Energy development

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Energy development is the ongoing effort to provide abundant and accessible energy resources through knowledge, skills, and constructions. When harnessing energy from primary energy sources and converting them into ever more convenient secondary energy forms, such as electrical energy and cleaner fuels, both quantity (harnessing more energy) and quality (more efficient use) are important.


Contents

Dependence on external energy sources

All biological life needs a supply of external energy. Most plants are capable of photosynthesis, some bacteria employ natural sources of chemical energy. Many other organisms thrive on energy passed along in food chains.

Beyond the biological needs of humanity, energy sources are used to enable advanced activities such as heating, cooking, transport, communication, warfare and social and leisure activities. This allows us, in general, to live under diverse climatic conditions, in great numbers and often in comfort. Level of dependence of human societies on external energy sources differs, as does the climate, comfort and output of each society.

Increased levels of human comfort require increased dependence on external energy sources. Energy development therefore embodies the idea of increasing human comfort and freedom by researching and implementing increasingly effective and responsible energy harvesting and utilisation schemes.


Limitations to energy development

Use of any given energy source in human societies encounters limits to quantitative expansion. At the beginning of the 21st century some issues have achieved global dimension. Principal fossil energy sources, such as oil and natural gas are approaching exhaustion that may occur within the span of a generation (see Hubbert peak hypothesis). Closely linked to energy development are concerns about the environmental effects of energy use, such as climate changes. Energy development issues are part of the much debated sustainable development problem.

Energy sources

Energy sources are substances or processes with concentrations of energy at a high enough potential to be feasibly encouraged to convert to lower energy forms under human control for human benefit. Except for nuclear fuels, tidal energy and geothermal energy, all terrestrial energy sources are solar. And ultimately, solar energy itself is nuclear.

Fossil Fuels

Main article: Fossil fuel

Fossil fuels, in terms of energy, involve the burning of coal or hydrocarbon fuels, which are the remains of the decomposition of plants and animals. This combustion heats water to create steam, which turns a turbine, which, in turn, generates electricity. There are three main types of fossil fuels: coal, petroleum, and natural gas.

Pros

  • Because it is based on the simple process of combustion, the burning of fossil fuels can generate very large amounts of electricity with a small amount of fuel. Gas-fired power plant are efficient, and coal power plants have improved over the past few years.
  • Fossil fuels are readily available and are currently plentiful. If more energy is required, the only step required is to obtain more fuel. Fossil fuels are easy to obtain by extraction. The transport of these fuels is also straightforward, especially if the plant is located close to the fuel source.
  • Fossil fuels are cheap compared to other types of energy. Because there are large deposits of fossil fuels in the world, the per-unit cost is relatively low. Furthermore, the technology already exists for the use of fossil fuels, meaning consumers do not have to spend money switching to other technologies.

Cons

  • They are considered non-renewable resources, which will eventually run out. Fossil fuels are actually produced continuously, but we are using them up at a rate 100,000 times faster than they are formed.
  • Extracting fossil fuels will become more difficult as we consume the most accessible fuel deposits. Extraction of fossil fuels is expected to become more expensive and more dangerous as mines get deeper and oil rigs go further out to sea.
  • The combustion of fossil fuels leads to the release of pollution into the atmosphere. Some of these by-products, such as carbon dioxide, are heat-trapping gases, which some scientists believe enhance the “greenhouse effect” leading to global warming. Other pollutants, including sulfur dioxide, are present in acid precipitation, and the drilling and transport of petroleum cause areas, which are susceptible to oil spills.

Wind Power

Main article: Wind power

This type of energy harnesses the power of the wind to propel the blades of wind turbines. These turbines cause the rotation of magnets, which creates electricity. Wind towers are usually built together on wind farms.

Pros

  • Wind power produces no water or air pollution that can contaminate the environment. Because there are no chemical processes involved in wind power generation, there are no by-products, such as carbon dioxide, left over.
  • Wind generation is a renewable source of energy, which means that we will never run out of it.
  • Wind towers can be beneficial for people living permanently, or temporarily, in remote areas. It may be difficult to transport electricity through wires from a power plant to a far-away location and thus, wind towers can be set up at the remote setting.
  • None of the environmental costs are left to future generations.

Cons

  • Wind power is not reliable, because consistent wind is needed to ensure continuous power generation. When the wind speed decreases, the turbine lingers and less electricity is generated. Thus, the production at any time is unpredictable.
  • One wind turbine does not generate very much electricity, when compared to the energy generated by one fossil fuel power plant. In fact, an entire field of wind towers, called a wind farm, is required, taking up a lot of land.
  • Installing wind farms in an area may destroy its natural beauty. Wind farms can have a significant visual impact on the horizon and may obstruct natural or man made landforms that may interest the viewer.
  • The effect of large scale wind farms on the climate is unknown. Energy is removed from prevailing winds and could affect weather or climate in ways not currently understood.

Biomass

Main article: Biomass

Biomass production involves using garbage or renewable resources, especially vegetation, like maize, to generate electricity. When garbage decomposes the methane produced is captured in pipes and later burned to produce electricity. Vegetation and wood can be burned directly, like fossil fuels, to generate energy, or processed to form alcohols.

Pros

  • Biomass production can be used to burn organic waste products resulting from agriculture. This type of recycling encourages the philosophy that nothing on this Earth should be wasted. The result is less demand on the Earth's resources, and a higher carrying capacity for Earth because non-renewable fossil fuels are not consumed.
  • Biomass is abundant on Earth and is generally renewable. In theory, we will never run out of organic waste products as fuel, because we are continuously producing them. In addition, biomass is found throughout the world, a fact that should alleviate energy pressures in third world nations.
  • When methods of biomass production other than direct combustion of plant mass, such as fermentation and pyrolysis, are used, there is little effect on the environment. Alcohols and other fuels produced by these alternative methods biomass are clean burning and are feasible replacements to fossil fuels.

Cons

  • The direct combustion leads to air pollution. It produces also carbon dioxide, but unlike fossil fuels, such release is not responsible for a surplus of accumulating CO2: it is part of a cycle where plants consume it to produce new biomass.
  • This type of energy production is not currently cost effective, because the production of biomass and its subsequent conversion to alcohols is particularly expensive.
  • If implemented on a small scale, biomass production most likely results in a net loss of energy because the energy required to grow the plant mass is greater than the electricity gained from it. Thus, large-scale generation is ideal.

Hydrogen Fuel

Main article: Hydrogen economy

Unlike the other energy sources in this article, hydrogen fuel cannot be collected or harnessed on earth. Hydrogen fuel must be manufactured with a net loss of energy. As such, it represents chemical energy storage like in other batteries, but it is not a primary energy source. In order to use hydrogen fuel as an energy source, either a) a fuel cell battery is needed to convert the chemicals hydrogen and oxygen into water, and in the process, produce electricity, or b) hydrogen can be burned (less efficiently than in a fuel cell) in an internal combustion engine (e.g. Mazda RX-8 rotary engine).

Pros

  • Hydrogen is colourless, odourless and entirely non-polluting, the only product of combusting oxygen and hydrogen is pure water. This eliminates the direct production of exhaust gases that lead to smog, and carbon dioxide emissions that enhance the effect of global warming.
  • Hydrogen is the lightest chemical element and has the best energy-to-weight ratio of any fuel. Because of this, hydrogen can be economically competitive with gasoline or diesel as a transportation fuel.
  • Hydrogen can be produced anywhere, insinuating that it can be produced domestically from the decomposition the most abundant chemical on earth: water. Consequently, countries do not have to rely on OPEC countries for fossil fuels. Hydrogen can be produced from domestic sources and the price can be established within the country.

Cons

  • It is currently very difficult to obtain hydrogen gas without expending energy in the process. Because it is an extremely reactive element, hydrogen never exists in its pure form in the environment. Furthermore, the process of splitting water into oxygen and hydrogen using electrolysis consumes large amounts of energy. It has been calculated that it takes 1.4 joules of electricity to produce 1 joule of hydrogen (Pimentel, 2002). If oil or gases are used to provide this energy, fossil fuels are consumed, forming pollution and nullifying the value of using a fuel cell. It would be more efficient to use fossil fuel directly.
  • There is currently a lack of infrastructure and distribution network required to support the widespread use of hydrogen as a fuel. It would cost a lot of money and energy to build hydrogen plants and to replace every car and bus with a hydrogen engine and fuel tank.
  • Hydrogen is complicated to handle, store, and transport. It requires heavy, cumbersome tanks when stored as a gas, and complex insulating bottles if stored as a cryogenic liquid. If it is needed at a moderate temperature and pressure, a metal hydride absorber may be needed. Transport is also a problem, because hydrogen leaks effortlessly from containers, reducing the efficiency of the fuel. These hassles make hydrogen power very expensive.
  • Current efficient fuel cell designs are expensive since they need Platinum as a catalyst.

Tidal power

Main article: Tidal power

Tidal energy involves building a dam across the opening to a tidal basin, called an estuary. The dam, called a barrage, is composed of turbines, located within tunnels in the dam that rotate when a tide comes in, generating electricity.

Pros

  • Tidal power is free once the dam is built. This is because tidal power harnesses the natural power of tides and does not consume fuel. In addition, the maintenance costs associated with running a tidal station are relatively inexpensive.
  • Tides are very reliable because it is easy to predict when high and low tides will occur. The tide goes in and out twice a day usually at the predicted times. This makes tidal energy easy to maintain, and positive and negative spikes in energy can be managed.
  • Tidal energy is renewable, because nothing is consumed in the rising of tides. Tidal power relies on the gravitational pull of the Moon and Sun, which pull the sea backwards and forwards, generating tides.

Cons

  • Tidal power is not currently economically feasible, because the initial costs of building a dam are tremendous. Furthermore, the efficiency of the tide is reduced because it only provides power for around 10 hours each day, when the tide is moving in or out of the basin.
  • The barrage construction can affect the transportation system in water. Boats may not be able to cross the barrage, and commercial ships, used for transport or fishery, need to find alternative routes or costly systems to go through the barrage.
  • The erection of a barrage may destroy the aquatic ecosystems surrounding it. The environment affected by the dam is very wide, altering areas numerous miles upstream and downstream. For example, many birds rely on low tides to unearth mud flats, which are used as feeding areas.

Solar power

Main article: Solar power

Solar power involves using solar cells to convert sunlight into electricity, or using sunlight hitting a parabolic mirror to heat water, producing steam.

Pros

  • Solar power is a renewable resource. As long as the Sun exists, its energy will reach Earth.
  • Solar power generation releases no water or air pollution, because there is no combustion of fuels.
  • In sunny countries, solar power can be used in remote locations, like a wind turbine. This way, isolated places can receive electricity, when there is no way to connect to the power lines from a plant.

Cons

  • Solar power is not very reliable because it depends on the amount of sunlight that reaches the Earth at any given time. This makes a solar cell ineffectual during the night when sunlight does not reach the part of the Earth in which the cell is located. It is also limited by the amount of cloud cover that blocks sunlight.
  • Solar power is not currently cost effective. A solar power station is expensive to build, and the energy payback time - the time necessary for producing the same amount of energy than needed for building the power device - for photovoltaic cells is large, of the order of five to six years.
  • In order to use solar power effectively throughout the day, storage and back up are necessary to accumulate the energy generated at times of sunlight.

Geothermal Energy

Main article: Geothermal power

Geothermal energy harnesses the heat energy present underneath the Earth. The hot rocks heat water to produce steam. When holes are drilled in the region, the steam that shoots up is purified and is used to drive turbines, which power electric generators.

Pros

  • Geothermal energy produces no air or water pollution because the steam released is not heated by the burning of a fuel, but rather, by the core of the Earth.
  • Once a geothermal power station is implemented, the energy produced from the station is practically free. A small amount of energy is required in order to run a pump, although this pump can be powered by excess energy generated at the plant.
  • Geothermal powers stations are relatively small, and have a lesser impact on the environment than tidal or hydroelectric plants. Because geothermal technology does not rely on large bodies of water, but rather, small, but powerful jets of water, like geysers, large generating stations can be avoided without losing functionality.

Cons

  • Geothermal energy is only sufficient as source of power in certain areas of the world. These regions require the presence of hot rocks near the surface to warm the water. The depth of these rocks must be enough so that one can drill down to them. The type of rock also plays a role because it must be easy to drill through.
  • A geothermal site is prone to running out of steam, meaning that the water is not heated at a high enough temperature to generate enough steam pressure. This makes the site useless, in terms of energy production, for decades.
  • Drilling holes underground may release hazardous gases and minerals from deep inside the Earth. It can be problematical to dispose of these subsidiary products in a safe manner.

Hydroelectric energy

Main article: Hydroelectricity

In hydro energy, the gravitational descent of a river is compressed from a long run to a single location with a dam or a flume. This creates a location where concentrated pressure and flow can be used to turn turbines or water wheels, which drive a mechanical mill or an electric generator. An electric generator, when there is excess energy available, can be run backwards as a motor to pump water back up for later use.

Pros

  • Hydroelectric power stations can promptly increase to full capacity, unlike other types of power stations. This is because water can be accumulated above the dam and released to coincide with peaks in demand.
  • Electricity can be generated constantly, because there are no outside forces, which affect the availability of water. This is in contrast to wind, solar or tidal power, all of which are far less reliable.
  • Hydroelectric power produces no waste or pollution, and does not contribute to global warming.

Cons

  • The construction of a dam can have a serious environmental impact on the surrounding areas. The amount and the quality of water downstream can be affected, which affects plant life both aquatic, and land-based. Because a river valley is being flooded, the delicate local habitat of many species is destroyed, while people living nearby may have to relocate their homes.
  • Dams are expensive to build, making the start-up costs of a hydroelectric power station very high.
  • Hydro electricity can only be used in areas where there is a large supply of water.

Nuclear Energy

Main article: Nuclear energy

Nuclear power stations work similar to fossil fuel power plants, except for the fact that the heat is produced by the reaction of uranium inside a nuclear reactor. The reactor uses uranium rods, which are split in the process of fission, releasing a large amount of energy. The process continues as a chain reaction with other nuclei takes place. The heat released heats water to create steam, which spins a turbine, producing electricity.

Pros

Cons

  • The waste produced from the nuclear fission of uranium is poisonous, and extremely radioactive, requiring constant and costly maintenance and monitoring at the storage sites. Moreover, the long-term disposal of the long-lived nuclear waste causes serious problems, since (unless the spent fuel is reprocessed) it takes from one to three thousand years for the spent fuel to come back to the natural radioactivity of the uranium ore body that was mined to produce it.
  • The operation of an uncontained nuclear reactor near human settlements can be catastrophic, as shown by the Chernobyl accident in the former Ukraine, where large areas of land were affected by nuclear fallout. Members of the public are hesitant about the safety of nuclear power.
  • Building a nuclear power plant requires a huge investment, and the costs of safe disassembling after it becomes obsolete (called decommissioning) must be included into the budget.
  • There can be connections between nuclear power and nuclear weapon proliferation, since both require large-scale uranium enrichment facilities.

Energy transportation

While new sources of energy are only rarely discovered or made possible by new technology, distribution technology continually evolves. The use of fuel cells in cars, for example, is an anticipated delivery technology. This section presents some of the more common delivery technologies that have been important to historic energy development. They all rely in some way on the energy sources listed in the previous section.

  • Fuels
Shipping is a flexible delivery technology that is used in the whole range of energy development regimes from primitive to highly advanced. Currently, coal,petroleum and their derivatives are delivered by shipping via boat, rail, or road. Petroleum and natural gas may also be delivered via pipeline. Refined hydrocarbon fuels such as gasoline and LPG may also be delivered via aircraft.
  • Electric grids

Image:Electricalgrid.jpg

Electricity grids are the networks used to transmit and distribute power from production source to end user, when the two may be hundreds of kilometres away. Sources include electrical generation plants such as a nuclear reactor, coal burning power plant, etc. A combination of sub-stations, transformers, towers, cables, and piping are used to maintain a constant flow of electricity.
Grids may suffer from transient blackouts and brownouts, often due to weather damage. During certain extreme space weather events solar wind can interfere with transmissions.
Grids also have a predefined carrying capacity or load that cannot safely be exceeded. When power requirements exceed what's available, failures are inevitable. To prevent problems, power is then rationed.
Industrialised countries such as Canada, the US, and Australia are among the highest per capita consumers of electricity in the world, which is possible thanks to a widespread electrical distribution network.
In the week of 3 August 2003, the US set an all-time national record for electricity use of 90,000 gigawatts. CurrentEnergy provides a realtime overview of the electricity supply and demand for California, Texas, and the Northeast of the US. African countries with small scale electrical grids have a correspondingly low annual per capita usage of electricity. One of the most powerful power grids in the world supplies power to the state of Queensland, Australia. This network's service provision and its administration is an ongoing issues for that states politicians.

Energy storage

Main article: Energy storage

While most fuels can be stored, electricity in itself cannot. For that reason, many methods of energy storage have been developed, which transform electrical energy into other forms of energy. A method of energy storage may be chosen based on stability, ease of transport, ease of energy release, or ease of converting free energy from the natural form to the stable form.

  • Chemical
Some natural forms of energy are found in stable chemical compounds such as fossil fuels. Most systems of chemical energy storage result from biological activity, which store energy in chemical bonds. Man-made forms of chemical energy storage include hydrogen fuel, batteries and explosives such as cordite and dynamite.
  • Gravitational
Dams can be used to store energy, by using excess energy to pump water into the reservoir. When electrical energy is required, the process is reversed. The water then turns a turbine, generating electricity. Hydroelectric power is currently an important part of the world's energy supply, generating one-fifth of the world's electricity. :[1].
Another example of gravitational energy storage is the counter-weight on elevators.
  • Electrical capacitance
Electrical energy may be stored in capacitors. These are often used to produce high intensity releases of energy (such as a camera's flash)
  • Mechanical
  • Pressure:
Energy may also be stored pressurised gases or alternatively in a vacuum. Compressed air, for example, may be used to operate vehicles and power tools. Large scale compressed air energy storage facilities are used to smooth out demands on electricity generation by providing energy during peak hours and storing energy during off-peak hours. Such systems save on expensive generating capacity since it only needs to meet average consumption rather than peak consumption.
  • Flywheels and springs
Energy can also be stored in mechanical systems such as springs or flywheels. Flywheel energy storage is currently being used for uninterruptible power supplies.

Image:Energyconsumption.jpg Image:Energyproduction.jpg

Historic energy development schemes

Human societies have relied and currently rely on various energy development schemes. Schemes that are most powerful are considered in the energy development field to be more advanced in that they contribute better to human comfort and freedom. As humans and societies move from more primitive energy development schemes to more advanced ones, it is typically said from an energy development point of view that they are advancing because the energy limits on comfort and freedom are shrinking. Sources and technologies in this section are presented in order of increasing energy development.

Future energy development

Main article: Future energy development

Extrapolations from current knowledge to future energy development offer a choice of energy futures. Some predictions parallel the Malthusian catastrophe hypothesis. Numerous are complex models based scenarios as pioneered by Limits to Growth. Modelling approaches offer ways to analyse diverse strategies, and hopefully find a road to rapid and sustainable development of humanity. Short term energy crises are also a concern of energy development.

Existing technologies for new energy sources, such as new renewable energy technologies, nuclear fission and fusion are promising, but need sustained research and development, including consideration of possible harmful side effects.

See also

References

  • Bilgen, S. and K. Kaygusuz, Renewable Energy for a Clean and Sustainable Future, Energy Sources 26, 1119 (2004).
  • Energy analysis of Power Systems, UIC Nuclear Issues Briefing Paper 57 (2004).


sl:Energija in razvoj

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