Climate Change and Energy Perspectives: Toward a Carbon-Free Energy System
by Jean Louis Bobin, Université Pierre et Marie Curie, and Lucien Deschamps, Association of Major Programs and Projects for the 21st Century
Since the beginning of our world, the development of the human societies has been driven by multiple sources of abundant and cheap energy. However, because fossil fuels exist in finite amounts under the Earth’s crust, their constant use has resulted in a dramatic rise of greenhouse gas concentrations, thus necessitating an energy transition. Hopefully, such a transition will be achieved by the second half of the 21st century. Here we review the present situation and current trends. The potential of energy technologies, among them renewable and nuclear sources, are presented, and proposed paths toward a carbon-free energy system are discussed.
From Holocene to Anthropocene
The present interglacial period is called “Holocene.” It has prevailed for the past 10,000 years. Meanwhile, humankind conquered our plants. Humans settled in every place offering resources and mild climates. They built up their environment via land use change, housing, transportation, energy, and communication networks. Unknown spots in terrestrial land no longer exist and seas were navigated all over. Space travel is now a reality although few individuals are experiencing it: some 40 years ago, a few astronauts walked on the Moon; since 1998, the permanently staffed International Space Station is orbiting the Earth.
Changes in the atmospheric composition are among the most spectacular environmental impacts of human acuities. Exhibiting a continuous growth for the last 200 years, the concentrations of greenhouse gases (GHG) increased tremendously. This is mainly due to the energy system in the developed and developing countries. Indeed, 80% of energy sources worldwide are fossil fuels: coal, oil, and gas – whose combustion releases GHG, mainly CO2 that accumulate in the atmosphere. According to most climatologists, a global warming might follow.
Most primary energy is heat, a large fraction of which is lost. For several reasons, this “thermal civilization” is not sustainable. Human population is expected to grow from the present 7 billion up to 9 billion by 2050. Highly populated countries like Brazil, China, India, and others are developing at a high rate. Consequently, energy demand is rapidly increasing. Our industrial societies are thus facing a number of questions:
- Although known reserves cannot match future demand, are there any further fossil resources to be discovered? Are fuel shortages looming?
- How, without fossil fuels, can societies fulfill an ever-increasing energy demand?
- Which technologies can be substituted for obsolete ones?
- Will humankind be able to mitigate environmental and human negative impacts of technologies, old and new?
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