Energy and Environment Encyclopedias Articles

Natural gas is widely promoted in energy transition projects as the "least polluting fossil fuel". This article looks at the various technical and economic elements of this sector, from production to end use, but also at its environmental impacts.

The evolution of climate change and its consequences is often summarised as the average temperature of the Earth with future scenarios ranging from +1.5°C, the objective of the Paris Agreement, up to +7°C. However, as climate sceptics often point out, this is not always what is observed on one's personal thermometer. So what exactly does this global temperature represent? How is it calculated and how can its variations be interpreted? This article proposes to clarify these points about this often misused indicator.

It is now difficult not to admit that we are living in a phase of global climate change. We regularly hear about various scenarios for the future, with temperature increases ranging from 1.5°C to more than 6°C by the end of the century. The Paris Agreement, which came out of COP21, aims specifically to limit this rise to 1.5 to 2°C. But where do these trajectories and objectives come from? In practice, these climate projections have been established by climate models. How are they designed? Are they reliable and robust? Under what conditions are they used to imagine the climate of the future? Find out through this article written by two researchers from the National Meteorological Research Centre.

Among the renewable energy sources that have been put on stage by the energy transition, biomass is the least known. Derived mainly from agriculture, livestock, forests and the seas, biomass is the source of very diverse end products, ranging from food and other materials to energy sources used for lighting and cooking, and especially fuels for heating. To fully understand the role played by biomass now – and the role it will increasingly play in the future energy balance – it is important to review what biomass is, its energy properties, its recovery cycle, and the various ways in which it contributes to meeting energy needs.

Some kinds of energy consumption are familiar: Litres of petrol or diesel purchased to fill your gas tank, or kilowatt-hours displayed on your electricity meter at home. But what are these measurements really for? To answer this question, we must first understand energy needs, which are not to be confused with energy consumption (because the same need can be met by different forms of consumption). Several concepts explained in this article help us understand this distinction, including technical systems and the energy paradigm, which explains the origin and evolution of real energy needs.

If today climate change is a well-known phenomenon for the majority of the population and is well understood by scientists, it is once again the result of a series of scientific discoveries and advances. From the discovery of the greenhouse effect to the creation of the Intergovernmental Panel on Climate Change (IPCC), it has taken several milestones to reveal the current risk and its magnitude.

India emits about 2.5 billion tonnes of CO2 per year, or 7% of global emissions. Admittedly, for the moment, this is not at the same level as China (10 GtCO2/year), but the strong growth (5%/year) must be taken into account, as it shows no signs of slowing down. The country must satisfy the needs of an ever-larger population, which is already suffering from many disparities. To achieve this, it still relies heavily on an abundant local resource: coal. How did this industry develop? Can its expansion be reversed?

Solar energy is taking an increasing place in the energy mix alongside other renewable energies. It can be used and transformed in various ways as required, either in thermal form or using photovoltaic panels. To this end, technologies have evolved considerably with the emergence of different processes that compete, replace and improve each other. The focus of this article is on photovoltaic technologies: How do they work and what are their evolution prospects?

In a world where we are gradually seeking to reduce our dependence on fossil fuels, particularly hydrocarbons, biofuels are emerging as an alternative, notably for transportation. However, the technologies underlying this solution are not fully mature yet. Indeed, most biofuels are made from crops (such as rapeseed and sugar cane) and a large-scale development of such fuels is not conceivable, since it would compete with the current agricultural system, which is dedicated to food. Yet other types of biofuels, based on microalgae, have been developed. They could overcome this limitation, and become a preferred solution to replace our consumption of fossil fuels.

Climate evolutions, favourable or not, were a determining factor in the rise or decline of the great ancient civilisations. Some of them managed to adapt to these climatic changes, thanks to their ingenuity, but other empires collapsed when the variations were too great. This is not unlike the situation of our own civilisation.

Whatever the reasons (air pollution, CO2 emissions, etc.), a growing number of players seem to be gradually turning their backs on mineral coal. Among them are organisations from various backgrounds: financial sector players (banks, pension funds, etc.), energy and mining sector players (coal and electricity companies, etc.) and also States (notably the European Union). Despite this trend, coal funding is still readily available, and coal is expected to retain a significant market share in global energy consumption for a few decades to come.

Today's environmental issues weigh on the transport sector and there is a multiplication of projects to invent the car of the future. As in any innovation process, many different energy sources and technologies are competing. However, the technical aspect is only one element in the success of an innovation, which is part of a broader analysis grid with cost, availability, social acceptance, public policies... Where do we stand on producing the car of tomorrow, what direction is it taking and at what pace?