Alternative energy

Summary: Although the boundaries of alternative energy are not commonly defined, alternative energy is deemed to be the set of energies put in place as a substitute for conventional fossil-based energy. It is generally accepted that the renewable energies are the main alternative ones.

Alternative energy focuses on types of energy that are distinct from those generally employed (namely oil and coal). Its boundaries are not precisely defined, and a variety of definitions are used worldwide. Some definitions include nuclear energy, natural gas, propane, and oil shale, while others exclude them. There is, however, a general acceptance that renewable energies are included under the umbrella of alternative energy.

It is worth noting that, for many centuries, renewable energies were the only energy options available and so these types of energy were the conventional ones. Nowadays, solar, wind, and geothermal sources of energy, as well as other forms, are deemed to be alternatives to the predominant fossil fuels). In fact, wind and water were used for a long time to power sailing ships and to turn windmills and waterwheels for mechanical needs. Also, until the 1880s, wood was the most significant energy source in advanced civilizations.

The Industrial Revolution and consequent increased energy requirements led to the discovery and use of the first hydrocarbon-based fuel: coal. When the use of this and other fossil fuels became possible on a large scale, few of the renewable-energy techniques could compete.

There was a renewed interest in energy alternatives in response to oil embargoes and a spike in oil prices in the 1970s, but it was not effectively sustained. The basic reason for the failure to develop renewable energy sources during those years was either a concern over the environment or their high costs, which became difficult to justify once oil prices began to decline.

However, in the first decades of the twenty-first century huge improvements in the performance and affordability of solar cells, wind turbines, and biofuels have paved the way for mass commercialization of these alternative technologies.

By 2014, around 11 percent of global final energy consumption derived from renewables, according to estimates by the US Energy Information Administration (EIA). That percent had increased to 13 percent in 2023, according to EIA. The IEA reported that renewable sources accounted for over 30 percent of global energy generation in 2023.

Benefits and Barriers of Alternative Energies

• Benefits of Alternative Energy
• Energy security: Enhancing diversity in energy supply and therefore strengthening energy security.
• Gas emissions: Considering their entire life cycle, even if most forms of alternative energy are not carbon-free they make a major contribution to the reduction of greenhouse gas emissions and other pollutants on a local and global scale.
• Local development: Creates job opportunities and spins off economic benefits for local communities in infrastructure manufacturing, installation, and maintenance.
• System flexibility: Increases flexibility of power systems.
• Energy source in rural areas: Provides energy in underdeveloped rural regions where electricity grids are absent.
• Environmental effects: In general, compared to fossil fuels, alternative energies have significantly fewer environmental effects, but they do exist: visual impact of wind farms, effects in the ecosystem of dams, deforestation in the case of biomass, and noise, among others.
• Global business: Renewable energy is becoming a global business and in this sense mobilizes important financial resources and creates millions of new jobs worldwide.

• Barriers to Alternative Energy
• Technology costs: The initial capital cost is probably the most significant barrier to the use of alternative energies on a large scale.
• Storage and distribution: Natural fluctuations of energy sources (such as solar and wind intermittency) create the need for storage. Also, their geographic availability may require long-distance transportation to be used.
• Technicalities: The conversion of energy from alternative sources to practical applications needs further development. Also, the vulnerability of infrastructures to elements (such as the potential for offshore wind farms to be damaged in storms) can be critical.
• Social barriers: The NIMBY (not in my backyard) phenomenon, in which populations claim to support a development in general but oppose it when it threatens to disrupt their direct neighborhood, is also a problem to be dealt with by alternative energies. Some examples of this are the competition between biofuel and food and the displacement of population caused by the creation of water reservoirs.

Wind Energy

Wind energy is one alternative source used to produce electricity. Wind power is considered a relatively mature technology. Its costs have been declining significantly and the efficiency of wind power technologies has steadily increased, making it more feasible for large-scale energy generation. Still, wind power is in most cases dependent on public subsidies.

In a wind turbine, the wind flows over airfoil-shaped blades, causing lift, which causes them to turn. The blades are connected to a drive shaft that turns an electric generator in order to produce electricity.

Wind power does have an environmental impact. The visual effects of wind turbines (which many deem unsightly) are often deemed the most important impact. Moreover, the impact on wildlife—particularly migratory birds and bats—has been debated, and studies with contradictory results have been published. Mark Jacobson ranked wind power as the winner among alternative energy sources in terms of its overall benefits with regard to the environment and human health. Jacobson also ranked wind-battery electric vehicles as the best vehicle solution.

The potential of wind power is largest at remote sites, but the costs of the grid connection often hamper the development of wind sites. Because of the limited availability of land as well as the fact that winds are stronger and more stable at sea, several countries are looking with increasing interest at offshore wind power stations.

Solar Energy

Solar energy produces both electricity and heat. The most familiar form of solar energy production is solar panels. Also known as photovoltaics (PV), these are arrays of cells with certain semiconductor material that converts solar radiation into direct current electricity. Solar photovoltaics are particularly flexible because they can be installed in different places: on the roofs or walls of houses and office buildings, or even sewn onto clothing to feed portable electronic devices with power. They can be combined into farms as well.

Also, sunlight can be harnessed through solar-thermal technologies, which collect sunlight to generate heat. These systems include solar water heaters that have long been used to provide hot water.

A third type of technology corresponds to the concentrated solar power in which sunlight is focused (concentrated) by mirrors or reflective lenses to heat a fluid in a collector at high temperature in order to produce electricity.

Solar technologies have a moderate environmental impact, but in no case is the impact of any renewable zero. It is important to note that solar devices need an external surface, which may result in user conflicts. Also, dismantled systems need proper waste management. Furthermore, in the thermal solar power plants, water, which is required in the steam system and in cooling towers, can be limited in certain locales.

The solar cell market has seen a huge increase over the last few years, but there are some associated disadvantages. The most important one is that the access on a short-term basis is uncertain—it is not easy to predict the efficacy and output of solar systems on a daily basis.

Geothermal Energy

Geothermal energy is heat energy from the Earth’s interior. This heat has two main sources: the original heat from when the Earth was created and the energy released as a result of ongoing radioactive decomposition in the Earth’s crust. Geothermal sources of energy are used to produce both electricity and heat in geothermal power systems. Geothermal sources with flow temperatures higher than 120 degrees Celsius can be exploited to produce electric power; other temperatures are used for heating (and even cooling). Technologies for the utilization of geothermal energy are established and mature, and their costs are competitive with those of conventional fossil fuels. Projects for the utilization of geothermal energy for electricity production involve a high level of economic risk, however. Research and experimental drilling must be carried out to know if the use of that geothermal resource is viable. The exploitation of low-temperature thermal energy, as opposed to high-temperature geothermal energy, is much less complex and is feasible all over the world.

Thermal pollution from the return of cooling water and the emissions of chemicals presented in hydrothermal liquid or steam are examples of the potential environmental impacts of these projects.

Hydropower

Hydropower produces electricity. Hydropower is considered a mature technology and has traditionally supplied the largest share of electricity among all renewables. Most hydroelectricity is produced by water falling from dams. It is also produced by water flowing down rivers and water stored in reservoirs. In standard hydroelectric power plants water drops gravitationally, driving a turbine and generator. It is simple to adjust production and can provide energy in seconds and therefore is often used for peaking power. The driving force behind the construction of dams is not only electricity production but also mitigation of flooding, support to irrigation, and water supply protection. Hydropower is a renewable energy form but is not always deemed to be a "green," or environmentally friendly, category of energy. Massive new projects are controversial for a variety of reasons. Changes in the flow of water can severely affect ecosystems, especially migrating fish and other aquatic organisms, and water reservoirs can occupy large areas of land, displacing humans as well as animals and plants. Another big challenge for hydropower is its dependence on rainfall. Moreover, the economic risk in hydropower projects can be large, since they are capital intensive.

Ocean Energy

The oceans have been used to produce electricity, though ocean energy technologies are considered immature. Much research and development is needed before the force of waves and tidal power become competitive with fossil energy sources. Of the two sources of ocean energy, waves and tides, wave power may have the technology closest to a commercial viability. Several tidal power stations were constructed around the world in the twenty-first century, including the Sihwa Lake Tidal Power Station in South Korea, which, at 254 megawatts, was the largest tidal facility in the world in 2022.

Biomass

Biomass as a source of energy is used to produce both electricity and heat. Bioenergy is used extensively all over the world. Biomass can be directly used as fuel or can be decomposed by microorganisms to produce biogas fuel in a biogas digester. The most common area of application for bioenergy is the production of heat. Electric power and liquid biofuel, such as biodiesel, can also be produced. Commercial bioenergy resources are derived mainly from forestry, farming, and waste (incineration plants where materials are burned and organic treatment plants or sanitary landfills where biogas is produced). Biomass includes wood, chips, bark, or refined products, such as briquettes, pellets, charcoal, and sawdust.

The combustion of solid fuels such as biomass generates bottom ash and flying ash. Fireplaces are also an important source in terms of particle emissions. It is important to note, however, that the combustion and gasification of biomass generally have lower emissions of certain pollutants (such as nitrogen oxides and sulfur) than the combustion of fossil fuels. Large biomass plants must have a gas treatment in order to control harmful emissions to the atmosphere.

Biofuel

Biofuels originate from biomass such as plants or organic waste and can be used as direct fuels or blended into diesel fuel or gasoline. Consequently, they are an important alternative source of transport fuel.

There are two main forms of biofuel today: ethanol and biodiesel, also known as fatty acid methyl esters (FAME). Ethanol is made from basic fermentation plants, such as corn and sugarcane (the most important ethanol crops), as well as sugar beets and wheat. Biodiesel is produced through a process called transesterification, which uses various raw materials, including corn, cottonseed, peanuts, sunflower seeds, and soybeans.

The impact of biofuel depends not only on the technology but also on the use of a raw material. Current biofuel technologies are already a viable renewable energy source but are not always as "green" as they originally appeared. Bioenergy made headlines for negative reasons in 2008, particularly for its association with rising food prices. In fact, biofuel demand was one of many factors contributing to the rise in food prices. Also, rising demand for biofuel and increasing world food consumption are considered to be leading to an expansion of world cropland at the expense of tropical rain forest and natural grasslands, which has a significant impact on biodiversity and consequences regarding climate change issues.

In addition, some studies mention that, in certain cases, turning some plants into fuel can use more energy than the resulting ethanol or biodiesel generates when all the energy inputs—including production of pesticides and fertilizer, running farm machinery and irrigating, and grinding and transporting the crop—are considered. On the other hand, biofuel derived from the correct feedstocks, grown on the right land with an efficient use of fertilizers and other resources, and produced in proper working conditions can be considered a sustainable biofuel.

Nonfood-based biofuels produced from inedible cellulosic material—leafy materials, stems, stalks, or even algae—are referred to as second-generation biofuels. They have received increased focus throughout the twenty-first century.

Hydrogen

Hydrogen is used to produce transport fuel and power. There is no monitoring of the world hydrogen; however, 45 million metric tons (500 million cubic meters) are estimated to be produced annually.

Even if some experts consider that hydrogen is a renewable source that comes from renewable sources such as water, others categorize hydrogen as a carrier (like electricity) because it must be produced from other substances. Although hydrogen is the most abundant element in the universe, it does not exist on Earth as a gas. Hydrogen atoms must therefore be separated from other elements. Hydrogen can be produced from a variety of resources, including water, fossil fuels, and biomass. A high percentage comes from fossil fuels.

The two most common methods of producing hydrogen are steam reforming and electrolysis. Steam reforming is less expensive. Normally, it is used in industry to separate hydrogen from methane (in natural gas). In this process, greenhouse gas emissions result. Electrolysis is a process that separates hydrogen from oxygen (water splitting). It results in no emissions; however, currently it is very expensive.

Hydrogen can be used to fuel internal combustion engines. Its most promising application, however, is in fuel cells. Fuel cells create an electric current when they cross a charged membrane, stripping the hydrogen of electrons. Small fuel cells can power electric vehicles.

Hydrogen fuel cells are considered an immature technology but are already in use. Iceland is a leading example in type of application. Niche applications for the use of hydrogen are abundant. These include laptop computers and cell phones. However, the costs remain high.

Conclusion

On a global scale, more than 60 percent of oil is consumed in transportation. In this sense, it is worth noting that alternative fuel is generally considered to include all alternatives to gasoline or diesel. It encompasses biodiesel, ethanol, and hydrogen, as described above, but also other resources, such as methanol, natural gas, propane, coal-derived liquid fuels, and electricity, as recognized by the US Department of Energy. Due to global warming and the effects of climate change, enhanced focus was placed on alternative fuel sources throughout the early twenty-first century.

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