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Conversion of biomass in syngas by means of indirect gasification offers the option to improve the economic situation of any fuel cell systems due to lower costs for feedstock and higher power revenues in many European countries. The coupling of an indirect gasification of biomass and residues with highly efficient SOFC systems is therefore a promising technology for reaching economic feasibility of small decentralized combined heat and power production (CHP). The predicted efficiency of common high temperature fuel cell systems with integrated gasification of solid feedstock is usually significantly lower than the efficiency of fuel cells operated with hydrogen or methane. Additional system components like the gasifier, as well as the gas cleaning reduce this efficiency. Hence common fuel cell systems with integrated gasification of biomass will hardly reach electrical efficiencies above 30 percent. An extraordinary efficient combination is achieved in case that the fuel cells waste heat is used in an indirect gasification system. A simple combination of a SOFC and an allothermal gasifier enables then electrical efficiencies above 50%. But this systems requires an innovative cooling concept for the fuel cell stack. Another significant question is the influence of impurities on the fuel cells degradation. The European Research Project ‘BioCellus’ focuses on both questions — the influence of the biogenious syngas on the fuel cells and an innovative cooling concept based on liquid metal heat pipes. First experiments showed that in particular higher hydrocarbons — the so-called tars — do not have an significant influence on the performance of SOFC membranes. The innovative concept of the TopCycle comprises to heat an indirect gasifier with the exhaust heat of the fuel cell by means of liquid metal heat pipes. Internal cooling of the stack and the recirculation of waste heat increases the system efficiency significantly. This concept promises electrical efficiencies of above 50 percent even for small-scale systems without any combined processes.

Cynara Cardunculus, commonly known as cardoon is a potential energy crop native to the Mediterranean region with high production yields reported. The aim of this work is to present an overview on the contradicting agronomic data available for cardoon and its potential exploitation in industrial thermochemical (i. e. combustion and gasification) applications. Moreover, experimental work on cardoon gasification is presented, focusing on the agglomeration problems it causes when using it in fluidized bed gasifiers. Cardoon cultivated in Greece was gasified in a100 kW thermal atmospheric circulating fluidized bed gasifier. Due to high ash content (rich in potassium) defluidization was observed at low temperatures (780°C ) during the first 30 minutes after the fuel feeding begun.The agglomerates are investigated with SEM/EDS in an effort to determine the gluing mechanism. The particular cardoon was rich in calcium, and this was apparent in the rich in silicates re-solidified melt.This has led into a recent rush of changing plantations to this plant for the production of biomass in Mediterranean regions. Nevertheless, there is very little positive evidence from applications of this fuel that it is trouble free.Cardoon is a perennial herbaceous species native to the Mediterranean region climate which is characterized by dry and hot summer conditions. The factors that influence the properties of cardoon are the chemical soil characteristics, the fertilizers, the harvesting method, and the different climatic condition and rain distribution. One of the major advantages of cardoon crops is the reduced irrigation demands, thus its cultivation costs are lower, compared to other crops [3][4][5][6][7].The plant has an annual development cycle, native to the Mediterranean region, mainly localized in Spain, Italy, and Greece (typical conditions are mild winters, hot dry summers, and low irregularly distributed annual rainfalls). Cardoon can survive the summer drought by growing a very deep rooting (up to 7 meters) and drying the aboveground plant part during the summer [8][9][10][11][12]. The height of plant can reach up to 2 m depending on climate and soil conditions. The reproductive cycle is completed during the summer so the harvest period can start in August when the ground part is dried. As a result, the crop leads to a high yield of dried solid biomass [13][14][15][16][17].Because of all the above qualities, Cardoon can also have a very negative effect in a local agricultural system, especially when farmers decide to change the cultivated crop. Cardoon has long been recognized as a horrific pest plant can also become a serious invasive species [18]. This is mainly because of its perennial tap-root, capable of vigorously regenerating unless the entire root system is destroyed. This task is very difficult or impossible even if plowing, chaining, scraping, and bulldozing are employed [19].Farmers should take into account the abovementioned character of Cardoon before deciding to engage its cultivation due to benefits of its h...

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