Understanding Energy Sources: Natural Gas, Nuclear, and Renewables
Natural Gas
Natural gas is a mixture of combustible gases found underground, often associated with liquid petroleum. The main constituent is methane, while hydrocarbons such as ethane, butane, and propane appear in smaller proportions. The formation of natural gas occurs parallel to oil, resulting from the fermentation of accumulated matter from sediments. Initially, natural gas that appeared in oil fields was burned off as waste. However, the need for new energy sources and the discovery of deposits with enormous natural gas reserves led to solutions for its storage and transportation. Its transport is straightforward and inexpensive, as the gas flows by itself due to pressure. It is transported via pipelines, and to move it from one country to another, it is liquefied under very low temperatures.
Nuclear Energy
Nuclear energy is derived from reactions between the nuclei of radioisotopes. Its rationale is based on Einstein’s famous formula (E = mc²), which states that the mass difference between atomic nuclei and the sum of the masses of protons and neutrons is due to the energy used in the formation of such nuclei. When particles are released from a nucleus, energy is also released.
Nuclear Fission
Nuclear fission occurs when neutrons bombard a heavy nucleus, causing it to decay into two smaller nuclei and release large amounts of energy. This process emits two or three neutrons, which can, in turn, cause more fissions by interacting with new nuclei, leading to a chain reaction. This principle underlies the operation of atomic bombs and nuclear reactors.
Nuclear Fusion
Nuclear fusion involves the combination of two very light nuclei to form one heavier and stable nucleus, releasing large amounts of energy. To achieve this fusion, the initial nuclei must overcome electrostatic repulsion forces, which requires thermal energy. These thermal reactions occur in fusion reactors and are considered a source of cheap energy, as the fuel (hydrogen) is abundant. Despite current technical difficulties, fusion is viewed as a potential energy source for the future. It has also been used for military purposes in the manufacture of hydrogen bombs.
Hydropower
Hydropower is obtained from the flow of rivers. Dams built by dikes or barriers block the mouth of valleys, allowing water to accumulate. Once the plant is constructed, the water from the reservoir is channeled through pipes to the blades of a turbine, which drives an electric generator, utilizing the gradient of the dam. The potential energy of the water, due to its height and mass, is converted into mechanical energy in the turbine and finally into electrical power.
Uses of Hydropower
- The water stored in reservoirs is also used to regulate river flows.
- It helps supply towns and industries.
- It supports recreational activities.
As long as the water balance is positive, water is continuously renewed in nature, making electricity produced in these plants clean, low-cost, and requiring minimal maintenance. Hydropower remains the most widely used renewable source for electricity production.
Alternative Sources of Energy
Alternative energy sources are those that can replace conventional sources and have the advantages of being clean and renewable. These energies are believed to be the future.
Solar Energy
All energy sources derived indirectly from the Sun are referred to as solar energy. This energy is generated in the Sun through nuclear fusion and reaches the Earth as electromagnetic radiation. Since it cannot be stored directly, it is transformed into thermal or electrical energy. The major forms of solar energy conversion include:
- Thermal energy conversion
- Photovoltaic energy conversion
- Solar architecture
Photovoltaic Conversion
Photovoltaic conversion involves the direct conversion of light into electrical energy through the photovoltaic effect. When solar radiation hits a semiconductor material, it causes a movement of electrons, resulting in a difference in potential that generates electricity. This is achieved using silicon photovoltaic cells mounted on solar panels that capture sunlight and convert it into continuous current. This energy can be stored in batteries for use outside daylight hours, producing electricity without pollution or noise. However, drawbacks include the need for sufficient installation space and visual impact.
Wind Energy
Wind energy has been harnessed by humans since ancient times. Currently, it is used to transform the kinetic energy of wind into electricity through wind turbines, which are the basic elements of wind farms. These turbines consist of a steel tower with a windmill that has two or three blades rotating around a horizontal shaft connected to a generator. They must be oriented to ensure the wind hits the plane of rotation of the blades.
Advantages and Disadvantages of Wind Energy
- Advantages: Inexhaustible, clean, and free.
- Disadvantages: Intermittent, random, and can have a visual impact and cause bird fatalities.
Galicia and Andalucía are communities with significant wind potential.
Carbon Cycle
The main pathway of the carbon cycle in the biosphere involves carbon dioxide (CO2) being converted into living material through photosynthesis. A second route for CO2 fixation occurs through biochemical processes in the shells and skeletons of organisms. Carbon returns to the atmosphere as CO2 through the cellular respiration of decomposers, particularly when organic waste accumulates in sediments or soil. Some carbon is removed from the main cycle through a slow process that stores it in sedimentary rocks. This carbon returns to the cycle through the burning of fossil fuels and organic matter or through dissolution by carbonated water acting on carbonate rocks.
Nitrogen Cycle
Nitrogen, which makes up 78% of the atmosphere by volume, cannot be used directly by most organisms. It must be converted into a usable form, such as inorganic nitrate, before being incorporated into living matter. Organisms capable of fixing atmospheric nitrogen include:
- Nitrogen-fixing symbiotic bacteria and fungi
- Free-living nitrogen fixers, such as aerobic bacteria, anaerobic bacteria, and cyanobacteria
Human intervention in the industrial production of fertilizers can lead to nitrogen fixation exceeding 10% of the amount fixed naturally by terrestrial ecosystems. Improper management of fertilizers and nitrogenous waste can result in rapid aquatic eutrophication.
Ammonification
Following the incorporation of nitrogen as nitrate anion, the products of assimilation and nitrogen-rich organic waste are processed by microorganisms into inorganic ammonia.
Nitrification
The conversion of ammonia to nitrates is called nitrification. Some soil chemosynthetic bacteria carry out this conversion in two stages: Nitrosomonas convert ammonia to nitrite anion, and Nitrobacter convert nitrite to nitrate anion.
Denitrification
Denitrification is the conversion of molecular nitrogen back to nitrate anion, performed by certain fungi and bacteria under anaerobic conditions. This process occurs in well-ventilated or low-oxygen soils rich in organic matter.
Oxygen Cycle
The oxygen cycle in the biosphere is complex due to the numerous chemical forms and combinations it presents. Oxygen, primarily in the form of molecular oxygen (O2), is a component of water (H2O) and organic compounds. The concentration of this element increased significantly only after the development of photosynthesis. Oxygen is one of the most abundant gases, but its solubility in water is limited. Photosynthetic oxygen production occurs almost exclusively in light-rich environments. Once oxygen is depleted, the decomposition of organic matter occurs anaerobically, releasing CH4, H2, NH3, H2S, CO2, and organic acids.
Sulfur Cycle
Sulfur is a component of amino acids and is essential for protein structure. Most sulfur incorporated by organisms is mineralized as sulfate anion by various decomposer bacteria and fungi. Sulfur can enter the atmosphere as sulfur dioxide from coal and oil combustion. Inorganic sulfur, as sulfate anion, can be transformed into elemental sulfur or hydrogen sulfide under anaerobic conditions by the action of sulfate-reducing bacteria. The presence of hydrogen sulfide in anaerobic zones of aquatic ecosystems is harmful to most organisms. Natural sources of the sulfur cycle include gaseous emissions from volcanic eruptions and dimethyl sulfide from algae. Human activities contribute significantly to atmospheric sulfur emissions in the form of SO2 due to fossil fuel combustion.
Phosphorus Cycle
Phosphorus is a crucial nutrient for organisms, forming part of nucleic acids, phospholipids, and ATP, and is essential for skeletal structures and shells. It plays a significant ecological role as a limiting nutrient in ecosystem production. Producers require phosphorus in the form of inorganic phosphate, which is made available to them by decomposers. Much of the phosphate is lost from the food web through physical processes like sedimentation. The deposition of phosphorus in skeletons and shells can lead to significant losses for ecosystems over extended periods.