After hydrolysis, the hydrolyzed products must be fermented by means of microorganisms such as yeasts (Hahn-Hagerdal et al., 2006). Since the hydrolyzed products are composed mainly of glucose, xylose, arabinose and cellobiose, the microorganisms used must be capable of fermenting all of them efficiently for ethanol to be produced on a large scale. The reactions that involve glucose and xylose are respectively:

The classic method used in the fermentation of the hydrolyzed biomass is separate hydrolysis and fermentation (SHF), in which the two processes are completed in different units. A commonly used alternative is simultaneous saccharification and fermentation (SSF), in which hydrolysis and fermentation are completed in the same unit. A last option is represented by consolidated bioprocessing (CBP).

When the SHF process is used, the solid fraction of the lignocellulose material undergoes hydrolysis and this process is called saccharification. The liquid fraction, on the other hand, goes first to the reactor for glucose fermentation, then it is distilled to extract bioethanol, leaving behind only the unconverted xylose, which is then fermented in a second reactor and then undergoes a second, final distilling phase.

The main advantage of this process consists in that separating the processes of hydrolysis and fermentation enables optimal working conditions to be adopted in each case. The enzymes are free to work at high temperatures, while the microorganisms can induce fermentation at more moderate temperatures.

Among the disadvantages, in addition to needing two twin reactors, there is the fact that the enzymes for hydrolyzing the cellulose are inhibited end products. The rate of hydrolysis progressively declines due to the accumulation of glucose and cellobiose.

This process has sometimes been used to produce ethanol from a mix of municipal solid waste: in this case, enzyme recycling was improved using micro — and ultra-filtering procedures, thus achieving the hydrolysis of 90% of the cellulose with a net enzyme load of 10 FPU/g of cellulose (where FPU stands for filter paper unit) (Sanchez & Cardona, 2008).

In the SSF procedure, enzymatic hydrolysis and fermentation take place simultaneously. Cellulases and microorganisms take effect in the same process, so the glucose produced by hydrolysis of the cellulose is immediately consumed by the bacterial cells that convert it into ethanol. SSF achieves the highest output of bioethanol at the lowest costs, since the lesser demand for enzymes is lower because the inhibitory effect of the cellobiose and glucose end products is alleviated by fermentation with yeast. This is a discontinuous type of process that uses natural heterogeneous materials containing complex polymers such as lignin, pectin and lignocellulose. The greatest advantages offered by SSF are a faster rate of hydrolysis thanks to the conversion of the sugars that inhibit cellulase activity, a low enzyme demand, a high product yield, the need for less sterile conditions, a shorter process time, and smaller overall reactor dimensions (Sun & Cheng, 2002).

This process also has far from negligible disadvantages, however, the most significant of which consists in the need to complete fermentation and hydrolysis in suboptimal conditions. That is why microorganism selection and preparation is so important for this process. The cocktail of enzymes for hydrolyzing the cellulose must likewise remain stable within a wide range of temperatures and pH. As for the Saccharomyces cerevisiae cultures, the typical working conditions in SSF involve a pH of 4.5 and temperatures of around 310 K. Experiments have recently been conducted with a new variant of this process called simultaneous saccharification and cofermentation (SSCF), in which the five — and six-carbon sugars are fermented simultaneously. In SSCF, hydrolysis continuously releases hexose sugars that increase the rate of glycolysis, so that the pentose sugars can ferment more quickly and produce a higher yield.

In CBP, four biologically-mediated conversions take place in a single process, i. e. the production of glycolytic enzymes (cellulase and hemicellulase), hydrolysis of the carbohydrate component of the pretreated biomass to obtain sugars, fermentation of the six — carbon sugars (mannose, galactose and glucose), and fermentation of the five-carbon sugars (xylose and arabinose).

The main difference between CBP and the other processes consists in that there is no single process focusing on cellulase production. CBP, also known as direct microbial conversion (DMC), requires just one microbial community for both cellulase production and fermentation. The weakness of this approach lies in the difficulty of finding an organism sturdy enough to simultaneously produce cellulase and ethanol with a high yield. Wyman (Wyman, 1994) wrote that many studies on CBP involved the use of the bacterium Clostridium thermocellum for enzyme production, cellulose hydrolysis and glucose fermentation, while Clostridium thermosaccharolyticum enabled the simultaneous conversion of the pentose sugars obtained from hemicellulose hydrolysis into ethanol. Using Clostridium thermocellum in the system also induces a 31% higher conversion of the substrate than when Trichoderma reesei or Saccharomyces cerevisiae are used. Recent studies have focused on cellulase production combined with a high ethanol yield using strains of Escherichia coli, Klebsiella oxytoca and Zymomonas mobilis as well as the yeast Saccharomyces cerevisiae. The expression of cellulase in Klebsiella oxytoca increased the yield from microcrystalline cellulose hydrolysis and enabled an anaerobic growth in the amorphous cellulose. Various cellobiohydrolases have likewise been functionally expressed in the Saccharomyces cerevisiae. Genetic engineering and metabolic studies will enable the development of new stable strains of microorganisms capable of converting the cellulose biomass into bioethanol, leading to improvements in the industrial bioethanol production process (Lynd et al., 2005).

The microorganisms used during the fermentation process must be capable of working efficiently on both monosaccharide and polysaccharide sugars, so they have to be very versatile. The survival of these bacteria is only assured in controlled pH conditions and the majority of the microorganisms cannot tolerate bioethanol concentrations in excess of 10­15% (w/v).

Saccharomyces cerevisiae is one of the microorganisms most often used because it affords a high ethanol yield from hexose sugars, and it can tolerate bioethanol and inhibitory compounds very well. It has the great disadvantage, however, of being unable to assimilate C6 sugars.

The ethanol-generating bacteria that seem industrially most promising are Escherichia coli, Klebsiella oxytoca and Zymomonas mobilis. Zymomonas, in particular, has demonstrated an aptitude for rapidly and efficiently producing bioethanol from glucose-based raw materials and, by comparison with the other yeasts, it has demonstrated a 5-fold higher yield. The ethanol it produces in the fermentation of the glucose corresponds to a yield that is 97% of the theoretical yield and in concentrations up to 12% (w/v). This bacterium is also capable of producing bioethanol efficiently from fructose and saccharose (C5), but not from C6 sugars.

There are also yeasts that naturally ferment xylose, such as Pichia stipitis, Candida Shehatae and Candida parapsilopis, and they can do so through the action first of xylose reductase (XR), which converts xylose into xylitol, and then of xylitol dehydrogenase (XDH), which converts xylitol into xylulose. Bioethanol fermentation from xylose can also be achieved by recombinant Saccharomyces cerevisiae using the heterologues XR and XDH of Pichia stipitis and xylulose kinase (XK) of Saccharomyces cerevisiae.

Table 1 summarizes the commonly used bacteria and microorganisms (Balat et al. (2008)), highlighting the principal parameters used to assess the performance of the various types of fermentation.

Fermentation can occur in various ways, i. e. discontinuously, continuously, with cells immobilized, and batch-fed (Chandel et al., 2007).

A problem encountered in enzymatic hydrolysis consists in the formation of inhibitors. The activity of the enzymes is strongly influenced by certain levels of cellobiose, glucose or products such as furfural and organic acids deriving from pretreatments.

Inhibitors form in relation to the conditions in which enzymatic hydrolysis takes place. Conditions can be selected that should provide maximum solubilisation and recovery of the hemicellulose component (low severity), optimum enzymatic hydrolysis of the water insoluble cellulosic component (high severity), and a compromise between the two conditions (medium severity). The combined severity (CS) links the severity factor (R0) to the ambient pH, and this index expresses the intensity of the previously-described factors. Its value is expressed as:

CS = logR — pH (6)

When the CS increases beyond the value that generates the highest concentrations of mannose and glucose, the cellulose and hemicellulose break down and there is a drop in the concentration of fermentable sugars that coincides with the formation of furfural and hydroxy methyl furfural (HMF), which subsequently degrade into levulinic and formic acids. To achieve both the maximum fermentability and a high yield of fermentable sugars, the CS should be around 3 (Palmqvist & Hahn-Hagerdal, 2000)).

Inhibitors can come from various sources, e. g. equipment, carbohydrate degradation, lignin decomposition, wood extracts and their decomposition. They can be classified according to their structure as organic, acid, furanes and phenolic compounds. The fermentation inhibitors in particular include the furane derivatives, such as furfural and 5-hydroxy­methyl-furfural (5-HMF), the aliphatic acids, such as acetic acid, formic acid and levulinic acid, and the phenolic compounds. The furane derivatives can further react to form certain polymeric materials. The formation of inhibitory compounds makes it necessary to introduce changes in the production process, such as process water recirculation. It was demonstrated (Palmqvist et al., 1996), for instance, that unconcentrated hydrolyzed products have a moderately inhibitory action, while five-fold concentrations of nonvolatile components almost completely inhibit the fermentation of ethanol by Saccharomyces cerevisiae.

The formation of inhibitors and consequently of toxic compounds is a problem that has a negative fallout on the rate of both enzymatic hydrolysis and fermentation. The toxic compounds can form during steam explosion pretreatments and also during hydrolysis in the presence of low acid concentrations, and they are mainly the products of lignin degradation.

Four main groups of inhibitors have been identified in hydrolyzed lignocellulose products these are acetic acid from the hemicellulose fraction, products of lignin degradation, products of sugar degradation, and extracts that have been solubilized during the pretreatment.

The fermentation inhibitors, on the other hand, can be divided into various groups, depending on their origin:

• substances released during pre-hydrolysis and hydrolysis: acetic acid and extracts including terpenes, alcohols and aromatic compounds (e. g. tannins);

• inhibitors produced as a byproduct of pre-hydrolysis and hydrolysis, due to sugar degradation (furfural, 5-HMF);

• products of lignin degradation, including sizable groups of aromatic and polyaromatic compounds with a great variety of constituents (cinnamaldehyde, p — hydroxybenzaldehyde, syringaldehyde);

• products of the fermentation process, such as ethanol, acetic acid, glycerol and lactic acid;

• metals released by equipment and additives, e. g. nickel, iron, copper and chrome.

The compounds revealing the greatest inhibitory potential are acetic acid and the products of lignin degradation (Larsson et al., 1999).

A detoxification procedure can be used to improve the sugars’ fermentability. Detox methods may be physical, chemical or biological, and they are impossible to compare directly with one another because the degree to which they can neutralize the inhibitors varies. The different microorganisms suitable for this purpose can tolerate the inhibitors to varying degrees. The choice of the most suitable method consequently depends on the raw materials involved and the composition of the hydrolyzed products. Figure 1 shows a flowchart of ethanol production from lignocellulose raw materials.

Another important factor that has to be taken into consideration when applying the 2-steps FIRSST process concerns the production of high quality pulp which may be tricky because of the severity of the reaction. Therefore, even if the second steam process is often based catalyzed, the severity of the treatment will lead to an indirect attack on cellulose which will reduce the fibre length if not suitably controlled. If ethanol production is intented, then the quality of the fibres produced after the FIRSST process is of lesser interest and both FIRSST treatments can be relatively severe. When dealing with quality cellulose fibres production, one must think about reducing the strength of the first FIRSST treatment in order to cope with the severity of the second treatment. So far the approach that has been developed in order to cope with such problem was to evaluate the composition of the lignocellulosic matrix at different severities for a first uncatalyzed FIRSST process. Optimal severity for the first process would lead to a drastic decrease of the hemicelluloses content whilst alterating minimally the long cellulose fibres (which are determined by quantification of the hemi,

Percentages are expressed in terms of bone dry biomass. Deviations from 100% closure are due to ash content. * Comprised in the holocellulose

For the specific case depicted in Table 5, we can assume the severity factor varying from 3.64 to 3.95 only had a minor impact on the alpha cellulose and therefore we can assume that the treatment targeted the hemicelluloses principally. The quantity of removed hemicelluloses can be assimilated to the conversion also presented in the same table which shows an increasing mass content in the lignin broth produced from the FIRSST process. In a situation where quality pulp would be intended, although the best conditions for removing all the hemicelluloses would be at a severity factor of approximatively 4.00, it would be more strategic to use a lower severity first process (210oC, 2 minutes as an example) to ensure that the second steam treatment will not affect to much the pulp quality downstream.

The second process is also tricky since ideally and economically, lignin should be recuperated at >80%. Increasing the severity of the treatment will lead to very low lignin content but will also affect the cellulose fibres. To a certain extent, concentration of lignin inferior to 1% can be obtained using steam treatment. The downside will be that the higher severity will also affect the cellulose fibres and overall, the conversion will be higher and the quantity of pulp recovered downstream will also be lower with regards to the original quantity of biomass used for the process. An example of this is depicted in Table 6 below:

* Yield is expressed in terms of %wt of dry biomass and can therefore be considered as the rate of pulping for the overall process.

In light of the results depicted in Table 5, it is clear that increasing severity will also affect the overall conversion which will lead, at higher severity to a lower production of pulp. Other less severe technique could be used for removing the residual lignin and it should be considered to accentuate the pulping yields and to reduce to chemical alterations that the process may have induce to the cellulose fibres. On the other hand, if hydrolysis of glucose is intended, it was previously reported that severe steam explosion process could have a beneficial effect on enzyme hydrolysis and therefore, reaching higher severity may be beneficial to the whole process even if part of the cellulose is solubilized in the lignin broth. Typical energy consumption for each of the steam process is approximatively 7% of the net biomass calorific value which represents approximatively 1.4 GJ per tonne of biomass process. A two step process could easily lead to a 15 % which now justifies investigations towards a one step process. Using triticale, our group compared the two — and one — step steam process. Since lignin has to be partially hydrolysed and removed, the one step steam process will require utilisation of a base-catalyst.

Althought the process was show efficient for the isolation of cellulose from triticale straws (unpublished results), the downside of such process is that it will generate a broth containing both hemicelluloses and lignin. Although lignin can be precipitated by reducing significantly the pH and mildly heating, it will nevertheless produce an ion-rich solution that will be overall hard to ferment without prior purification. Depending on the targeted downstream processes for hemicelluloses and lignine, the one-step or the two-step process may be more suitable and the choice of one or another should be influenced by the economic of the added-vapue products that will be generated from this biorefinery.

The catalysts for biodiesel can be separated into two major groups: homogeneous e heterogeneous. Homogeneous type forms a single phase mixture when added to oil and alcohol while the heterogeneous do not mix in the reaction medium. The group of homogeneous catalysts is divided into acid and basic and heterogeneous into metal oxides, metal complexes, active metals loaded on supports, zeolite, resins, membranes, and lipases The criterion for choosing which type of catalyst use should take into account firstly, the quality of raw material, but also the type of alcohol, the costs of the catalysts and technological route to be used for biodiesel production.

1.1.1 The effect of reaction time

The conversion rate of vegetable oils into biodiesel increases with reaction time. Freedman et al. (1984) transesterified peanut, cottonseed, sunflower and soybean oils under the condition of methanol to oil ratio of 6:1, 0.5% sodium methoxide catalyst and 60°C. After 1 minute, a yield of 80% of biodiesel was observed for soybean and sunflower oils, and after 60 minutes, the conversions were almost the same for all four oils.

During the transesterification of beef tallow with methanol the reaction was very slow during the first minute due to the mixing and dispersion of methanol into beef tallow. In the next five minutes, the reaction proceeded very fast (Ma et al., 1998). The production of beef tallow slowed down and reached the maximum value at about 15 min. The di — and monoglycerides increased at the beginning and then decreased. At the end, the amount of monoglycerides was higher than that of diglycerides.

3.2 Perspectives of biobutanol use in road transport

The preferred use of biobutanol is the production of motor fuels for spark ignition engines by mixing with conventional gasoline; therefore biobutanol could become an option to bioethanol due to better potential in terms of its physico-chemical properties. Biobutanol concentration in fuel can reach up to 30% v/v without the need for engine modification. Since the butanol fuel contains oxygen atoms, the stoichiometric air/fuel ratio is smaller than for gasoline and more fuel could be injected to increase the engine power for the same amount of air induced. The oxygen content is supposed to improve combustion, therefore lower CO and HC emissions can be expected. Biobutanol and its mixtures can be used directly in the current gasoline supply system, such as transportation tanks and re-fuelling infrastructure. Biobutanol can be blended with gasoline without additional large-scale supply infrastructure, which is a big benefit as opposed to the bioethanol use. Finally biobutanol is non-poisonous and non-corrosive and it is easily biodegradable and does not cause risk of soil and water pollution.

In general, the linear limits of viscoelastic behavior are determined by identifying the range of stress values over which G’ and G" are constant and thus independent of stress. Storage and loss modulii of bio-oil from different feedstocks as a function of shear stress are depicted in Fig. 4. Shear stress from 10-100 Pa exhibited the linear regions for all the bio-oils as noted in Fig. 4. A shear stress of 55 Pa was selected for frequency and temperature sweep. As evident from the figure, the storage modulus (G’) was predominant than that of loss modulus irrespective of the feedstocks, whereas Ba et al (2004) observed the loss-modulus as dominant behavior of the bio-oil produced from softwood bark through vacuum pyrolysis. In another study, Garcia-Perez et al (2008) reported that the storage modulus was lower than that of loss modulus for the bio-oil produced from mallee woody biomass. Ba et al (2004) identified four different regions including two plateaus for G’, which was not observed in this study. The bio-oils from corn cob (3 and 4) produced in a batch MAP had a high storage modulus than that of bio-oils from corn cob produced in continuous MAP as evident from Fig. 5. The bio-oil produced from batch MAP (corn cob 3 and 4) had lower loss modulus than the bio-oil from continuous MAP of corn cobs and batch MAP of other feedstocks. The storage and loss moduli were similar for the bio-oils produced from corn cob in a batch MAP with or without catalyst (Fig. 5).

The frequency sweep was conducted in the range of 0.1-100 Hz and found the linear region between 1 and 100 Hz. Accordingly, the frequency sweep experiments were repeated and identified the linear region between 10 and 100 Hz as shown in Fig. 3. As G’ approaches a slope of more than 2, which confirms the existence of linear viscoelastic region (Tzanetakis et al., 2008). Similarly, G" approaches a slope of more than 2 (less than slope of G’), which is also consistent with linear viscoelastic behavior. A frequency of 50 Hz was selected from the linear range depicted in Fig. 4 for temperature sweep. The frequency sweep was also confirmed that the storage modulus was predominant than that of respective loss modulus of each bio-oil. Tzanetakis et al (2008) reported that the loss modulus was ten times higher than that of storage modulus for the bio-oil produced from hardwood, and it was an

opposite observation. Similar to stress sweep, the bio-oil produced from corn cob 3 and 4 in a batch MAP had lower loss modulus than the bio-oil from other feedstocks including corn cob. The storage and loss moduli were overlapping between the bio-oils at a low frequency (10Hz) and a clear difference was observed as frequency increases. The bio-oil from aspen and canola had a higher storage and loss moduli than that of bio-oils from corn cob.

10 Shear stress, Fa

In all hydrogenation experiments except those at temperatures below 200oC, the product obtained consisted of two liquid phases, viz. an aqueous phase and brown-red organic phase. For all of them, relevant (basic) characteristics were determined, viz. elemental composition (vide supra, Figure 7), water content and average molecular weight. Additionally, to get some insights in the coking tendency, the samples were analyzed using thermogravimetric analysis (TGA). Here, the residual weight of the sample, heated under N2 up to about 900oC, was taken as a measure of coking. A high residue indicates a high tendency for coking and thus a low thermal stability at elevated temperature. The residue after a TGA measurement is a strong function of the process severity, see Figure 9 for details.

Fig. 9. Mass average molecular weight and TGA residue of products from (1) stabilisation,

(2) mild hydrotreating, and (3) 2-stage hydrotreating.

At low process severities, the TGA residue increases and the highest value (22%) is observed at intermediate severities. A further increase in severity leads to a strong reduction in the TGA residue. Thus, it may be concluded that intermediate severities lead to product oils with a high TGA residue and consequently have a higher tendency for coking and may be less suitable as a refinery feedstock.

The organic products were analyzed using gel permeation chromatography (GPC) to determine the average molecular weights and the results are given in Figure 9. The molecular weight of the product oils increases compared to the pyrolysis oil feed at low severity hydrotreatment reactions. Apparently, polymerisation occurs and this has also been observed when heating up pyrolysis oil to 275°C in the absence of catalysts (HPTT process) (Rep et al., 2006). A further increase in the severity (higher temperatures, shorter WHSV’s) leads to a reduction of the molecular weight and a value of less than 300 is observed at the highest severities.

Of particular interest is the relation between the molecular weight of the products and the TGA residue. Products with a higher Mw also lead to higher TGA residues and this may be rationalized by assuming that the higher molecular weight fragments in the products are precursors for coke formation.

Kawakita and Ludde (1971) performed compression experiments and proposed an equation for compaction of powders based on observed relationship between pressure and volume (Equation 3).

P = 1 P C ab a

Where,

Vo-V

V0

C = degree of volume reduction or engineering strain; a and b = Kawakita-Ludde model constants related to characteristic of the powder.

The linear relationship between P/C and P allows the constants to be evaluated graphically. This compression equation holds true for soft and low bulk density powders (Denny, 2002; Kawakita and Ludde, 1971), but particular attention must be paid on the measurement of the initial volume of the powder. Any deviations from this expression are sometimes due to fluctuations in the measured value of V0. The constant a is equal to the values of C = Сю at infinitely large pressure P.

Vo-Vcc

Where, Vx = net volume of the powder, m3.

It has been reported that the constant a is equal to the initial porosity of the sample, while constant 1/b is related to the failure stress in the case of piston compression (Mani et al., 2004).

For operating the machines, during this century and part from the previous: man has used greater amounts of energy from fuels. Fuels coming from forest resources like wood and natural energy coming from sun have not been enough to satisfy the energy appetite that this modern civilization has (Silvestrini, 2000).

This growing demand has created an energy crisis that has led to create programs, proposals, funding and research, to find processes for greater efficiency in energy generation, consumption reduction and uncover alternative sources that allow a diverse offering and increase life span of existing resources.

As long as societies develop, it is clear that energy dependence increases. As a result, the search for more efficient, cleaner, more economic new energy sources and fuels becomes a social need. Therefore, in many processes and business it is possible and feasible to replace oil with natural gas; electric power with solar power; firewood with biogas; tractors with animal traction, etc. At the moment, there is an increase and trend for the conversion of internal combustion engines (ICE) that use gasoline by replacing them with CNG (compressed natural gas). Several CNG dispensers have been installed in the main cities of Colombia. The introduction and claimed benefits have been linked with reductions in pollution and operation costs.

Mankind’s welfare has always been associated with high-energy availability; unfortunately a society’s progress is directly related to its level of consumption. Man needs energy to survive, manage his environment and produce goods. In distant times, at least, he needed energy to keep from starving. Over millions of years, the time it took to get from primitive forms to its present forms; mankind’s evolution is closely linked to the different forms and quantities of energies that were available during each period. The energy consumption growth per capita and energy control has been a constant feature. Evolution changed Man from a gathering society, to a hunting society, an agriculture society, until today becoming a technological society, where per capita consumption in the U. S.A is close to 450 MBTU/inhab. Perhaps primitive man during his tenure in a gathering society consumed no more than 10 BTU/ inhab. This growth in consumption is an indication of progress and risks as well as the complexities of the social organizations in which we live.

Although the safety and quality of our energy supply is of real concerns, we must avoid viewing the energy problem from a local perspective, surrounding countries, and in short term perspectives, now and in the near future. A realistic and deep approach regarding the energy issue must consider that a third of humanity lacks supply of electricity and any other form of advanced energy. It must take into account the safety of supplies for future generations and must be aware of the consequences of the environmental impact that energy production and consumption are having on the planet being passed on to our descendants. The amount of energy needed in the future mainly depends on its efficient production and use. With the purpose of evaluating energy efficiency, energy intensity may be applied as an indicator, i. e. energy consumption per GDP unit in each country. Along the way a trend in energy intensity reduction can be observed alongside the increase in economic development (Perez, 2002).

Since the 70s it has been common to correlate the Gross Domestic Product (GDP) with countries’ energy consumption. In the beginning it was an indicator of a developing country to see their energy consumption growing: more infrastructures and vehicles, appliances, heating and air conditioning systems, more power and better quality demand. It went from a traditional economy based on biomass combustion to an economy that makes a general use of electricity and fossil fuels, both for automotive and industrial use. On the other hand, increased consumption means more man-made fibers to fulfill clothing demands, larger workplaces and leisure trips, more housing space and in general more services. A country’s welfare for better or worse is associated with increased income and this leads to an energy consumption increasing per capita (Valero, 2004).

In the last thirty years, global energy use has increased almost 70%, but this growth is uneven, because developing countries have almost tripled their energy consumption, while industrialized countries increased by 21%. The world’s energy consumption grows faster than wealth or population because developing countries hold the 77% of the world’s population. On the other hand, since 1973 the countries belonging the Organization for Economic Co-operation and Development (OECD) have reduced their energy intensity or energy use by 24%per GDP unit. Energy demand has annually increased more than 2% since the 1973 crisis until today, and if current trends persist, this rate will continue over the next fifteen years (Brown et al., 2000).

Because the population is increasing and countries are getting industrialized, the global energy demand grows. That growth’s projection classified by economic sectors can be seen in Figure 1. In addition, fossil fuels that are used are the main source of pollution in the atmosphere. The important role that energy plays in all human activities is widely recognized. Energy is not only transformed but it also transforms society. With its many developments and uses, energy has substantially changed modern life, by creating new services related to technological progress, and becoming the principal supply for the development and progress of any society.

According to the International Energy Agency (2006), dynamic growth in the biofuels market is associated with the evolution of the world’s demand for primary energy, where fossil fuels have increased participation. Energy demand depends on factor’s performance such as: a) world population increasing b) economic growth c) technological developments which allow maximize efficiency production and use d) implementation of measures towards climate change such as the development of alternative energy sources. Thus, the IE A estimates that by 2020 energy demand will be 16,000 Mtoe (Million Tonnes of Oil Equivalent), it means an annual growth rate of 1.7%.

The World Energy Council considers that in the next twenty years, world energy consumption shall approximately increase by 50%, which means it could be possible to provide energy to 4,000 million people (2,000 million that currently do not have it, plus the other 2,000 expected during this period).

But at the moment, energy has six considerable issues that must not be ignored in the scope any global economic analysis (Casilda, 2000).

First problem: production and consumption in unequal distribution around the world: large areas of primary energy production are different from the major consumption areas.

Second problem: has to do with the limited energy sources currently in use. Still nowadays, about 80% of the world’s primary energy production comes from fossil fuels (coal, oil and natural gas), i. e. non-renewable sources and limited reserves.

Third problem: is the dominant role that oil plays within energy supply, oil where there is huge gap between production and consumption.

Fourth problem: comes from the relationship between energy and its development. The current energy consumption per capita is varied, as are the geographic levels of development. If in the coming years part of the developing world were come close to the level of energy consumption of industrialized countries, the world would face a long energy crisis, and Latin America would have an uneven behavior, as countries like Mexico and Venezuela would be favored, the two largest oil producers in the region and others would not, well most of them, due to their dependence. Likewise, developed countries would also be seriously affected.

Fifth major problem: production and energy consumption pose serious environmental problems that affect other productive resources worldwide, which could lead to climate change of irreparable consequences.

Sixth problem: is the ability to increase energy supply, which directly depends on the capital to be allocated for this purpose. In many Latin American countries capital is restricted due to regulations and low energy prices.

The use of different types of (electricity, motion, light or heat) and forms of energy (fossil fuels like coal, oil and natural gas, hydropower, nuclear energy or alternative energy) necessary for technologic and economic advancement, has produced the energy crisis that, since 1970, questions the possibility of keeping the current development model, in addition to other harmful effects, both because of the uneven development and the environmental consequences (pollution, global warming, etc.)

The nature of non-renewable fossil fuels and the high level of participation within transport sector of the total primary energy consumption and air pollution, have become the force behind promoting research of alternative sources for vehicles, mainly those sources derived from biomass. This has resulted in an increasing environmental consciousness, and seeks to replace fossil fuels or provide blends that reduce their consumption, mainly searching for those sources in agribusiness. Tropical countries play lead roles because it is where the greatest variety of plant species can be found and where the environmental conditions make production of these more advantageous.

Add to this the geopolitical crisis existing with the U. S.A and Iran, Iraq and Venezuela, and the decrease in global reserves that have influenced oil prices (over 75 U. S.D $/barrel), threatening the stability of many economies that do not have energy self-sufficiency. Under these circumstances, biofuels have become a strategic matter for the U. S.A: in 10 years they are seeking to replace 20% of oil consumption, and so does the European continent.

A technological solution to this problem is the use of biofuels; however, the price competitiveness of these compared to liquid fuels is still disputable. One of biofuels’ restrictions is the cost of raw material and its transformation; so low-cost substrates are required to reach competitive price levels.

In practice, different raw materials can be used for industrial alcohol and biodiesel production; however, it is fair to consider that production cost of each liter or gallon strongly depends on geopolitical crisis the characteristics of the raw materials used and the type of process or technology used for their production.

Mainly in industrialized countries, biofuels supply behavior has been due to: biomass availability for their production, production costs and subsidies, and incentives for their production and use. In such respect, demand has been associated with fossil fuels dynamics and the growing interest for the reduction of greenhouse gases (GHGs), from major fossil fuel consuming countries, the latter being an opinion that is under discussion worldwide and must be evaluated in the country.

The contribution of biomass, wood, agricultural, livestock and urban-world residues to energy consumption is currently limited to traditional use as a fuel, especially in Least Developed Countries. However, advanced technologies like gasification, fermentation and anaerobic digestion for biomass exploitation, are increasing its important role as a sustainable energy source like liquid fuel or electricity production. When biomass is grown for burning, there are no net CO2 emissions in the whole process.

Current challenge with biomass is its sustainability management. By 2050 the calculated potential of energy production from biomass is about 10 times the current production, which would be enough to meet the current global energy needs. However, there are several factors that restrict this potential, among them the principal being water availability (UNDP, UNDESA, WEC, "World Energy Assessment, United Nations Development Program, 2000). According to the growth projections from the International Energy Agency, it is estimated that biofuels participation within the energy market will be 4% by 2030 in comparison with the current 1%. The United States, the European Union and Brazil will be the leading countries in biofuels demand. On the other hand, developing countries will have an important role in such energy supply, so that it is estimated Asian and African countries participation for ethanol production, and Malaysian and Indonesian for biodiesel. Considering this, the expected biofuels demand by 2020 is estimated in 50 Mtoe, which is an annual increasing of 6.3%. Thus, it is estimated that ethanol production will be 524 mmba and biodiesel will be mmba 397.

It becomes important to reconsider current energy consumptions, given the evidence that free energy flows will be renewed as long as earth is habitable, unlike stored energy (oil, coal, gas), which is finite, or in constant decrease with increasing cost. This reason justifies the systematic capture of free energy flows (solar, wind, hydraulic, geothermal) or the use of biomass for generating biofuels. Thus, as long as man and society dominate and know the physical phenomena and natural contributions, the more energy that can be exploited. Therefore, it is not whether there is or is not enough energy to sustain human development, but the physical limits of energy use are going to be or have already been overcome. Recently, within the scenario of energy generation from diversified sources, rises the clash of the feasibility for replacing crops for human consumption or for biofuels production in the automotive industry. The burden on agriculture for energy production seems to be very hard and biofuels promotion measures in many countries may trigger a very serious food conflict, with still unknown impacts on the poorest countries. In short term they could bring higher food costs.

The world faces complex challenges, it can not be considered the solution to life survival on Earth based on the alternative of renewable energy from biofuels, as it would increase food crops replacement by monocultures, deforestation for energy crops, would boost diversity extinction, cause reduction of fertile lands and water; plus social consequences caused by population displacement.

The use of a specific type of energy depends on two factors: availability for potential energy and technological capacity to turn it into heat or work. Of these two conditions, Colombia has enough natural energy resources (coal, oil, gas, water falls, solar radiation, wind, biomass), being researched and developed in very early stages for its use. Therefore, replacing some conventional energy sources by renewable energies, with endless reserves, aims to reduce pollutant loads and is more environmentally friendly.

The kind or type of energy source used together with the application or purpose, varies over time within the countries, because the use of one or another depends on demand, pricing, availability in the same country or importation, technical reasons, international political situations, etc. In Colombia it can be said that most of current energy comes from burning fossil fuels, which are petroleum products processed in refineries.

Fossil fuels’ finite and non renewable nature, plus the high air pollution from major population centers, automotive sector which has a high proportion in the total primary energy consumption; all this has promoted new energy or biofuels from organic resources (plants or animals). Colombia is a vulnerable country in regards to oil due to limited exploratory programs, lack of important new discoveries and decreasing reserves. As a result, the country is about to lose its oil self-sufficiency in the short term (2020), in the midst of high prices unfavorable situation. In addition there it is of poor quality due to its high sulfur content, especially in diesel which exceeds the international standards. Diversification of energy sources, preventing degraded climate change, and promoting social rejecting of polluting energy sources, constitute the challenges faced in order for science and technology to make a contribution for a development that is sustainable, recognized and supported by citizens

A condition for sustainable economic development is to ensure self-sufficiency in energy supply, which must be supported in a flexible and diversified energy structure; being at the same time, energy policy components. This policy should consider the agricultural sector’s characteristics, pressed by other energy consumption patterns. Energy as a transformation, transference and accumulation process, should lead those communities to a more efficient use of the different available sources.

It must be a national goal to plan actions for replacing and optimizing the use of different energy forms. External energy inputs replacement by original sources in agricultural production units is one of the self-sufficiency energy objectives through the use of digesters, animal traction, solar, wind, mini stations and alternative fuels (alcohol, vegetable oils, natural gas, etc.)

The prospects resulting from energy optimization and replacement, will allow greater coverage of efficiency and economy of incorporated social benefits. Promoting this energy replacement, due mainly to higher oil prices in recent years, an increase that represents an onerous burden on the world’s poorest countries’ economies.

An energy program must be an integrated set of studies or research projects within biomass production, processing and the areas of energy consumption, linked to socio-economic studies and systems analysis, aimed to develop techniques and technologies on various energy sources (biogas digesters, gasifiers, solar cells, windmills, micro stations), bioenergy systems in rural areas, use of waste and design systems. Productivity and profitability paradigms that favor: high production values per unit of time, area and, invested money, must be accompanied by processes that also favor energy efficiency, in terms of consumption and savings.

Bioenergy is a rather broad term covering all energy products obtained from agricultural commodities or animal waste conversion processes, mainly required to meet automotive sector’s demand in developed countries. Biofuels are a reality in several countries, including

Colombia. Biofuels have become an agro-industrial development model, which attempts to take part in the economic landscape and for this it has stimulus and a broad policy framework as well as multiple advocates and detractors.

Given the biofuels impressive growth (biodiesel and bioethanol) as a renewable energy source, it is necessary to consider in a more analytical and balanced way its options; benefits and limitations in a society that also requires increased food production. In any case, the use of these alternative fuels has negative effects both in natural and socio-economic levels. Despite some partial benefits, from the incorporation of new lands for the production of energy crops and agro-industrial development processes with the collateral effects on employment and possible exports as an added tax product. It is also necessary to face the nearly inevitable competition possibility between food and biofuels production, that within a high poverty levels society, it is worrying that production displacement in our food and agricultural system.

Biofuels present both opportunities and risks. The outcome would depend on the specific context of the country and the policies adopted. Current policies tend to favor producers in some developed countries over producers in most of developing countries. The challenge is to reduce or manage the risks while sharing the opportunities more widely. Biofuel production based on agricultural commodities increased more than threefold from 2000 to 2007, and now covers nearly two percent of the world’s consumption of transport fuels. The growth is expected to continue, but the contribution of liquid biofuels (mostly ethanol and biodiesel) to transport energy, and even more so, for global energy use will remain limited. Despite the limited importance of liquid biofuels in terms of global energy supply, the demand for agricultural feedstocks (sugar, maize, oilseeds) for liquid biofuels will continue to grow over the next decade and perhaps beyond, putting upward pressure on food prices (FAO, 2008).

Today Colombia seeks different alternatives for solving the increasing difficulties set out by its development, mainly its population’s diet in a natural sources panorama, especially when related to water and soil which may be eroded and contaminated. In order to prevent irreversible changes and reduce the impact of greenhouse gases on Earth’s climate, many countries have decided to put their hopes on diversification of energy production strategies by using renewable sources. The first strategy has been replacing petroleum fuels with biofuels, achieving thereby a reduction in CO2 emissions generated by mobile sources (1). Therefore it is urgent to start using alternative energies, i. e. clean and renewable. For this reason biofuels can be a choice, not without question.

It is becoming more urgent to use other fuels in vehicles, mainly for replacing gasoline and diesel, diesel being the one that is gaining preference because of the costs (2). Therefore, it is advisable to research diesel replacements as opposed to gasoline.

The feasibility of using alcohol or biodiesel as automobile fuel in greater proportions than those currently stipulated is a proven fact. Even though there are great expectations, regarding hydrocarbon reserves existence underground in Colombian, the possibility that in a few decades the country has used all its oil must be. This consideration makes it necessary to pay attention to Brazil’s experience, which aims to replace oil with other fuels. With optimism of our economy recovery, if new options are not found, the country will: increase its fossil fuels consumption of high priced products within the international market, that in the near future could consume our currency. No matter what, its price tends to increase as a result of the world demand and conflicts with governments in the Middle East and Venezuelan. For that reason, it is advisable to have a replacement from organic sources available, such as alcohol and biodiesel.

Unlike the oil industry, the new agro-energy industry involves a productive chain that impacts different economic sectors more directly, especially with regard to employment generation and agricultural and agribusiness development. The addition of Biofuels to blends helps to mitigate oil import requirements. This supports the national biofuel policy facing the balance of energy trade, and to some extent, defines security settings on the supply level.

Colombia has a great potential for establishing a big biofuel industry. Developing this industry gives the country an opportunity for exploiting its comparative advantages, as a tropical country with an agricultural tendency (biomass production) and suitable soils for feedstocks. Moreover, it becomes a technologically scientific challenge for research groups to focus their efforts on achieving proprietary technological developments by working together and interdisciplinary with public and private sectors. Unfortunately the substitution of conventional fuels with biofuels (ethanol and biodiesel) is also having ecological consequences.

Because of the current high demand, which is expected to increase in the coming years, many countries are cutting down large areas of tropical forests to cultivate biofuels. Although this is not the case in Colombia, as long as a favorable competition for energy feedstocks are shown (given the high government incentives and subsidies), against food without any government protection and also competing with the different free trade agreements. This is worrying given the large expanses of land necessary for feedstocks.

In conclusion, to really consolidate a coherent policy on new energy matter within the Colombian bucket, the following remarks must be considered:

• Environmental Ethics.

• The physical boundaries (finite resources).

• Climatic and geographical conditions.

• Crop Yields (kg/ha, l/ha, l/t).

• Energy intensity and energy return rate.

• Water requirements.

• Self Sufficient Process.

• Technology, return on investment (ROI) and profitability.

Not forget that compressed natural gas — natural gas vehicle (CNG-NGV) is another strong rival among the already diverse energy supply.

In that context, the National Government has promoted research and of new renewable energy sources that are sustainable with the increasing pace of life, while oil and its derivatives are partially replaced in different applications, mainly in transport sector. This promotion must also consider the implications when allocating millions of hectares for bioenergy production. This reality highlights the urgent need of fulfilling food needs or allocating those lands and feedstocks to meet the automotive industry energy requirements. Energy is, undoubtedly, both a solution and a problem for sustainable development. As such, the hope is focused on the dilemma for fulfilling growing consumption needs while minimizing the social impact and ensuring resources. The world energy problem, fossil fuel reserves reduction, the air pollution problem and global warming, are matters of great importance for humanity without a global solution until now.

As we mentioned before, the renewable energy source, especially, the biomass energy source would be promising for global warming protection. Using the biomass feedstock, there are many fuels which can be converted through the gasification, the fermentation or another process. Here, we concentrated to the biomass gasification process by which electricity and thermal energy or Bio-H2 fuel are produced. Also, the CO2 emission due to

LCA methodology, which is estimated in order to understand the impact of Global warming numerically, was estimated. As a next step, we have to create the countermeasure for promotion of our proposed system. However, there is not example in which the relationship between the supply and the demand is argued enough. Based on the sequential and entire system, we have to judge the effects and/or the benefits such as CO2 emission etc. (See Fig. 1).

Here, as a good example, we introduce the following system. However, that might be difficult to promote our proposed system due to the cost barrier against a conventional system at the present time. The combined system in which the renewable energy such as Bio-H2 can be available would have a significant meaning in the future utilization for Global warming protection. Simultaneously, we have to create the new business model which would be suitable for the end users.

Now, there is the proposal to install an advanced cell phone (a smart phone) with a PEFC unit so as to get CO2 benefit. A smart phone is an electronic device used for two-way radio telecommunication over a cellular network of base stations known as cell sites. The sale of mobile phones has been one of the fastest growing markets in the world today. For instance, the cell phone users of Japan were approximately 107 million in 2005 (Infoplease, 2005). At present, around 85% people in America have used cell phone. In addition, new technology of a mobile communication is being developed very quickly. A few years ago, people used their cell phone just for making a call or sending a short mail through a SMS function. However, at the current time, there are a lot of features of a smart phone such as music player, video player, game, chatting, internet browsing and email, etc. These factors should increase energy consumption and increase CO2 emission.

The current power supply system in a smart phone is dominated by a Li-ion battery, which has some advantage such as wide variety of shapes/sizes without a memory effect. In addition, the rapidly advancing needs for mobile communication are increasing the consumer demand for portable application with even higher power output, longer operation time, smaller size, and lighter weight. A Li-ion and other rechargeable battery system might not be suitable for high power and long time span portable devices due to their lower energy density, shorter operational time, and safety. Li-ion batteries are well established as a power supply for portable devices. Recently, since the power demand has been increasing faster than battery capabilities, the fuel cells might become a promising alternate for niche applications. A fuel cell is an electrochemical device which continuously converts chemical energy into electricity and thermal energy by feeding H2 fuel and oxygen into it. A fuel cell power supply can be higher energy per a unit mass than conventional batteries. Also, the using of fuel cell system is not harmful to the environment, if compared with a Li-ion battery (Hoogers, 2003). Also, there are the following two types of fuel cell: 1) Polymer Electrolyte Fuel Cell (PEFC) and 2) Direct Methanol Fuel Cell (DMFC), which are operated in low temperature. These two systems are almost same, the difference is only in fuel, that is, the PEFC is operated by H2 (gas) and DMFC is done by methanol (liquid). Here, we focused on the PEFC into which H2 fuel is fed. The reason why we concentrate the system is that the fuel for a PEFC can be produced by the renewable resources such as biomass feedstock with a lower CO2 emission in comparison to the conventional production system. In the area where there is plenty of biomass feedstock (e. g. Indonesia and Malaysia etc.), there is a good potential to install that. A PEFC is applied to replace a Li-ion battery. A comparison of CO2 emission between a Li-ion battery cell phone and a PEFC cell phone was calculated using Life Cycle Assessment (LCA) methodology, in consideration of the user’s behaviour.

Marek Szmigielski, Barbara Maniak, Wieslaw Piekarski and Grzegorz Zaj^c

University of Life Sciences in Lublin

Poland

1. Introduction

Utilization of post-frying plant oils which are waste product of operation of, serving fried products, gastronomical points, for many years has been growing and complex problem of technological, ecological and economical nature. It must be noted that methods of solving this problem were subject of numerous research [Alcantara 2000; Buczek and Chwialkowski 2005; Dzieniszewski 2007; Leung and Guo 2006]. Conception of utilization of post-frying plant oils as components for production of substitute of diesel fuel seems to be promising. However, it is necessary to investigate in detail properties of such oils, so that elaborated technologies of their utilization are optimal. Answer to question concerning influence of assortment of fried products on quality of post-frying oil, and its usefulness, when aspect of differences in utilization of particular batches of such oil, obtained after frying various food products, seems to be the most significant issue.

Most commonly used method of frying food in gastronomical points is deep frying. During this type of frying, processed food is submerged in frying medium and contacts oil or fat with most of its external surface. The main role of frying medium is keeping processed food in proper position to source of heat and transferring proper amount of heat energy into a fried product [Drozdowski, 2007; Ledochowska and Hazuka, 2006]. Frying fat, which is a frying medium, and products subjected to culinary processing form a specific system in which partial penetration of these two compounds and two-way transfer of energy and weight take place. As a result of frying, product loses significant amount of water and, depending on its composition, some of its compounds e. g. food dyes, taste and flavour compounds and partially, transferred to frying fat, lipids. They are replaced with some amount of frying fat, which content in fried food, according to approximate data, may vary significantly and reach even 40% [Ledochowska and Hazuka, 2006].

Water present in processed products and released during submersion frying has got diverse and multi directional influence on changes occurring in oil, among which is, causing partial increase of acid number (AN) of oil, fat hydrolysis. Moreover, transport of heat emitted with released water vapours favours decrease of temperature of fried food and partly inhibits oxidation transformations of fat by displacing oxygen in it [Ledochowska and Hazuka, 2006].

Oxygen dissolved in frying fat together with water vapour are also significant factors of so called thermooxidative transformations, which have not been fully explained yet. As a result of these transformations numerous substances, having complex and not fully determined structure, are formed. They are precursors of secondary transformations, products of which can be usually classified in one of two categories: volatile compounds (hydrocarbons, fatty acids and carboxylic compounds) and non-volatile (monomers, dimers, polymers and also some aldehydes and ketones, as well as fatty acids characterizing with changed melting point) [Drozdowski 2007, Paul and Mittal 1996, Blumenthal 1991, Choe and Min 2006, Clark and Serbia 1991, Hoffman 2004, Ledochowska and Hazuka 2006].

Gastronomical fryers are usually containers having fairly high capacity, in which, next to the surface layer, which is environment determining properties of processed product, some volume of oil deposited near a bottom of a fryer can be distinguished. Bottom zone of a fryer, adjacent usually to the source of heat emission and having relatively low content of oxygen and water vapour, favours free radical or polymerization transformations of unsaturated fatty acids occurring in frying fat. The most common result of these transformations are numerous, having complex structure, non-polar thermal polymers. Macroscopic result of this type of reactions are increase of viscosity and darkening as well as increase of melting point of frying medium, what results in change of its state of aggregation. Products of these transformations are main components of dark brown deposits found on walls of a fryer, which can be a reason for many problems related to utilization of such oil [Hoffman 2004].

It should be noted that direction and intensity of frying fat transformations depends on numerous factors accompanying this process during frying of food products. In literature [Ledochowska and Hazuka 2006] at least few groups of such factors are named. As the basic ones, conditions of carrying out the process (its duration, temperature and periodicity) and degree of unsaturation of fatty acids in triglycerides of fat, are mentioned. Among all factors affecting properties of frying medium many other, accompanying frying process, like oxygen availability and amount and composition of compounds released from food (e. g. pro and antioxidants and presence of water), play a significant role [Ledochowska and Hazuk’a 2006].