The research described here is principally meant to produce pyrolysis oil derived products with the potential to be co-fed in crude oil refineries. It is of interest to discuss some of the relevant product properties that likely are crucial for this application. An important product property of the product oil is its tendency to produce coke upon heating, for example determined by the ‘Conradson Carbon Residue’ (CCR) or residue upon an thermographimetric analysis (‘TGA residue’, vide supra) (Furimsky, 2000)- In general, pyrolysis-oils show CCR values around 20 to 30% (Samolada, 1998) and this limits its direct use as a co-feed. The TGA residues for upgraded oils obtained with Ru/C and cat D as presented in this paper, show values between 3 and 22 wt% (see Figure 14) and are tunable by process severity (temperature, residence/batch time). It should be realized that low TG residue values are accessible for hydrotreated products which still contain considerable amounts of bound oxygen (> 10 wt%). Thus, stable oils may be prepared despite relatively high bound oxygen contents. From a processing point of view this is also advantageous as it
limits the hydrogen usage for the catalytic hydrotreatment process, a major variable cost contributor.

Recently investigations have been reported on the co-processing of hydrotreated pyrolysis oils obtained with a Ru/ C catalyst (oxygen contents > 5 wt%) in a lab scale simulated FCC unit (MAT) (de Miguel Mercader et al., 2010). The hydrotreated products were successfully dissolved and processed in Long Residue (20 wt% upgraded oil). The yields of FCC gasoline (44-46 wt.%) and Light Cycle Oil (23-25 wt.%) were close to the base feed and an excessive increase of undesired coke and dry gas was not observed. Experiments with undiluted upgraded oils were less successful and dry gas and coke yield were significantly higher than in case of co-feeding. This clearly demonstrates that co-processing is necessary to obtain good product yields. This study also shows that, in contrast to initial thoughts, it is likely not necessary to aim for an upgraded oil with an oxygen content lower than 1 wt%.

Further MAT testing with product oils derived from catalyst D is in progress and will allow the establishment of detailed process-product relations for co-feeding purposes. The upgraded oils prepared with cat D have a much higher thermal stability than the original pyrolysis oil, as evident from the TGA residues (Figure 14). Preliminary investigations have shown that this allows distillation of the oil in various fractions without the formation of excessive amounts of char. Further detailed studies are in progress and will be reported in due course.

6. Conclusions

The upgrading of pyrolysis oil by catalytic hydrotreatment reactions using heterogeneous catalysts was studied in detail using a Ru/C catalyst. The investigations provided valuable insights in the chemical transformations occurring during catalytic hydrotreatment and include both thermal and hydrogenation/hydrodeoxygenation pathways. The repolymerisation pathway in which the oils are further condensed to soluble oligomers and eventually to char components competes with a catalytic hydrogenation reaction. In case H2 is present with a proper catalyst, these soluble oligomers may be depolymerised to stabilized components that can be further upgraded. In this respect, the pyrolysis oils show reactivity typically observed for carbohydrates, which is rationalised by considering the high amounts of oligo — and monomeric sugars in the oil. New, highly active Ni-based catalysts have been developed, which show much better performance than conventional ones and provide products with improved properties.

Experimental work is foreseen to elucidate the reaction pathways occurring during catalytic hydrotreatment in more detail and to develop efficient processes to obtain a stabilized oil with the desired product properties at the lowest manufacturing costs. These include:

— Determination of the effects of reactor configuration on the reaction rates (including mass transfer issues) and subsequent reactor selection;

— Determination of relevant physical properties (e. g hydrogen solubility);

— Optimisation of the hydroprocessing conditions and particularly the required hydrogen levels

— Determination of product-process relations. The effective hydroprocessing severity required for further co-refining must be defined;

— The source and availability for hydrogen: perhaps even syngas is applicable;

— Effects of reaction exothermicity need to be determined.

7. Acknowledgement

The authors would like to acknowledge the EU for partial funding of the work through the 6th Framework Program (Contract Number: 518312). We also would like to thank the partners of BIOCOUP project, and especially D. Assink (BTG), A. Ardiyanti and J. Wildschut (RuG, The Netherlands) for performing (part of) the experiments and mutual interpretation of results, VTT (Finland) and particularly A. Oasmaa for the fractionation analysis and V. Yakovlev and S. A. Khromova of the Boreskov Institute for Catalysis (Russia) for catalyst preparation and stimulating discussions. Furthermore, financial support from SenterNovem (in CORAF, project no. EOSLT04018, and NEO-project, no. 0268-02-03-03­0001) is gratefully acknowledged.

The durability of pellets can be measured following the AS ABE Standard S269 (2007). The method states that 100 g of pellet sample should be weighed and placed in a dust-tight enclosure/ chamber, and tumbled for 10 min at 50 r/min. A 5.70 mm sieve should used to determine the fines produced by the pellets during the tumbling process. The mass of pellets left on the sieve, as percentage of the total mass of pellet sample used during the test, was considered as the durability of the pellets.

Hill and Pulkinen (1988) reported an increase in pellet durability by about 30 to 35% with an increase in pellet temperature from 60 to 104°C. A die length-to-diameter ratio (l/d) of 8 to 10 was also reported to be ideal for making high quality pellets. Similarly, Tabil and Sokhansanj (1996) conducted a study for improving the physical quality of alfalfa pellets by controlling and optimizing the manufacturing process. The process conditions investigated were steam conditioning temperatures, die geometry (length to diameter or l/d ratio), hammer mill screen sizes used in grinding dry chops, and die speed. They reported that a higher conditioning temperature (95°C) resulted in improved durability of processed pellets. The durability of samples was generally better using the smaller die (higher l/d ratio). The hammer mill screen size did not show any affect on pellet durability. Finally, they reported that high durable pellets are obtained at low die speed (250 rpm). Theerarattananoon et al. (2011) also observed that an increase in length / thickness of die resulted in significant increase in durability of biomass pellets.

Larsson et al. (2008) and Serrano et al. (2011) reported that the most influential factor affecting pellet durability was raw material moisture content and showing a positive correlation. The maximum durability was obtained at moisture content of 14.9% without steam addition, and at 13.7% (w. b.) with steam addition of 2.6% (Larsson et al., 2008). Serrano et al. (2011) found that the highest mechanical durability reached for barley straw pellets was 95.5% at moisture content of 19-23% (w. b.), while no pellets were formed below the 19% moisture content. In addition, they observed that the durability of barley straw pellets increased with addition of pine sawdust at 2, 7 and 12% bu weight. However, the percentage increase in pine sawdust did not have significant effect on durability. Colley et al. (2006) observed highest durability of 95.9% for pellets from switchgrass at a moisture content of 8.6% (w. b.). The moisture content in the range of 9-14%, 9-11% and 14-16% (d. b.) did not have any significant effect on maximum durability of 96.8%, 96.8% and 89.5% for pellets from wheat straw and corn stover, big bluestem grass, and sorghum stalk, respectively (Theerarattananoon, et al., 2011); however, further increasing the moisture content reduced pellet durability for respective agricultural biomass. Also, the durability was observed to be positively correlated to die temperature (Larsson et al., 2008).

Adapa et al. (2010b) reported that the durability of pellets obtained from non-treated straw samples at 1.6 and 0.8 mm, and customized sample having 25% steam exploded straw at 0.8 mm screen size were significantly different (Table 5). In general, higher durability values were observed for non-treated straw samples at 0.8 mm hammer mill screen size. The durability of pellets significantly increased with a decrease in grind size for non-treated samples from 1.6 to 0.8 mm. However, addition of steam exploded straw to non-treated straw at 0.8 mm screen size resulted in a decrease in durability, except for wheat straw. This could be due to the fact that steam exploded material has lower soluble lignin content and higher cellulose and hemicelluloses content compared to non-treated straw (Table 1). This observation is in contrast to Lam et al. (2008), who reported that the quality (durability) of pellets produced from steam exploded sawdust was 20% higher than non-treated sawdust. Though, it is important to note that high durability values (>80%) were obtained for all pilot scale pelleting tests.

In Colombia due to the act (693/2001), production of biofuel is it is expected to increase for use it in transportation as a measure to reduce greenhouse gas emissions. A target by 2010 is to replace 10% of fuels, used today for transportation, with biofuels that will increase up to 20%. With that, reduce CO2 emissions to the atmosphere that cause the greenhouse effect. One of the main problems is that it causes higher prices for basic foods. Biofuels are produced from products like maize (corn), sugar cane, wheat or soybeans; and when the availability of them decreases in the food market, it drives up prices. At the same time, available area for food crops also decreases because most of these crops are for biofuels, which results in increasing the agricultural commodity’s price in general.

Economic effects from this rising food prices are being felt in recent years, especially in some poor countries. For example the crisis that took place in Mexico because of the maize tortillas rising price, which has doubled in recent years (similar to what is happening in our country with the rising price of bread and milk).

Replacement of conventional fuels with biofuels is also generating adverse ecological consequences. Most of the feedstocks needed for processing take place in developing countries, mainly in Latin America and Asia; most of these countries are cutting down large areas of tropical forests for growing biofuels.

For the production of clean fuels it is necessary to use dirty fuels as energy source. For instance, intensive sugar cane crops (for ethanol) or other oil crops (for biodiesel) will need petroleum products: fertilizers, insecticides, fuel pumps, transport and industrial processing. Therefore it is possible that pollution levels increase by using dirty energy sources for producing and exporting clean energy sources.

So far it is clear that bio in biofuels must have a question mark. Then, it can not be neither justified nor adopted policies for biofuels promotion and support, based on ecological arguments, or in industrialized countries (where people want to use agro-energy) or in developing countries (where people want to produce them).

To classify biofuels as bio, it would necessary to grow in degraded and poor soils that are unsuitable for food production (the so-called second generation biofuels). This prevents the rising prices of food and deforestation. An international certification scheme could ensure the sustainability of agricultural practices for the production of raw materials for biofuels.

In order to reduce possible impacts caused by biofuel production, certification for procedures of its production have been developed around the world; this is how the Dutch government, among others, aims that imported biofuels are certified according to environmental and social criteria. Certification of the entire process shall be necessary to ensure the world sustainability production and the use of biofuels (Testing framework for sustainable biomass, 2007).

Likewise, one of the most important factors for defining biofuel production feasibility is energy balance (the comparison between the energy used for producing biofuels and energy production). From the energy perspective, it is not enough to take into account the energy generated by a fuel, but it also must be considered the global energy balance, considering energy expenditures for fuel production and energy derived from it. Undoubtedly, for the production of that fuel to be profitable, the balance must be positive, i. e. it must generate more energy than consume.

Again the usefulness of biofuels as potential replacement for fossil fuels in the reduction of greenhouse gas emissions has been questioned. Several specialists have shown that the cultivation and use of, is not as efficient as a measure to slow down climate change as their advocates say.

Specifically deforestation, caused because of these feedstocks expansion, can have devastating effects in terms of climate, as well as from the ecological perspective. According to studies, forests from a particular area can reduce CO2 emissions nine times more than a biofuel feedstock with the same area, as well as the subsequent use of those biofuels for transportation.

If that wasn’t enough, along the acquisition process of these fuels (including cultivation, processing, transportation and distribution), more CO2 is released than those crops can absorb while growing. This is because large amounts of fossil fuels are needed; resulting in emission of greenhouse gases, that in the case of bioethanol, these plants cannot entirety absorb. This, linked with the high water consumption required for producing them, especially biodiesel (for one liter of biodiesel 12 liters of water are consumed), makes them a non-sustainable alternative compared to fossil fuels.

Given the multiple problems shown by first generation biofuels, once again a technological solution is offered: liquid biofuels production (BtL, Biomass to Liquid), which can be obtained from lignocellulosic biomass such as straw or wood chips. These include bio­ethanol produced by hydrolyzed biomass fermentation and biofuels obtained via thermo chemistry, such as bio-oil obtained from pyrolysis (carbonization), gasoline and diesel oils produced by Fischer-Tropsch Synthesis, among others.

Based on the above analysed results, we estimated the CO2 emission of a smart phone use. Here, we considered the indirect and the direct CO2 emissions. The direct CO2 emission is equivalent to the fuel consumption origin. On the other hand, the indirect one is mainly on the device of a smart phone. In this study, we focused on HTC Desire X06HT made in Taiwan as a model phone. The indirect CO2 emission is calculated by Input-Output (IO) table, and this emission referred to the prior result. Also, we estimated the conventional smart phone including Li-ion battery in order to compare to the new one. Assuming that the holding time (life time: LT) when one user has a smart phone until he or she change the new one is 2.6 years, the indirect CO2 emission of HTC Desire X06HT including Li-ion battery would be 15.32 kg-CO2/unit. The emission of a smart phone with a PEFC unit would be 15.30 kg-CO2/unit. Although there are uncertainties on the storage tank of H2 to some extent, referring to the data of DMFC storage tank which has already developed, we estimated the emission as almost same as the conventional case (Dowaki et al., 2010a).

Next, the direct CO2 emission is affected by the specific CO2 emission of each fuel. Here, the CO2 emissions of conventional electricity, H2 fuel of natural gas origin (on-site) and Bio-H2 are assumed to be 123.1 g-CO2/MJ, 121.3 and 39.6 g-CO2/MJ-H2, respectively. The CO2 emission per one life cycle is shown in Fig. 9. Note that the specific emission of Bio-H2 is a minimum level (see Fig. 5).

According to this result, due to application of a PEFC unit to the smart phone, we would be able to reduce CO2 emissions of 3.9% to 6.1 % in comparison to the conventional phone. Especially, in the category of younger generation, the CO2 reduction benefit would be effective.

Raw, purchased plant oils characterised with typical properties, fulfilling requirements of recommended in Poland norm [PN — A — 86908] with regard to peroxide number (PN) and acid number (AN) (fig. 2 and 3).

Heating edible oils in conditions corresponding to frying potato chips, breadcrumbs coated fish fingers and heating without a product lead to significant changes of investigated oils properties. It caused mainly distinct changes of acid number (AN) and peroxide number (PN).

Differences in properties of oils subjected to cyclic heating without fried product and in which potato chips or breadcrumbs coated fish fingers were fried may result from course of temperature changes for various investigated batches (Fig. 1).

♦ heating in process of potato chips frying

—•— heating in process of breadcrumbs coated fish fingers frying

Fig. 1. Course of rapeseed oil temperature changes in relation to time of potato chips and breadcrumbs coated fish fingers frying (presented data based on authors own research [Szmigielski et al. 2009] )

The highest temperature for each of investigated oils and in each of five heating cycles was observed in case of samples heated without fried products, in which temperature remained at 180oC. Changes of temperature of oil heated in the process of frying potato chips or breadcrumbs coated fish fingers had dynamic course, reaching the lowest value in approximately beginning of fifth minute. However, value of this minimum was depended on weight of fried product but main factor was fried product to frying medium weight ratio (fig. 1).

Conducted research show that heating plant oils caused noticeable increase of peroxide number (PN) value, when compared to samples not subjected to thermal processing. It must be noted that diverse course and intensity of these changes were observed in case of samples heated without product, samples heated in process of potato chips and breadcrumbs coated fish fingers frying (Fig. 2).

□ heating in process of potato chips frying

□ heating without fried product

□ heating in process of breadcrumbs coated fish fingers frying

Fig. 2. Peroxide number of rapeseed oil subjected to cyclic heating [mMO kg-1]/ data for oil heated in process of potato chips frying and heated without addition of product according to Szmigielski et al. 2008/

Typical course of peroxide number changes in relation to number of frying cycle was presented in Fig. 2. In case of each of five heating cycles, highest value of peroxide number in rapeseed and soybean oils was observed in samples heated without a product [Szmigielski et al. 2008]. It was characteristic, that in these samples peroxide number value increased fast until third or fourth cycle, after which decrease of its value was noted (Fig. 2). Most probable cause of such course of peroxide number changes, in relation to heating cycles, is formation of oxidation products, which partially evaporate from the environment of reaction in form of volatile products. An exception to the rule were analyses conducted for samples of soybean oil (firs and second cycle of heating), in which temporarily highest value was observed in samples heated in process of breadcrumbs coated fish fingers frying [Szmigielski et al. 2011]. Most probably it results from influence of fat present in fried product on a final result of determination.

Samples of oil heated in the process of potato chips frying, characterised with lower values of peroxide number, for each of five heating cycles, when compared to samples heated without the fried product. Stabilizing effect of potato chips, caused by sorption of oxidation products on their surface or partial absorption of frying fat, is most commonly mentioned probable cause of such course of PN changes in these samples [Maniak et al. 2009, Szmigielski et al. 2008, 2009, 2011]. It should be noted (Fig. 1) that PN level in samples of rapeseed and soybean oil heated in process of potato chips frying [Szmigielski et al. 2008], had similar course, stabilizing respectively at approx. 2 mMo/100g and approx. 1,5 mMo/100g [Szmigielski et al. 2011] (with exemption of null samples and first cycle of soybean oil heating). Results of investigation of soybean and rapeseed oil samples heated without fried product differed significantly — reaching almost two times higher value of peroxide number (PN) than respective samples heated in process of potato chips frying. As opposed to this research, heating sunflower oil in process of potato chips frying caused only slight decrease of its peroxide number (PN) when compared to samples heated without fried product [Maniak et al. 2009].

Typical course of acid number (AN) changes of heated oil samples in relation to number of frying cycles was presented in Fig. 3. Acid number of heated oil samples was higher than in raw oil, however, heating in process of potato chips frying caused stabilization of acid number value (AN) at similar level (0,02 mgKOH/g) regardless of number of oil heating cycles, while heating without the product caused systematic increase of AN. Very similar course of acid number changes of investigated post-frying oils was also observed in analogous research on rapeseed oil [Szmigielski et al. 2008] and sunflower oil samples [Maniak et al. 2009]. It is believed, that the most probable cause of observed changes of acid number of these samples is sorption of oxidation products on surface of, subjected to culinary processing, potato chips or partial absorption of oil surrounding the product into its deeper, more distant from surface of investigated raw product layers.

Acid number (AN) of plant oils (rapeseed and soybean) heated in the process of frying breadcrumbs coated fish fingers was increasing systematically. It should be noted that AN for first two cycles of heating remained at level similar or lower than AN determined in respective samples heated in the process of potato chips frying. However, starting from the third heating cycle AN exceeded this value and was systematically increasing with each of heating cycles, reaching values lower than in respective samples of soybean oil heated without fried product (fig. 3). It is believed that two opposing processes were the most probable cause of above described course of changes of acid number (AN) in samples of oils heated in process of breadcrumbs coated fish fingers frying. Increase of AN value should probably be explained with oxidation of fatty acids and hydrolytic effect of water vapour, released from product as a result of frying, while reduction of its level occurred as an effect of sorption of oxidation products on surface of fried product [Szmigielski et al. 2009; 2011]. Five-time cyclic heating of plant oils caused significant changes in composition of fatty acids, which can be simply characterised as significant decrease of fatty acids content. It concerns mainly unsaturated fatty acids, and significant increase of oxidation products content, what can be easily observed on example of soybean oil (fig. 4-6). Similar course of fatty acids composition changes of investigated post-frying oils was also observed in research of, subjected to cyclic heating, samples of rapeseed oil [Szmigielski et al. 2008;2009] and sunflower oil [Maniak et al. 2009]. Five-time cyclic frying of breadcrumbs coated fish fingers or potato chips caused partial stabilization of fatty acids composition, what can be noted in case of two, dominating in soybean, fatty acids i. e. oleic and linolic. Their content in typical raw soybean oil often exceeds 75% (fig. 3-5), [Staat and Vallet 1994, Tys et al. 2003].

Heating this oil only slightly changed proportion of oleic to linolic acid, for in raw oil, on one particle of oleic acid approx. two particles of linolic acid are found. After process of heating, this rate is approx. 1,5 — from 1,4 for sample heated without fried product to 1,50 for sample heated in the process of frying potato chips, and up to 1,63 when sample of oil heated in the process of frying breadcrumbs coated fish fingers is investigated.

Similar effect, when ratio of unsaturated fatty acids (oleic and linolic) is taken into consideration, was also observed in research of sunflower oil used as frying fat in cyclic frying of potato chips.

Fresh sunflower oil usually contains over 80% of these fatty acids, while, statistically on one particle of oleic acid 2,47 particles of linolic acids are found. After five-time cyclic heating in process of potato chips frying this proportion remains unchanged, while it changes only in case of oil heated without fried product [Maniak et al. 2009].

In fresh rapeseed oil, proportion of linolic acid to oleic acid is 1 : 2,72. Five-time cyclic heating in process of potato chips frying caused significant change of this proportion to 1 : 2,37, while, for example, effect of disturbance of this fatty acids ratio occurring during similar cycle of heating without fried product reached 1:3,77 [Szmigielski et al. 2008]. The same processes of heating caused also slight changes of saturated fatty acids ratio. In fresh soybean oil, on one particle of stearic acid 2,66 particles of palmitic acid are found, while after five cycles of heating this ratio was from 1 : 2,1 in oil heated without product (Fig. 4), 1 : 2,31 in oil subjected to heating in process of potato chips frying (Fig. 6) to 1 : 2,38 in oil subjected to heating in process of breadcrumbs coated fish fingers frying (Fig. 5).

Fig. 3. Acid number of rapeseed oil subjected to cyclic heating [mgKOH g-1]/ data for oil heated in process of potato chips frying and heated without addition of product according to Szmigielski et al. 2008/

Fig. 4. The composition of fatty acids of soybean oil treated five-time cyclic heating, heating without fried product /presented data based on authors own research [Szmigielski et al.

2011] /

[% content]

Commercial soybean oil Oil after I cycle of heating Oil after II cycle of heating

Oil after III cycle of heating Oil after IV cycle of heating Oil after V cycle of heating

Fig. 5. The composition of fatty acids of soybean oil treated five-time cyclic heating, heating in process of breadcrumbs coated fish fingers frying /presented data based on authors own research [Szmigielski et al. 2011]/

[% content]

Fig. 6. The composition of fatty acids of soybean oil treated five-time cyclic heating heating in process of potato chips frying /presented data based on authors own research [Szmigielski et al. 2011]/

Similar, slight fluctuations of stearic and palmitic acids ratio were noted after five-time cyclic heating of rapeseed oil, and ranged from 1 : 2,97 in fresh oil, to 1 : 3,03 after heating in process of cyclic potato chips frying and 1 : 2,94 after cyclic heating without fried product [Szmigielski et al. 2008].

It should be noted that similar cyclic heating of sunflower oil did not cause change of ratio of two main saturated fatty acids present in investigated oil e. g. stearic acid and palmitic acid. The ratio was 1 : 1,69. Both in fresh sunflower oil and in oil after five-time cyclic heating without fried product or heated in process of potato chips frying, this ratio did not change [Maniak et al. 2009].

Presented in graphs 7-10 research data, obtained during engine tests, in which mixtures of diesel fuel containing 10% of fatty acids methyl esters were utilised, indicate on similar character of changes of investigated parameters of 2CA90 engine powered with methyl esters obtained from purchased raw soybean oil and post-frying oils obtained after five-time cyclic heating without fried product as well as five-time cyclic frying of potato chips or breadcrumbs coated fish fingers. Mixtures containing 10% addition of esters have similar influence on changes of power and torque of investigated engine in relation to its rotational speed (Fig. 7 and 8).

Curves of specific and hourly fuel consumption for investigated fuel mixtures, containing 10% addition of fatty acids methyl esters, characterised with higher values of energetic parameters, when compared to diesel fuel, for each of five investigated rotational speeds. It should be noted that they characterize with identical nature and high similarity of their course, what suggests insignificance of differences between them. Analogous results of research were obtained by Szmigielski et al. [2009], who, in similar conditions, investigated rapeseed oil samples.

2. Conclusion

0. Model, cyclic heating of plant oils, and especially three first cycles, contribute to significant changes in composition of their fatty acids. Significant changes of peroxide number (PN) and acid number (AN) of investigated oils were noted. Content of unsaturated fatty acids decreases, while increase of oxidation products is observed.

1. Heating plant oils in process of frying products like breadcrumbs coated fish fingers or potato chips affects stabilization of amount of peroxide products present in post-frying oil, what leads to decrease of peroxide number (PN) of such oil in comparison to process of heating without fried products.

2. Acid number (AN) of post-frying oils obtained after frying potato chips stabilized, while frying breadcrumbs coated fish fingers and heating oil without fried product contributed to gradual increase of AN.

3. Frying breadcrumbs coated fish fingers and potato chips favours stabilisation of proportion of fatty acids in investigated post-frying oils, and the proportion is similar to one noted in case of purchased raw oils.

4. Change of properties of post-frying plant oils occurring during stage of chemical conversion to fatty acids methyl esters, contributes to unification of properties of biofuels prepared on base of various batches of post-frying oils and favours utilization of post-frying oils which proved as suitable for production of biofuel as fresh vegetable oils.

5. Unidentified oxidation products undergo similar transformations in the process of fatty acids methyl esters formation, and are not a significant obstacle in correct operation of diesel engines powered with such biofuel.

6. Results of research confirmed usability of post-frying plant oils as a raw material for production of diesel fuel biocomponent.

7. It is currently necessary to elaborate efficient ways of recovery of post-frying fats from points of small gastronomy, and technology of their purification and utilization as components of fuel for diesel engines.

Ne [kW]

1500 1700 1900 2100 2300 2500 2700 2900 3100 n [rpm]

-*-DF Н-Щ -*-M2 ж M3 -*-M4

Fig. 7. Changes of the course of engine power 2CA90 powered by diesel fuel (ON) and mixtures containing 90% diesel fuel and 10% methyl esters of fatty acids and diesel fuel: M1 — esters obtained from purchased fresh soybean oil, M2 — esters obtained from soybean oil without addition of fried product, M3 — esters obtained from soybean oil frying of potato chips, M4 — esters obtained from soybean oil frying of breadcrumbs coated fish fingers. /presented data based on authors own research /[Szmigielski et al. 2011]/

Mo [Nm]

1500 1700 1900 2100 2300 2500 2700 2900 3100 n [rpm]

-*"DF H-M1 -*-M2 ж M3 -*-M4

Fig. 8. Changes of the course of engine torque 2CA90 powered by diesel fuel (ON) and mixtures containing 90% diesel fuel and 10% methyl esters of fatty acids and diesel fuel: M1 — esters obtained from purchased fresh soybean oil, M2 — esters obtained from soybean oil without addition of fried product, M3 — esters obtained from soybean oil frying of potato chips, M4 — esters obtained from soybean oil frying of breadcrumbs coated fish fingers. /presented data based on authors own research /[Szmigielski et al. 2011]/
ge [§’ ( kWh4)]

1500 1700 1900 2100 2300 2500 2700 2900 3100 n [rpm]

—з*-M2 ж M^

Fig. 9. Changes of the course of unitary fuel consumption engine 2CA90 powered by diesel fuel (ON) and mixtures containing 90% diesel fuel and 10% methyl esters of fatty acids and diesel fuel: M1 — esters obtained from purchased fresh soybean oil, M2 — esters obtained from soybean oil without addition of fried product, M3 — esters obtained from soybean oil frying of potato chips, M4 — esters obtained from soybean oil frying of breadcrumbs coated fish fingers. /presented data based on authors own research /[Szmigielski et al. 22011]/

Gp [kg’ h-1]

DF Ml M2 x M3 -*-M4

Fig. 10. Changes of the course of hourly fuel consumption engine 2CA90 powered by diesel fuel (ON) and mixtures containing 90% diesel fuel and 10% methyl esters of fatty acids and diesel fuel: M1 — esters obtained from purchased fresh soybean oil, M2 — esters obtained from soybean oil without addition of fried product, M3 — esters obtained from soybean oil frying of potato chips, M4 — esters obtained from soybean oil frying of breadcrumbs coated fish fingers. /presented data based on authors own research /[Szmigielski et al. 2011]/

Due to their chemical composition, biodiesel fuels are more sensitive to oxidative degradation than fossil diesel fuel. This is especially true for fuels with a high content of di — and higher unsaturated esters, as the methylene groups adjacent to double bonds have turned out to be particularly susceptible to radical attack as the first step of fuel oxidation (Dijkstra et al. 1995). The hydroperoxides so formed may polymerize with other free radicals to form insoluble sediments and gums, which are associated with fuel filter plugging and deposits within the injection system and the combustion chamber (Mittelbach & Gangl, 2001). Where the oxidative stability of biodiesel is considered insufficient, antioxidant additives might have to be added to ensure the fuel will still meet the specification.

1.8 Acid value

Acid value or neutralization number is a measure of free fatty acids contained in a fresh fuel sample and of free fatty acids and acids from degradation in aged samples. If mineral acids are used in the production process, their presence as acids in the finished fuels is also measured with the acid number. It is expressed in mg KOH required to neutralize 1g of biodiesel. It is influenced on the one hand by the type of feedstock used for fuel production and its degree of refinement. Acidity can on the other hand be generated during the production process. The parameter characterises the degree of fuel ageing during storage, as it increases gradually due to degradation of biodiesel. High fuel acidity has been discussed in the context of corrosion and the formation of deposits within the engine which is why it is limited in the biodiesel specifications of the three regions. It has been shown that free fatty acids as weak carboxylic acids pose far lower risks than strong mineral acids (Cvengros, 1998)

In the academic community, green microalgae serve as model organisms for photosynthetic research; Chlamydomonas reinhardtii is the most reputable species for this work (Harris, 2001). Volvox carteri, a multicellular microalga, is another well-established model species for the elucidation of the genetic basis of cellular differentiation (Miller, 2002). In recent years, the green alga Dunaliella salina has been utilized to complement the study of photosynthesis, osmoregulation, carotenogenesis, and glycerol production (Jin et al., 2001; Liska et al., 2004; Thompson, 2005; Shaish et al., 1992; Chitlaru et al., 1991). Dunaliella salina is an attractive platform for both commercial and academic pursuits owing to its intriguing and advantageous abilities to survive in conditions of extreme salinity and produce significant amounts of |3-carotene. Currently, the aspiration to genetically and metabolically engineer this organism in order to probe its biological networks and eventually enhance its productivity is an ambitious goal. Until recently, the stable expression of transgenes by this organism has been limited due to inexperience with genetic transformation and insufficient knowledge of the species’ genome. While molecular methods of manipulation make C. reinhardtii and V. carteri experimentally tractable at many levels, there is a pressing need for the same tools to be developed for D. salina.

This section discusses attempts to genetically engineer D. salina through the development of selectable marker systems. The investigation includes detailed characterization of the growth response of D. salina to a number of antibiotics and herbicides commonly used for selection of microalgae, such as bleomycin, paromomycin, and phosphinothricin (PPT). Based on reported genetic sequence information for D. salina, promoter and 3′-UTR regions of highly active genes were selected as targets for genomic PCR, with the hopes of creating

D. salina-specific plasmid transformation vectors. Although these efforts did not yield the intended results, this work establishes a foundation for genetic engineering of D. salina, which is expected to continue now that the sequenced genome has been made available (Smith et al. 2010).

CO2 + 3H2 = CH3OH + H2 O -49.67 KJ/mol (17)

CO + H2O = CO2 +H2 -41.14 KJ/mol (18)

In this case, the main reaction leading to methanol is hydrogenation of CO2.

It should be noted that according to this reaction, the synthesis of methanol proceeds predominantly by direct hydrogenation of CO2 and not CO. It should also be noted that the

WGS reaction proceeds in the forward direction, consuming CO to produce the main reactants: CO2 and H2, thus boosting the eventual methanol productivity. A number of authors (Cybulski, 1994, Lee et al., 1989) have tried a variety of reaction to elucidate the true reaction pathways or mechanistic pathways, including isotope labelling studies and kinetic studies involving complete absence of one of the syngas components.

The application of pre-processing operations such as particle size reduction/ grinding is critical in order to increase the surface area of lignocellulosic biomass prior to densification (Mani et al. 2004). Particle size reduction increases the total surface area, pore size of the material and the number of contact points for inter-particle bonding in the compaction process (Drzymala, 1993). Size reduction is an important energy intensive unit operation essential for bioenergy conversion process and densification to reduce transportation costs (Bitra et al., 2009; Soucek et al., 2003). Energy consumption of grinding biomass depends on initial particle size, moisture content, material properties, feed rate of the material and machine variables (Lopo, 2002). A comprehensive summary of literature review on size reduction of lignocellulosic biomass is provided in Table 4.

Knife and Hardwood • Effect of screen size (from 1.6 • Negative correlation between screen Cadoche and

Hammer Mills Chips, Wheat to 12.7 mm) on specific energy size and specific energy Lopez, 1989

Straw and Corn • Specific Energy is material dependent

Stover

Hammer Mill Red Winter • Effect of screen size (from 1.59 • Negative correlation was observed Fang et al.,

Wheat Straw to 4.76 mm) on specific energy between screen size and specific 1997

• Effect of feed rate (from 1.5 to energy

2.5 kg/min) on specific energy • Feed rate did not have significant effect on specific energy

Hammer Mill Oat Straw, Rattle • Effect of Screen size (from 1.0 • Negative power correlation between Soucek et al.,

Grass and to 10.0 mm) on specific energy screen size and specific energy 2003

Miscanthus • Effect of moisture content on • Positive correlation between moisture

specific energy content and specific energy;

significantly higher specific energy is required at smaller screen sizes

Hammer Mill Corn Stover • Effect of hammer thickness (6.4 • Negative correlation between hammer Vigneault et

and 3.2 mm) on Specific Energy thickness and Specific Energy al., 1992

• Effect of hammer thickness (6.4 • Negative correlation between hammer

and 3.2 mm) on Grinding Rate thickness and Grinding Rate

•

Effect of hammer tip speed (54 • Positive correlation between hammer to 86 m/s) on Specific Energy tip speed and Specific Energy

Table 4. A comprehensive summary of literature review on size reduction of lignocellulosic

biomass.

1.1.4 Different offered possibilities

A promising approach consists in using metallophtalocyanines to realize glucose oxidation. Particularly, cobalt phtalocyanines seem to exhibit interesting properties (Zagal et al., 2010). Furthermore, reactivity of these electrodes can be modulated by simple modification of the complex structure what is of interest for the development of electrodes. These catalysts could be used for glucose electrooxidation in glucose/O2 biofuel cells but it is not still developed.

The other approach lies in the use of metallic nanomaterials as catalysts. Oxidation of glucose on metallic surfaces has extensively been studied. Among all these investigations, numerous ones have been devoted to the understanding of catalytic effect of platinum on glucose oxidation process (Kokoh et al., 1992a; Kokoh et al., 1992b; Sun et al., 2001). Experiments led to conclude that the major oxidation product is gluconic acid (Kokoh et al., 1992b; Rao & Drake, 1969). Actually, the oxidation process involves dehydrogenation of the anomeric carbon of glucose molecule (Ernst et al., 1979). The major interest in including platinum in the catalyst composition lies in its ability to oxidize glucose at very low potentials (lower than 0.3 V vs. RHE). However, it is also well-known that platinum surfaces are particularly sensitive to poisoning with chemisorbed intermediates (Bae et al., 1990; Bae et al., 1991). To solve this problem, different heavy atoms (Tl, Pb, Bi and W) have been used as adatoms to modify platinum surfaces to raise electrochemical activity of platinum (Park et al., 2006). Other studies relate glucose oxidation on platinum alloys in which the second metal can be Rh, Pd, Au, Pb (Sun et al., 2001), Bi, Ru and Sn (Becerik & Kadirgan, 2001). It appears that the most efficient catalysts are Pt-Pb or Pt-Bi (Becerik & Kadirgan, 2001). However, these catalysts are sensitive to dissolution of the second metal which prevents their use in fuel cells systems. Moreover most of the materials previously cited are toxic. The only one which could be environmentally friendly is gold even if the oxidative stress caused by nanoparticles on living cells is not well-known. Besides, synthesis of alloyed materials allows increasing significantly catalytic activity of pure metals by synergistic effect. This has noticeably been observed with platinum-gold nanoalloys (Moller & Pistorius, 2004).