The oldest known traces of the physic nut tree date back 70 million years. That is the age experts assign to fossils discovered in the Peruvian Belen. Physic nut, or Jatropha curcas as it is known by its botanical name, has a natural distribution covering the neotropics from Mexico to Brazil and including the Caribian Islands. There this small tree has been valued for centuries as shade tree and living fence due to its resistance to damage by browsing animals. But perhaps it was more due to its medicinal properties as purgative and antiseptic that this Euphorbiaceae was so eargerly distributed in all the tropics by the earliest seafarers to reach the American continent. Whether it was Arab or Portuguese traders that introduced it to the old world cannot now be explained that it is now distributed througout the entire tropics of Africa and Asia as well.

Interestingly enough it are these new host countries that have been most eager to exploit the extraordinary features of this plant. Since the Germans experimented with physic nut oil as possible fuel substitute during the second world war, interest in the properties of curcas oil has never ceased. Self sufficiency in energy needs has been envisaged for rural villages in the arid North-East of Thailand and the World Bank has proposed village scale projects in the Indian state of Maharashtra. In Mali the German Technical Cooperation Agency GTZ is promoting the use of curcas oil as fuel for sorghum mills to benefit the local woman in rural areas.

But now it seems that the continent of origin of this multi-purpose tree species is once again taking the lead in the exploitation of its many beneficial properties. For the past five years intensive research has been conducted with the objective to improve the production and processing of curcas oil in Nicaragua.

The project concentrated initially on the energy production with biogas reactors installed on agroindustrial sites like slaughterhouses and the like. Soon interest arose in making use of alternative energy via the introduction of additional biomass into the gas reactors. The Austrian bilateral ODA supported the progamme and, through the cooperation of Austrian universities, introduced ample know-how on the production and extraction of vegetable oils as fuel, which have recently received much attention as one possible strategy to reduce the emmissions of so-called green house gases in industrialized countries. Thus experiences gained in the transesterification of rape oil was rapidly converted into research on the processing of curcas oil to methyl esther, a substance that can be used as diesel substitute in any diesel engine without the necessity of further modifications.

Little by little the initial idea to cultivate physic nut as additive to biogas changed into a scheme for the industrial production of biological fuel on a grand scale. The socioeconomic background of Nicaragua proved to be the ideal site for the first mayor physic nut industry.

Nicaragua is a small country on the Central American corridor uniting the northern and southern halves of this continent. Agriculture is the source of two thirds of its export income, but the continuous fall of raw material prices, particularly in the important sectors coffee and cotton, led to a decline in the output in the course of the eighties. Particularly cotton producing land in the semi-arid Pacific lowlands are left untilled; soil compactation and agrochemical residuals do not permit the cultivation of food crops on these areas. These problems were aggraveted by the results of the Sandinista revolution of 1979. Land reform led to a decapitalization of the agricultural sector, human capital was lost due to emigration and vast tracts of formerly productive land was left idle and without the necessary infrastructure for renewed production of cash crops for exportation. At the same time unemployment has reached sixty percent of the work force during the ensuing structural adjustment programmes enforced by the post-sandinista Government installed in 1992.

There are no known petroleum reserves in Nicaragua, and even the importation of crude oil is more expensive than in other countries due to the lack of adequate harbours for ocean going vessels and the decrepit internal transport infrastructure. Thus failling export income is acompanied by a steady rise in the expenditures of energy imports, which required 59% of export revenues in 1992.

The criteria for a cost effective curcas oil project, as defined by the World Bank, are fulfilled in Nicaragua: high transportation expenses, extensive wastelands unfit for agricultural production of food and cash crops, availability of labour for harvesting and processing and the need to offset hard currency expenditures on diesel imports. The economic feasiblity was proved by a study conducted by the national energy authority Petronic, basing the final price for « emat », the Spanish acronym for curcas oil methyl

ester, on the current import parity price for diesel.

Soon the Austrian Government approved the first step to this innovative enterprise, that should lead to profound changes in the Nicaraguan countryside. A revolving fund was initialized, which enabled agricultural collectives, that had been introduced by the former Sandinista Government in an effort to reform land tenure, to obtain credit for the establishment of physic nut plantations. The Austrian project, in cooperation with Petronic, provides technical and agricultural extension services on the management of this new crop. In April 1994 nurseries for the big scale production of physic nut seedlings were created, and in June of the same year the first 1000 hectares were planted with well over one million physic nut trees. What had been bare lands and thornscrubs were converted to perennial cultures.

Two different sources of seed material were used: a local variety characterised by big leaves that are completely deciduous during the dry season and produce an oblong fruit on a long peduncle, and a smaller leaved variety from the Cape Verde Islands, that produces roundish fruit with smaller seeds throughout the year. The trees are placed to follow the contours of the flat hills so as to reduce erosion and make the best use of the scarce water ressources in a region that receives between 1085 mm of rain per year in Managua and 1861 mm in Chinandega.

The first year already produced a small harvest of nearly 700 tons of physic nuts as this plant flowers and bears fruit within six months of its germination under Nicaraguan conditions. It will be from the fifth year onwards that the harvest will reach 33 tons per hectare, or 33,300 tons in total. This amount of fresh fruit will be processed by an agroindustrial complex that is due to be built with Austrian aid in the course of 1996. The treatment of the fruit beginns with the depulping which leaves the bare seeds. These can be dried and stored, or they may be fed immediately into the second step of the production line, which consists in the removal of the seed coat. The kernel is then heated and dried with steam and pressed. The resulting crude oil is filtered. The 33,300 tons of fresh fruit will yield approximately 5,000 tons of dry seed. From this approximately 1,600 tons of crude oil per year can be extracted. This is the raw material for the transesteri-fication. This process converts the triglycerids into methylester which helps to lower the oil’s viscosity and eliminates the risk of resulting carbon deposits in the engines. Otherwise these can be the cause of reduced engine life.

A continuous one-step process for the transersterification has been developed for this purpose. Methanol is mixed with the raw oil, and potassium hydroxyde is added as catalyst. After mixing a chemical exchange is completed and the oil separates into free glycerine and methyl and ethyl esters. The glycerine by-product, which is heavier than the esters, is drained from the bottom of the tank and the remaining traces of alcohol and potassim hydroxide are washed with water for purification of the methylester. 98% percent of the crude oil is thus transformed to a valuable fuel.

The processing plant will also be financed by a revolving fund, initially capitalized by the Austrian Government. It will be jointly managed by the agricultural producers,

represented by the Union of Agricultural Cooperatives (UNAG) and Petronic. Whereas the UNAG will be in charge of the cultivation of the physic nut, Petronic has the overall control and will see to the marketing of the final product. This will be accomplished through their own group of petrol stations, where the curcas oil methyl ester will be sold as a mix with conventional diesel. The first 1000 hectares of physic nut plantations alone will cover 0.3% of the national diesel market. As the producers repay their debts into the revolving fund both the area planted with physic nut and the output will increase. New work opportunities will be created at a rate of 840 temporary and 45 permanent jobs per 1000 hectares added. Macroeconomic gains are obtained by the import

substitution and the resulting improvement of the balance of payemnet. The local environement benefits by the establishment of perennial crops, that reduce soil erosion and require little agrochemical inputs, as well as by the reduction of toxic emissions during the combustion of curcas oil methyl esther, which is practically free of sulphureous coumpounds. The substitution of fossil fuels with sustainably produced plant oils leads to a reduction of greenhouse gas emissions that threaten the global climate.

The installation of the processing plant and thus the introduction of vegetable fuel based on curcas oil is well under way in Nicacaragua. Meanwhile research and development activities continue around the globe. Nicaraguan and Mexican universities are working hard on the improvement of agricultural practices and on the installation of gen banks to preserve different varieties of Jatropha curcas from all over the

world. Plant breeding experts in Germany are improving the seed material used for the establishment of plantations, increasing the yield and improving the adaptation to environmental conditions. The chemical components of curcas oil are analyzed in Austrian laboratories to detect pharmaceutical and technical

uses of new substances. Technologies are being developed for both the detoxification of the oil, so that it can be used in the food industries, as well as the residual oil cake, which is a protein rich feed for cattle, fish and poultry. There seem to be no end of this oldest of Euphorbiaceaes, that began its symbiosis with man as simple shade tree and living fence.