In the analysis of the environmental impact of bioethanol (and other biofuels too), some of the key factors concern the impact of the increasing quantities of dedicated crops on soil carbon levels and subsequent photosynthesis: these changes will also influence the atmospheric concentrations of GHG such as CO2 and CH4.

The main problem concerns the fact that, when a system in equilibrium experiences persistent changes, it can take decades before a new equilibrium with a constant carbon level is reached. Taking the current situation in Europe as concerns wheat and sugar beet crops, there is an estimated depletion of approximately 0.84 t of C or 3.1 t CO2 equivalent ha-1 years-1 from the ground. If no crops were grown on the soil, this depletion would be even greater, i. e. 6.5 t of C each year for sugar beet and 4.9 t of C for wheat. Apart from the effects on ground carbon levels, there are also signs of other adverse effects indirectly linked to crops grown for energy purposes, such as the increase in the amount of C in the atmospheric levels of GHG. Irrigation with good-quality water also exacerbates carbon sequestering: the water used for irrigation contains dissolved calcium and carbon dioxide (in the form of HCO3-); Ca and HCO3- react together, giving rise to the precipitation of CaCO3 and the consequent release of CO2 into the atmosphere. In the typical dry conditions of the USA, further reactions take place and irrigation is responsible for the transfer of CO2 from the ground into the atmosphere (Rees et al., 2005). An important type of crop that can be used to reduce soil carbon sequestering is defined as "zero tillage", which means that it can be grown year after year without disturbing the soil. Seed crops (such as wheat) may be zero tillage, but not root crops (such as Panicum virgatum). Zero tillage has variable effects, and in some cases carbon sequestering in the soil may even increase, but this phenomenon can be completely overturned by a one-off application of conventional tillage. If only the carbon in the soil is considered, zero tillage leads in the long term to less global warming than growing conventional crops in damp climates, but in areas with dry climates, there is no certainty of any such beneficial effect (Six et al., 2004). Using straw from cereals can increase the carbon levels in the soil. Such residue is useful in maintaining soil carbon levels (Blair et al., 1998; Blair and Crocker, 2000) because it has a low rate of breakdown, so it is important for the residue to go back into the ground in order to keep the farming system sustainable. Since removing the residue from the ground has other negative effects too, such as an increased soil erosion and a lesser availability of macro — and micronutrients, some have suggested in the United States (Lal, 2005) that it would be advisable to remove only 20­40% of the residue for the purposes of bioethanol production, whereas it was claimed (Sheehan et al., 2004) that if up to 70% of the residue were removed to produce bioethanol, the carbon levels would initially decline and then remain stable for about 90 years. Increasing the land used to grow energy crops would have a substantial impact on the concentrations of carbon-containing gases in the atmosphere. If areas covered with forest were converted into arable land, the carbon sequestering would go from values of around 50-145 t-ha-1 to approximately 50-200 t-ha-1, assuming a 60-year rotation (Reijinders & Huijbregts, 2007).

According to the results obtained by the operation, it has been confirmed that the output gas mixture possesses the properties indicated in Fig. 12. As shown in the figure, high-calorie gas featuring 15-18MJ/Nm3, that could not be achieved by gasification by "Norin Green No. 1" test plant through partial oxidation (ca. 10 MJ/Nm3; using O2 and H2O as gasifying agents) or conventional gasification using air as a gasifying agent (ca. 5 MJ/Nm3), can be produced when the reaction temperature is 800-900°C, H2O/ C mole ratio is lower than 5.0, and the reaction time is ca. 2 seconds. In addition, this gas mixture contains over 20% hydrogen (H2). This value is higher than the threshold value of 10% for applicability in terms of ignition and combustion rate for gas engines and micro gas turbines, which indicate that the gas mixture is a high-quality gas fuel. Besides, given that the compositional ratio of H2 to CO is higher, the threshold combustion temperature is 90°C higher than that of methane. Figure 13 explains a comparison of theoretical combustion temperatures of this gas mixture and various fuels, such as methane, gasoline, propane, methanol and ethanol.

Biomass means any form of lignocellulosic materials.

3. Conclusion

As the gas mixture generated with "Norin Green No. 1" test plant and high-calorie gas produced with "Norin Biomass No. 3" test plant using the high calorie gasification technology is temporarily stored in a cold gas state, it can be used in a manner similar to natural or city gas, with widespread applications.

Obviously, since "Norin Biomass No. 3" plant, which efficiently converts biomass into high calorie gas mixture with a small system, can be easily used as a fuel for gas engines and micro gas turbines, it can also be used for small-scale power generation and co-generation. Accordingly, high-efficiency and small-scale power generation can be achieved.

The potential applications of the gas mixture generated by gasification through high-calorie gas production are as follows;

1. Co-generation in buildings, hospitals, industrial parks, factories, etc.

2. Commercial power (targeted efficiency of 25-35%, with at least 1 million kWh/year)

3. Peak cut (reduction of contracted power) and emergency use for large-scale factories

4. Gas fuel for industrial parks (e. g. ceramics and porcelain)

5. Supplementary fuel for incinerator (dioxin countermeasure for industrial waste processing)

6. Fuel for boilers of greenhouse agriculture

7. Fuel for food processing industries by the use of residues produced in the process.

8. Synthesis of biomethanol for BDF production, for batteries of direct methanol fuel cell (DMFT), and a liquid fuel mixed with gasoline for flexible fuel vehicles (FFV).

Three "Norin biomass No. 3" plants processing 4-6 dry t/day of biomass feedstock are under construction by private companies and local government with the 50% financial support from the Government.

This study demonstrates that the gasification of readily available biomass materials both by partial oxidation technology and by high calorie gasification technology could be optimized for generation of gas mixtures primarily composed of H2, CO and producing methanol yields ranging theoretically from ca. 40 to 60% by dry weight. A test plant utilizing gasification through partial oxidation with 2t/day gasifier can achieve a methanol yield of ca. 20% from the biomass raw material (by weight). This creates an opportunity to utilize a wide range of high yielding with low sugar and starch content such as Erianthus and Miscanthus. Non-palatable lignocellulosic byproducts such as sawdust and crop residues such as straw and husks of rice from various industries would also have suitable application. Sawdust, rice bran, refuse of sugarcane mills (bagasse etc.) and rice husks are particularly attractive and provide a ready-to-use biofuel resource. It is anticipated that the cultivation and utilization of biomass crops will be attractive as carbon neutral biomass feedstocks for biofuel production in the future.

The potentially positive economic impact of biomethanol production on Japanese farming and social systems from planting grasses and trees in unutilized land is immense (Nakagawa 2001; Harada 2001). Reduced CO2 emissions, recycling of abandoned upland and paddy field and woodland in mountainous areas, and recycling of wastes of agricultural products would all be possible by promoting biofuel production system based on the gasification technologies. This technology is particularly attractive since biomethanol can be produced from a wide range of biomass raw materials.

4. Acknowledgements

Authors would like to express their sincere thanks to Dr. Bryan Kindiger, USDA-ARS, Grazinglands Research Laboratory for his critical reading of the manuscript.

This researches were supported by a grant from Ministry of Agriculture, Forestry and Fisheries of Japan, named "Development of sustainable ecosystem for primary industries towards the 21st century" (2000-2002), "Bio-recycle of wastes from agriculture, forestry, and fisheries" (2003-2005), and "Rural Biomass Research Project, BEC (Biomass Ethanol Conversion)" (2006-2010).

This parameter is an important tool, like distillation temperature, for determining the presence of other substances and in some cases meeting the legal definition of biodiesel (i. e. mono-alkyl esters). Low values of pure biodiesel samples may originate from inappropriate reaction conditions or from various minor components within the original fat or oil source. A high concentration of unsaponifiable matter such as sterols, residual alcohols, partial glycerides and unseparated glycerol can lead to values below the limit.

As most of these compounds are removed during distillation of the final product, distilled methyl esters generally display higher ester content than undistilled ones (Mittelbach and Enzelsberger, 1999).

1.3 Density

The densities of biodiesels are generally higher than those of fossil diesel fuel. The values depend on their fatty acid composition as well as on their purity. Density increases with decreasing chain length and increasing number of double bonds, or can be decreased by the presence of low density contaminants such as methanol.

1.4 Viscosity

The kinematic viscosity of biodiesel is higher than that of fossil diesel, and in some cases at low temperatures becomes very viscous or even solid. High viscosity affects the volume flow and injection spray characteristics in the engine, and at low temperatures may compromise the mechanical integrity of injection pump drive systems (when used as stand alone B100 diesel fuel).

With the limitations of ethanol as a biofuel and the need to expand beyond food crop-based biofuel production, there is a pressing need for second — and third-generation biofuels. Since there appears to be little consensus on the meaning of second, third, and further generations of biofuels, we will adopt the term advanced or next-generation biofuels. Next-generation biodiesel is a triglyceride derived fatty acid methyl ester (FAME), which does not originate from food crop sources. Additionally, there are clear limitations in some non-food crop terrestrial plant sources of triglycerides for biodiesel, such as palm oil and jatropha. Palm oil is rapidly becoming a major source of biodiesel to fulfill the European Union mandate of 10% liquid transportation biofuels by 2010 (European Parliament, 2009). Europe is a much larger consumer of diesel fuel for passenger vehicles with approximately 50% of the passenger cars sold in the EU currently having diesel engines (Smolinska, 2008). Unfortunately, the net result of the substantial increase in demand for palm oil has been an accelerated rate of palm plantation development and deforestation in tropical ecosystems. Another promising group of next-generation biofuels are the alcohols with longer chains than ethanol, such as butanol and branched-chain alcohols. These fuels have a higher energy density than ethanol, do not absorb water as ethanol does, and possess very favorable combustion characteristics, such as high octane ratings. These alcohols are somewhat more unusual and rare in nature, but one example of a microorganism that is adept at producing these compounds is Clostridium acetobutylicum. Regrettably, there are limitations on the use of this slow growing anaerobic organism for biofuel production. A search for other means for producing these promising longer and branched-chain alcohol biofuels in photosynthetic organisms is currently underway (Fortman et al., 2008).

While ethanol produced from cellulosic biomass is commonly touted as a promising advanced biofuel solution, the end product is still ethanol, which has all of the limitations stated above. There is strong motivation to move beyond ethanol, but what other means are available? Conversion of the sugars released by deconstruction of cellulosic biomass could easily be directed more usefully to one of the more desirable next-generation biofuels, such as microorganism-derived biodiesel or branched-chain alcohols. In a throwback to biofuels efforts of World War I, recently there has been renewed interest in the ability of Clostridial species to produce butanol and possibly other longer chain alcohol biofuels (Sillers et al., 2008). With the availability of genomes for these anaerobic bacteria, means to genetically enhance their productive capacities may be at hand. However, there are still a number of significant barriers to overcome for anaerobic fermentation to be a truly viable means of biofuel production. Alternatively, microbes such as bacteria and microalgae show promise as a renewable feedstock for a biofuels ranging from ethanol to biodiesel. The capacity of photosynthesis to capture solar energy is particularly attractive for producing renewable fuels because no intermediate chemical feedstock is required.

The same assumption as for section 2 is assumed; the amount of energy in the wet biomass feed stock is 100, 50% of the energy value of the wet biomass consists of the energy value of reactant sugars such as starch, cellulose and others, and the amount of energy of the original sugar component (50) transfers to ethanol (46) and heat (4) through chemical reactions (saccharification and fermentation) with water.

By applying the self-heat recuperative distillation and azeotropic distillation process to the distillation and dehydration process, the additional heat energy for distillation is converted to power. At the same time, the energy (23) in Figure 1 is reduced to 4. This value was estimated from the energy reduction results from the self-heat recuperative processes in section 3.

By integrating the aforementioned biomass gasification in section 4 with the self-heat recuperative processes introduced in section 3, bioethanol (46) and power (1) can be produced as co-products from wet biomass (100) during bioethanol production, as shown in Fig. 8. Wet residue (non-reactants contain a large amount of water, for which the higher heat value is almost equal to the required evaporation heat, leading to net heat value of 0) in Figs.

1 and 2 can be utilized as the energy supply. Thus, it can be understood that 46% of the energy of the wet biomass is transferred to the bioethanol and 1% of the energy to power. Furthermore, the additional wet biomass (38) required to provide the distillation heat (23) is no longer necessary for this bioethanol production. Thus, power (4) can be generated from the additional wet biomass by using a self-heat recuperative drying process and biomass gasification, as shown in Fig. 9. As a result, 33% (= 46/138×100) of the energy of the wet biomass is transferred to bioethanol and 4% (= 5/138×100) is transferred to power for co­production. It can be said that this bioethanol production procedure achieves not only energy savings but also reduction of exergy dissipation for the whole process, leading to achievement of optimal co-production. In addition, substituting the azeotropic distillation process by dehydration uses a membrane separation. All of the self-heat recuperative processes and biomass gasification are applied to produce this energy. The energy required can be decreased to 4 as power, where the same assumptions as used for the results described above are used in the calculation, such that power generation efficiency from dry biomass is 25% and 75% of the energy required for the membrane separation process is provided by electricity. This value of power is the same as the energy required by applying self-heat recuperative processes to the distillation and dehydration processes. Although the energy required by membrane separation process is smaller than that of azeotropic distillation in the conventional processes, it becomes equal after applying the self-heat recuperative processes.

Fig. 8. Energy balance for bioethanol production with self-heat recuperation

3.

Conclusion

In this chapter, a newly developed self-heat recuperation technology is introduced and the feasibility of co-production of bioethanol and power by integration of self-heat recuperative processes and biomass gasification for power generation is examined based on energy balances. From analysis of the energy balance for the conventional bioethanol production processes, a large amount of energy is consumed for separation of water (distillation and drying) so that the operational costs for bioethanol production are high, limiting the potential contribution of bioethanol to society. However, by incorporating self-heat recuperative processes for distillation, azeotropic distillation and drying, not only are the energy requirements reduced dramatically due to heat circulation in the processes, but also wasted residue can be utilized as a power source through biomass gasification. Thus, it is shown that co-production of bioethanol and power is feasible, enabling the economic impact of the bioethanol product. Finally, this system is expected to help the uptake of bioethanol and decrease global CO2 emissions.

Fourier Transform Infrared Spectroscopy (FTIR) can be used to rapidly characterize and quantify cellulose-hemicellulose-lignin composition prior to and after application of various methods of pre-processing and pre-treatment of biomass (Adapa et al., 2009). The quantitative analysis of FTIR absorption spectrometry is based on the Bouguer-Beer — Lambert law (Sherman Hsu, 1997). According to this law, the intensities of absorption bands are linearly proportional to the concentration of each component in a homogenous mixture or solution.

Regression equations to predict the lignocellulosic content of agricultural biomass can be developed using pure cellulose, hemicelluloses and lignin as reference samples, and
subsequently mixing them in different proportions to determine the change in absorption intensity at characteristic peak height (Adapa et al., 2011b). An overview of the experimental procedure to characterize the lignocellulosic composition is provided in Figure 3.

Pure cellulose has five distinct characteristic/ prominent peaks at wavenumbers of 1431, 1373, 1338, 1319 and 1203 cm-1. Similarly, hemicellulose (xylan) has prominent peaks at wavenumbers of 1606, 1461, 1251, 1213, 1166 and 1050 cm-1. The lignin spectrum has characteristic peaks at wavenumber of 1599, 1511, 1467, 1429, 1157 and 1054 cm-1. The intensity of absorption at characteristic peak heights of cellulose, hemicellulose and lignin were used to develop regression equations to predict lignocellulosic composition of any agricultural biomass (Table 1) (Adapa et al., 2011b).

FOURIER TRANSFORMED INFRARED (FTIR) SPECTROSCOPY USING PHOTOACOUSTIC CELL

Obtain FTIR spectra of samples at the Mid-Infrared Beamline, Canadian Light Source (Synchrotron Radiation); average of 32 interferograms collected from wavenumbers of 2000 to 400 cm’1 at a resolution of 4 cm ■*

NORMALIZE FTIR DATA

Carbon Black Data: Eliminate wavenumber-dependent instrumental effects
Mass of Sample: Eliminate effect of bulk density of samples
Normalize from 0 to 1: Standardize the methodology

PEAK HEIGHT METHOD

Characteristic peak heights and corresponding wavenumbers of 100% cellulose, hemicellulose and
lignin were determined. Subsequently, characteristic wavenumbers were used to determine the pea
heights of lignocellulose in reference sample mixture

A comparision between results from lab
experiments and predicted values was
performed to validate the regression
models

Fig. 3. Experimental procedure followed to characterize lignocellulosic composition of agricultural straw (Adapa et al., 2011b).

%Cellulose = -135.10 + 781.35 (РЯ_1319) — 795.57(РЯ_1431) — 135.26(РЯ_1203) + 436.11 (РЯ_1338) — 94.24(РЯ_1373)

VoHemicellulose = 1638.72 — 2581.71(РЯ_1251 X РЯ_1461) — 1260.90(РЯ_1213)

— 2518.05(РЯ_1166) + 1573.69(РЯ_1213 X РЯ_1251)

+ 118.74(РЯ_1050) + 3128.51(РЯ_1166 X 1251)

+ 2179.65(РЯ_1461) + 92.36(РЯ_1606) — 2294.15(РЯ_1251)

— 59.29(РЯ_1461 X РЯ_1606)

%Lignin = 7110.87 + 388.32(РЯ_1511 X РЯ_1599) — 16440.93(РЯ_1467)

+ 447.36(РЯ_1599)2 + 19572.82(РЯ_1157 X РЯ_1467)

+ 18374.36(РЯ_1157) + 15659.98(РЯ_1054 X РЯ_1429)

— 4952.80(РЯ_1157 X РЯ_1599) + 800.20(РЯ_1511)

— 3032.75 (РЯ_1429)2 — 11269.16(РЯ_1429)

— 948.04(РЯ_1511)2 + 3444.69(РЯ_1599)

________________ — 12344.90(РЯ_1054) — 16689.44(РЯ_1157)2_____________

Note: PH — Characteristic Peak Height (Photoacoustic Units)

Table 1. Regression equations to predict the lignocellulosic composition of agricultural biomass (Adapa et al., 2011b).

Except the lack of stability of enzyme molecules due to their proteic nature, one of the major problems encountered with enzymatic electrodes concerns electron transfer between the enzyme and the electrode surface. In the next part we will describe the different electron transfer mechanisms occurring between an enzyme and the electrode as well as the immobilization techniques of the protein.

1.1 Electron transfer between enzyme and electrode

Enzymes are proteins which have high molecular weights. The active sites of these molecules are located in the organic matrix at a depth of several angstroms from the surface. It is thus easy to understand that kinetically fast electron transfer between enzymes and electrodes surface is difficult to obtain because of great insulation of the active centers (Armstrong et al., 1985). Different strategies have been used by the past to make efficient electrical connections between the enzyme and the electrode surface. Corresponding electron transfer mechanisms can be arranged in two different classes: mediated electron transfer (MET) and direct electron transfer (DET).

The major interest in directly transferring electrons between enzymes and electrodes is to reduce the electrode overpotential which is of particular importance for biofuel cells applications. DET is possible as soon as the distance between the active center of the enzyme and the electrode surface is in the order of a tunneling one (Degani & Heller, 1987). Different evidences for DET between enzymes classically used in glucose/O2 biofuel cells and electrodes have already been given. Actually, laccase (Gupta et al., 2004), bilirubin oxidase (Shleev et al., 2005) and glucose oxidase (Wang et al., 2009) are capable of exhibiting non­negligible catalytic current densities without the presence of a redox mediator.

In the case of MET, a redox molecule acts as a substrate and is able to transfer electrons between the electrode surface and the active center of the enzymatic molecule. Let’s notice that current densities obtained with MET are generally higher that what can be delivered in the case of DET. However, to get efficient MET, the redox mediator must possess some properties which can be deduced from Marcus theory as it was already mentioned by Rusling et al. (Rusling et al., 2008). This theory is used to describe outer sphere electron transfer between an electron donor (D) and an electron acceptor (A) as depicted in Fig. 1.

Fig. 1. Curves presenting potential energy of reactants (R) and products (P) (A5—D5+) as a function of reaction coordinates (RC).

The rate (k) of electron transfer can be described as follows (Eq.1.) by an Arrhenius type law.

f (ag+xA

I 4RTX I

k = AKe1 J (1)

where A is the collision frequency, K is the electronic transmission factor, AG° is the Gibbs free energy, R is the gas constant and T the temperature. X is the reorganization energy (energetic cost associated to the reorganization of both solvent and molecules and necessary to proceed in electronic transfer between the donor and the acceptor). From this relation it can be deduced that to have an efficient electron transfer between enzyme and mediator, it is essential that the redox mediator used presents a highly reversible redox system to minimize X value. It is also fundamental to minimize the AG° value. Thus it is very important that formal potentials of mediator and enzyme are close. Moreover, since active centers of enzyme are greatly insulated in high molecular weight molecules it is necessary to use small mediator molecules to reduce the distance of electron transfer and to guarantee a high k value.

Colombia, in order to reduce gasoline and diesel consumption, has implemented policies to encourage domestic production of biofuels. This purpose is economically boosted compared to fuels consumption reduction by the automotive industry and the best environmental indicators of mobile source emissions given the oxygenating effect of biofuels in combustion. For that reason in 2001 it is passed the Act N° 693 and in 2004 the Act N° 939, which states regulations on alcohol fuels and vegetable oils in the country, and creates incentives for their production, marketing and consumption.

In this regard, the Government has promoted development of biofuels through different measures to encourage their production and use. In this matter there is a broad regulatory and incentives for bioenergy production in Colombia, namely (Ministerio de Minas y Energia, 2007; Cala, 2003):

Act 693/2001: the regulations about the use of alcohol fuels are thereby stated; Incentives are created for their production, marketing and consumption. This act makes obligatory the use of oxygenated components in fuels for vehicles from cities with more than 500,000 inhabitants. A deadline of 5 years was established for gradual implementation of this regulation.

Act 788/2002: tax reform where exemptions were introduced to the Value Added Tax (VAT), the income tax and surcharge on alcohol fuel blended with gasoline engine.

Act 939/2004: defines the legal framework for the use of biofuels, by which the production and commercialization of biofuels of plant or animal origin, are thereby encouraged for use in diesel engines and other purposes. Exempts biodiesel from VAT and the income tax and establishes a net income exemption for 10 years to new oil palm plantation. This exemption applies to all plantations to be developed before 2015.

Act 1111/2006: establishes a 40% income tax deduction of investments in real productive fixed assets of industrial projects, including financial leasing.

Act 1083 2006: some regulations on sustainable urban planning and other provisions are thereby stated.

Resolution 1289/2005: establishes biofuels criteria quality for their use in diesel engines, states the date of January 1st 2008 as a blending start of 5% of biodiesel with diesel fuel. Resolution No. 180127/2007: the heading "MD" in Act 4 from Resolution 82439 from December 23th, 1998 is thereby amended and amends Act 1st from Resolution 180822 from June 29th, 2005 and, states the provisions relating to Diesel Fuel pricing structure.

Decree 383/2007: Amends the Foreign-Trade Zones Decree 2685 of 1999, regulates the set up of Special Foreign-Trade Zones for high economic and social impact.

Decree 3492/2007: Act 939 of 2004 is thereby regulated.

Decree 2328/2008: The Intersectoral Commission for Biofuels Management is thereby created.

Decree 4051/2007: Permanent Foreign-Trade Zones area requirements is thereby stated; requirements for stating the existence of a Special and Permanent Foreign-Trade Zone and Industrial User recognition.

Resolution No. 180158/2007: clean fuels are stated thereby in accordance with the Paragraph in Article 1, Act 1083.

Resolution No. 180782/2007: biofuels quality criteria for use in diesel engines as a component of the blending with fossil diesel fuel in combustion processes are thereby amended.

Resolution No. 180212/2007: Resolution 181780 December 29th, 2005 is thereby partially amended, regarding the pricing structure of diesel fuels blended with biofuel for their use in diesel engines.

Decree 2629/2007: provisions for promoting the use of biofuels in the country are thereby stated, as well as applicable measures for vehicles and other motorized devices that use fuels. From January 1st, 2010 timetable is thereby set up for extending the mandatory blending of biofuels of 10% and, 20% from 2012 as well as the requirement that from January 1st 2012, new vehicle parc and other new motorized devices should be Flex-fuel at least 20%, for both E-20 blending (80% of gasoline from fossil fuel, with 20% of alcohol fuel) and B-20 (80% of diesel fuel with 20% of biofuels).

Decree 1135/2009: In connection with the use of alcohol fuels in the country and applicable measures to motor vehicles using gasoline, decree 2629, 2007 is thereby amended. And which states in its article 1: from January 1st, 2012 motor vehicles up to 2000 cm3 manufactured, assembled, imported, distributed and marketed in the country and requiring gasoline to operate, must be soup up so that their engines run Flex-fuel system (E85), i. e. they can work normally by using either basic gasoline or blends composed of basic fossil fuel with at least 85% alcohol fuel. To meet the above, each brand shall sell vehicles in the Colombian market according to the following schedule and provisions:

From January 1st, 2012: 60% of its annual supply must support E85.

From January 1st, 2014: 80% of its annual supply must support E85.

From January 1st, 2016: 100% of its annual supply must support E85.

From January 1st, 2013: vehicles with engine cubic capacity greater than 2000 cm3 from all brands and models shall bear E85.

It is worth mentioning CONPES-3510/2008 document (in English: National Council for Economic and Social Policy document 3510/2008), where a policy to promote the

production of sustainable biofuels in Colombia is thereby established, by taking advantage of economic and social development opportunities which are offered by biofuels emerging markets. Thus, it intends to expand the known biomass crops in the country and diversify the energy basket within a framework of production that is financially, socially and environmentally efficient and sustainable, that makes possible to compete in domestic and international markets.

Likewise the promotion of biofuels is also done through: the National Development Plan (NDP), the establishment of a regulatory framework and the development of financial and tax incentives. Also, the National Government has policy guidelines in areas such as: agriculture, research and development, infrastructure and environment that influence biofuels development.

There are also other complementary policy developments in the form of decrees and ministerial decisions that define the technical regulations, quality standards, as well as pricing, margins and rate parameters for fuel ethanol and biodiesel transport. There is an applicable regime in the Foreign-Trade Zone and several soft loan sources for agricultural development (Gonzalez, 2008).

Among them, in the framework of Agro Ingreso Seguro Program (AIS), financial instruments that provide soft loan sources for growing crops that produce biomass for ethanol and biodiesel production have been implemented. In addition, through the Incentivo a la Capitalization Rural, ICR (in English: Rural Capitalization Incentive) it is promoted, among others, oil palm crops establishment and renewal, and the construction of infrastructure for biomass processing (Consejo National de Politica Economica y Social (CONPES, 2008)

Despite this broad regulatory framework, there is uncertainty about changes in: regulation, raw material prices and emerging new technologies. In particular, with gallon prices as defined by state intervention (subsidies), that generates the discussion about how much does it mean for the national treasury, and whether it is advisable or heavy subsidies is fair to benefit a minority that supply biofuels, for even small domestic market and one that is difficult to be exported.

As shown, the Colombian Government has a fairly strong policy and information that allows for investment in projects, sustainable energy and biofuels plans and programs through a set of tools, studies and institutional strengthening.

Therefore, the Colombian Government has promoted assessments that seek to: a) study the implications of the biofuel industry, from planting crops for biofuel production to the final consumers of ethanol or biodiesel (flex-fuel or normal vehicles); b) analyze the current infrastructure requirements for the expansion of the biofuel market; c) know the sector current status, as well as the economic instruments, regulatory elements, policies and tax incentives required or recommended for promoting renewable energy, energy efficiency and biofuels; d) analyze the renewable energy potential, energy efficiency and carbon credits through the Clean Development Mechanism. Likewise, institutional strengthening assessment required by the Ministerio de Minas y Energia (English: Ministry of Mines and Energy) (MME), in energy efficiency, renewable energy, bioenergy and carbon financing. This set of measures that promote the enthusiasm for liquid biofuels such as the mandatory blending of biofuels with fossil fuels and tax incentives, have created a fast artificial growth in biofuel production. These incentives have broad social impacts, as they are resources that do not come into the State, and are taken for solving important issues such as health, education and basic sanitation.

These measures entail high economic, social and environmental costs and should be monitored promptly.

Giovanni Di Nicola1, Eleonora Santecchia1, Giulio Santori2 and Fabio Polonara1

1Dipartimento di Energetica, Universita Politecnica delle Marche, Ancona Universita degli Studi e-Campus, Via Isimbardi 10, Novedrate (Co)

Italy

1. Introduction

Henry Ford, father of the modern automobile, constructed his Model T in the early years of the 20th century, when he planned to fuel it with ethanol obtained from cereals. Ford promoted the use of this fuel with such conviction that, by 1938, plants in Kansas were already producing 18 million gallons of ethanol a year (about 54,000 t/year). But interest in ethanol declined after the Second World War because of the enormous availability of natural gas and oil.

At the end of the Seventies, following the first oil crisis, various oil companies began to sell a petrol containing 10% of ethanol, called gasohol, taking advantage of the tax deductions granted on ethanol. Bioethanol did not immediately meet with the success it deserved, however, because it already had competitors on the market, such as methyl tert-butyl ether (MTBE), which was better than ethyl tert-butyl ether (ETBE) in both economic terms and performance. In subsequent years, MTBE proved to be heavily polluting, so it was banned and bioethanol returned to become one of the most attractive prospective solutions for reducing CO2 emissions.

Another factor that helped to relaunch bioethanol was the growing awareness that we are nearing the so-called tipping point, i. e. the moment commonly indicated as the critical point of no return, when the curve of the demand for oil intersects the declining curve of its availability.

There is an ethical issue, however, that particularly concerns bioethanol, but also affects the other fuels of biological origin. Biofuels are obtained mainly from raw materials such as plants and cereals, that would otherwise be destined for the foodstuffs industry.

To deal with this problem, recent research has been concentrating on an inedible perennial herbaceous plant called Miscanthus giganteus that has a calorific value of approximately 4200 kcal/kg of dry matter. Using lignocellulose materials, municipal solid waste or the wheat wasted each year (around 5%, which would provide about 9.3 Gl of bioethanol) could also overcome the ethical obstacles.

Bioethanol can be used in various forms: added in proportions of 5-10% to the diesel oil in diesel engines; mixed in proportions of 10-85% in petrol for internal combustion engines, or to replace 0-100% of the petrol used in flexible fuel vehicles (FFV). The number of FFV on the roads is constantly increasing: in Brazil their sales now reach 400,000 vehicles/year and

there are approximately 1,500,000 of them (mainly public vehicles) circulating in the USA; in Europe, Sweden has around 15,000 vehicles of this type fueled with E85 (85% ethanol). Research is also underway on improved engines fueled with bioethanol, and on fuel cells that use the internal reforming of bioethanol to obtain hydrogen.

Miniature power systems using biocatalysts have received increased attention associated with demand for micro-scale power supplies for implantable medical devices. Development of miniature biofuel cells offers a great opportunity to serve as long-term power sources in implantable device where frequent replacement of battery is not practical. The ability of biocatalyst in converting available indigenous fuels into electrical energy makes miniature biofuel cells attractive to enable long-term and self-sustained power system. The success of medical implants is akin with the effective miniaturization of power sources. This can be achieved by miniaturization of different functional components such as electrodes, power supply, and signal processing units. Some of the effective techniques for miniaturization involve fabricating microfluidic systems using photolithography, etching, polymer molding, and metal deposition (Kim et al., 2008). For example, Siu and Chiao (Siu & Chiao, 2008) applied photolithography and polymer molding to fabricate polydimethylsiloxane (PDMS) electrodes. It was also used by Hou et al. (Hou et al., 2009) to fabricate gold electrode arrays for the microbe screening. Besides polymer molding, etching can also be used to transfer micro-patterns onto device-building substrate. Chiao (Chiao et al., 2006) applied wet etching to construct silicon-based chambers containing serpentine channels. Additionally, C-MEMS microfabrication technique for 3D microstrustures, involving the pyrolysis of patterned photoresist has been developed which can be used as microelectrodes for miniature biofuel cells (Wang & Madou, 2006). With current microfabrication processes, the miniature biofuel cells offer unique advantages such as large surface area to volume ratio, short distance between the electrode, fast response time and low Reynolds number. In the following section, we will discuss the developments of both miniature MFCs and EBFCs. The experimental demonstration of miniature biofuel cells, along with the discussion of the key challenges and opportunities for realizing the practical potential of miniaturized biofuel cells for medical implants will be discussed.