Aggregation of Energy

Divisia index A method of aggregation used in economics that permits variable substitution among material types without imposing a priori restrictions on the degree of substitution. emergy The quantity of solar energy used directly and indirectly to produce a natural resource, good, or service. energy quality The relative economic usefulness per heat equivalent unit of different fuels and electricity. energy/real gross domestic product (GDP) ratio (E/GDP ratio) The ratio of total energy use to total economic activity; a common measure of macroeconomic energy efficiency. energy return on investment (EROI) The ratio of energy delivered to energy costs. exergy The useful work obtainable from an energy source or material is based on the chemical energy embodied in the material or energy based on its physical organization relative to a reference state. Exergy measures the degree to which a material is organized relative to a random assemblage of material found at an average concentration in the crust, ocean, or atmosphere. Granger causality A statistical procedure that tests whether (i) one variable in a relation can be meaningfully described as a dependent variable and the other variable as an independent variable, (ii) the relation is bidirectional, or (ii) no meaningful relation exists. This is usually done by testing whether lagged values of one of the variables add significant explanatory power to a model that already includes lagged values of the dependent variable and perhaps also lagged values of other variables. marginal product of energy The value marginal product of a fuel in production is the marginal increase in the quantity of a good or service produced by the use of one additional heat unit of fuel multiplied by the price of that good or service. net energy analysis Technique that compares the quantity of energy delivered to society by an energy system to the energy used directly and indirectly in the delivery process.