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ment and private sectors. An outline of future energy policy for the food system as formulated by the 1977 Asilomar Conference in California should help students and future decision-makers understand the complexi ty of solutions. It is only one of many future policy recommendat ions that have been developed but it adequately serves an instructional purpose. The energy situation is ever changing and recommendat ions can be expected to change accordingly. The author recognizes this turmoil with the s tatement that the politics and economics of energy are much more volatile than the technical and engineering aspects -- and the technologies for alternatives to petroleum are continuously being altered.

Overall, the subject of the U.S. agricultural energy situation is accurately and clearly presented with unbiased discussions of various positions that have been posed by various pro and con special interest groups.

ROBERT G. YECK Shriver Laboratory, University of Maryland

College Park, MD 20742, U.S.A.

INTERACTING FUTURES OF ENERGY AND AGRICULTURE

Energy and Agriculture: Their Interacting Futures. Policy Implications of Global Models. M. L6vy and J.L. Robinson (Editors). Harwood Academic Publishers for the United Nations University, New York, NY, 1984. 370 pp., US$78.00. ISBN 3-7186-0187-7.

A symposium held in Paris on global models with a focus on the food- energy complex forms the basis of this book. Included are discussions about the food and energy problem and several perspectives on global modelling.

The symposium participants endeavored to find ways in which global models could be helpful in national and world policy making. " No govern- ment has used global models as instruments for decision making", as Dr. Herrera commented. There was agreement that the extreme complexi ty of most models made them difficult to comprehend. Dr. Hraborszky indicated that "quick, simple models answer 90% of a quest ion" and he might have added that simple models have a better chance of being used in policy mak- ing because they are understandable. With global models, encompassing all resources, the policy implications "may be buried in detail".

In one discussion about the use of models as related to development, Dr. Leach expressed the sound view that the "development process" at the "level of the village" should be the focus. Dr. Sachs further emphasized this when he pointed out that "ei ther development happens locally or there is no development at all".

In analyzing energy problems at the village level, the symposium group agreed that " the largest single world energy problem is the severe crisis of

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wood scarcity". Without wood as a fuel, communit ies may collapse. Wood in many communit ies is the only source of fuel for cooking food and heating homes. Already in some regions the people can only cook food once a day. Economists and modelers at times have referred to wood and dung as "free goods"; however, it was pointed out that " they are not free at all -- there are heavy costs in labor and otheI' efforts". In some areas women and children spend a large part of each day collecting and carrying f irewood back to their homes. Few can afford to pay the high price that fuelwood sells for today.

This difference in viewpoint among modelers and other scientists re- emphasized the need for interdisciplinary efforts in modelling, especially that for decision-making. The decision-maker is concerned with helping the many social groups that he is involved with, whereas the modeler most often is concerned with the structure of the model.

This deficiency was also apparent in the optimistic data presented on the conversion efficiency of feed stocks into alcohol. For example, the reported conversion efficiency of sugar-bearing crops and starchy crops was 77% and 55%, respectively. These percentages are exceptionally high when it is known that about 70 000 BTU or 73.8 MJ (not including the energy inputs used to grow the crops) are expended during the fermentation/disti l lation process for one gallon (19.5 MJ per l) of ethanol that has the energy potential of only 76 000 BTU or 80.2 MJ. Thus, if the high conversion factors were used. in a model, the results would be misleading.

Also in the discussions of biogas conversions, the conversion efficiencies were unrealistically high. Furthermore, it was suggested that the methane gas produced from the small digestors could be used to produce nitrogen fer- tilizer. Unfortunately, this is impossible because there is no efficient way to collect and transport the small amounts of biogas to a central plant pro- ducing nitrogen fertilizer. The impracticality of this suggestion was not considered. Again, this emphasized the need for accurate data, careful anal- yses, and simple models so that sound information produced will be useful for policy makers.

Despite some deficiencies in data and modeling proposals, much valuable information was presented on the energy/agriculture nexus and the role of global modeling. The leaders of the symposium are to be complimented for organizing this symposium and their selection of speakers and topics. One would hope that future symposia would be planned as this important sharing of ideas continues. The book is recommended to all those who are interested in understanding the complex relationships that exist among the essential land, water and biological resources of agriculture and energy and world society.

DAVID PIMENTEL Department of Entomology, Cornell University

Ithaca, N Y 14853, U.S.A.