Economy & Energy
Ano XII-No 66
February - March
ISSN 1518-2932


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Convergence of Agriculture and Energy:

I.Celullosic Biomass Production for Biofuels and Electricity

Hydrogen and Fuel Cells

CO2 Emissões from Fuel Combustion

Comparison between the IEA Values and those of e&e/MCT

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O Crepúsculo do Petróleo
Mauro F. P. Porto


Convergence of Agriculture and Energy:

I.Celullosic Biomass Production for
Biofuels and Electricity

Claudinei Andreoli[1]


Demand for biofuel feedstock will dramatically increase the amount of crop dry matter required to satisfy both its traditional use and new demand. Simply adjusting the allocation of crop biomass among competing demands will not accommodate enough feedstock to achieve renewable goals. A new energy strategy must include maximizing the capture and use of light and CO2 available on arable land and then increase the efficiency of input use of dry matter. Effective policies and educational efforts will stimulate rapid adoption of current agronomic technologies to expand the productivity and efficient input use. In order to advance agro-ecosystem production beyond that achievable with existing practices, new knowledge, new systems, and new genetic resources must be created, and incentives for continued discovery must be provided.


biofuels, biomass, genetic resources, petrol, energy.


The decrease of petroleum supply and the concerns regarding global warming have generated a new world panorama regarding energy demand. The substitution of the fossil energy system for new economical and environmental sustainable strategies is growing especially in what regards the more expensive traditional energy sources. Several government agencies and working groups have been planning the decrease of fossil fuels consumption in the short term and substituting them for renewable energy (BUSH, 2007; FOUST et al., 2007; PERLACK et al., 2005; SMITH et al., 2004). The alignment and continuity of these goals are illustrated in Figure 1.

 Biomass Production (million tons)



Figure 1. All studies have concluded that the biomass quantity necessary for reaching the biofuel goals are much larger than the present biomass quantity harvested for energy production.

 The present biofuel production in Brazil and in the Unites States is based respectively on conversion of sugarcane and corn to ethanol However, the production of ethanol and of other biofuels is expanding more intensely than the production of raw material grains.

The Bush Administration has defined a frame of recommended technologies, processes and practices for the production of energy from biomass that aims at improving the conversion rate and more efficient use of energy. The plan has also committed that a significant portion of energy supply to the country in 2017, especially transport fuel, will come from the conversion of biomass to liquid fuel. Considering only the contribution of biomass fuels, approximately 250 million tons of grains and cellulosic biomass per year will be necessary to reach the 10-year goal and from 650 to 700 million tons/year, to reach the goal of 2025 (Figure 1). In order to satisfy this goal with anhydrous ethanol from sugarcane, Brazil would have to increase tenfold the sugarcane plantation area in the next 10 years.

Ethanol from sugarcane in Brazil and from corn in the United States was the first step for the introduction of renewable energy in the fuel system. The largest problems are the current impact on food prices, the planned production capacity and the availability of corn for traditional uses. Large scale biofuel production will demand much stronger raw material sources than corn and sugarcane and cellulosic ethanol will fill this gap (PERLACK et al., 2005). The large quantity of biomass necessary for achieving these goals (Figure 1) is not presently available. However, optimistic projections of some reports indicate a future production system that would satisfy the projected biomass demand (PERLACK et al., 2005, SMITH et al., 2004). In fact, the production, harvesting and processing of cellulosic biomass should be sustainable and lucrative for biomass producers and for refineries so that projections become a reality.

 Development, supply and biomass conversion systems, genetic improvement and agricultural handling practices should be improved in order to cope with the challenge of an agricultural system that produces food, fodder, fibers and fuel. The difficulties of the emerging cellulosic ethanol industry are the inefficiencies associated with the practices of raw material production, market and logistic system and the conversion processes (ANDREOLI e SOUZA, 2007). If the biofuel technology is not mature in all aspects, from production to distribution, it will be partially capable of accommodating the price increase of commodities caused by the effects of supply and demand.

 Regarding gasoline and corn ethanol that are mature technologies, the cost of raw material represents 50% of the production cost (EIA, 2006; SHAPOURI e GALLANGHER, 2004). In the case of sugarcane in São Paulo state, raw material represents 60% of ethanol costs. Since the biofuel technology is just starting, commercial cellulosic refineries have consumed only 40% of costs in order to produce one gallon of ethanol from biomass (FOUST et al., 2007). The limiting bottlenecks are still more problematic because the industry depends not only on new conversion technologies but also on the new raw material and on the delivery, harvesting, transport and processing system. Presently, the estimated cost for producing and delivering large quantities of cellulosic biomass for ethanol production exceeds in 40% the estimated cost of ethanol production (KUMARA and SOKHANSANJ, 2007). Cost reduction regarding raw material, production and logistic technologies and cellulosic conversion associated with its industrial development could make biofuels more competitive. However, in the medium term political and regulatory solutions are necessary so that the production of cellulosic biomass ethanol becomes the largest component of the transport energy matrix.

  Sugarcane and Corn Cellulosic Ethanol

 The estimate of the Brazilian sugarcane production is 475.07 million tons of which 47% (223.48 million tons) are for sugar production and 53% (251.59 million tons) are for alcohol production (CONAB, 2007). Of the national sugarcane production, São Paulo has used 58.55% (278.18 million tons) with a total alcohol production of 12,144 million liters. The productivity was 86.7 tons per ha and the average industrial yield was 84 liters per ton (CONAB, 2007).

One hectare of sugarcane produces in an economical and ecological friendly way about 7,500 liters of ethanol; in the United States, in spite of strong criticisms, corn produces 3,000 liters of ethanol and 3,000 kg of animal fodder (DDGS). For the industrial processes of ethanol and sugar production, the plants use from 85 to 87% of bagasse and it remains only 13 to 15% for energy cogeneration or for ethanol production. One ton of sugarcane produces on the average 84 liters of ethanol and 250 kg of bagasse with 50% if humidity (125 kg of dry matter). Considering a yield of 200 liters of ethanol (cellulosic) per ton of sugarcane bagasse, one ton of sugarcane would add only 3.75 liters of ethanol (125 x 0,15 x 0,20). Therefore, one hectare of sugarcane in São Paulo state, that produced on the average in the 2007 crop 84 tons, would produce additional 315 liters of cellulosic ethanol per hectare (ANDREOLI, 2007: data not published). If fossil energy would be used for ethanol production in Brazil, as the Americans do for corn ethanol, sugarcane ethanol would also be economically and environmentally unviable.

The same reasoning is also valid for corn biomass. If we consider a productivity of 8,800 kg of grains per hectare and a production of 5,000 kg of dry matter per hectare and leaving behind 75% of straw on the soil for organic carbon recycling, about 3,250 liters of grain ethanol would be produced and only 250 liters of biomass ethanol per hectare. In order to satisfy the American projection of 36 billion gallons (136 billion liters) in 2020 it would be necessary to cultivate and harvest 40 million hectares of corn (planted area in 2007). This is the reason of the American government rush to look for new alternatives of cellulosic biomass.

 Cellulosic Biomass for Electric Energy Production

 Brazil has structured its electric sector with peculiar characteristics relative to other countries. Hydroelectricity is predominant in its energy matrix that guarantees clean, renewable and cheaper energy (Table 1). Generation from sugarcane bagasse biomass corresponds to 2,720 MW, 2.6% of the total energy matrix.

Some studies such as the ENTREPRENEURIAL ENERGY COUNCIL (2006), TRANSPARENT ENERGY PROGRAM (2006) and DELFIM NETO (2007) have insistently indicated the possibility of a new supply crisis or rationing similar to the 2001-02 Blackout Crisis. Supply has no been growing in the desired and necessary pace for GDP growth, 4,000 MW annually on the average (CASTRO and BUENO, 2007).

One of the solutions for reducing the energy crisis is energy generation using cellulosic biomass. It seems that the government has decided to bet on the potential of the sector and the Ministry of Mines and Energy has published in December the Administrative Rule nº 331 that establishes for April 15, 2008 the date of the first auction exclusively for biomass energy buying and selling, to be produced in 2010. Even so, the government will not satisfy the demand of 4,000 MW annually.

 Energy Cogeneration from
 Sugarcane Bagasse and Nappier Grass

 In the 2007 harvest, sugarcane production for alcohol and sugar production was 475 million tons (CONAB, 2007). Assuming that one ton of sugarcane produces 250 kg of bagasse with 50% of humidity (125 kg of dry matter) and one kg of dry bagasse releases 20MJ then one has 2,500 MJ/t. Assuming as well a 15% share of bagasse for energy cogeneration and 33% thermal efficiency, then one ton of sugarcane will generate 35 kWh. This means that one hectare of sugarcane will produce on the average 3034 kWk= 3.0 MWh in the state of São Paulo.

 Table 1. Brazilian Energy Matrix – May 2007 (№ of plants, MW and %)1.


Installed Capacity



Nº of Plants























Mineral Coal
















1 Source: CASTRO and BUENO, 2007.

Therefore, to satisfy the additional annual electric energy demand of 4,000 MW, the sugarcane-alcohol sector will have to produce and harvest approximately 4.8 million hectares (400 million tons of sugarcane), that is almost all plants should operate in energy cogeneration. The medium and long term actions described in Table 2 used as a manual for biofuel production could also be used in the electric energy cogeneration using biomass. In order to reach this goal the government agencies must urgently decide who will invest in the transmission and distribution networks. The industry is certainly ready to face the energy challenge in the next decade with efficiency and competitiveness.

Another dormant energy potential is Nappier grass (Penissetum purpureum Schum), a C4 tropical plant from Africa of the Poaceae family with a high capacity of converting solar into chemical energy. With low use of input and investments, one hectare of this grass can produce from 20 to 25 tons of dry matter (DM), generate 450 GJ/ha, the equivalent of 42 MWh/ha. The net energy balance of the Nappier grass is much higher than those of sugarcane and corn. The small electric power plants close to the urban centers could immediately use Nappier grass biomass for electric energy generation. Perhaps the public organs have no perception and policies and there are no actions concerning the development of production culture and logistic, harvesting and transport. Scarce public and private resources have been assigned for researching this energy plant.

 Research, Development and Policies for Reaching the Goals

In order to reach the future energy goals, new and large investments in research and development (R&D) will be necessary, as well as governmental policies to overcome the ideological, technical and economical difficulties.

Table 2 shows the R&D, political and educational actions necessary for reaching the immediate goals in the next 10 years (230 million tons of biomass/year) and in the future in the next 20 years (700 million tons). The actions were focused on different areas and ranked in immediate (within 10 years) and continued (long-term goals, 2030).

Table 2. Immediate and continued actions necessary for cultivating, harvesting and delivering the quantity of biomass necessary for producing ethanol within the goals.





(within 10 years –
230 million t)


(next 20 years –
700 million t)




Produce regional and state inventories of the present and projected cellulosic raw material.

Expand the national survey of cultures to include biomass.

Expand data survey to include geo-spatial reports and mathematical models for biomass anticipation



Produce manuals of sustainable procedures for removing agriculture residues without breaking agronomical and environmental practices.

Develop agricultural systems for reducing biomass cost.

Large increase of investment in R&D for developing systems that maximize sustainable biomass production.

Integrate the energy and strategic handling cultures in the present system.

Develop agricultural systems to increase carbon sequestration and improve the energy balance.

Develop conservation programs and norms that accommodate and stimulate the production of cellulosic biomass. 

Improvement of


Improve existing plants and develop new ones with higher biomass yield and higher conversion efficiency.

Investment in germoplasm development and in biotechnology.

Develop plants with higher photosynthesis and energy capacity and higher abiotic resistance.

Implement policies and programs that facilitate the introduction and use of new cellulosic cultures.

Logistic and Supply of Raw Material

Develop production engineering technology for reducing 25% of ethanol production total cost.

Implement financing and regulatory programs that stimulate more efficient logistic systems.

Develop a common raw material supply system for cellulosic biomass for geographic regions and for conversion technologies.




Develop educational programs for training the manpower necessary for bio-economy.

Create educational programs for advance public knowledge of the new bio-economy and the energy conservation policies.


Focus I: Validation of Natural Resources

 The validation of estimates in “Billion Tons View” (PERLACK et al., 2005) ? has been discussed in the literature (LAL and PIMENTEL, 2007) but these estimates should be checked and regionalized. The biofuel industry will need realistic and reliable present and future evaluations including supply stability. These evaluations should be regional or state-wise besides the national survey of all cultures with potential yield of biomass. The reliable biomass inventories will help the agribusiness as well as public policies regarding planning for the development of biomass fuel.

 Focus II. Agronomic Systems

 Research is necessary for identifying the different sustainable systems for biomass production. These production practices should maintain or increase the soil fertility, productivity, the soil’s organic carbon (SOC) and should also control the soil erosion. In order to become a viable biomass source this production method should also have high productivity and high efficiency regarding input use.

The agriculture systems will be situated in loco and will try to maximize the efficient use of inputs (light, water, CO2, nutrients and pesticides) that are more adequate for each site. The key to develop these systems will be the creation of an experimentation network for the main eco-regional systems. The main necessary research investments are: i) information and data base that will guide local practices aiming at increasing yields and soil’s organic carbon (SOC) and erosion control; ii) the use of harvesting systems that will permit biomass collecting at appropriate levels in sites with different characteristics.

 Focus III. Culture Development

 Even though progress has been made by adapting the existing cultures and cultivars to sustainable production systems, higher gains for the production of biomass and ethanol in quantities to satisfy the goals in the next 10 and 20 years (Figure 1) will demand cultivars specifically developed for these purposes. No matter which one, the new plants identified for biomass production should have small or zero possibility of becoming invading plants (CAST, 2007).

Due to the fact that the dedicated work of the “improvers” in the last 50 years has been focused on yield gains regarding grains and oils of commodities such as corn and soybean, there are few studies concerning the improvement and development of energy biomass plants. For example, in spite of the fact that the USDA has highlighted switchgrass (Panicum spp. L.) in the United States while in Brazil the Nappier grass (Penissetum pupureum L) has been indicated as prominent biomass raw materials, these species have little attention from the scientific community because of lack of resources. 

The improvement of plants is a long-term undertaking, from 12 to 15 years, for launching a new variety or hybrid plant in the market. However, the increase of knowledge regarding genetics, biochemistry and physiology of specific characters, combined with molecular biology tools, have the potential to accelerate the improvement processes. Development of new biomass for biofuel production is necessary for building scientific specialist trained in plant genetics, physiology, genomics and production system improvement for these new and evolutionary energy plants.

 Focus IV. Raw Material Supply Logistic

 The harvest, loading and transportation logistic involves steps that start at collecting the biomass from the soil and ends at the bio-refinery. In collective terms, these pre-processing activities represent one of the biggest challenges to the success of the industry. Even though the production costs depend on various factors, biomass production and logistic represent from 35 to 65% of the total cellulosic ethanol cost and the logistic operations can consume from 50 to 75% of these costs. If the logistic costs exceed 25% of the total production costs of cellulosic ethanol there is a small margin in the system for the biomass producers and the industry.

The logistic costs vary from region to region depending on the climate, transport system, loading limit, type of biomass, drying and storage. Improvements in the biomass density and circulation are crucial for optimizing the harvesting and transport handling, decrease the fossil fuel expenses, standardize the biomass forms and maximize inputs in the system of biomass ethanol production.

 Focus V. Education and Extension

 The public needs information for evaluating the costs and benefits associated with the transition from energy based on petroleum to a biofuel economy. Extension and educational programs for the different cultivates and practices for biofuel production and harvesting will be an essential component of the renewable energy future. Educational programs should encompass all aspects of bioenergy including the “Energy x Food“dilemma, environmental questions and life-cycle of net energy savings. Furthermore, the public should be alert for the different transport fuels as well as the need of energy conservation as an essential component for the success of a national energy strategy.

An energy economy based on biofuel will demand a trained and qualified task force relative to the plants harvesting and transport processes designed for converting biomass into ethanol. Trained and qualified scientists and engineers in multidisciplinary fields will be necessary for expanding raw material supply and satisfy the 2030 goals. Foment and public support for research in these areas should be added. As new cultures and agricultural systems will be developed, the Ematers and the extension programs should receive training for educating rural producers and the production chain of the new biofuels.


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[1] Agronomy Engineer, Researcher, Embrapa Soja, Caixa Postal 231, Londrina, PR – CEP 86.001-970.


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