A workshop on sampling and analysis of gas impurities (mainly condensables (tar)) in gases from thermochemical conversion processes was held in Berlin at the 19th EU BC+E. Here the outcomes are shortly summarized and the activities in the after course of the workshop are briefly discussed. An international working group formed to further discuss the important topics of analytics in these gas families was formed. Further ongoing and planned activities will be mentioned.

Biomass combustion is a major contributor to ambient air pollution. Thus, knowing the real-life emissions of biomass heating systems is crucial. Within the project Clean Air by biomass a field measurement campaign was conducted. 15 biomass heating appliances were tested in households at the end user according to their usual operation. Emission factors for gaseous and particulate emissions, as well as for the genotoxic and carcinogenic substance benzo(a)pyrene, were evaluated and compared to current proposed European and Austrian emission factors used for emission inventories. Moreover, the shares of particles and benzo(a)pyrene in hot and cooled flue gas were determined. Results showed a high variability of emissions in the field. Highest values and ranges occurred for room heaters (TSPtotal: 226 mg/MJ). Biomass boilers showed clearly lower emission factors (TSPtotal: 184 mg/MJ) in the field than room heaters and also than the proposed European and Austrian emission factors, in many cases. Emission factors for tiled stoves showed a similar trend (TSPtotal: 67 mg/MJ). The share of condensable particles in the flue gas was remarkable. Especially benzo(a)pyrene was found mostly in the condensable fraction of the particles.

Biodiesel (rapeseed oil methyl ester) was aged in a Rancimat device at a temperature of 110°C and an air flow of 10 L/h. Time-resolved analyses applying gas chromatography-flame ionization detection, gas chromatography-mass spectrometry, and ion-exchange chromatography on the formation of aging products were performed. Formic and acetic acid, fatty acids with chain lengths from 5 to 18 carbon atoms, fatty acid methyl esters, and epoxides were quantified. After 12 h of aging, the concentrations of formic and acetic acid were 5600 ± 80 and 1360 ± 80 mg/kg, respectively. Fatty acid concentrations were in the range of <18-4200 mg/kg after 18 h of aging. Linoleic acid methyl ester and linolenic acid methyl ester (19 and 9.1 mass % of the non-aged fuel) were shown to be fully decomposed after 24 and 18 h of aging, respectively. After 51 h of aging, the concentration of oleic acid methyl ester (63 mass % of the non-aged fuel) decreased to 2.2 mass % and trans-epoxy stearic acid methyl ester and cis-epoxy stearic acid methyl ester reached concetrations of 5.9 and 0.7 mass %, respectively. The fuel composition shows only minor changes in early stages of aging, and a strong timely correlation of the formation of aging products with the end of the induction period of fuel was observed. © 2014 American Chemical Society.

In the presented work the fuel quality and basic data about production processes of wood pellets from
all over Europe are investigated. For this purpose pellets producers were interviewed and fuel samples were analysed. Information from 91 companies was evaluated, covering about 50% of the European pellets production capacity, and pellets samples of 51 companies from 18 different countries were examined. It was found, that the raw material for pellets production is mainly taken from local resources. 75% of the plants process soft wood, whereas the use of hard wood is more common in Eastern Europe, Italy, Spain and France. Regarding the fuel properties of the pellets, differences were mainly found with regard to ash content and mechanical durability. In spite of these strong variations, almost all samples fulfilled the requirements according to the respective quality standard declared, and a clear correlation of valid standards and available pellets qualities was observed.

Glycerol is a co-product compound of biodiesel production with an interesting heating value. In this work pyrolysis kinetic parameters for a pellet made with a mass fraction of 90% sawdust and a mass fraction of 10% glycerol are derived through thermogravimetric analysis. A new parallel reaction scheme with four components (cellulose, hemicellulose, lignin and glycerol) is adopted and the kinetic triplet for each component is derived using a model fitting approach applied to this particular kind of pellet. The isoconversional method Kissinger-Akahira-Sunose is employed both to provide initial values for model fitting simulations and to check final results. Results show that activation energies and pre-exponential factors are respectively: 149.7 kJ mol⁻¹ and 1.98*10¹¹ s⁻¹ for hemicellulose, 230.1 kJ mol⁻¹ and 1.84*10¹⁷ s⁻¹ for cellulose, 154.3 kJ mol⁻¹ and 5.14*10⁹ s⁻¹ for lignin, 74.5 kJ mol⁻¹ and 2.17*10⁵ s⁻¹ for glycerol with a first reaction order for all components, except for lignin (n = 2.6). Through evolved gas analysis it was demonstrated that the thermal degradation of glycerol contained in the pellet can increase hydrogen content in pyrolysis gases.

Current levels of ambient air fine particulate matter (PM_2.5) are associated with mortality and morbidity in urban populations worldwide. In residential areas wood combustion is one of the main sources of PM_2.5 emissions, especially during wintertime. However, the adverse health effects of particulate emissions from the modern heating appliances and fuels are poorly known. In this study, health related toxicological properties of PM₁ emissions from five modern and two old technology appliances were examined. The PM₁ samples were collected by using a Dekati® Gravimetric Impactor (DGI). The collected samples were weighed and extracted with methanol for chemical and toxicological analyses. Healthy C57BL/6J mice were intratracheally exposed to a single dose of 1, 3, 10 or 15mg/kg of the particulate samples for 4, 18 or 24h. Thereafter, the lungs were lavaged and bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation, cytotoxicity and genotoxicity. Lungs of 24h exposed mice were collected for inspection of pulmonary tissue damage. There were substantial differences in the combustion qualities of old and modern technology appliances. Modern technology appliances had the lowest PM₁ (mg/MJ) emissions, but they induced the highest inflammatory, cytotoxic and genotoxic activities. In contrast, old technology appliances had clearly the highest PM₁ (mg/MJ) emissions, but their effect in the mouse lungs were the lowest. Increased inflammatory activity was associated with ash related components of the emissions, whereas high PAH concentrations were correlating with the smallest detected responses, possibly due to their immunosuppressive effect. © 2012 Elsevier B.V.

A mathematical model is developed to simulate synthesis gas production by methane steam reforming process in a fixed bed reactor filled with catalyst particles. Due to the endothermic nature of the reforming reactions heat is supplied into the reactor by means of electrical heating, therefore, the reactor and catalyst particles are exposed to significant axial and radial temperature gradients. A pseudo heterogeneous model is used in order to exactly represent diffusion phenomena inside the reactor tube. Heat and mass transfer equations are coupled with detailed reaction mechanisms and solved for both the flow phase and within the catalyst pellets. The reaction has been investigated from a modeling view point considering the effect of different temperatures ranging from 873 to 1073 (K) on methane conversion and hydrogen yields. The result provides temperature and concentration distribution along the reactor axial and radial coordinates and strong radial temperature gradients particularly close to the entrance of the reactor have been found. © 2013 Elsevier B.V.

Energy systems have increased in complexity in the past years due to the everincreasing integration of intermittent renewable energy sources such as solar thermal or wind power. Modern energy systems comprise different energy domains such as electrical power, heating and cooling which renders their control even more challenging. Employing supervisory controllers, so-called energy management systems (EMSs), can help to handle this complexity and to ensure the energy-efficient and cost-efficient operation of the energy system. One promising approach are optimization-based EMS, which can for example be modelled as stochastic mixed-integer linear programmes (SMILP). Depending on the problem size and control horizon, obtaining solutions for these in real-time is a difficult task. The progressive hedging (PH) algorithm is a practical way for splitting a large problem into smaller subproblems and solving them iteratively, thus possibly reducing the solving time considerably. The idea of the PH algorithm is to aggregate the solutions of subproblems, where artificial costs have been added. These added costs enforce that the aggregated solutions become non-anticipative and
are updated in every iteration of the algorithm. The algorithm is relatively simple to implement in practice, re-using almost all of a possibly existing deterministic implementations and can be easily parallelized.
Although it has no convergence guarantees in the mixed-integer linear case, it can nevertheless be used as a good heuristic for SMILPs. Recent theoretical results shown that for applying augmented Lagrangian functions in the context of mixed-integer programmes, any norm proofs to be a valid penalty function. This is not true for squared norms, like the squared L 2 -norm that is used in the classical progressive hedging algorithm. Building on these theoretical results, the use of the L 1 and L-infinity-norm in the PH algorithm is investigated in this paper. In order to incorporate these into the algorithm an adapted multiplier update step is proposed. Additionally a heuristic extension of the aggregation step and an adaptive penalty parameter update scheme from the literature is investigated. The advantages of the proposed modifications are demonstrated by means of illustrative examples, with the application to SMILP-based EMS in mind.

In cooperation between Vienna University of Technology and Bioenergy 2020+ a project was done which had the objective to evaluate the prospects for the production of Biofuels by integration in existing Austrian biomass industry. The advantages of such integration are the good access to renewable energy resources like wood chips, existing infrastructure for electricity and heat, existing logistics of resources and the utilization of waste heat from Biofuel production to substitute fossil fuels. One work package included the process simulation of thermo-chemical biomass gasification and the production of a second generation Biofuel by the use of Fischer – Tropsch (FT) - synthesis. The process simulation tool IPSEpro was used for the simulation. The simulation of technical processes allows the prediction of the behavior of processes on the base of mathematical models. The quality of a simulation model depends substantially on the used model and the process parameters. The used technologies in the process simulation were the biomass gasification with the Fast Internal Circulating Fluidized Bed (FICFB) – gasification system and the Fischer –Tropsch (FT) - synthesis. The FICFB was developed by the Vienna University of technology. This gasification technology is used in the well known demonstration plant is Güssing (Austria). The produced product gas is nearly nitrogen free and has a high content of hydrogen (45 – 35 Vol%_dry) and carbon monoxide (25 – 20 Vol%_dry). These product gas components are used in the FT - synthesis for the production of FT – raw product. A FT - Trial Plant is also situated in Güssing since the year 2005. A slurry reactor is used in the Trial Plant for the FT – synthesis. The target for the simulation was the production of FT – raw product as well as the substitution of fossil fuels. The waste heat of the process should be used for the production of steam. An amount of 120 tons per hour of fossil produced steam should be substituted. The
Off-Gas of the FT – process was also used for the production of steam. Two different models for location number one were considered. The used fuel was wood chips. The data out of the simulation were used to calculate the economic efficiency of the plants. An important parameter was the price of the FT – raw product per liter. The total costs and the production capacity were set equal to calculate the marginal revenue. Also a sensitivity analysis was done to evaluate the effects of rising fuel costs and increased investment costs.