RESEARCH WORK

Agroenergy production from biomass in integrated agroforestry systems: an alternative to achieve food security and environmental protection

J. Suárez y G. J. Martín

E-mail: jesus.suarez@indio.atenas.inf.cu

ABSTRACT

The objective of this paper is to offer considerations about agroenergy production from biomass in integrated agroforestry systems. At present, worldwide, marked by a group of hazards that threaten human existence, there is a challenge mainly in the rural context: how can the coexistence of agroenergy, food security and environmental protection be achieved?, in the presence of climate changes, environmental degradation, food crises and the growing biofuels vs food contradiction, generated by a senseless policy for obtaining first-generation agrofuels from large extensions of food monocrops, which is morally rejectable. Biofuels are also considered an ecological alternative to fossil fuels, because of their reduction capacity in the emission of greenhouse gasses and because they promote the development of rural communities in southern countries; this is enhanced in integrated agroforestry systems, in which biofuels, of first as well as second generation, can be produced, especially with the application of the concept of biorefinery which allows converting biomass into many products, which total added value can be higher than the one generated by fossil fuels. International projects, which promote integrated and sustainable food and energy production in the context of agroforestry integrated systems, at local scale, contribute to this purpose. The authors consider that the execution of projects and experiences about agroenergy has the main objective of achieving energetic sustainability and food security at local scale, in rural areas, taking into account environmental protection.

Key words: Agroenergy, agroforestry systems, biomass

INTRODUCTION

When renewable energy sources in rural areas are approached, it is unavoidable to speak about agroenergy or bioenergy, biofuels, food insecurity and climate change, largely important and controversial topics. For such reason, the combined meeting of the Expert group on Bioenergy policy, markets, trade and food security, and Global perspectives of food and fuel security (FAO, 2008a), focused on the current situation and the future perspectives of biofuels, and identified priority action sectors which approach the effects of climate change and biofuel production on food security; in addition, the possible opportunities presented by such production for agricultural and rural development, were determined.

On the other hand, the remarkable growth of the world population since 1950 and the expectations of a higher standard of living are two of the main aspects that drive the growing demand of agricultural products (FAO, 2009a), which causes increasing pressure on natural resources, such as land, water, natural forests and biodiversity. At the same time, the industrialization, commercialization and globalization of the economic activity have increased the pressure on natural resources, because such resources and the services of the ecosystem have been traditionally undervalued or depreciated by the market and, consequently, excessively used. Likewise, the climate change and the widening of biofuel production as possible source of clean energy subject the bases of the Earth's natural resources to remarkable additional pressure (FAO, 2009b).

According to the International Energy Agency, the dependence on fossil fuel-based energy is not sustainable, in terms of supply security as well as environmental effects (FAO, 2008b). Agroenergy has the potential for contributing to satisfy, partly at least, the growing energy demand; in the foreseeable technological hypotheses, it is acknowledged that the quantity of necessary biomass to produce biofuels can supply only a fraction of what is currently obtained from fossil fuels. However, bioenergy production considerably affects the markets and trade of basic products, and the evolution of technology can alter the scope and nature of these effects.

In this sense, it demands the development of new knowledge and policies that promote access of people to energy by means of agroenergy, but achieving food security without affecting the environment; thus the initiatives to be developed can offer new opportunities to rural communities. One of them is agroenergy production from biomass in integrated agroforestry systems, which allows the compatibilization of food security and environmental protection; in 2007, biomass was used to satisfy around 10% of the world demand of primary energy (FAO, 2008c). Hence the objective of this paper is to present considerations about agroenergy production from biomass in integrated agroforestry systems.

Current global situation: how is coexistence between agroenergy, food security and environmental protection achieved?

The current global situation is marked by a group of hazards that threaten human existence, such as the following:

• Declination of non-renewable resources: fossil fuels, underground waters, soils, minerals and biodiversity.

• Environmental deterioration, due to contamination and global warming. The most developed countries contribute 46,2% of global CO₂ emissions¹.

• Increases of the world population and the demand for agricultural and livestock products.

• Subsidies to farmers (but not from the richest countries).

• New energy, food and financial crises.

• Eighty five percent of the world energy is produced from fossil fuels; so that the current global consumption is 85 million barrels daily, which is unsustainable.

• The United States consumes 26% of the petroleum extracted in the planet; while the energy consumption of the European Union is also based on fossil fuels (79%).

At present, 1,6 billion people in the planet do not have access yet to electricity and more than two thousand millions depend, daily, on biomass to cook their meals and get warm, which generates a remarkable environmental impact, because a high proportion of this biomass wood and coal causes deforestation; besides, less than 5% of tropical forests are sustainably managed (World Bank, 2008)². In addition to this critical situation, according to FAO's estimations, each year 113 million forest hectares are turned into agricultural areas, mainly in the tropics. This process of forest loss and the incomplete combustion of biomass have a noticeable contribution in the climate change, which exists and it is not possible to avoid it, but it can be mitigated in an efficacious and environmentally reasonable way.

Likewise, there is a marked global food crisis; so that 1 000 million people suffer hunger (Castro, 2007), which increases, because the financial crisis is replacing it in the governmental and public discussion, and this constitutes a threat to its solution (Afonso, 2009). Likewise, the growing food crisis has been propitiated, partly, by a senseless policy for obtaining biofuels also called agrofuels of first generation from large extensions of food monocrops and large firms, but creating the big biofuels vs food contradiction.

These liquid biofuels are promoted by a growing business based on agreements among agricultural and oil companies, automobile manufacturers and biotechnology centers, with billions of dollars invested in an irrepressible industry, in which poor countries turn their lands into monocrops and transportation systems are prepared to take those biofuels to the First World. This policy has generated a remarkable increase of food prices and, often, hunger, poverty, environmental degradation and biodiversity loss Indonesia and its 6,5 million hectares of oil palm monocrop is a sad example.

This record increase of food prices is generated by the fast increase of the demand of raw materials for biofuels, which has had effects on other basic products. The inflation of food prices is especially problematic in developing countries with considerable food purchases, which import bill increased 10% from 2005 to 2006 and a proportion of 36% from 2006 to 2007 (FAO, 2008b). The authors of this paper consider that using food for producing biofuels is morally rejectable, while a very considerable part of the world population suffers hunger and malnutrition.

On the other hand, biofuels are considered by governments and international institutions as an ecological alternative to fossil fuels, due to their capacity of reducing greenhouse gasses (GHG) a very controversial aspect, with defenders and detractors besides promoting the development of rural communities in Southern countries, which are the producing zones. One of the defenders of the sustainable production of liquid biofuels is the United Nations Environment Program (UNEP, 2007) and the Bioenergy and Food Security Program (FAO, 2008d), which promotes the development of sustainable regulations and in this sense, organized an international round table in 2007 about Jatropha curcas, a non-edible tree adequate for these purposes.

The world production of liquid biofuels is estimated in more than 35 billion liters (European Commission, 2006), of which bioethanol comprises more than 90%³. Regarding biodiesel, the global production reached 3 500 million liters in 2005, led by the EU (43%), and Germany (highest consumer), Italy and France stood out; the USA and Brazil (they comprise 12% worldwide) also stand out. Similar trend is shown by the production and trade of pellets, briquettes and other types of solid biomass for combustion, which providers are concentrated in North America and Western Europe, where the highest market exists.

Agriculture and climate change: their interactions

Nowadays, agriculture and climate change are highly interrelated, according to Nelson (2009), because of several key reasons:

• The climate change has (and will have much more) large negative effects on agriculture.

• Agriculture can help to mitigate it, because it contributes today with 14% of annual GHG emissions especially livestock -, as well as19% of the changes in land use, including forest loss.

• The agricultural producers of the Third World need help to adapt to the climate change.

In this sense, agriculture and the changes in land use, such as deforestation, contribute to 13 and 17%, respectively, of the total GHG emissions; in addition, although the carbon dioxide emissions from agriculture are reduced, the emissions of the sector represent 60% of all the nitrous oxide (N₂O), due to the use of fertilizers, and around 50% methane (CH₄) mainly from natural and cultivated wetlands and enteric fermentation (FAO, 2008b). This organization foresees that methane and nitrous oxide emissions will increase in 35-60% for 2030, boosted by the increasing use of nitrogen fertilizers and the increase of livestock production in response to the growing food demand.

However, agriculture and forestry activities have, in principle, a considerable potential of GHG mitigation. The Intergovernmental Panel of Experts on Climate Change estimates that the world technical potential of mitigation corresponding to agriculture (excluding the forestry sector) will oscillate between 5 500 and 6 000 Mt of CO₂ per year by 2030, of which 89% will derive from carbon retention in soils (Metz et al., 2005).

Likewise, for mitigating the climate change, it is essential to solve the energy problem, from decarbonization of the energy supply, by means of four non-excluding options (Nestle, 2008): nuclear energy, energetic efficiency, carbon capture and sequestration and renewable energy sources; integrated agroforestry systems play a key role in it.

Mitigation is a political objective of agroenergy development in many countries. In this regard, FAO (2008c) considers that the systems which use organic wastes and agricultural and forestry residues, as well as the plantation of perennial species for energy generation in degraded lands, offer a high reduction potential of GHG emissions.

In the case of GHG emissions from agroenergy, an adequate balance of them depends on the effective use of coproducts⁴ from agroenergy conversion and processing, according to criteria of the World Wide Fund for Nature (WWF, 2006), with which the emissions of these gasses, as well as soil erosion and degradation, can be minimized. An example is Brazil, where in sugarcane the relation between renewable energy produced and fossil energy was 8,9 for bioethanol, about five times better than in the case of corn; likewise, bioethanol generates GHG emissions almost four times lower than the ones produced by the bioethanol manufactured from cereals (Anonymous, 2009).

Current trends and experiences in agroenergy development worldwide

FAO (2008b) identified a group of trends that show the current understanding of the context that links biofuels, climate change and food security, which are the following:

• The acceleration of investments in biofuels is in contraposition to the changes in the rural sectors of developing countries, which are promoted by commercial integration and the fast increase of food prices, which are foreseen to continue increasing (30-50%) over the preceding balance levels.

• At present, the increasing of biofuel production is boosted by the policy measures adopted to promote farmers' incomes, energy security, climate change mitigation and rural development, especially in developed countries.

• The increase of food as well as petroleum costs (the latter exceeds 80 USD/barrel, and has even reached more than 130 USD), is causing financial difficulties to poor families. Particularly, most of the countries labeled by the FAO as countries suffering food insecurity are also net importers of food and petroleum.

• The increasing attention to climate change, GHG emissions, changes in land use and connected environmental issues, has been focused on whether biofuels represent a solution to these problems or are rather aggravating them5.

• The increase of the petroleum price contributes to increase the costs of basic products, especially foodstuffs; in addition, as the price of petroleum increases, it is more cost-effective for biofuel producers to increase their production and pay more for agricultural raw materials, which generates a competition that increases their prices and, indirectly, food prices, and thus their costs for consumers increase.

Regarding experiences, although the sources for producing agroenergy are diverse and they include anaerobic digestion for biogas production, gasification and biomass pyrolysis for electricity, fuel wood and coal production, among others, the most approached technological alternatives, at present, are those associated to liquid biofuels.

There is a «first generation» of biofuels, produced with oils from plants and animal fats, such as bioethanol and biodiesel. Bioethanol has based its production on sugarcane production specifically from its molasses or directly from its juice -, by means of fermentation and later distillation, in tropical countries; and on corn and other amylaceous plants, with a similar process, but preceded by hydrolysis, in temperate countries. Recently, experiences have been developed with other plants, as in India, where sweet sorghum varieties have been developed, with high saccharose content and adapted to arid and semiarid zones for producing bioethanol; while in Thailand, China and Colombia the use of cassava is beginning.

Regarding its competitiveness, the production of some biofuels, especially bioethanol, is more competitive in large-scale industry, due to the high cost of the investment related to the elaboration process (FAO, 2008c). Nevertheless, positive experiences have been developed in mini-distilleries for bioethanol production, from sugarcane, in Brazil, and from cassava in Colombia, promoted by the International Center of Tropical Agriculture (Ospina, 2009).

Biodiesel uses as raw material the oils of conventional crops, such as soybean (average yields in oil of 420 L/ha), sunflower (890) and rape (1 100), in temperate countries, and Africal oil palm (5 500 L/ha) in the humid tropics, in addition to animal fats, by the transterification process. However, in recent years the use of tropical trees is gaining an important space, for example J. curcas and Ricinus communis (both Euforbiaceae), as sources of non-edible oil for producing biodiesel (1 600 and 1 320 L/ha, higher than the above-mentioned yields, except African palm), in Brazil, India, China, Colombia, Guatemala, Dominican Republic and Mexico.

The social consequences of biofuel development depend on the raw material and the production system (FAO, 2008c). If they are economically viable⁶, the small-scale cultivation of such plants as Jatropha and the utilization of biofuel in the exploitation or the community can revitalize rural economies, by means of mechanization, irrigation and decentralization of the energy supply; in addition, biodiesel production generates byproducts, such as glycerin, feedstuffs, manures and bioproducts for plant and animal health.

An example of the usefulness of agroenergy in the Third World is shown in the project «Policy Innovation Systems for Clean Energy Security», which appreciates energy as a component of the large rural value chain and considers that it is possible to achieve efficiency of natural resources in small-scale initiatives (Practical Action Consulting, 2009). Such project offers the results of case studies in countries from Asia, Latin America and Africa, among which the following stand out:

• Crude Jatropha oil to produce electricity in rural towns of Mali and India.

• Jatropha biodiesel to feed water pumps and the use of coproducts press cakes and glycerol as fertilizers and feed for cattle and poultry (India).

• Biodiesel production in 170 ha of Jatropha, by a cooperative of 150 families in Guatemala, with yields of 2 123 L/ha/year⁷. Another experience of cooperative production with this plant is conducted in Thailand villages, with cero residues.

• Briquette production from plant coal dust in Senegal communities.

• Cookers of ethanol produced with sugarcane in Ethiopia.

• Utilization of the biogas produced from sisal residues in villages of Tanzania, for cooking and electricity and fertilizer production.

• Sustainable biodiesel production from palm oil, in 4 400 ha in Tanzania.

• The remarkable experience with biogas in small agricultural producers in Viet Nam.

• Briquette production in Kenya and Senegal, from herbaceous weeds.

• Bioethanol micro-distilleries from sugarcane in Minas Gerais, Brazil.

• Recycling of plant oils used by restaurants and supermarkets in Lima, Peru.

In recent years technological developments have occurred which are originating a «second generation» of liquid biofuels, from lignocellulosic residues (LCR)⁸, algae oils and the combustion of the biomass pyrolysis. Concerning LCRs for ethanol production, studies are being conducted, especially in the USA, Brazil, Denmark, Sweden, Spain, Mexico and Cuba (University of Matanzas). In this strategy a key role is played by the concept of biorefinery for maximizing the value of agroenergy, which is based on the transformation of all the components in useful products, as it is done in a petroleum refinery, and by means of which an attempt is made to maximize the advantages and utilization of intermediate products, with which value is added; for example, in the production of bioethanol from LCR other products of high added value can be obtained, such as prebiotics, antioxidants, antimicrobials, lignin (solid fuel, caloric value 10 500 KJ/kg), residual yeast and biogas, among others.

With this concept it is possible to formulate the following questions: 1) Can energy, fuel and chemicals production, based on plant cultivation and processing, compete with fossil fuel-based production?; 2) is it adequate to produce only energy or also high value chemicals?; 3) what is more feasible for it: small- or large-scale operation?, and 4) which would be the most adequate sustainability criteria?

The concept of biorefinery allows turning the biomass into many products: bioenergy, biochemicals, biofood and biomaterials, which total added value can be higher than the one generated by fossil fuels. Regarding the production scale, the small one has advantages, such as the decrease of product transportation (a considerable part of the inputs is generated in the agricultural exploitations, and the intermediate and final products are consumed in them); reduced recycling cycles, by utilizing the residues in these exploitations, as well as the integration of the energy flow, labor and organizational structure in the framework of the productive chain, among others. In this regard a question can arise: What about the advantages of scale economies? This is applied to manufacturing processes, but it does not occur that way in biological processes.

Likewise, in order to develop all the potential of agroenergy, the growth must be sustainably managed in order to fulfill the requisites of the economic, social and environmental requisites of sustainability. Concerning the most adequate sustainability criteria, this is a widely studied and discussed topic nowadays, in the scientific and academic sector, and in the NGOs linked to the environment, as well as in the organisms of the United Nations the work of PNUMA/UNEP stands out and it is considered that no solid conclusions have been reached yet; thus, this is an aspect that needs to be attended.

World political options regarding agroenergy

At present, the FAO (2008c) considers that there are three highly discussed political options associated to agroenergy. The first option is to continue as until now, with all the countries establishing the political frameworks, considering the international implications of the political decisions only when they are compatible to national priorities; this approach could start up some warrants for mitigating the negative effects of the increase of biofuels, by means of the agreement of national efforts, although it can not fully approach the issues with worldwide repercussions, such as negative impacts on food security and the environment. If such negative impacts continue increasing, it is possible that a lasting current of hostile public opinion against biofuels would emerge, which would eliminate a market with real potential for attaining the economic, environmental and social objectives.

The second political option is the «moratorium», which implies a temporary banning of biofuel production, worldwide and raw material-specific, in order to provide the necessary time for technologies to be conceived and regulation structures are introduced; this has been requested by the Special Rapporteur on the Right to Food of the UN, for five years, in order to prevent the negative environmental, social and human effects, and has recommended that measures are adopted during the moratorium to guarantee that biofuel production has positive consequences and respects the right to adequate feeding, as well as includes the reduction of energy consumption, energetic efficiency, immediate change to second generation technologies and protection of farmers who suffer food insecurity.

The FAO (2008c) considers that such world moratorium could not be sufficiently differentiated and, in fact, it would only allow postponing the necessary search for better technologies and adequate regulation solutions; it also states that the immediate and abrupt change to second generation biofuels could be little realistic, due to the lack of investment potential in almost all developing countries and to the lack of experience with this generation.

On the other hand, the moratorium could prevent or persuade some countries from participating in the global learning process associated to biofuels and cause investments to stop abruptly and thus make the interest in research and development disappear, and it would not represent a fair solution for the national and local complexities of the relation between bioenergy and food security. According to such organization, this option seems too rigid to utilize the dynamic advances and potentially positive effects for rural development, climate change and food security; besides, it would delay or prevent the necessary search for technological innovation and knowledge development.

The third option is to develop an international intergovernmental consensus about sustainable biofuels, which assumes that national political measures and consensus in the industrial sector are necessary, as well as giving responses to the challenges of climate change mitigation, biodiversity conservation and food security, related to the supply of world's environmental goods and services, which can not be guaranteed only in the national environment; likewise, an international agreed approach is advisable, because the biofuel demand is focused on developed countries and the supply potential is in developing countries.

In order to create an international consensus on sustainable biofuels respectful of food security, the governments could apply international instruments which are relevant for agroenergy, food security and sustainability, such as:

• The Framework Convention of the United Nations on Climate Change, of 1992, supports agroenergy, for considering it one of the «precaution measures to foresee, prevent or reduce to the minimum the causes of climate change and mitigate its adverse effects».

• The Kyoto Protocol, in 1997, acknowledges the importance of the contribution of renewable energy to the mitigation of the climate change. The clean development mechanism (MCD), which was established as a consequence of the Protocol, attempts to attract international financing relative to carbon and destine it to bioenergy projects, in order to help developing countries to achieve sustainable development and allow industrialized countries to fulfill their emission reduction objectives, to which they have committed.

• The Convention on Biological Diversity, in 1992, is relevant for the sustainable development of agroenergy, because its parties are committed to preserve biodiversity.

• The International Treaty on Plant Genetic Resources for Food and Agriculture aims at promoting the conservation and sustainable utilization of plant genetic resources for food and agriculture, as well as the fair and equitable distribution of the benefits derived from their utilization.

• The Convention to Combat Desertification, of 1992, forces the parties to the increase of land productivity, rehabilitation, conservation and sustainable utilization of land and water resources, to improve rural living conditions; and it also aims at the reduction of poverty and the participation of local communities.

• The General Agreement on Tariffs and Trade (GATT), of 1994, rules all trade, including the commerce of goods related to biofuels and forces the countries to promote a free commercial regime by decreasing taxes in each round of international commercial negotiations.

Which is the approach to follow with the utilization of integrated agroforestry systems?

Based on a holistic and systemic vision, the first aspect is to assume the need to adapt these systems to the available resources and utilize the comparative advantages of tropical crops, including trees and shrubs, criteria defended by Preston (2007), to promote a change towards smaller and more self-sustainable systems, in which the production of food, energy and construction materials is integrated, and achieve an increase of the resilience of agroecosystems.

Considering this approach, the consequences of food and raw material production for agroenergy in soil erosion depend, to a large extent, on the agricultural techniques used, especially, tillage practices, soil cover and crop rotation. In places where perennial basic materials are used for agroenergy production, instead of annual crops, the permanent cover and root formation, a well as direct planting, rotation, intercropping and diversification of food crops, help to improve soil management and reduce its erosion.

This adoption of good agricultural practices, according to FAO (2008c), can also reduce the threat to biodiversity, especially in the soil; in addition, wild habitats can be improved through the introduction of landscaping approaches in agricultural zones and the maintenance of ecological aisles, as well as through the sustainable utilization of biomass sources of high biodiversity as basic materials, for example, pasturelands.

The promotion of local systems of food and energy production, by means of the combination of basic material and crop productions and livestock feeding with the biomass that is not used for energy production or soil cover, can prevent losses and increase the general productivity of the food and energy generation system.

Biofuel production can be oriented towards sustainable local development, which favors the inclusion of small farmers, and in turn they are organized in cooperatives for processing and commercializing the bioenergetic raw material, as the addition of value to their products, in addition to maximizing the opportunities derived from agroenergy production and minimizing the risks of negatively affecting food security and the environment.

All this demands investing in research and technological innovation, fundamental aspect to achieve long term food and fuel security, which requires new and important investments in research and development programs, which can contribute to improve technical efficiency and determine the strategies and opportunities to face scarcity situations and adapt to climate change. For this purpose, the FAO (2008c; 2008d) considers that the objectives should be:

• Developing production and processing technologies that utilize local resources and with high utilization of raw materials.

• Improving the physical and economic efficiency of raw material production and the conversion processes of biofuels, even at small scale, to benefit small farmers through the self-consumption of clean energies.

• Obtaining a new generation of crops with high productivity and higher yields of utilizable energy per biomass volume, including those that provide raw material for biofuels to reduce pressure on soils -, as well as animals adapted to the foreseen changes in climate conditions.

• Identifying new technologies and practices for adaptation to the climate change in the agriculture, energy and transportation sectors.

• Utilizing efficiently residues for energy production.

• Making economic analyses that consider second generation biofuels in different sociocultural contexts

• Evaluating the production potential of second generation biofuels on marginal lands.

• Transferring technologies from and to other regions.

This is the approach ruling the International Project «Biomass as renewable energy source for Cuban rural areas» (BIOMAS-CUBA), supported by the Swiss Agency of Cooperation for Development (COSUDE) and led by the Experimental Station «Indio Hatuey». The general objective of such project aims at proving and communicating, through pilot experiences, local ecological alternatives for energy generation from biomass, which are economically, socially and environmentally effective, in order to improve the living conditions of women and men in rural areas of the country.

Such alternatives are associated to:

• The production and use of biogas from animal excreta, directly applied as fuel or transformed into electric energy, in the conservation of fruits, grains and seeds.

• Biodiesel production, generated from non-edible oil plants intercropped in agroforestry systems, to be used within the productive exploitations; as well as obtaining and utilizing coproducts of high value for animal feeding, biofertilizers and raw materials for other industries.

• Gasification of non-edible agroforestry and agricultural products.

• Production, at pilot scale, of bioethanol from lignocellulosic residues.

The authors consider that in the execution of projects and experiences on agroenergy at local scale in rural areas a group of key principles must be considered, which comprise: a) the utilization of local resources in integrated agroforestry systems which recycle residues; b) the destination of the biofuels obtained in the livestock production exploitations, from raw materials not committed to food, is food production, energy generation and improvement of the living conditions in farms and communities; c) tree plantations for biofuel production are intercropped with crops or pasturelands for producing food and providing diverse environmental services; d) the local shareholders must be the protagonists of solutions. All this has the main purpose of achieving energy sustainability and food security at local scale in rural areas, considering environmental protection.