Future of biodiesel? A look at the potential benefits of Jatropha

From 26-28 March 2007 the Dutch FACT Foundation organized an international seminar on the agronomy and genetics of Jatropha curcas, attracting experts from twenty-six different countries. Eize de Vries attended the meeting on behalf of Renewable Energy World and reports on the current status of Jatropha as a source biofuel, as well as the latest expert views on the challenges lying ahead.

The worldwide effort to find a sustainable and environmentally friendly alternative to today’s fossil fuel dominated energy supply has already resulted in a substantial and rapidly growing demand for biofuels. Prof. Bart Muys, Head of the World Agro-forestry Centre at the University of Leuven (Belgium), attributes the current hype (especially for tropical biofuel feedstocks) in Europe to several factors, including fears about energy security and climate change, ambitious new EU policies on renewable energy sources, binding Kyoto obligations, and the existence of support schemes such as tax exemption and subsidies for imported bio-energy. He also commented that the limited availability of agricultural land in Europe, and potentially higher crop yields and cheaper agricultural production in tropical countries, mean that there is potential for much feedstock to be imported. Across the developing world, several crops are now being examined to see if they are suitable for biofuels production.

Background to Jatropha

Jatropha curcas is a perennial, oil-seed bearing shrub originating from Central America, and which has now been introduced to other tropical regions in Africa and Asia. Unlike palm or soy, which are key edible cooking oils, Jatropha trees become poisonous within months of growth, meaning that the branches, leaves and seeds cannot be eaten by humans or animals. The net result of this is that Jatropha oil does not suffer from direct competition with food crops, as is the case with most other biofuels feedstocks. This is important, as edible oil prices are volatile and competition between food and fuel uses is pushing up prices, with potentially negative impacts on low-income consumers in the developing world.

Another of the claimed benefits of growing Jatropha is that it grows well on degraded agricultural land, and that the trees have a ‘built-in’ capacity to combat desertification by restoring vegetative cover. In addition, the plant is relatively drought resistant, although as will be discussed later this largely depends on the method of cultivation.

Jatropha seeds are inedible by humans or animals and as such will suffer less from competition with food sources d1 oils

When mature, Jatropha trees produce large quantities of seeds, which can be crushed to produce oil. This oil can be used directly as fuel in some older type diesel engines (like the Indian-made Lister engines based on a pre-war British design) or further processed by trans-esterification to produce biodiesel which can be used in modern engine. Although most modern diesel vehicles can run lower blends of biodiesel, some modifications are required for 100% use.

Degraded land

As has already been mentioned, one of the key perceived benefits of growing Jatropha as an energy crop is its ability to revitalize degraded farmland.

One of the greatest benefits of growing Jatropha is its ability to survive in dry conditions fact foundation

The term ‘degraded agricultural land’ refers to land which has lost its fertility, often related to non-sustainable and sometimes even destructive man-made land use activities. Effects of degradation include soil erosion, loss of the fertile topsoil layer, waterlogging due to soil compaction, soils becoming saline due to poor irrigation practice, etc. George Francis of the University of Hohenheim (Germany) estimates that in his home country of India 130 million hectares can be characterized as degraded agricultural land. Based on latest UN figures, the world’s combined degraded land loss amounts to 23% of all agricultural land available, with an annual increase estimated at 6-10 million hectares. The UN estimates the resulting economic loss at US$45 billion annually. However, in the worst affected developing countries in Africa and Asia land is becoming increasingly scarce leaving the poor farmers that suffer with no other alternative than to continue working in the low-yielding degraded fields with their families.

Leader in biofuels

For all these reasons, several developing nations have already begun to focus on cultivating Jatropha at a very large scale. According to Muys: ‘Some of these countries regard developing commercial Jatropha crop plantations as so promising that they envisage for themselves a future “OPEC nation” status as a biofuel exporter. Such objectives differ per individual pioneer country and include a desire to produce a cash crop with a high stable price – unlike coffee and cocoa, to become independent of oil imports, or to achieve a (more) positive import-export balance.’ In West Africa, for instance, Senegal is aiming at becoming one of the continent’s leaders in biofuel production. To this end, Senegal intends to plant 800 million Jatropha trees on 321,000 hectares of marginal lands before the end of 2008. However, some participants at the seminar criticized these plans as unrealistic, arguing that the limited time available for implementation, the extensive know-how base required, and the expected difficulties in finding all financial and other resources would cause problems.

Drought resistance

Another potential advantage of cultivating Jatropha is its relative drought resistance – it has a minimum requirement of 300 mm rainfall per annum to survive, and 600 mm needed to bear fruits. One of the reasons for this is that Jatropha trees grown by ‘natural’ generative plant propagation (from seeds) have a unique root architecture, comprising a thick central taproot and four laterals. According to Reinhard Henning of Bagani, a Germany based organization: ‘With this central taproot a tree can extract minerals from deep inside the soil like a “minerals pump”, which promotes soil fertilization recovery and faster plant growth. Secondly, when the taproot is simultaneously able to withdraw water from deeper soil layers this contributes to the tree’s drought resistance and a further increase in overall plant growth and seed production.’ In addition, the four lateral roots as a distinct Jatropha plant feature provide additional structure to the surrounding soil, which gives a positive contribution to the soil water storage capacity and soil erosion control.

Seeds emerging 120 days after planting in Indonesia fact foundation

In many developing countries small farmers use a technique called intercropping, whereby two or more different crops are cultivated together in the same field. The reasons behind this strategy are essentially risk spreading in the event of adverse weather, although crops can also benefit from plant shadowing effects, and ‘natural’ disease and pest control. A combination of certain selected food crops and Jatropha might have positive overall impacts on yields and farmer income, but such trials are still at an early stage of research and further work is needed. One of the issues which needs to be addressed is that plant propagation for large-scale cultivation is often conducted from tree cuttings (vegetative), as opposed to from seeds. Crucially, Jatropha trees grown in this way lack a central taproot, something which is essential for dry land conditions. Thus for arid regions, growing from seeds is preferable. In humid geographical regions with plenty of rainfall, such as in South East Asia, vegetative propagation by planting tree cuttings is regarded a well-suited method.

Yield potential

A distinct characteristic of individual free standing Jatropha trees is that they can grow to heights of 5-6 metres and develop multiple branches. Tree seed production increases in the first 3-8 years, depending on planting density, and then stabilizes. A full-grown solitary tree will have a leaf canopy capable of covering an area several metres wide.

Aside from solitary trees, Jatropha are often found in rural villages in the form of hedges around buildings or being used for other natural boundary protection purposes. In this case the trees are planted in a line with a typical internal spacing of 100-200 mm. Like any plant arrangement, a hedge has its own implications for the yield potential per hectare.

Intercropping is a common practice in many developing countries fact foundation

Jatropha as a species is also characterized by a high rate of light sensitivity in relation to plant growth. Optimal spacing or plant density is therefore crucial as individual trees compete for light, and also for water and minerals. Proper spacing is also essential with regard to vulnerability for pests and plant diseases. Total tree canopy leaf surface area, orientation, and spacing (plants/ha) are all key variables determining together the maximum yield potential through photosynthesis. In arid and semi-arid African regions a lack of water availability is most often the limiting growth factor, while in South-East Asian countries such as Indonesia weather can be cloudy during the rainy season, meaning that solar radiation could become the key limiting growth factor. Raymond Jongschaap, a researcher of the Wageningen University Plant Sciences Group (NL) demonstrated the crucial importance of sufficient water and nutrients for optimized plant growth by a picture slide example. First he showed a picture of a young plant with sufficient water available but short of nutrients: the plant did not grow at all. In a second picture the same plant was fed with sufficient nutrients but was this time short of water: here plant growth was meagre. In the third and final picture again the same plant was fed with both sufficient water and nutrients and grew over twice in height. Jongschaap concluded that each plant needs the right conditions to flourish, Jatropha curcas included.

Based on today’s knowledge, annual production levels of up to 8 tonnes of dried Jatropha seeds per hectare seem feasible under optimal growth conditions, however reported dry seed harvest levels are on average much lower and can vary greatly. Perhaps even more challenging is that the application of non-standardized local collection and processing methods in various countries and regions introduces variables that are hard to compare systematically and on a scientifically sound basis. In order to get superior comparable quantifiable data, the experts in Wageningen agreed on an information exchange and systematic data-collection scheme. As part of a first effort to collect scientifically usable data on Jatropha cultivation from different parts of the world, a detailed questionnaire has been developed by Wageningen University. Some of the key areas seminar participants agreed to look into together include Jatropha field mapping with regard to geographical position, orientation of slopes, tree spacing, tree dimensions, age of the trees, tree characteristics like number of branches, et cetera. In addition to standardize methods for systematic seed collection and seed drying, in order to be better able to compare yield levels per hectare. Again, based on today’s experience, the researchers agreed that – per mass unit of seeds – between 20%-40% of pure plant oil is extractable. This latter figure translates into 1600-3200 litres of pure Jatropha oil per hectare. Interestingly this oil contains no valuable nutrients as these remain behind in the seedcake. It is possible to produce biogas (CH4) from this seedcake to further optimize the Jatropha’s greenhouse gas (CHG) balance. This biogas can be burned in a combined heat and power (CHP) plant to generate electricity and heat while the leftover fermented seedcake (compost) still contains nearly all the minerals taken from the soil for seed production and plant growth upkeep. If this fertilizer is ploughed back into the soil, fertility is maintained.

Poverty alleviation

A special issue which the seminar focused on was the contribution Jatropha oil can make to combating poverty in poor countries – both by generating income and increasing the overall efficiency of rural and agricultural processes. The availability of ‘cost-free’ local plant oil in this respect also serves as an effective rural development tool that encourages electrification at rural village level. Such a basic community owned power plant comprises a diesel-generator set fuelled by Jatropha oil that generates electricity supplied to a locally built and maintained grid. And, as many studies on poverty alleviation have shown, the availability of electricity gives people the opportunity to do some additional work during evening and night hours and allows children to complete their homework for school.

A long way to go

The development of Jatropha curcas into a high-yielding and efficient new biofuel source is still at a relatively early stage. Small-scale production has commenced in a limited number of countries – including Mozambique, Tanzania and India – and the first results have already been evaluated. ‘So far progress on Jatropha was achieved by a careful step-by-step process approach’, says FACT Foundation Founder Prof. Kees Daey Ouwens. ‘Such care is required from an R&D perspective as well as the need to learn from experiences.’ He says that one of the key short to medium term research objectives is to search for superior species aimed at higher overall yield levels. This will be achieved through systematic seed selection from different regions and supported by a scientific seed-breeding programme. A second key area of attention is to refine tree propagation techniques for specific climates and a wide variety of environmental conditions.

Jatropha can yield 1600-3200 litres of pure Jatropha oil per hectare fact foundation

Kees Daey Ouwens: ‘Big corporations are increasingly eager to step into Jatropha production at a massive scale and in multiple countries and regions. FACT has recently had regular requests from many countries for Jatropha cultivation projects covering 100,000 hectares to over one million hectares. If the introduction of Jatropha starts to take place at such a huge scale without having the right instruments in place, results can prove very disappointing. If on the other hand the “big money” corporations can restrain themselves, chances for success will increase for everybody involved. Even more important for FACT is that a careful introduction of Jatropha does indeed and in the first place benefit the large number of small farmers and other peasants that live today in poor rural villages of Africa and Asia.’

Eize de Vries is a freelance journalist specialized in renewable energy sources and is the Wind Technology correspondent for Renewable Energy World
e-mail: rew@pennwell.com

Pure plant oil and biodiesel

At present, pure plant oil and biodiesel fuels mainly originate from rapeseed (i.e. Germany), soybeans (Brazil), sunflower seeds, and palm oil. In addition, technologies have become available that produce biodiesel from slaughterhouse waste like animal fat and other waste residues, with several companies producing biodiesel from ‘old disused’ frying fat or frying oil. The world’s two largest palm oil producers are Malaysia and Indonesia. Of the main crops, oil palm trees produce by far the highest annual yields: 4000-6000 litres/ha/year, as compared to about 1200 litres/ha for rapeseed and 800 litres/ha for sunflower oil. The reason for these huge yield differences is that oil palms grow in the tropics where the growth season is much longer compared to countries with a colder moderate climate. In addition oil palm is a perennial species. Once a tree has fully matured a large fraction of the total potential energy for plant growth through photosynthesis, is available for seed production. Annual crops by contrast need a substantial proportion of the total potential energy through photosynthesis for the development of the root system, stem, leaves and ovary. But while oil palm trees score high in terms of oil yield per hectare, the cultivation methods are criticized with claims being made of massive destruction of tropical rainforests to make room for plantations.

Other popular biofuels are available in the form of alcohols (i.e. ethanol and methanol). However, the large-scale conversion of maize and wheat into ethanol has already begun to drive up food prices. Opinion is also mixed with regard to claimed net environmental benefits of this food crop to alcohol conversion process compared to the direct use of fossil fuel based transport fuels. A promising second generation biofuels, will be largely derived from non-edible plant residues and other biological by-products. These new generation biofuels are claimed not to compete so heavily with food crops, while the energy balance based on a ‘dust-to-dust’ product life cycle (PLC) analysis is said to be much more favourable.

FACT Foundation

The FACT Foundation was established in 2005 by a team of experts led by Prof. Kees Daey Ouwens. The key objective is to promote biofuels in developing countries to the benefit of their local economies. FACT collects, analyses and disseminates knowledge and expertise on biofuel production, application and marketing. FACT also conducts R&D on agricultural as well as technical aspects of biofuels, and initiates rural development projects. FACT is situated at the campus of Eindhoven University of Technology; www.fact-fuels.org

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