Environment

17 Oct Energy Vectors

National Academy of Technologies of France (NATF)
2015

Changes in energy procurement/uses have often followed differing ‘trajectories’ in different countries while being related by factors such as oil prices and climate change.  While these forces are still active, time-scales have shifted (e.g. for peak oil and gas). The Fukushima accident has recently shaken confidence into nuclear power. This Report proposes a robust methodology helping in situations of energy transition to make relevant choices on both economic and ecological levels. Focussing on the French situation, it defines Energy Vectors as the support system delivering energy in the form of electricity, petrol, gas, or heat, etc. to consumers and deals with the intermediary stage of vectors between energy sources (coal, gas, U, wind, hydro) and demand of final energy (for transport, heating, industrial processes, etc.). But end-consumers are often not aware of the source for the final energy they receive. Distinguishing between sources would allow economic and ecological competition (when C02 emissions carry a price-tag).  This report throws new light on the political decisions that must be taken and provides guidelines with a long-range relevance - the parametric structure allowing application to any given case. Group Leader: Gilbert Ruelle, Former Director of the Alstom Division Alternators, Honorary President of CREEBEL, and NATF Fellow

17 Oct Methane

National Academy of Technologies of France (NATF)
2016

Strong variations of atmospheric concentrations of methane, a potent greenhouse gas, have accompanied glacial and interglacial periods. Such variations influence the timetable and magnitude of climate changes. The report describes and analyses natural and human-related sources and sinks of atmospheric methane with particular attention to potentially massive emissions from thawing permafrost in Arctic wetlands and marine methane hydrates (clathrates). The methane fluxes between main reservoirs and the atmosphere is measured via ground-based networks or from outer space, allowing a better understanding of evolving atmospheric concentrations and interaction between sinks and sources. As atmospheric methane is destroyed over time (half-life ~7 years), its CO2 equivalence, in terms of GHG-efficiency is not straight-forward, depending on the time-scale applied.  While increasing fossil fuel exploitation is an important methane source, emissions could be limited at reasonable cost.  Feedbacks from wetlands and soils are more difficult to control. A number of recommendations on how to limit methane release are made in areas such as agricultural practices, waste- and landfill management, biomass combustion, exploitation of coal, natural gas and oil. Carefully follow developments in boreal zones, especially regarding the possible exploitation of methane from permafrost and marine clathrates. Group Leader: Jean-Claude André, Former Director of the European Centre for Research and Advanced Training in Scientific Computing (CERFACS), and NATF Fellow

17 Oct Biogas

National Academy of Technologies of France (NATF)
2016

The 14 members of the NATF working group on biogas published its report in early 2016.  Historically speaking, biogas, resulting from the decomposition of organic matter, has been known since the late 18th century, when Alessandro Volta analysed the composition of swamp gas, finding methane as the main component.  In France and India, the exploitation of this process through bacterial “fermentation” in digesters started in the late 19th century while China builds a whole infrastructure around biogas, but always on a local scale, taking advantage of carbon credits from European industry for their funding.  In Europe, the production of biogas on an industrial scale takes off somewhere between 1980 and 1990, while France joins in at a somewhat slower pace than some other countries