Search

Bioenergy will be one of the most important renewable energy sources in the conversion from fossil fuels to bio-based products. Short rotation coppice Salix could be a key player in this conversion since Salix has rapid growth, positive energy balance, easy to manage cultivation system with vegetative propagation of plant material and multiple harvests from the same plantation. The aim of the present paper is to provide an overview of the main challenges and key issues in willow genetic improvement toward sustainable biofuel value chains. Primarily based on results from the research project "Optimized Utilization of Salix" (OPTUS), the influence of Salix wood quality on the potential for biofuel use is discussed, followed by issues related to the conversion of Salix biomass into liquid and gaseous transportation fuels. Thereafter, the studies address genotypic influence on soil carbon sequestration in Salix plantations, as well as on soil carbon dynamics and climate change impacts. Finally, the opportunities for plant breeding are discussed using willow as a resource for sustainable biofuel production. Substantial phenotypic and genotypic variation was reported for different wood quality traits important in biological (i.e., enzymatic and anaerobic) and thermochemical conversion processes, which is a prerequisite for plant breeding. Furthermore, different Salix genotypes can affect soil carbon sequestration variably, and life cycle assessment illustrates that these differences can result in different climate mitigation potential depending on genotype. Thus, the potential of Salix plantations for sustainable biomass production and its conversion into biofuels is shown. Large genetic variation in various wood and biomass traits, important for different conversion processes and carbon sequestration, provides opportunities to enhance the sustainability of the production system via plant breeding. This includes new breeding targets in addition to traditional targets for high yield to improve biomass quality and carbon sequestration potential.

This report is the result of a collaborative project within the Swedish Knowledge Centre for Renewable Transportation Fuels (f3). f3 is a networking organization, which focuses on development of environmentally, economically and socially sustainable renewable fuels, and  Provides a broad, scientifically based and trustworthy source of knowledge for industry, governments and public authorities,  Carries through system oriented research related to the entire renewable fuels value chain,  Acts as national platform stimulating interaction nationally and internationally. f3 partners include Sweden’s most active universities and research institutes within the field, as well as a broad range of industry companies with high relevance. f3 has no political agenda and does not conduct lobbying activities for specific fuels or systems, nor for the f3 partners’ respective areas of interest. The f3 centre is financed jointly by the centre partners, the Swedish Energy Agency and the region of Västra Götaland. f3 also receives funding from Vinnova (Sweden’s innovation agency) as a Swedish advocacy platform towards Horizon 2020. Chalmers Industriteknik (CIT) functions as the host of the f3 organization (see www.f3centre.se).

Coagulation is the most common way to remove the bulk of natural organic matter (NOM) from moorland source waters during drinking water treatment. Deteriorating water quality and tightening regulations have created the need for more effective treatment options. A review of the literature identified a range of enhanced treatment options that are available for NOM removal. A novel highly charged Zr coagulant (referred to as Zr-OCl) has also been proposed to enhance NOM removal. The aim of this thesis was to evaluate the use of Zr-OCl as a coagulant in continuous operation at pilot scale by benchmarking the performance of Zr-OCl against a conventional ferric coagulant (referred to as Fe-Coag). The potential use of Zr-OCl in a blend with Fe-Coag was also investigated. The removal of NOM, turbidity and disinfection by-product (DBP) precursors as well as the zeta potential and the strength of flocs was measured. The characteristics of Zr were related to the mechanisms of the coagulation process. It was clear that Zr-OCl could remove more NOM than Fe-coag displaying 7-10 % increased removal of dissolved organic carbon (DOC), 6-10 % increased removal of absorption of ultraviolet light at 254 nm (UV254), 31- 62 % increased turbidity removal and 23-38 % lower THM-FP. Zr-OCl also added more charge to the system and operated over a wider zeta potential range which explained the increased removal. The higher charge and wider operational range was explained by the characteristics of Zr found in the literature review. The Zr-OCl flocs were stronger than the Fe-Coag flocs resulting in less breakage during solid-liquid removal. When different blends of Zr-OCl and Fe-Coag were used there was an incremental increase in performance as a result of an increased amount of Zr in the blend for a given dose. The possible use of Zr-OCl a coagulant was put into context by comparing it to the other treatment options investigated in the literature review.