first generation) ethanol production from food and feed crops (mainly sugar and starch based crops), cellulosic (or second generation) ethanol provides better performance in terms of greenhouse gas (GHG) emissions savings and low risk of direct and indirect land-use change. However, despite the policy support (in terms of targets) and significant R&D funding in the last decade (both in EU and outside the EU), cellulosic ethanol production appears to be still limited. The paper provides a comprehensive overview of the status of cellulosic ethanol production in EU and outside EU, reviewing available literature and highlighting technical and non-technical barriers that still limit its production at commercial scale. The review shows that the cellulosic ethanol sector appears to be still stagnating, characterized by technical difficulties as well as high production costs. Competitiveness issues, against standard starch based ethanol, are evident considering many commercial scale cellulosic ethanol plants appear to be currently in idle or on-hold states

The potential role of biomethane for the decarbonization of transport: An analysis of 2030 scenarios in Italy

This paper aims at evaluating the best allocation of potential biomethane generation for the decarbonization of the transport system, presenting a case study in Italy. The country has some peculiar features, such as several operating biogas plants, additional potential feedstock for biogas/biomethane generation, a well-developed natural gas network and established relevant natural gas uses in different final sectors, including transport. Based on current estimates for sustainable biomethane potential by 2030, ranging from 2.3 to 7.6 billion cubic meters depending on the scenario, the analysis compares technologies for the generation, distribution and final use of biomethane. The results of the analysis confirm the potential interesting contribution of biomethane in decarbonizing the Italian transport system: a billion cubic meters of biomethane can lead to 2.33–4.37 MtCO2e savings, depending on the feedstock mix and the application. On a national basis, annual climate emission savings in 2030 range from 10.0 to 26.7 MtCO2e, depending on the scenario. Additional 3.1–8.1 MtCO2e of emissions can be avoided if the CO2 captured during the biomethane upgrading can be stored or reused. The proposed methodology could be used to extend the analysis to other countries, and to the European context

Potential and limiting factors in the use of alternative fuels in the European maritime sector

The maritime sector is a key asset for the world economy, but its environmental impact represents a major concern. The sector is primarily supplied with Heavy Fuel Oil, which results in high pollutant emissions. The sector has set targets for deacrbonisation, and alternative fuels have been identified as a short-to medium-term option. The paper addresses the complexity related to the activities of the maritime industry, and discusses the possible contribution of alternative fuels. A sector segmentation is proposed to define the consumption of each sub-segment, so to compare it with the current alternative fuel availability at European level. The paper shows that costs and GHG savings are fundamental enablers for the uptake of alternative fuels, but other aspects are also crucial: technical maturity, safety regulation, expertise needed, etc. The demand for alternative fuels has to be supported by an existing, reliable infrastructure, and this is not yet the case for many solutions (i.e. electricity, hydrogen or methanol). Various options are already available for maritime sector, but the future mix of fuels used will depend on technology improvements, availability, costs and the real potential for GHG emissions reduction.(c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Biomethane as alternative fuel for the EU road sector: analysis of existing and planned infrastructure

The views expressed here are purely those of the authors and may not, under any circumstances, be regarded as an official position of the European Commission

Bio-Hydrocarbons through Catalytic Pyrolysis of Used Cooking Oils: towards sustainable jet and road fuels

Vegetable Oil (VO) is today the most used feedstock for transport biofuel production by transesterification to biodiesel. Other commercial technologies for renewable fuels production are mainly based either on Fischer-Tropsch (FT) synthesis from coal, natural gas and possibly biomass, or hydro treating of vegetable oil (Hydrotreated Vegetable Oil, HVO): this also includes Hydrotreated Renewable Jet fuel, HRJ, Used Cooking Oil (UCO) is a highly sustainable feedstock (based on EC-RED scheme): it is therefore considered as a possible alternative to VOs for greening of air transport and, under proper circumstances, for reducing the feedstock cost component. However, the use of UCO is not trivial in reactors, as catalysts are sensitive to impurities and contaminations, which are typical of waste oils. Moreover, the chemical composition of UCO is variable regionally as well as seasonally, because the type of base-vegetable oils vary with Country and period of the year. In the framework of the ITAKA EU FP7 project, (catalytic) thermochemical conversion of UCO has been considered to obtain an intermediate biofuel suitable for upgrading by hydrotreating. The catalytic conversion of UCO and Fatty Acids were investigated in a 1.5 kg/h pilot unit. UCO, properly filtered and conditioned, was characterized, and then converted in bio-oil by means of thermal and catalytic reactionsunder controlled conditions. The type of catalyst and the reaction conditions, including several parameters such as temperature, reactor geometry, heating rate and residence time, were evaluated, and selected combinations were tested. The bio-oil was characterized in terms of main constituents and hydrocarbons content, and GC-MS and GC-FID analyses were used to qualitatively and quantitatively assess the composition of the fuel

Biomass carbonization: process options and economics for small scale forestry farms

Bioenergy represents a unique opportunity for forestry companies to diversify the sources of income and create new stable business opportunities: a large number of initiatives has started in the last decades especially regarding decentralized power generation; nevertheless the conversion of the farmers to energy producers is not a trivial issue. The present work has focused on a possible alternative to biopower generation for forestry farms: the biomass carbonization (i.e. biomass slow pyrolysis). Charcoal making presents good prerequisite conditions for successful biomass based systems in the forestry sector: the system results incentive-independent, the power generation represents the co-product of a different primary production (resulting a real additional income), the plant capital cost is affordable for small scale farmers, operations requires technical skills normally available in the forestry sector and the reliability of the system is proven and credible, reducing the risks contained in business plans based on "number of hours of operation over several years". Moreover charcoal is a well known product, familiar to forestry companies for a very long time, the market is well defined, the technology is known but still offers opportunities for further improvements (in terms of efficiency, costs and environmental impacts), the technology does not present major risk, the investment is well suited to small farmers and the process and technology gives a great opportunity for small scale and local supply chain development. Based on these considerations, the present work investigated the technological opportunities for small scale charcoal making systems. Various process configurations have been examined, focusing on advantages and disadvantages representative of each solution in view of small scale application suitable for the Italian case and a designed pilot plant has been proposed

Thermochemical conversion of microalgae: challenges and opportunities

Research in Advanced Biofuels steadily developed during recent years. A number of highly innovative technologies have been explored at various scale: among these, lignocellulosic ethanol and CTO (Crude Tall Oil)-biofuel technologies already achieved the early-commercial status, while hydrotreating of vegetable oils (HVO, or HEFA) can be considered today fully commercial. However, despite the level of innovation in each specific technological process under consideration, the feedstock maintains a central role in making a biofuel chain really sustainable. In this context, microalgae grown in salt-water and arid areas offers a considerable opportunity for advanced biofuel production: at the same time, however, they also represent a considerable challenge. Processing microalgae in an economic way into a viable and sustainable liquid biofuel (a low-cost mass-produced product) is not trivial. So far, the main attention has been given to cultivating the microorganism, accumulating lipids, extracting the oil, valorising co-products, and treating the algae oil into biodiesel (through esterification) or HEFA (Hydrotreated Esthers and Fatty Acids), this second one representing a very high quality biofuels, almost a drop-in fuel (suitable either for road transport or for aviation), which production exceed 2 Mt y-1 today. However, extracting the algae oil at low cost and at industrial scale is not yet a full industrial mature process, and the still limited market size of algae-to-biofuels makes difficult the development of industrial-scale systems. Nevertheless, another option can be considered, i.e. processing the whole algae into dedicated thermochemical reactors, thus approaching the downstream processing of algae in a completely different way from separation. The present work examines the possible routes for thermochemical conversion of microalgae, distinguishing between dry-processes (namely pyrolysis and gasification) and wet-processes (near critical water hydrothermal liquefaction and hydrothermal gasification). Typical expected elementary composition of major products is given. Main peculiarities of batch versus continuous processing are also discussed from an engineering point of view. Major engineering advantages and challenges in thermochemically conversion of algae are identified and discussed, in view of the production of a transport biofuel. Finally, future perspectives for each route are given in terms of current and expected technological readiness level

Are algae ready to take off? GHG emission savings of algae-to-kerosene production

Aviation alternative fuels are perceived as an effective short-term mean to decarbonise our flights. Sustainable aviation fuels from algae have been recently approved for commercial flights, and here we present an assessment of their greenhouse gas (GHG) savings. Three case studies have been investigated with different plant designs and cultivation strategies. The Carbon Offsetting and Reduction Scheme for International Aviation's Life Cycle Assessment methodology is used as a guideline to assess the GHG saving potential of aviation fuels from algae. The approach here presented allows having a sound comparison with other alternative fuel production pathways. We show that the cultivation strategy based on oil maximisation does not necessarily provide significant advantages in terms of GHG savings. The assessed GHG savings fall in a wide range, being dependent on the inputs and cultivation strategy considered. In the best-case scenario, up to 68% of GHG savings can be achieved, therefore offering a substantial advantage over traditional fuels. When compared with the GHG saving of kerosene from other traditional bio-based feedstocks, like rapeseed, the results confirm algae as an interesting alternative, provided that certain conditions for their cultivation, such as high process optimisation, nutrient recycling and use of renewable energy to meet input demand, are met. The study also assessed the area potentially needed for an algae production plant able to supply large volumes of raw material to an existing commercial biorefinery. The findings confirm the potential of this feedstock to mitigate land abandonment on the coasts of the Mediterranean basin