Читать книгу Energy Transition in Metropolises, Rural Areas, and Deserts - Louis Boisgibault - Страница 14

The word energy comes from the ancient Greek, energia, the force in action. The dictionary characterizes it as a physical system, keeping the same value during all internal transformations of the system (conservation law) and expressing its ability to modify the state of other systems with which it interacts. The units used in the international energy system are the joule (J), the Watt-hour (Wh) and the ton of oil equivalent (TOE) due to the economic and political significance of oil.

Energy sources can come from raw materials (Vidal 2017) such as hydrocarbons (crude oil, natural gas and coal), uranium or natural phenomena such as wind, sun, hot springs, organic matter fermentation, tides and marine currents. These sources can be primary, i.e. directly from nature such as wood, hydrocarbons, uranium, organic waste or secondary, i.e. from human transformation such as electricity and gasoline. The energies used by mankind have evolved over the centuries in different transitions due to the discovery of new raw materials, the domestication of natural phenomena and technological progress. The final energy is that which is delivered to and consumed and paid for by the inhabitant.

Why are these definitions already an issue? Because it is necessary to count energy to see the evolution of production and consumption in metropolitan areas, rural areas and deserts. Energy metering is always tedious, but it is essential to establish a diagnosis that then makes it possible to prepare an action plan, with more or less significant investments. We are confronted with the difficulty of knowing whether we are thinking in terms of primary energy or final energy and how to compare 1 liter of fuel oil with 1 kWh of wind energy. Statistics have been compiled in TOE since 1972. In France, for electricity, 1 MWh was equivalent to 0.222 TOE, which corresponded to an average efficiency of 38.7% for a thermal power plant (43.7% – 5% loss during distribution). This affects a primary energy conversion factor of 2.58 (1/0.387) per kWh in the energy balances.

The first problem is that thermal power plants have lost market share to nuclear and renewable energies since 1972 and that the nuclear power plant has a better load factor than the photovoltaic plant. The load factor is the operating factor of a power plant. It is the ratio between the electrical energy actually produced over a given period and the energy it would have produced if it had operated at its maximum power during the same period. However, the photovoltaic plant does not produce at night. The International Energy Agency standardized the conversion by specifying that nuclear MWh was equivalent to 0.2606 TOE and renewable MWh was equivalent to 0.086 TOE in primary energy balances.

The second problem is that fossil fuels do not undergo any increase in coefficient. If a thermal regulation requires each new dwelling built to consume less than 50 kWh of primary energy per square meter per year, this implies that the electrical dwelling will be penalized by this coefficient compared to the fossil dwelling, whereas it emits less than CO₂/m²/year.

The question today is whether primary energy is an appropriate criterion for regulating energy use and which primary energy conversion coefficient to use. The final energy makes it possible to link regulation with bills the consumer receives.

The energy transition is not new in itself. It is considered to reflect the gradual abandonment of some energies in conjunction with the development of others. One might think that this is due to the arrival of new energies driven by innovation. In fact, wind, water and sun energies have always existed. Humanity has experienced various energy transitions. First, the domestication of fire by prehistoric man, 70,000 years ago in Africa, made it possible to control heat. The creation of tools, in the Bronze Age, may have been facilitated by this heat, which is a transition. Since the Middle Ages, Europeans have built windmills, river water mills and tidal mills (Woessner 2014) along the Atlantic coast, the English Channel and the North Sea. There are examples of these mills, which use the tides to operate, on Île de Bréhat, Île Arz, Arzon, Trégastel and Pont-Aven in France but also in Portugal, Spain, the United Kingdom and Belgium.

For hydrocarbons, coal mining took on an industrial dimension in the 18th Century. The invention of the steam engine by the Scotsman James Watt, before the French Revolution, was a major event since an external combustion engine transformed the thermal energy of the water vapor produced by a boiler into mechanical energy. This allowed a revolution with the arrival of the steam locomotive and a new energy transition. In 1859, when Colonel Edwin Drake first operated an oil well in Titusville, Pennsylvania, and 20 years later Thomas Edison invented the electric light bulb, one of the most important energy transitions occurred as oil and electricity replaced existing fuels. At the beginning of the 20th Century, electricity and city gas arrived in homes, which was another important energy transition, replacing the kerosene lamp, coal stove and wood fire.

Coal mining was the driving force behind the industrial revolution of the 19th Century. Its extraction, through underground or open-air galleries, is an essential economic activity that has marked the history of the research field in the north of France chosen for this project, but also the European Union and the world in general. Several techniques are used. The room and pillar method consists of manually digging, consolidating the coal vein and its ceiling by installing pillars that form underground chambers and galleries. The long method consists of drilling the coal vein with a cutting machine and recovering the ore by letting the ceiling collapse. The coal is then brought to the surface, once by humans or animals, then by conveyors and wagons, to be treated by immersing it in an appropriate liquid. Opencast mining is more profitable and is carried out using giant excavators. The treated coal is then transported to the consumption sites by road or ship.

Oil and gas exploration and production were later carried out in the 20th Century. The discovery and exploitation of deposits has created a value chain from upstream to downstream. The crude oil and natural gas extracted only make sense if they are properly processed and transported to consumption areas. A disconnection took place between production areas (desert areas, rural areas in emerging countries, offshore) and consumer areas (metropolitan areas and rurality in developed countries) and major battles have been fought for access to springs (Chevalier 2004). The research sites in Saudi Arabia selected for this project have been disrupted by this industry.

The downstream oil sector includes oil refining, i.e. the transformation of crude oil from offshore fields into finished products (such as gasoline, diesel, fuel oil and bitumen) and distribution. Distribution consists of storing finished products, transporting them and organizing marketing to the end customer. Generally speaking, crude oil is transported by ship or pipeline from the production sites to the refineries. The pipeline requires significant infrastructure investment. Its destination cannot be changed once the construction is completed.

For natural gas, the logic is similar to the processing of extracted natural gas and its transport. Its transport is more difficult than oil. It is carried out in gaseous form by gas pipelines and in liquid form by LNG carriers. The majors were less interested in natural gas fields because molecules were less profitable to transport, especially when the field was small. The plants, located near the extraction sites, were built to liquefy natural gas at –160°C so that it would lose 600 times its volume. Liquefied natural gas (LNG) is loaded onto the LNG carriers and transported to other plants, which regasify and odorize it so that it can be injected into the transmission and distribution networks.

The civil nuclear sector has developed well since the 1970s. Its value chain extends from uranium mining and transportation, particularly from Niger, to the construction of nuclear power plants, the manufacture and reprocessing of fuel and the conditioning of radioactive waste. The European and Saudi Arabian research sites selected for the book are heavily impacted by this sector, with the commissioning of reactors in northern France in the 1980s and the construction of new reactors in Saudi Arabia, i.e. with a 40-year delay.

Everyone is aware of the crucial importance of innovation in the energy sector and in the energy transition. How do new technologies, including nanotechnologies, biotechnologies, information technology and cognitive science (NBIC), affect the energy transition? How can we preserve the planet’s non-renewable stocks of hydrocarbons and uranium by better exploiting the flows of sun, wind, rivers, tides, currents and waste?

Nanotechnologies focus on objects at the molecular and atomic scale. They affect the energy sector in many ways, for example, in the manufacturing of photovoltaic cells. They are based on monocrystalline silicon, polycrystalline silicon, thin films and organic substances. For crystalline silicon, the silicon is melted and then gently cooled to obtain a single homogeneous crystal (monocrystalline) or more quickly to obtain multiple crystals (polycrystalline).

The crystal is cut into ingots to work at a scale of 200 µm and form photovoltaic cells. For thin films, silicon is fixed in thin layers of only a few micrometers on a glass or plastic support.

Other rare materials such as copper, indium, gallium, selenium and cadmium telluride can be used. For organic photovoltaic cells, an active layer is made up of organic molecules. Nanotechnologies miniaturize equipment and increase its performance at a lower cost.

Biotechnology is defined by the OECD as “the application of science and technology to living organisms, as well as its components, products and modeling, to modify living or non-living materials for the production of knowledge, goods and services”. They make it possible, for example, to produce biofuels, organic products alternative to oil and gas from raw materials, plant sugars and algae, which are transformed into finished products and biogas using microorganisms. They also allow the treatment and elimination of pollution.

New generation computing impacts data processing capacity, production systems, microelectronics, energy system components, smart grids, data transmission and blockchain.

Finally, the cognitive sciences aim to describe, explain and simulate the mechanisms of animal and human thought. They model complex information processing systems capable of acquiring, storing, using and transmitting knowledge. This artificial intelligence helps to consume less energy, to better appreciate local consumption to adjust production and to preserve the planet’s limited and non-renewable hydrocarbon resources.

These NBICs are currently transforming the exploitation of stock energy (hydrocarbon and nuclear), with their associated networks, and will allow flow energy to become more competitive for the production of electricity, heat, fuel and fuel.

Table 1.1. Properties of renewable energies

Sectors	Electricity	Heat	Combustible	Fuel
Biofuel				X
Biomass	X	X	X	X
Biomethane	X	X	X	X
Marine energies	X
Wind turbine	X
Geothermal energy	X	X
Hydropower	X
Solar photovoltaic	X
Thermal solar energy		X
Thermodynamic solar energy	X	X

Biofuel is an agrofuel produced from non-fossil organic materials, vegetable oil (rapeseed, algae) or alcohol (sugar, starch). It is important for metropolises and rural areas to reduce dependence on fossil fuels.

Biomass comes from organic matter of plant or animal origin in solid/liquid form that can be used as an energy source. Its direct combustion produces heat which, through cogeneration, can also produce electricity. The fermentation of organic matter can produce biogas or biomethane (CH₄). Its chemical transformation by pyrolysis can produce fuel and biofuel. Wood fire, which is the combustion of solid biomass, is the traditional means of heating in all spaces. In metropolitan areas and rural areas, the challenge of collecting, sorting, incinerating and recycling household waste is important for producing recovered heat and electricity. A collective heating system can be powered by organic waste and pallets, shreds and wood pellets, i.e. biomass fuel of various kinds. Methanization units require more space and in rural areas allow the use of manure and agricultural waste by fermentation to produce biogas.

Marine energies are made up of six sectors, namely tidal energy, wave energy, current energy, ocean thermal energy, osmotic energy and wind energy (large offshore wind). The use of algae to produce biofuels that can be used to power the internal combustion engine of vehicles is currently being studied. These energies are still marginal in the global energy mix. Their potential should not be underestimated as they can benefit coastal areas. Do they benefit metropolitan areas, rural areas or deserts? We can have metropolises, rural areas and deserts by the sea that benefit from this electricity, which is repatriated to land by cable, and then fed into the grid or possibly self-consumed.

Wind turbines convert the kinetic energy of the wind into mechanical energy, which is then most often transformed into electricity. This mechanical energy has been used for centuries to grind grain in traditional mills. It is transformed into electricity by modern horizontal and vertical axis wind turbines. These wind turbines can be small for urban and rural buildings. Others are very large, with a mast longer than 150 m, a nacelle for mechanical components and a rotor to receive the blades. They can only be installed in parks located far from residential areas.

Geothermal energy consists of exploiting the energy from the earth, which is recovered by geothermal collectors, in the form of usable heat that can potentially be converted into electricity. At low energy, the heat comes from shallow depths and its temperature is not sufficient (5–10°C) to be used directly for heating. A heat pump must be added to increase the temperature, a popular feature in single-family homes in urban and rural areas. At medium and high energy, heat drawn at a high temperature (from 50°C to over 150°C) or at high depth (from 600 m to over 2,000 m), can be used directly. It is suitable for certain urban areas, both for collective and tertiary buildings, which are then supplied by a heating network. For higher temperatures, often in volcanic areas, when the flow rate is sufficient, the heat can be converted into electricity.

Hydraulics converts the movement of water into kinetic energy, which is then most often transformed into electricity. This kinetic energy has been used for centuries to grind grain in traditional water mills. It is located in rural areas for small and large hydropower, although the electricity produced by the turbines of the dams can then supply the cities.

Solar energy can take many forms. The French physicist Edmond Becquerel discovered the photovoltaic effect in 1839. This is one of the effects that is implemented in photovoltaic cells from solar radiation. It is used to produce electricity. Solar thermal energy makes it possible to produce heat and hot water from solar collectors. Concentrated thermodynamic solar energy converts solar energy into heat at high temperature and then converts it into electricity. The sun’s rays are concentrated on a heat transfer fluid in several possible configurations and heated to very high temperatures to produce heat. The four technological fields are cylindro-parabolic mirrors, Fresnel mirrors, the solar tower and the parabola stirling. Building integrated solar photovoltaics and solar thermal can enable urban and rural buildings to produce electricity and heat. Solar streetlamps can help with street lighting. Ground-based photovoltaic farms can only be designed in large rural and desert areas. Concentrated thermodynamic solar energy is intended for the desert.

The methods of evaluating energy systems and their importance are beginning to be fully recognized (Lachal 2018). The concepts of energy and technological systems, innovation, learning through use and feedback must be analyzed from the perspective of the host territories.