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.

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What is still Limiting the Deployment of Cellulosic Ethanol? Analysis of the Current Status of the Sector

A growing world population and a growing number of applications for vegetable oils are generating an increasing demand for these oils, causing serious environmental problems. A sustainable lipid production is then fundamental to address these problems. Oleaginous yeasts are a promising solution for sustainable lipid production, but, with the current knowledge and technology, they are still not a serious alternative in the market. In this review, the potential of these yeasts is highlighted and a discussion is made mainly focused on the economics of the oleaginous yeast oil production and identification of the key points to be improved to achieve lower production costs and higher income. Three main stages of the production process, where costs are higher, were identified. To render economically feasible the production of oils using oleaginous yeasts, a reduction in production costs must occur in all stages, lipid yields and productivities must be improved, and production must be targeted to high-value product applications.

/pdf/oleaginous-yeasts-for-sustainable-lipid-production-from-58d0g28iwh.pdf

Oleaginous yeasts for sustainable lipid production—from biodiesel to surf boards, a wide range of “green” applications

The European Union relies largely on bioenergy to achieve its climate and energy targets for 2020 and beyond.

We assess, using Attributional Life Cycle Assessment (A-LCA), the climate change mitigation potential of three bioenergy power plants fuelled by residual biomass compared to a fossil system based on the European power generation mix. We study forest residues, cereal straws and cattle slurry.

Our A-LCA methodology includes: i) supply chains and biogenic-CO2 flows; ii) explicit treatment of time of emissions; iii) instantaneous and time-integrated climate metrics.

Power generation from cereal straws and cattle slurry can provide significant global warming mitigation by 2100 compared to current European electricity mix in all of the conditions considered.

The mitigation potential of forest residues depends on the decay rate considered. Power generation from forest logging residues is an effective mitigation solution compared to the current EU mix only in conditions of decay rates above 5.2% a−1. Even with faster-decomposing feedstocks, bioenergy temporarily causes a STR(i) and STR(c) higher than the fossil system.

The mitigation potential of bioenergy technologies is overestimated when biogenic-CO2 flows are excluded. Results based solely on supply-chain emissions can only be interpreted as an estimation of the long-term (>100 years) mitigation potential of bioenergy systems interrupted at the end of the lifetime of the plant and whose carbon stock is allowed to accumulate back.

Strategies for bioenergy deployment should take into account possible increases in global warming rate and possible temporary increases in temperature anomaly as well as of cumulative radiative forcing.

/pdf/climate-change-impacts-of-power-generation-from-residual-28r1iwp4nl.pdf

Climate change impacts of power generation from residual biomass

Biomass production, supply, uses and flows in the European Union - First results from an integrated assessment

Algae are without doubt the most productive photosynthetic organisms on Earth; they are highly efficient in converting CO2 and nutrients into biomass. These abilities can be exploited by culturing microalgae from wastewater and flue gases for effective wastewater reclamation. Algae are known to remove nitrogen and phosphorus as well as several organic contaminants including pharmaceuticals from wastewater. Biomass production can even be enhanced by the addition of CO2 originating from flue gases. The algal biomass can then be used as a raw material to produce bioenergy; depending on its composition, various types of biofuels such as biodiesel, biogas, bioethanol, biobutanol or biohydrogen can be obtained. However, algal biomass generated in wastewater and flue gases also contains contaminants which, if not degraded, will end up in the ashes. In this review, the current knowledge on algal biomass production in wastewater and flue gases is summarized; special focus is given to the algal capacity to remove contaminants from wastewater and flue gases, and the consequences when converting this biomass into different types of biofuels.

https://www.mdpi.com/1996-1073/11/3/664/pdf

Algal Biomass from Wastewater and Flue Gases as a Source of Bioenergy

The use of biofuels in transport is being promoted as a means of tackling climate change, diversifying energy sources and securing energy supply. Biofuels production also provides new options for using agricultural crops. However, it also gives rise to environmental, social and economic concerns which are the subject of intense debate worldwide. This study provides a detailed overview of biofuels production and consumption and of related policies worldwide. It also contains comprehensive analysis and discussion of key aspects affecting the overall sustainability of biofuels. These include, in particular, their impact on agricultural markets, emissions from indirect land-use change, and greenhouse gas emissions

L. Garcia-Lledo

Papers

The impact of biofuels on transport and the environment, and their connection with agricultural development in Europe

Is Bioenergy from Residues Really and Always Sustainable? Qualitative Assessment for Policymakers