Biodegradability of biomass pyrolysis oils: Comparison to conventional petroleum fuels and alternatives fuels in current use

Concern with environmental issues such as global climate change has stimulated research into the development of more environmentally friendly technologies and energy sources. One critical area of our economy is liquid fuels. Fast pyrolysis of lignocellulosic biomass for liquids production is of particular concern, as it is one of the most interesting ways to produce renewable liquid fuel for transport and heat and power production.The aerobic biodegradability of various pyrolysis oils from different origins and of a EN 590 diesel sample was examined using the Modified Sturm (OECD 301B). The results demonstrate that all fast pyrolysis oils assessed are biodegradable with similar shaped curves with 41–50% biodegradation after 28 days, whereas the diesel sample reached only 24% biodegradation. Since pyrolysis oils achieved biodegradability over 20% these are classified as inherently biodegradable. Modelling of biodegradation processes was successfully performed with a first-order chemical reaction.The biodegradability results obtained for biomass pyrolysis oils are compared to those of conventional and alternative fuels.     

Structural studies of enzyme-based microfluidic biofuel cells

An enzyme-based glucose/O₂ biofuel cell was constructed within a microfluidic channel to study the influence of electrode configuration and fluidic channel height on cell performance. The cell was composed of a bilirubin oxidase (BOD)-adsorbed O₂ cathode and a glucose anode prepared by co-immobilization of glucose dehydrogenase (GDH), diaphorase (Dp) and VK₃-pendant poly-l-lysine. The consumption of O₂ at the upstream cathode protected the downstream anode from interfering O₂ molecules, and consequently improved the cell performance (maximum cell current) ca. 10% for the present cell. The cell performance was also affected by the channel height. The output current and power of a 0.1 mm-height cell was significantly less than those of a 1 mm-height cell because of the depletion of O₂, as determined by the shape of the E–I curve at the cathode. On the other hand, the volume density of current and power was several times higher for the narrower cell.     

Monitoring of electro-active biofilm in soil

The present paper describes a new tool for on-line monitoring of biofilm growth in the soil. The work deals with the application in soil of the same electrochemical techniques already successfully used in water systems to monitor biofilm growth and mainly based on the cathodic polarisation of stainless steel electrodes. Experiments at laboratory level with sterilised and unsterilised soils, different soil humidities, different levels of nutrients have been performed by using a set of soil microcosms containing electrochemical probes. Weekly humidity tests and adjustments, chemical and microbiological analyses of the soils have been regularly carried out. Microbiological analyses and microscopy observation performed on the surface of the stainless steel electrochemical probes at the end of the tests confirmed a direct correlation between the increase of cathodic characteristic and the biofilm development on the working electrodes. The results suggest that simple electrochemical techniques are applicable in soil to monitor the early stage of biofilm growth on stainless steel. It was confirmed, in particular, a key role of soil humidity in the development of a stable and easily detectable biofilm. Soil humidity level resulted as the most critical and limiting factor for biofilm growth, more than the environment temperature, nutrient and carbon content. The best conditions to achieve a quick and full electro-active biofilm on electrodes in a soil microcosms suitable for experiments and studies at laboratory level have been detailed.     

Composites as cracking catalysts in the production of biofuel from palm oil: Deactivation studies

Composite catalysts HZSM-5/alumina (CZA) and Al-MCM-41/alumina (CMA) were synthesized and tested for their catalytic cracking activity in the production of biofuel from palm oil. Both composite catalysts were characterized for their structure, acidity and surface morphology. The addition of alumina in the composite catalysts improved their hydrothermal stability due to the changes in the surface morphology. The deactivation of the catalysts was studied by obtaining time on stream data by varying the palm oil to catalyst ratio of 8–16. The deactivation data were analyzed using different activity models and the deactivation parameters were determined.     

Integrated transport and renewable energy systems

No single technology can solve the problem of ever increasing CO₂ emissions from transport. Here, a coherent effort to integrate transport into energy planning is proposed, using multiple means promoting sustainable transport. It is concluded that a 100 per cent renewable energy transport system is possible but is connected to significant challenges in the path towards it. Biomass is a limited resource and it is important to avoid effecting the production of food. The integration of the transport with the energy system is crucial as is a multi-pronged strategy. Short term solutions have to consider the long term goal. In a short term proposal for 2030 it is concluded that it is possible both to reduce CO₂ emissions substantially and, at the same time, gain economic benefits. Biofuels are not able to solve the problems within the transport sector but play an important role in combination with other technologies.     

Adiabatic flame temperature from biofuels and fossil fuels and derived effect on NOx emissions

There is currently a sustained interest in biofuels as they represent a potential alternative to petroleum derived fuels. Biofuels are likely to help decrease greenhouse gas emissions and the dependence on oil resources. Biodiesels are Fatty Acid Methyl Esters (FAMEs) that are mainly derived from vegetable oils; their compositions depend on the parent vegetables: rapeseed (“RME”), soybean (“SME”), sunflower, palm etc. A fraction of biodiesel has also an animal origin (“tallow”). A key factor for the use of biofuels in gas turbines is their emission indices (NOx, CO, VOC, and PM) in comparison with those of conventional “petroleum gasoils”. While biodiesels reduce carbon-containing pollutants, experimental data from diesel engines show a slight increase in NOx. The literature relating to gas turbines is very scarce. Two recent, independent field tests carried out in Europe (RME) and in the USA (SME) showed slightly lower NOx while a lab test on a microturbine showed the opposite effect. To clarify the NOx index of biodiesels in gas turbines, a study has been undertaken, taking gasoil and natural gas (NG) as reference fuels. In this study, a calculation of the flame temperature developed by the 3 classes of fuels has been performed and the effect of their respective compositions has been investigated. The five FAMEs studied were RME, SME and methyl esters of sunflower, palm and tallow; these are representative of most widespread vegetable and animal oil bases worldwide. The software THERGAS has been used to calculate the enthalpy and free energy properties of the fuels and GASEQ for the flame temperature (T_f), acknowledging the fact that “thermal NOx” represents the predominant form of NOx in gas turbines. To complete the approach to structural effects, we have modeled two NG compositions (rich and weak gases) and three types of gasoil using variable blends of eleven linear/branched/cyclic molecules. The results are consistent with the two recent field tests and show that the FAMEs lie close to petroleum gasoils and higher than NG in terms of NOx emission. The composition of the biodiesel and regular diesel fuel influences their combustion heat: methyl esters with double bonds see a slight increase of their T_f and their NOx index while that of gasoil is sensitive to the aromatic content.     

Atomization and combustion of canola methyl ester biofuel spray

The spray atomization and combustion characteristics of canola methyl ester (CME) biofuel are compared to those of petroleum based No. 2 diesel fuel in this paper. The spray flame was contained in an optically accessible combustor which was operated at atmospheric pressure with a co-flow of heated air. Fuel was delivered through a swirl-type air-blast atomizer with an injector orifice diameter of 300 μm. A two-component phase Doppler particle analyzer was used to measure the spray droplet size, axial velocity, and radial velocity distributions. Radial and axial distributions of NO, CO, CO₂ and O₂ concentrations were also obtained. Axial and radial distributions of flame temperature were recorded with a Pt–Pt/13%Rh (type R) thermocouple. The volumetric flow rates of fuel, atomization air and co-flow air were kept constant for both fuels. The droplet Sauter mean diameter (SMD) at the nozzle exit for CME biofuel spray was smaller than that of the No. 2 diesel fuel spray, implying faster vaporization rates for the former. The flame temperature decreased more rapidly for the CME biofuel spray flame than for the No. 2 diesel fuel spray flame in both axial and radial directions. CME biofuel spray flames produced lower in-flame NO and CO peak concentrations than No. 2 diesel fuel spray flames.     

Hydrogen turbulent nonpremixed flames blended with spray or prevapourised biofuels

The low radiant intensity of hydrogen flames may be enhanced by adding biofuels with a high sooting propensity. This paper reports the effect of biofuel concentration and phase on the combustion characteristics of turbulent nonpremixed hydrogen-based flames. The 0.2 and 1 mol% vapourised/spray biofuel surrogates blended flames exhibit limited soot loading, except for 1 mol% spray toluene and anisole blends where soot starts to form. Spray additives benefit the formation of soot by creating localised fuel-rich conditions. Blending 3.5 and 4 mol% vapourised toluene attains a sooting flame and significantly enhances the luminosity and radiant fraction. The global NO_x emissions increase with prevapourised/spray biofuel surrogates due to the enhanced NO formation via thermal and prompt routes. Reducing the hydrogen concentration from 9:1 to 7:3 in H₂/N₂ (by mole) leads to large increases in luminosity and radiant fraction by 34 times and 135%, respectively, and a reduction in NO_x emissions by 68%.     

Neue Entwicklungen im Bereich Cellulase‐Engineering

Degradation of cellulose represents a key step for efficient generation of biofuels such as ethanol or butanol from non‐food crops. Several strategies aim to improve the performance of cellulases in order to make the overall process more cost‐efficient. In one strategy, novel arrangements of cellulases are developed. The resulting so‐called designer cellulosomes might allow equipping fermenting hosts with sufficient cellulase activity to grow on cellulose as sole carbon source and, thus, enable consolidated bioprocessing. Other strategies aim to engineer cellulases with higher thermostability and activity to make cellulose hydrolysis more efficient. Current developments in the field of cellulose engineering are summarized and achievements as well as limitations are highlighted.     

循环流化床燃烧稻壳改造的实践

根据国家节能减排的基本国策,因地制宜利用生物质燃料,合理改造循环流化床锅炉,实现节能减排,提高企业的经济效益.