Pradeep J. Tharakan

Hydrocarbons and the evolution of human culture

Most of the progress in human culture has required the exploitation of energy resources. About 100 years ago, the major source of energy shifted from recent solar to fossil hydrocarbons, including liquid and gaseous petroleum. Technology has generally led to a greater use of hydrocarbon fuels for most human activities, making civilization vulnerable to decreases in supply. At this time our knowledge is not sufficient for us to choose between the different estimates of, for example, resources of conventional oil.

Growing fuel: a sustainability assessment of willow biomass crops

2to the atmosphere. The implementation of good management practices will maintain productivity over multiple rotations. Rural development and environmental benefits associated with deployment and use will accrue to the local community because of the willow system’s short supply chain. The economic valuation of these benefits are necessary for the deployment of woody crops, which in turn can help society become more sustainable.

Energy feedstock characteristics of willow and hybrid poplar clones at harvest age

Abstract Woody biomass feedstock produced from willow and hybrid poplar can be converted into bioenergy via thermochemical and biochemical processes. Variation in key properties that relate to the quality of biomass feedstock and determine its value for energy conversion were determined at rotation age (3 years), in 30 willow and seven hybrid poplar clones, grown in a short-rotation intensive culture (SRIC) system in central NY. Substantial clonal variation in the concentrations of nitrogen (2.9– 5.0 g kg −1 ), phosphorus (0.4– 0.8 g kg −1 ) potassium (1.2– 2.4 g kg −1 ), sodium (0.09– 0.20 g kg −1 ), calcium (3.9– 8.9 g kg −1 ), magnesium (0.2– 0.6 g kg −1 ), ash (13.2– 27.2 g kg −1 ) and bark percentage (3.6–8.1%) was found in stem (bark+wood) samples. A lower amount of variation was documented for specific gravity (0.33– 0.48 g cm −3 ) and percent moisture (49–56%). Bark had a higher concentration of inorganic elements and ash, relative to wood. Willow clones as a group had a higher specific gravity, bark percentage and calcium concentration relative to hybrid poplar clones, which had a higher potassium concentration. The two groups were similar in terms of the concentrations of other elements and ash. Clonal variation in these characteristics present opportunities for manipulating feedstock quality through selection, breeding and plantation management.

Multivariate approach for integrated evaluation of clonal biomass production potential

Abstract Evaluating the performance of clones to be used in short rotation intensive culture (SRIC) plantations for biomass production is critical for identifying superior clones and matching them with sites on which they will perform best. This will lead to increased production and a strengthening of the commercial prospects of these plantations. The primary objective of this study was to use a multivariate approach to evaluate the relative clonal performance of 38 willow and hybrid poplar clones, deployed in a genetic selection trial based on a coppice rotation system established in central New York State (NY) in 1997. Cluster analysis was conducted using survival, several individual plant growth attributes, and insect defoliation, all measured during or at the end of 1998. Two linear functions developed using discriminant analysis, comprising primarily of attributes related to tree vigor and site adaptability; tree volume index and length of growing period, explained most of the variation (98.5%) among the clusters. Eight of the 38 clones evaluated are expected to be high biomass producers, and are recommended for more extensive clone-site trials and commercial scale plantations across central NY and the northeastern United States (US). The results of this study indicate a possible approach to more effective juvenile selection in tree improvement programs, and insights for a refinement of the current SRIC tree ideotype.

Twenty five years of industrial development: a study of resource use rates and macro-efficiency indicators for five Asian countries

Abstract Economic and population growth in Asia over the last three decades has been unprecedented. While conventional economic indicators have been increasing consistently, indicators of resource and environmental quality have been deteriorating, raising questions about the implications of future growth. Economic growth in the future is considered to be contingent on ensuring a more efficient use of natural resources, while simultaneously striving to reduce environmental impacts. We examine time trends of three efficiency indicators; agricultural efficiency, energy efficiency of economic production and carbon efficiency of energy use, for the five most populous countries in Asia in order to assess whether industrial development has lead to increased resource use efficiency and an associated reduction in total resource use and environmental impacts. Our results indicate that agricultural efficiency has decreased in all five countries. Results are mixed for energy and carbon efficiencies. Where increases in energy and carbon efficiency have occurred, they have been completely overwhelmed by absolute increases in energy use and carbon emissions caused by increases in the scale of economic activity. Based on this analysis, we study the potential for further improvements and policy implications for future food supply, energy consumption and carbon emissions in the region.

erratum: Hydrocarbons and the evolution of human culture

This corrects the article DOI: nature02130