Energy economics is a broad scientific subject area which includes topics related to supply and use of energy in societies.[1] Due to diversity of issues and methods applied and shared with a number of academic disciplines, energy economics does not present itself as a self-contained academic discipline, but it is an applied subdiscipline of economics. From the list of main topics of economics, some relate strongly to energy economics:Computable general equilibriumEconometricsEnvironmental economicsFinanceIndustrial organizationInputoutput modelMicroeconomicsMacroeconomicsOperations researchResource economicsEnergy economics also draws heavily on results of energy engineering, geology, political sciences, ecology etc. Recent focus of energy economics includes the following issues:Climate change and climate policyDemand responseElasticity of supply and demand in energy marketEnergy and economic growthEnergy derivativesEnergy elasticityEnergy forecastingEnergy markets and electricity markets - liberalisation, (de- or re-) regulationEconomics of energy infrastructureEnergy policyEnvironmental policyRisk analysis and security of supplySustainabilityEnergy policy is the manner in which a given entity (often governmental) has decided to address issues of energy development including energy conversion, distribution and use. The attributes of energy policy may include legislation, international treaties, incentives to investment, guidelines for energy conservation, taxation and other public policy techniques. Energy is a core component of modern economies. A functioning economy requires not only labor and capital but also energy, for manufacturing processes, transportation, communication, agriculture, and more. Energy sources are measured in different physical units: liquid fuels in barrels or gallons, natural gas in cubic feet, coal in short tons, and electricity in kilowatts and kilowatthours.