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Abstract: This paper addresses the fundamental question of where hydrogen might fit into a global sustainable energy strategy for the 21st century that confronts the three-pronged challenge of irreversible climate change, uncertain oil supply, and rising pollution. We re-envision the role of hydrogen at national and international strategic levels, relying entirely on renewable energy and energy efficiency. It is suggested the time for an exclusive ‘hydrogen economy’ has passed, since electricity and batteries would be used extensively as well. Yet hydrogen would still play a crucial role: in road and rail vehicles requiring a range comparable to today’s petrol and diesel vehicles; in coastal and international shipping; in air transport; and for longer-term seasonal storage on electricity grids relying mainly on renewables. Hydrogen fuel cell vehicles are proposed where medium and long distance trips are required, with plug-in battery electric vehicles reserved for just short trips. A hierarchy of spatially-distributed hydrogen production, storage and distribution centers relying on local renewable energy sources and feedstocks would be created to limit the required hydrogen pipeline network to the main metropolitan areas and regions by complementary use of electricity as a major energy vector. Bulk hydrogen storage would provide the strategic energy reserve to guarantee national and global energy security in a world relying increasingly on renewable energy. It is recommended that this vision next be applied to specific countries by conducting detailed energy-economic-environmental modeling to quantify its net benefits. [Copyright &y& Elsevier]

Abstract: In this paper, different electricity demand scenarios for Spain are presented. Population, income per capita, energy intensity and the contribution of electricity to the total energy demand have been taken into account in the calculations. Technological role of different generation technologies, i.e. coal, nuclear, renewable, combined cycle (CC), combined heat and power (CHP) and carbon capture and storage (CCS), are examined in the form of scenarios up to 2050. Nine future scenarios corresponding to three electrical demands and three options for new capacity: minimum cost of electricity, minimum CO2 emissions and a criterion with a compromise between CO2 and cost (CO2-cost criterion) have been proposed. Calculations show reduction in CO2 emissions from 2020 to 2030, reaching a maximum CO2 emission reduction of 90% in 2050 in an efficiency scenario with CCS and renewables. The contribution of CCS from 2030 is important with percentage values of electricity production around 22–28% in 2050. The cost of electricity (COE) increases up to 25% in 2030, and then this value remains approximately constant or decreases slightly. [Copyright &y& Elsevier]