After the preparatory stage, the glucose solution can be fermented in ethanol. The temperature of the glucose is lowered to around 35°C, and then the yeast (usually Saccharomyces cerevisiae) is added and the anaerobic fermentation process begins, which converts the glucose into ethanol and carbon dioxide.

Glucose S^cchfrrfycesce:7la > 2 EtOH + 2 CO, (8)

As a rule, the preferred method is to conduct the saccharification and fermentation steps during the same stage of the production process. Fermentation can be completed in two stages (Verma et al., 2000) using starch treated with a-amylase and glycoamylase. Fermentation may be continuous or discontinuous, it makes no difference. When the fermentation broth reaches an ethanol content of around 8-10% v/v (beyond which the yeast can no longer survive), the ternary mixture is distilled by adding benzene or cyclohexanone, or using molecular sieves. After distillation, the ethanol is 95% pure.

In 2006, a research group (Robertson et al., 2006) experimented with the so-called "cold hydrolysis" of starch, concluding that the potential use of this method relies on the discovery and characterization of more efficient enzymes and the development of processes with a high level of integration, such as simultaneous liquefaction, saccharification and fermentation, along with other factors. Figure 2 shows the flow chart for bioethanol production from materials containing starch.

3.3 Raw materials containing saccharose

For the purposes of bioethanol production, the most important raw materials containing saccharose are unquestionably sugar cane and sugar beet. Two thirds of the world’s sugar production derives from cane, the other third from beet.

The idea and technology of gasification systems that generate soot and tar is not new. Our methods of gasification technology through partial oxidation and implementation of a new high calorie gasification technology, has been developed focusing on the perfect gasification at 900-1,000°C without the production of soot and tar. The result of these technologies is the production of a superior mixture of biogases for producing liquid biofuels through thermo­chemical reaction with Zn/ Cu-based catalyst or electricity through generator. The first test plant, named "Norin Green No. 1 (the "Norin" means Ministry of Agriculture, Forestry and Fisheries in Japanese; later renamed as "Norin Biomass No. 1")" was completed on April 18, 2002 and second plant with a new high calorie gasification technology, named "Norin Biomass No. 3" was completed in March in 2004.

Generally, the biodiesel quality can be influenced by several factors:

The quality of the feedstock.

The fatty acid composition of the parent vegetable oil or animal fat.

The production process and the other materials used in this process.

Post-production parameters.

1.2 Production process factors

1.2.1 Reaction

The most important issue during biodiesel production is the completeness of the transesterification reaction. The triglycerides are converted to diglycerides, which in turn are converted to monoglycerides, and then to glycerol. Each step produces a molecule of a methyl or ethyl ester of a fatty acid. If the reaction is incomplete, then there will be triglycerides, diglycerides, and monoglycerides left in the reaction mixture. Each of these compounds still contains a glycerol molecule that has not been released. The glycerol portion of these compounds is referred to as bound glycerol. When the bound glycerol is added to the free glycerol, the sum is known as the total glycerol.

1.2.2 Free glycerol

Free glycerol refers to the amount of glycerol that is left in the finished biodiesel. Glycerol is essentially insoluble in biodiesel so almost all of the glycerol is easily removed by settling or centrifugation. Free glycerol may remain either as suspended droplets or as the very small amount that is dissolved in the biodiesel. Alcohol can act as co-solvent to increase the solubility of glycerol in the biodiesel. Most of this glycerol should be removed during the purification process. Water-washed fuel is generally very low in free glycerol, especially if hot water is used for washing. Distilled biodiesel tends to have a greater problem with free glycerol due to glycerol carry-over during distillation. Fuel with excessive free glycerol will usually have a problem with glycerol settling out in storage tanks, creating a very viscous mixture that can plug fuel filters and cause combustion problems in the engine.

The water — fuel miscibility is very important factor for distribution of fuel blends. The content of small amounts of free water in the fuel is connected with the risk of corrosion problems, whereas larger amounts of water can impair fuel supply to the engine. Hydrocarbons in gasoline are very slightly miscible with water as opposed to alcohols. The solubility of water in petroleum gasoline is only 100 mg. kg-1, while bioethanol is completely miscible with water and solubility of water in biobutanol is 19.7% w/w. Bioethanol is very hygroscopic and its blends with gasoline are partially miscible with water depending on temperature and the ethanol concentration in the blend. Phase separation of water with bioethanol can occur at lower temperatures, which causes formation of the heterogeneous system composed of the hydrocarbon phase and water-ethanol phase. This fact is the reason why the bioethanol — gasoline blends cannot be distributed via common pipelines but only separately using tankers. Contrary to bioethanol, the ability of biobutanol to absorb significant amount of water is very low (Peng et al., 1996). Biobutanol has high affinity to hydrocarbons and the risk of potential phase separation is therefore minimized. Moreover, biobutanol remains in the hydrocarbon phase if the phase separation occurs. Biobutanol is not hygroscopic that is an important factor for the long-term storage of fuels. Accordingly, high stability of gasoline-biobutanol mixtures in the presence of water comparing with bioethanol was reported.

Ethers MTBE and/or ETBE can be added to the gasoline on purpose for increasing the octane number and oxygen content or they can be accidentally mixed in the fuel tank due to another type of gasoline fuelling. The presence of MTBE and ETBE slightly increases the miscibility of butanol-gasoline blend with water and decreases the temperature of the phase separation. Ethanol has the same behaviour, nevertheless due to the bioethanol ability to absorb humidity its presence in the blends is rather unfavourable.

It assumed that the amount of energy in feed stock wet biomass is 100 and that 50% of this energy consists of that from reactant sugars, such as starch, cellulose and others. Thus, the amount of energy of the original component of sugar (50) transfers to ethanol (46) and heat (4) through chemical reactions (saccharification and fermentation) with water. This energy is estimated from the following calculation; the caloric value of sugar is 685 kcal/mol, the caloric value of ethanol is 316 kcal/mol and 2 mol ethanol is produced from 1 mol sugar through the above reaction. The pure ethanol product is then separated by distillation and additional heat energy (23) is required for this distillation work when azeotropic distillation is used for the separation. Non-reactants contain a large amount of water, for which the higher heat value is almost equal to the evaporation heat, leading to a net heat value of 0. The above energy relation is shown in Fig. 1. Beyond this, some additional energy is required to produce heat energy from the wet biomass for distillation (23). This additional energy (15) is used to dry the wet biomass in a heater to produce dry biomass that is used as fuel for distillation. Figure 2 shows the total energy balance including this additional energy. It is noted that 50-80% moisture content in wet biomass is assumed in this energy analysis, because many types of wet biomass exist in this range, such as those that originate from ligneous, garbage and sludge. It can be seen from Fig. 2 that 138 units of energy in the wet biomass feed stock is required to produce 46 energy units of ethanol and that about 1/3 of the energy of the wet biomass can be utilized as bioethanol for fuel. Thus, 2/3 of the wet biomass feed stock energy is wasted. Even though this wasted heat energy could potentially be heat sources for other processes, the exergy ratio and temperature of the waste heats are quite low. Thus, it is difficult to achieve energy saving from this by heat integration technologies such as cascading utilization. In fact, the highest required temperature during bioethanol production is normally at the distillation column reboiler and this temperature is lower than 150 °C. This heat is exhausted from the condenser at below 100 °C. To utilize the biomass energy more effectively, it is clear that the energy consumption during distillation for separating water and product ethanol and for drying of the wet biomass must be reduced. When an integrated system of distillation and membrane separation processes are utilized to substitute for azeotropic distillation, the energy required can be decreased from 23 to 12 units (8: distillation, 4: membrane separation). However, the pressure difference for membrane separation requires electric power. If we assume that the power generation efficiency from dry biomass is 25% and 75% of the energy for the membrane separation process is provided by electricity, 35 energy units from wet biomass are required for distillation and dehydration by membrane separation.

2. Self-heat recuperation technology and self-heat recuperative processes

Self-heat recuperation technology (Kansha et al. 2009) facilitates recirculation of not only latent heat but also sensible heat in a process, and helps to reduce the energy consumption of the process by using compressors and self-heat exchangers based on exergy recuperation. In this technology, i) a process unit is divided on the basis of functions to balance the heating and cooling loads by performing enthalpy and exergy analysis, ii) the cooling load is recuperated by compressors and exchanged with the heating load. As a result, the heat of the process stream is perfectly circulated without heat addition, and thus, the energy consumption for the process can be greatly reduced. By applying this technology to each process (distillation and dehydration), the energy balance for the ethanol production can be changed significantly from that described above. In this section, the design methodology for self-heat recuperative processes is introduced by using a basic thermal process, and the self­heat recuperative processes applied to the separation processes are then introduced.

The development of highly active metal catalysts is of prime importance to reduce the tendency for repolymerisation during catalytic hydrotreatment. All data presented in this chapter so far are based on a Ru/C catalyst. Ru, however, is an expensive noble metal and there is an incentive to identify not only more active but also cheaper catalysts for the hydrotreatment reaction. A possibility is the use of cheaper bimetallic metal catalysts based on Ni. Ni is known to have high hydrogenation activity for a variety of organic functional groups and particularly for reactive ketones and aldehydes, and as such is a potential active metal for hydrotreatment reactions. However, monometallic Ni catalysts (on silicon oxide, y — or 8-alumina, or other supports) at the typical temperature and pressures applied here are not suitable to be used as a hydrogenation catalyst. There are basically two reasons: 1) Ni requires high reduction temperature (typically 700 oC) for complete reduction, and 2) Ni catalysts are known to deactivate rapidly at elevated conditions by char deposition ("coking"). The carbon deposition can block the nickel surface, or the pore mouths, and, eventually leading to a strong reduction in the reaction rates. These two drawbacks regarding the use of Ni were solved a. o. by using another element (metal or non-metal), also designated as a promoter. One of these proprietary catalysts was studied in detail and will be referred to in the following as catalyst D.

Figure 12 shows the liquid phase after a hydrotreatment over Cat D versus the severity of the process, showing the original oil (left) and an oil derived at the most severe conditions tested here on the right. Interestingly, the product oils obtained over cat D are much more transparent than those derived from the Ru/C catalyst.

A van Krevelen plot gives valuable insights in the difference in performance between catalyst D and Ru/ C (Figure 13). A similar pattern for both is observed as a function of severity but the curve for Cat D is shifted to higher H/ C values. Thus, at a similar oxygen content, the H/C ratio is higher for catalyst D. This is indicative for a higher hydrogenation rate for cat D and is known to be favorable regarding product properties.

Repolymerisation reactions appear to occur to a limited extent when using cat D instead of Ru/C. This is evident when comparing the average molecular weight of the final products (Figure 14a), as determined by GPC, for both Cat D and Ru/C. For Ru/C the average molecular weight shows a significant increase from 400 up to 1000 Da at low severities, but a constant value over the oxygen content interval of 400-450 Da for catalyst D is observed.

TGA residues of the product oils using cat D (Figure 14b) show carbon residues of around 5%. Surprisingly, and not expected on basis of test carried out using other catalysts, already at less severe operating conditions, a significant reduction in the TGA residues is achieved. Thus, products with a higher H/C ratio and a lower carbon residue were obtained with cat D indicating that the rate of the hydrogenation/hydrodeoxygenation reactions over catalysts D are higher than for Ru/C.

An important product property for the upgraded oils is the viscosity. In Figure 15, the viscosity profile of the product oils versus the oxygen content is compared for conventional catalysts (Ru/C and NiMo, CoMo) and catalyst D. Clearly, the viscosity in the mid range of oxygen contents is much lower for cat D. Further testing at the extreme of low oxygen content will be required to grab the full picture but it is clear that cat D gives upgraded products with a lower viscosity than for conventional catalysts. The lower viscosity is likely the result of a lower average molecular weight of the products, as shown earlier and the result of higher hydrogenation/hydrodeoxygenation rates for Cat D compared to Ru/C.

On the basis of the product properties of the upgraded oils obtained with cat D, we can conclude that repolymerisation is not occurring to a considerable extent. As a result, product oils with a lower molecular weight and a concomitant lower viscosity, lower TGA residue is obtained. Thus, the reaction pathway for catalyst D may be simplified considerably, see Figure 16 for details.

Oxygen content (wt%)

◄—- Process severity

The mass, length and diameter of individual pellets should be used to determine individual pellet density in kg/m3. The bulk density of manufactured pellets can be calculated by measuring the mass of pellets filled in a cylindrical container of known volume.

Larsson et al. (2008) reported that the most influential factor for the pellet bulk density was raw material moisture content and showing a negative correlation. Similarly, two other studies have observed that the bulk density of wheat straw, big bluestem grass, corn stover, sorghum stalk and switchgrass decreased with an increase in moisture content (Colley et al., 2006; Theerarattananoon, et al., 2011). Larsson et al. (2008) did not find any correlation between pellet bulk density and die temperature, which contradicts to the observations made by Hill and Pulkinen,1988, and Tabil and Sokhansanj (1996). Serrano et al. (2011) did not observe any significant effect of hammer mill screen size (4 mm and 7 mm) on pellet density. However, pellet density decreased with an increase in moisture content.

Adapa et al. (2010b) reported pellet density 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 (Table 5). In general, pellet density increased with a decrease in screen size from 1.6 to 0.8 mm. However, no significant differences in density values were observed for non-treated samples at 0.8 mm and customized samples, except for canola and oat straw. This could be due to large fluctuation in individual pellet density values. All of the pellet density values reached near individual biomass particle densities at respective grind sizes (Adapa et al., 2010b).

Bulk density of pellets from barley, canola, oat and wheat straw showed significant difference with grind size and customization, except for wheat straw pellets at 0.8 mm for
non-treated and customized samples (Table 5). In general, the average pellet bulk densities obtained for customized straw samples were higher (except for barley straw), which is consistent with increase in particle densities. The bulk densities of pellets manufactured were higher than the minimum design value of 650 kg/ m3 suggested by Obernberger and Thek (2004) for wood pellet producers.

There is no doubt that development and energy use are closely linked. In the coming years, a key matter will be how to ensure that energy sources are economical and reliable enough to guarantee us an adequate level of development. Energy availability is an obstacle for development; but environmental impacts may also limit or put the development at risk. However, this is not the entire problem. It is clear that all activities will have an impact on the environment. The issue is when this impact becomes negative or even irreversible. Throughout history there are a lot of examples of societies that made their environment collapse and in turn they collapsed.

At the global level the impact of energy activities on climate change must be highly considered, the so-called greenhouse effect. Climate change is not indeed the only global threat to environmental sustainability, but many agree it is the most important. Its extent, complexity and direct connection with energy activities make climate change a paradigm. For example, the success or failure in the implementation of the Kyoto Protocol is still an excellent indicator of global community and each country’s commitment with sustainable development (Perez, 2002).

The impact of the production and use of energy has been observed for a long time. Deforestation of many areas and pollution associated with industrial processes are well known cases. But, although they were serious, it was about local impacts. In the last hundred years local effects have become global threats. The recognition of the association of energy with global environmental problems is a recent event that is affecting human health and quality of life, but especially that of future generations.

Undoubtedly, human activity has a big impact with respect to the environment. Today, Sustainable Development is mentioned a lot; in fact this is a contradiction of terms. Indeed, if we consider that development (which involves the permanent increase in the use of resources) must always increase. It is inevitable that within a long or short term we find crucial restrictions for development because of the inevitable shortages of resources. It is, therefore, essential to know the difference between growth and development. Indeed, a country can have strong growth, all the while achieving a high level of development simply at a slower pace. It is also possible to have large development increases with low growth rates. It is important to tell the difference between these two concepts as it allows taking a look at the evolution of a country from another perspective. In the last decade it is clear that Colombia has had enough growth; however our degree of development has been much lower. It is also clear that a finite growth is not viable because it involves having unlimited resources, which is not the case in our planet.

During the last century, impacts of human activity have been higher had taken place since the beginning of civilization. Footprints of human activity are changing the world at a rapid pace and energy has a lot to do with this impact.

Instead of detesting the technological development, it is necessary that some philosophical, ethical and social principles guide it. Not everything is good, cars have not given humans more freedom: because now travel time has increased, people need to work longer hours to pay it, cities have become uninhabitable, it is literally asphalting the living space, social conflicts are increasing because of the lack of communication, and due to noise and urban stress increasing, we move away from downtown and then our dependence on the car and our isolation increases. From that overview, it doesn’t look like the car is synonymous with social development and welfare (Valero, 2004).

Based on the duration time, we measured the performance of a PEM-cell which is based on a PEFC unit for a smart phone. That is, using the result of output capability of a PEM-cell and the maximum duration time, we designed the cell area of a PEFC, and estimated the energy consumption for each function.

Here, in order to have a good reliability, 10 times experiments have been done for the following tasks: a talking, a SMS, music (MP3), a game, a web-site (internet) and an e-mail checking, respectively. In our experiments, we used the electric measurement device (AC/DC POWER HiTESTER 3334, HIOKI E. E. Corp.) to measure the voltage and the current, and the power which is obtained by these factors.

Next, for the purpose of estimating the cell performance, we measured the potential of a PEM-cell in varying currents. The apparatus consists of a PEM-cell (Micro Inc.) and a
potentiostat (HAB-151, Hokuto Denko Corp.). The size of the cell with low platinum loading electrodes (1.0 Pt mg/cm2) and Nafion® 115 is 4 cm2*3 cells. Using a potentiostat, 1) an open circuit voltage V0 [Volt] was measured and 2) the relationship of current density J vs. cell potential V was evaluated between approximately 200 mV / cell and an open circuit potential V0 . Also, H2 flow in anode was up to 20 ml/min and the concentration of H2 was 100 vol.% at a constant percentage (see Fig.8). Note that each parameter on the performance of a PEM-cell is decided at the condition which is not rate-limiting. In this case, we adopted the flow rate condition of 20 ml/min. The cathode was stayed at the atmospheric condition. The conditions in both the anode and cathode sides were not saturated by steam (Dowaki et al., 2010a, Dowaki et al., 2011b).

Next, the relationship between a cell’s potential and current density, in the low and intermediate current density region of a PEM-cell, has been shown to obey the following Eq. (19) (Kim et al., 1995). Note that the result was shown by the condition of a single PEM — cell.

Current density [mA/cm2]

Next, due to the questionnaire for smart phone users (see Fig. 7), the energy consumption for each function and the performance of PEFC using a PEM-cell experimental result, we estimated CO2 emission on basis of LCA methodology. Using Eq. (19), the H2 flow rate in practice use is able to be calculated. Here, a PEFC would be operated between 1.17 and 2.63 Volt. The specific energy consumption in each function was between 0.39 and 37.7 Nml/min.

Samples of soybean oil which remained after laboratory samples had been taken from each of three batches, differentiated by type of initial preparation (frying potato chips, frying breadcrumbs coated fish fingers and heating without fried product), were separately subjected to esterification with methanol. Fatty acids methyl esters were obtained by method analogous to the one used in investigation of fatty acids composition by means of gas chromatography. Fuel obtained this way was used in engine tests including main engine work parameters. Four mixtures were prepared, each containing 90% diesel fuel and 10% addition of fatty acids methyl esters obtained in research and marked as:

a. M1 — esters obtained from purchased fresh soybean oil,

b. M2 — esters obtained from soybean oil subjected to five-time cyclic heating, without addition of fried product,

c. M3 — esters obtained from soybean oil, previously used for five-time cyclic frying of potato chips,

d. M4 — esters obtained from soybean oil, previously used for five-time cyclic frying of breadcrumbs coated fish fingers.

Results of internal combustion engine running on diesel fuel (DF) were used as reference for determination of work parameters of engine powered with fuel blends. Above mentioned fuel mixtures, were used for powering 2CA90 diesel engine installed on dynamometric stand for purpose of conducting measurements of its energetic work parameters. Test bed comprised of following devices:

— internal combustion diesel engine 2CA90;

— dynamometric stand composed of eddy-current brake AMX210 and control — measurement system AMX201, AMX 211;

— fuel consumption measuring system;

— system measuring engine parameters: exhaust gasses temperature — tsp, engine oil temperature — tol, oil pressure — pol;

— system measuring state of environment: temperature of environment — tot, atmospheric pressure — pa, and air humidity — ф.

Measurements for each of investigated fuels were conducted and obtained results of energetic parameters were elaborated. Data yielded by measurements was used to draw external characteristics of the engine for rotational speed ranging from minimal to nominal. Carried out research included kinematic and dynamic parameters of the engine: torque — Mo, rotational speed — n, time in which set amount of investigated fuel was used — t. Amount of fuel used for purpose of this characteristic was 50 g. Methodology of measurements and methods of measurements and results reduction of power and torque, were in conformity with norms: PN-88/S-02005, BN-79/1374-03.