RESEARCH WORK

Experiences of the BIOMAS-CUBA Project. Energy alternatives from biomass in Cuban rural areas

ABSTRACT

This paper provides experiences of the international project BIOMAS-CUBA in the implementation of energy supply alternatives from biomass in rural areas, which are compatible to food security and environmental sustainability. These experiences are comprised between 2009 and 2011, within the agroenergetic farm concept, and are related to research and technological innovation processes associated to: the morphological, productive and chemical evaluation of germplasm of non-edible oil plants with potential to produce biodiesel, ethanol and other products; the planting and agricultural management of associations of Jatropha curcas and 21 food crops; the cleaning and oil extraction of Jatropha seeds; the physical-chemical characterization of such oil; the production of biodiesel and its co-products; the biogas production from excreta and bioproducts and biofertilizers, with the effluents of biodigesters; the gasification of ligneous biomass to generate electricity; the characterization and classification of integrated food and energy production systems. Likewise, the socioeconomic and environmental studies allowed appreciating adequate economic-financial feasibility, remarkable increases in food production, the formation of human capital and the improvement of the people's quality of life, a positive environmental impact and a substitution of energy porters and conventional fertilizers.

Key words: Biomass, energy.

INTRODUCTION

When energy production in rural areas is approached, it is essential to make reference to agro-energy or bioenergy, biofuels, food security, as well as mitigation and adaptation to the climate change, highly important and controversial topics. The combined meeting of the Groups of Experts, on bioenergetic policy, markets, commerce and food security as well as on world perspectives of food security and fuels (FAO, 2008a), approached the current situation and future perspectives of biofuels, the identification of priority actions associated to the effects of climate change and biofuel production on food security and the opportunities in biofuel production for agricultural and rural development.

Likewise, the remarkable growth of the world population and the expectations of a better living status are aspects which drive the growing demand for food, imposing an increase of the stress on land, water, forests and biodiversity. To this stress an additional one is added: the climate change and the enlarging of biofuel production, approached by Ministry of Agriculture, Livestock and Food Supply (2006), Embrapa Agroenergía (2008), FAO (2009) and Practical Action Consulting (2009), because the dependence on fossil-fuel energy is not sustainable (Aranda, 2007; Preston, 2007; FAO 2008b; Nestle, 2008).

On the other hand, there is a growing and remarkable global food crisis, which has been influenced, among diverse causes, by an insensible policy to obtain first-generation biofuels bioethanol, biodiesel- from enormous extensions of food monocrops and large enterprises, creating a great contradiction: biofuels vs. food, which has been acknowledged in diverse scenarios (Suárez, 2008; Emanuelli et al., 2009; Suárez and Martín, 2010).

However, agroenergy referring to energy production from biomass- has the potential to contribute to satisfy the growing energy demand, which requires the development of new knowledge and policies that promote the access of people to this energy source, but achieving food security without affecting the environment. Thus, the initiatives developed for agroenergy production from biomass must allow: a) compatibilizing food security and environmental protection; b) offering new opportunities to rural communities; and c) constituting an ecological alternative to fossil fuels, due to their capacity to reduce the emission of greenhouse gases (Metz et al., 2005; UNEP, 2007; FAO, 2008c).

During the last decade, an increasing trend has occurred in the price of petroleum and food, as well as significant climate and ecological changes at regional and global scale. This situation is ascribed to two main factors: 1) the cumulative result of the irrational use of natural resources, and 2) the unstable geopolitical situation and the economic and environmental crisis.

In the case of Cuba, after the collapse of socialism in Eastern Europe which triggered the crisis of the 90's and severely affected the Cuban economy, this situation has been intensified with the enhancement of the embargo maintained during 50 years by the U.S.A. One of the main impacts was the reduction of more than 80% of the availability of primary energy and material resources, which had negative incidence on agriculture (based on intensive energy consumption and mechanization) and generated a remarkable reduction in food production and the neglect of great amounts of land, which in many cases were invaded by aggressive ligneous weeds; others underwent losses of their potential due to soil salinization, flooding or overexploitation (Montes de Oca et al., 2007). In this sense, the implementation of energy supply alternatives, which are compatible with food security and environmental sustainability, in rural areas is necessary.

The BIOMAS-CUBA project

The Experimental Station «Indio Hatuey» (EEPF-IH), since its creation in 1962, has conducted many studies and innovation processes aimed at the sustainable development of the Cuban agricultural sector on agroecological bases (Blanco et al., 2007), but since 2006 it has been exploring alternatives to achieve the energetic sustainability of production systems, based on local sources, and provide feasible technologies to reduce the external energetic dependence in agricultural systems and, thus, achieve sustainability of agriculture and livestock production.

With this purpose, together with other Cuban institutions, it began to implement in 2008 the international project "Biomass as renewable energy source in Cuban rural areas" (BIOMAS-CUBA), with funds from the Swiss Cooperation and Development Agency (SDC), aimed at introducing, developing and/or improving technologies and systems to use biomass as renewable energy source and contribute to improving the living conditions in rural zones, within the framework of a multi-institutional project of pluridisciplinary innovation, which comprises the production and utilization of biodiesel and biogas, the gasification of lignocellulosic biomass and the production of cellulosic bioethanol from residues.

The BIOMAS-CUBA project is supported on the definition of a group of key principles:

• It is a multi-institutional, multidisciplinary, participatory project, with wide geographical cover and considers the technological, productive, economic, social and environmental dimensions.

• Technological development and technology and (technological and social) innovation assimilation are combined, with basic research to find solutions.

• The sun as primary energy source for biomass production, without which there is no biofuel; for such reason it has to be promoted.

• Use of local resources in integrated agricultural systems which recycle residues and energy.

• Biofuel is produced to be used for food production and improve the living conditions (integrated and local production of energy and food in the farm).

• In biodiesel production lands, which are not utilized in agriculture, and non edible trees are used, intercropped with food crops and pastures (diversification of production) providing environmental services, such as erosion control, recovery of degraded soils and carbon sequestration.

• Integral use of biomass as a source of energy, food and chemical products (value maximization).

• The local stakeholders are protagonists in the solutions and the main beneficiaries.

• Assimilation of technologies, equipment and experiences appropriated in Cuba and at international level, for a later process of inverse engineering (proper technological development).

• Permanent process of follow-up and evaluation of the integral impact in each demonstrative area and the nearby communities.

• The main purpose is to contribute to energy sustainability, with environmental compatibility and food security at local scale in rural areas.

Within the framework of the Project, focused on searching for synergies between science, technology, innovation and social development, research and technological innovation processes are conducted associated to:

• Evaluation of plant germplasm with potential for producing biodiesel.

• Planting and agricultural management of Jatropha curcas plantations associated to food crops.

• Harvest, cleaning and oil extraction of J. curcas seeds. Production of biodiesel and its co-products.

• Production of biogas from excreta and biofertilizers with the effluents from biodigesters.

• Gasification of ligneous biomass for electricity production.

• Characterization and classification of integrated food and energy production systems.

• Socioeconomic and environmental studies.

In this process the concept `agroenergetic farm' is used, which is conceived as: «the productive exploitation where technologies and innovations are developed, improved and evaluated to produce, in an integrated way, food and energy, which is used as input to produce more food in the farm itself, in order to improve the rural quality of life and protect the environment»; this concept is introduced in the scenarios where the project is developed to promote a transition from agricultural to agroenergetic farms.

Main research and innovation results obtained in the Project

Characterization of germplasm from oil plants with potential for biodiesel production

The morphological and productive variability of J. curcas, Ricinus communis and Aleuritis trisperma provenances was characterized in germplasm banks established in the Matanzas, Sancti Spiritus and Guantánamo provinces, as key element to determine their potential for biodiesel production. In order to have access to the germplasm of these species, collection missions were carried out in certain zones of the Sancti Spiritus, Matanzas, Villa Clara and Guantánamo provinces.

In J. curcas seed and, preferably, propagules were obtained; while in R. communis and A. trisperma only seeds were collected. The accessions of J. curcas (23), R. communis (5) and A. trisperma (10) were indistinctly evaluated at the EEPF "Indio Hatuey" and the Stations of Pastures in Sancti Spiritus and Guantánamo.

A higher quantity of J. curcas accessions was evaluated, because this species, highly geographically distributed, has wide genetic variability in its populations (Machado and Suárez, 2009). This variability, according to Toonen (2007), is related to two components: the environmental one (climate, especially rainfall, soil and crop) and that associated to genotype. For such reason, Toonen (2007) proposed its domestication and breeding, with the objective of obtaining uniform harvests and predictable yields, at short term, because the use of wild provenances is done without knowing their yield potential, susceptibility to diseases, resistance to drought and flooding, tolerance to salinity and potential on marginal soils. This presupposes conducting essays from the available material in the germplasm banks, as long as the necessary width is acquired for any type of program aimed at breeding.

For executing the establishment stage, the provenances, planted from propagules (cuttings) or seeded, were placed in 8,0 x 2,0-m plots, spaced at 2,0 m between rows and 2,0 m between plants, separated by 3,0 m in both directions. During this stage observations were made on the number of rooted and emerged plants, from which the survival percentage was calculated.

The characterization of the J. curcas provenances was made when the plants were one year old. The evaluated indicators were: plant height; stem diameter at the base and the primary branches; number of primary, secondary and tertiary branches; number and weight of the harvested fruits; weight of 100 seeds; percentage of trees with diseases (leaf curl and infestation produced by fungi); number of seeds in a kilogram; seed dimensions; fruit productivity per tree; total seed yield and seed yield per area unit, as well as oil content.

Through a principal component analysis the indicators which preponderance value was equal to or higher than 0,70 were identified as influential. From the pattern of principal components a classification was made in groups, of the characterized materials, by means of a cluster analysis which only considered the variables that fulfilled the above-mentioned requisite.

The high degree of differentiation among the R. communis and A. trisperma provenances was evident for the vegetative as well as the reproductive features, for which it was not necessary to conduct multivariate analyses to identify the factors with the highest influence in their variability. In addition, the scarce number of provenances did not allow a reliable PCA.

Among the characterization results the following stand out:

• Propagule diameter is an important indicator at the time of collection; a diameter lower than 1,0 cm causes a trend to mortality and to show a lower number of shoots and leaves when they are a able to take root.

• The age and selected parts of the plant in the donor material, as well as seed quality, seem to influence remarkably the variation of the necessary days for shooting or emergence; as well as the survival percentage under nursery conditions.

• The variation pattern, in terms of rooted plants and survival percentage under field conditions, was similar to the one found in the nursery. Under field conditions the effect of the stress caused by the transfer to the new condition was evident.

• The provenances have acute differential vegetative as well as reproductive characteristics, which constitutes an encouraging element in the identification process of prominent materials at present and in the future.

• The growth degree reached in the first year in J. curcas did not depend on the propagation means, but on the productive characteristics of each provenance.

• Provenances with high production potential or those that did not fructify or produced very few fruits were indistinctly found, which ratifies the evident existing variation signs and the need to continue the introduction and collection.

• The affectations produced by diseases reached moderate or high values, with some exceptions, in high fruit-producing individuals as well as in those that did not reach the reproductive phenophase. This warns about the need to do further studies aiming at establishing the relation between diseases and fruit production, and the possible noxious potential that could be represented by the presence of pests.

• In the J. curcas provenances evaluated at the EEPF "Indio Hatuey" accessions were identified capable of reaching seed yields similar to those of foreign provenances, as in the ones called San Miguel and SSCE-10. However, Cabo Verde is still the most outstanding provenance.

• A high contrast was detected in productive terms for the J. curcas material evaluated in San Antonio del Sur, Guantánamo. The best provenance to promote production areas is San Miguel, collected in Matanzas province, although it is possible to consider the varieties India and Mazal-3.

• The fruit characteristics and the oil content of the provenance SSCE-10 were very similar to those of Cabo Verde, although the latter produced twice as much oil (estimate) as the former per area unit.

• Morphological variability was detected in the R. communis materials in Sancti Spiritus, as well as in its productive and stress-tolerance characteristics.

• The performance of the R. communis provenances collected in Cuba was lower than the Brazilian ones, although the ones called Plantas 2 and 3 stood out, with higher seed yields, productivity per tree and per area unit, as well as oil production.

• The A. trisperma material established on Brown soils of Sancti Spiritus showed a contrasting performance in terms of height and bifurcation degree of the plants.

Characterization of the shells, press cakes and oil from non-edible oil plants

A chemical characterization was made of the shells, press cakes and oil from six non-edible oil plants: J. curcas, Azadirachta indica (neem), Moringa oleifera, R. communis, A. trisperma and A. moluccana, with the support of the University of Vigo and the Biomass Energy Department (belonging to the National Center of Renewable Energy, Pamplona), in Spain.

The seeds were manually shelled and the shells were dried at 50ºC during 24 h, ground, sieved to a particle size of 1 mm and preserved at 4ºC until the moment of analysis. The oils were extracted by pressing the beans, with a pneumatic press. The R. communis seeds were directly pressed, without shelling, due to the impossibility of processing the beans in the press.

All the oils were immediately transferred to Eppendorf tubes and preserved at 4ºC until the analysis. The residual oil of the press cakes was extracted with hexane for 16 h at 35ºC. The defatted cakes were recovered by vacuum filtration and dried at 40ºC during 24 hours. The dry cakes were ground and sieved to a particle size of 1 mm and preserved at 4ºC. The oil content was gravimetrically determined.

The chemical characterization of the shells and press cakes was conducted according to the norms of the NREL (Sluiter et al., 2008). The moisture content was determined by drying an aliquot at 105ºC to constant weight. For determining minerals, the sample was
incinerated at 550ºC during 3 h. The extractives were gravimetrically determined, after an extraction with ethanol at 96% in a Soxhlet extractor during 24 hours. For carbohydrate and lignin quantification an analytical acid hydrolysis was made with 72% sulfuric acid at 30ºC, during one hour, and then 4% at 121ºC for another hour. The mixture was separated by vacuum filtration and the solid residue was used for the gravimetric determination of lignin. The analysis of hydrolizates was made by HPLC, with refractive index detector. Glucose, xylose, arabinose and acetic acid were separated in an ION-300 column (Transgenomic, Inc., USA) with H2SO4 3 mM at a flow rate of 0,4 mL min-1 as mobile phase. In the analysis of the composition of the press cakes, fiber determination was made through the sequential Goering-Van-Soest method (Goering and Van Soest, 1970).

The nitrogen determination was made with a Finnigan Flash EA 1112 elemental analyzer (Thermo Fisher Scientific, USA), using 130 and 100 mL min-1 of He and O2 with an oven temperature of 50ºC. The protein content was calculated multiplying the elemental N content by the universal factor 6,25.

The content of fatty acids in the oils was determined by GC-MS of the previously methylated oils. A gas chromatographer (TRACE DSQ, USA) was used. The injection volume was 0,5 mL and He was used as mobile phase. For the separation a capillary HP-Innowax column of 60 m x 0,25 mm x 0,25 µm was used. The temperature was kept at 80ºC during 2 min, it was programmed to 130ºC at 5ºC min-1, then to 210ºC at 30ºC min-1, it was maintained for 10 min. The acids were identified by comparing their retention times and their mass spectra, with a data library of mass spectra from known compounds.

The oil yield, main indicator of an oil plant to be industrialized, in the Aleurites bean was around 60% -the highest, among the studied seeds-, while it was 50% in J. curcas and between 35 and 40% in the other oil plants, which coincided with the reports in literature. Only in A. trisperma the yield was considerably higher and in R. communis it was lower than the above-reported values. If the oil yield in the beans and the bean content in the seeds are considered, A. trisperma and J. curcas showed the highest potential as oil sources among the studied oil plants (Martín et al., 2010).

It stands out that the oleic acid represented 71% of the acids contained in M. oleifera and, due to its high content the M. oleifera oil is appropriate for applications that require a source of this acid. Recent reports stress the potential of M. oleifera for different applications, including biodiesel production (Anwar et al., 2005). Another interesting result is that the 10-octadecenoic acid, which had not been detected in previous reports, was identified as the second most important component of the oil from the Cuban M. oleifera.

Due to its yield, high oil content and profile of fatty acids, J. curcas was identified as the most appropriate non-edible oil plant for producing biodiesel in Cuba. A. trisperma showed oil content higher than 60%, but its high content of polyunsaturated acids (about 50% of the identified fatty acids) limits its possibilities for this purpose.

The cakes obtained in the pressing of edible oil plants are rich in proteins, with high nutritional value to be used in animal feeding and as raw material in bioprocesses for obtaining products of high added value, such as aminoacids, enzymes, vitamins, antibiotics and biopesticides (Ramachandran et al., 2007). Fewer studies have been conducted on the non-edible oil cakes, and their uses are limited to the production of biofertilizers and biogas.

A common characteristic of all the cakes was their high protein content, comparable to, and even higher than, the cakes of edible oil plants (Ramachandran et al., 2007). The protein content varied between 38,7% in A. trisperma and 68,6% in M. oleifera. In the cakes of A. moluccana, J. curcas and R. communis it was approximately 60%.

In spite of its high protein content, the press cakes of non-edible oil plants can not be directly used as protein supplements in animal feeding, due to the presence of toxins, such as ricin in R. communis (Anandan et al., 2005) and curcin in J. curcas (Trabi et al., 1997; Gübitz et al., 1999), for which they should be previously detoxified.

In addition, the cakes of A. trisperma and R. communis are evaluated as potential raw material for some fermentation processes, due to their relatively high carbohydrate content.

The shells are the result of seed shelling, before oil extraction. They have generally low economic value and are discarded or burned; in some cases they are used as fuel or raw material for the production of activated charcoal.

A study was conducted to evaluate the potential of shells as raw material for hydrolytic and fermentative productions. The study of the chemical composition of the shells has received little attention, because most reports about the composition of oil plant species are restricted to the bean components (Martín et al., 2010).

The results showed wide variation in the composition of the studied materials. The A. indica shells showed a similar composition to hard woods and agricultural residues (Martín et al., 2006), while most of the others turned out to be more lignified than typical lignocellulosic materials; even lignin contents were high in A. trisperma (62,9%) and A. moluccana (51,6%).

The high cellulose content in the shells from A. indica and M. oleifera indicates that they can be considered as glucose sources for the production of ethanol, lactic acid and other fermentative products. The A. indica shells, due to their high xylan content, have potential for producing xylitol, furfural or other xylose derivatives; while the abundance of acetyl groups favors the increase of the reactivity of the material in the cellulose and hemicellulose hydrolytic degradation. In the case of M. oleifera, its high protein content could be positive to decrease the cost of nutrient supplementation in fermentative processes.

Sowing and agricultural management of J. curcas plantations associated to food crops

Between 2009 and 2011, 93 ha of J. curcas associated to crops were planted at the EEPF-IH, at the Stations of Pastures in Sancti Spiritus and Las Tunas, as well as the Paraguay Farm and many farms of the Guantánamo province, territory which has most of its area planted; from them, 55% are located on soils that can not be used for other agricultural productions, which are found, in high proportion, in high-fragility areas, with environmental affectations and hydrographic basins.

At the EEPF-IH and in Guantánamo, planting distances were studied and eight combinations were evaluated; the following frames stood out:

• 2,5 x 4,0 m (1 000 trees/ha), appropriate for mechanized productive systems, with a land occupation of 72% for food production and 28% for energy.

• 2,5 x 3,0 m (1 333 trees/ha), appropriate for systems with tillage by animal draught, with a land occupation of 64% for food production and 36% for energy.

In these frames the performance of 21 intercropped agricultural crops was evaluated (Sotolongo et al., 2009; Suárez et al., 2010); considerable food productions were obtained, especially in beans, soybean, peanut, corn, cassava and sorghum, under survival irrigation and moderate fertilization conditions, with biofertilizers; J. curcas showed moderate productivity values (table 1).

Until now 147 000 seedlings of J. curcas, neem and fruit trees have been produced, but mainly of the first species, with application of the ECOMIC® fertilizer elaborated from mycorrhizae; an infrastructure was created to produce up to 80 000 seedlings in one year, with two nurseries, in Guantánamo.

Harvest, cleaning and oil extraction from J. curcas seeds. Production of biodiesel and its co-products

The schedule of cleaning, extraction, filtration, degumming and neutralization at the biodiesel production plant was defined, as well as the technological and industrial plan and the raw material needs. In this sense, a productive flow of 264 days/year was designed, with one work shift at the biodiesel plant of eight daily hours, from an annual harvest of 608 721 kg of fruits; the moisture of the shells and dry fruits was 24,7 and 13,5%, respectively.

This moisture is reduced to 15 and 6% (shells and seeds) through a process of 3-5 days of solar drying in a 1 000-m2 area, which constitutes the first stage of the plant of fruit and seed cleaning and extraction, filtration, degumming and neutralization of J. curcas oil.

Afterwards, the fruits are shelled in a mechanical process, at a rate of 329 kg of fruits/hour, which generates 115 kg of shells/hour, which are chopped in a knife mill to reduce the particle size. The next step is oil extraction from the seed through cold pressure, at a rate of 226 kg of seeds/hour, which generates 507 kg of oil/day (528 L/day) and 152 kg of press cake/day (11% of oil). Both processes (shelling and pressing) generate, daily, 528 liters of filtered, neutralized and degummed oil, after the cleaning, and 1 074 kg of shells and cakes, appropriate as raw material to produce compost (284 t per year).

This oil, which physical-chemical characteristics are shown in table 2, is turned into biodiesel through a transesterification process with a BD JET 400 reactor, in the biodiesel plant acquired from the Costa Rican enterprise Central Biodiesel and installed at the Paraguay Farm (Guantánamo), with a production capacity of 400 L of biodiesel/day in an eight-hour shift (105 600 L per year), using anhydrous ethanol and potassium hydroxide.

As a result 105 600 L of biodiesel and 13,5 t of glycerol (raw material to produce glycerin, and which can be used in the perfume and cosmetic industry) are annually obtained. This biodiesel can be used pure in engines designed for this biofuel or mixed with diesel in traditional engines, as well as in food cooking with biodiesel burners (60-70 mL/hour without smoke emission) or pressurized kerosene burners.

In this sense, an integral technological proposal was elaborated for the agronomy and micro-industrialization of J. curcas and the economic use of the process co-products (shell, press cake and glycerol).

Production of biogas from animal residues and biofertilizers with the biodigester effluents

Biogas is a mixture of different gases produced by the anaerobic decomposition of organic matter. In its chemical composition methane (CH4) stands out, with 60-70%, but there are traces of hydrogen sulfur (H2S), which must be eliminated from the biogas current before being used as fuel; for that purpose, it is enough to make the biogas flow pass through a filter filled with iron filings.

The technologies selected to build anaerobic biodigesters were the fixed dome (Chinese model), the plastic tubular or polyethylene bag with continuous flow (Taiwan type) and the anaerobic lagoon covered with a geomembrane of high-density polyethylene (HDPE).

The shape of the fixed dome biodigester, of Chinese origin, is similar to a sphere and the gas is stored within the fixed drum at variable pressure, which is obtained by displacing the liquid under digestion towards a chamber called hydrostatic pressure chamber; the construction materials are blocks and/or bricks, cement and steel. These digesters are semi-continuously charged: the first charge is made with cellulosic material and manure, in addition to the corresponding inoculum, up to 70% of the capacity (Hilbert, 2003); then, charging is maintained as in a continuous digester; 120-180 days afterwards it is completely discharged and the cycle is restarted. Abroad from China, generally, these digesters are continuously managed.

The plastic tubular biodigester consists in a type of elongated polyethylene bag, with a length-width ratio of approximately 5:1 although for efficient construction reasons the proportions may differ (Frederiks, 2011)- which is placed in a pit. This biodigester is much less costly than the fixed-dome one, but it has a shorter useful life (less than 25%).

The anaerobic lagoon covered with high density polyethylene is a technology developed by the Biogas Technology Center of Hanoi for large residue volumes and a quantity of solids (around 3%), with low construction and operation costs, solving the limitations of the uncovered anaerobic lagoons, which produce methane emissions and unpleasant odors to the atmosphere, and also do not allow recovering the biogas. Its bottom and walls can be made of impermeable clay, blocks, bricks or reinforced concrete, while the HDPE cover floats on the lagoon surface and is resistant to ultraviolet rays.

Biodigesters, in addition to producing biogas which energy content in 1 m3 of biogas (60% CH4 and 40% CO2) is approximately 6 kWh/m3 (Hilbert, 2003)-, allow reducing the uncontrolled methane emission from livestock production, the increase of CO2 concentration in the atmosphere from the use of fossil fuels, the emission of nitrous oxide and ammonia by applying the biodigester effluents as fertilizer and the organic contaminants present in the excreta, due to the use of pesticides which are decomposed in the anaerobic digestion.

In the project, 69 biodigesters have been built, from them nine are plastic tubular, one has mobile dome (Indian model), two covered anaerobic lagoons and the other 57 are of fixed dome, with total digestion capacity of 1 665 m3 and annual productions of 200 020 m3 of biogas and 867 t of biofertilizers (equivalent to 604 barrels of petroleum -90 USD/barrel- and 116 t of whole NPK fertilizer-650 USD/t, respectively). The development of a software supported on LabVIEW 7.1 and its corresponding handbook to design biodigesters and secondary and tertiary treatment lagoons, when necessary, in order to decrease the biochemical oxygen demand BOD from the liquid effluent, contributed to this process.

Likewise, 28 plants were installed for bioproduct production from biodigester effluents, enriched with native microorganisms, which are used in animal and plant health, crop nutrition, elimination of bad odors in livestock production facilities, bioremediation of lagoons contaminated with organic residues and also in bioceramic filters.

Gasification of ligneous biomass for electricity production

Biomass gasification is the conversion of solid biomass (wood, lignocellulosic forestry and agricultural residues) in a mixture of fuel gas, which is used in internal combustion engines to generate electricity, within a partial combustion process that occurs when the supplied air (oxygen) is lower than the one necessary for the biomass combustion to be completed. Biomass contains carbon, hydrogen and oxygen molecules, for which the complete combustion produces carbon dioxide (CO2) and water vapor (H2O), while the partial combustion generates carbon monoxide (CO) and hydrogen, which are fuel gases.

This biomass gasification is much more efficient (conversion efficiency higher than 75%) than its traditional combustion as wood or coal (the efficiency of conversion to enezrgy is lower than 10-25%). The gas produced has a net calorific value of 4-6 MJ/m3, that is, 5-7 times lower than natural gas (36 MJ/kg) or biogas (22 MJ/kg) (FACT, 2010).

The selected technology was fixed-bed and downdraft with four stages within the gasifier (drying, pyrolysis, oxidation and reduction), and its provider was the Indian firm Ankur Scientific Energy Technologies, one of the world leaders in low capacity gasifiers (lower than 100 kW.h), from which two gasifiers were purchased with their generators, with capacity of 20 and 40 kW.h; they were installed at the Experimental Station "Indio Hatuey", in Matanzas, and the sawmill "El Brujo" in the Gran Piedra-Baconao region, Santiago de Cuba, which work with wood from Dichrostachys cinerea (an invasive thorny ligneous plant) and residues from pruning in livestock production agroforestry systems, as well as wood residues.

This technology produces less tar than the updraft technology, for which it is more appropriate for the gas use in engines (FACT, 2010); however, it requires strict specifications of the fuel biomass (moisture, size).

Socioeconomic and environmental studies

The economic-financial analysis made in stage I of BIOMAS-CUBA, with a horizon until 2014, provided a cost/benefit ratio that, at the end of this year is estimated in 3,4, including the investment made by the Swiss Cooperation Agency and the counterparts, with a net present value (NPV) higher than 34 million CUP and an internal rate of return (IRR) of 7,4%, with an investment recovery at the beginning of 2009, which confers adequate efficiency to the project. Likewise, a net profit higher than 48,2 million CUP, between 2009 and 2014, was calculated.

On the other hand, an increase was generated in food production (3 196 t of vegetables, fruits, milk, meat and eggs) in 2009-2011, directly influenced by the project, which, according to the prices in the local market, increased from 1,6 to 19,7 million CUP; the productive lines were also diversified, although the offer is still lower than the demand. In addition, in such period a local production of biogas, biofertilizers, rice and milk was achieved in 14 municipalities from five provinces equivalent to substituting diesel, fertilizers and food with a value of 280 626 USD.

Regarding the improvement of the people's quality of life, the following achievements stand out: the creation of 108 direct jobs with mean monthly salary of 469 CUP, higher than the mean salary of the four provinces involved (451 CUP), from which 14% is occupied by women under equal conditions; an improvement of the quality of life of 1 198 people directly in the 14 municipalities, due to the increase of jobs, incomes, access to equipment and productive inputs, better working conditions and the availability of gas cooking; the generation of 43,1 million CUP as income, during 2009-2011, with a mainstreamed gender approach (new jobs for women with equal salary, better working and living conditions) and an increased empowering of farmer women, who decide to study and begin a working life to acquire economic independence; self-financing and governance initiatives were even created in associationism actions.

Regarding the positive environmental impact between 2009 and 2011, the sequestration of 1 567 t of CO2 was evaluated (a J. curcas tree captures 6 kg of CO2/year), which could generate incomes of 175 472 CUP (equivalent to € 20 533) according to the world values of the carbon credit market (13,10 €/t of CO2); 93 ha were reforested with J. curcas associated to food crops in 70% of the area, 55% of that land located on soils which were unusable for other agricultural productions, (in a high proportion) in high-fragility areas, with environmental affectations and hydrographic basins, as well as 97 ha of fruit trees and 15 ha of neem, with a survival higher than 80%; the contamination generated by cattle and pig dung was eliminated in 67 productive scenarios through the construction of biodigesters; 117 ha of soil invaded by D. cinerea, which had a high deterioration rate due to overexploitation in sugarcane plantations and salinization in Guantánamo, were recovered; and 1 830 ha of soils were improved by applying biofertilizers produced with biodigester effluents.

Concerning human capital formation, 911 producers and 41 managers have been trained through printed materials and participatory learning and experimentation methods, with gender approach, to enhance their abilities, from 20 technical talks, 36 workshops/courses, nine field days and more than 37 documents of different formats. Likewise, a network of people and institutions related to the food and energy productive chain has been created (63 institutions and organizations, 212 experts, extension workers and producers), which works actively; its members interact by e-mail and in periodic meetings and benefit from the services of the knowledge management network created in the project. Such network is enhanced with a virtual reference nucleus on Agroenergy at the EEPF "Indio Hatuey", supported on the web site http://biomascuba.ihatuey.cu, which is implemented on software CMS Joomla version 1.5.20 and servers with operative system Linux and it is supported on a cluster system on Proxmox Virtual Environment 1.9, which provides produced and systematized scientific and practical knowledge.

Relevant aspects which have contributed to the Project's success

• Thematic approach: integrated food and energy production in rural areas, on agroecological bases, and the application of the agroenergetic farm concept.

• Wide network relations among all the stakeholders, which was the main success cause and facilitated the synergies among stakeholders from several sectors at local, territorial and national scale.

• Innovation model aimed at the achievement of practical results and which promoted the link between the academic sector and producers.

• Local agricultural innovation processes, where technologies and innovations are improved with wide participation of the beneficiary, which generates improvements and sustainability.

• Decentralization of the project management, to increase creativeness, create leadership opportunities for people and institutions and make decisions in real time.

• Gender equity with a strategic position in the project, with activities conceived as «multisex» and not aimed only at the female sector.

• Synergies with other SDC-financed projects and with such institutions as the National Association of Small Farmers, local governments, municipal Agriculture delegations, branches of the Cuban Association of Animal Production and of the Association of Agricultural and Forestry Technicians, Cubaenergía, the Renewable Energy Direction of the Ministry of the Basic Industry and the Governmental Groups of Forestry and Organic Biomass, Biogas and Liquid Fuels.

• Permanent process of socialization of results, experiences, good practices, technologies and designs, etc., aimed at project direct beneficiaries and managers, governmental authorities and other policy-makers, at local, provincial and national scale.

• Participation and protagonist role of producers and their families.