Introduction to Renewable Energy Sources
Renewable energy sources are defined as the energy sources that exist in abundance in our natural environment (sun, biomass, wind, etc.). It is the first form of energy that man used, almost exclusively until the beginning of the last century, when he turned to the intense use of coal and hydrocarbons. The interest in the better utilization of renewable energy sources, as well as the development of reliable and economically acceptable technologies that bind their potential, was initially presented after the first oil crisis of 1973, strengthened after the second crisis of 1979 and consolidated in the last decade, after in the meantime global environmental problems were realized. The advantages of renewable energy sources and their substantial contribution to the energy independence of humanity from exhaustible energy resources justify this shift. For many countries renewable energy is a domestic source of energy, with potential for development at national and local levels. They contribute significantly to their energy balance and contribute to reducing dependence on expensive imported oil and strengthening the security of their energy supply. At the same time, they play a key role in the effort to protect the environment, since it has been established for years that the energy sector is mainly responsible for environmental pollution. Almost 95% of air pollution and a significant part of thermal pollution is due to the production, transformation and use of conventional fuels (coal and oil). It seems that the only way for the E.U. to reach the ambitious goal set in 1992, i.e. to limit CO2 emissions to 1993 levels by the year 2000, is to accelerate the development of renewable energy sources.
Main forms of renewable energy sources. The main forms of renewable energy sources are: Renewable Energy Sources (Photovoltaics, Wind turbines, geothermal energy, hydraulic energy)
1. Solar energy
The economics of using solar systems to replace electricity is undeniable. Solar energy is harnessed with technologies that exploit both the sun's heat and electromagnetic waves. The technologies used for the exploitation of solar energy are:
- a) energy solar systems. They convert solar radiation into heat, usually replacing energy sources such as oil,
- b) passive solar and hybrid systems. They concern appropriate architectural solutions and the use of such building materials that maximize the direct exploitation of solar energy for heating, cooling or lighting. The potential of Greece for the application of passive systems and techniques of bioclimatic architecture is great, due to the great sunshine and the mild climate, which contribute to the creation of thermal comfort with simple and economical methods. The economic viability of passive systems is also due to the fact that in our country there is a large consumption of fuel, both for heating and for electricity, with a corresponding increase in CO2 emissions into the atmosphere.
- c) Photovoltaic solar systems. They convert solar energy directly into electricity. The largest photovoltaic systems have been installed in our country by PPC. These applications concern the production of electricity for the islands and the electrification of small villages. A large number of photovoltaic systems, more than 350, of smaller
ENERGY TECHNOLOGY IN AGRICULTURE
but power, have been installed by the Navy's Lighthouse Service. An even larger number have been installed by private individuals to power country houses, small hotel units, monasteries, etc. These facilities have been built without any financial support from the state.
2. Wind energy
It is the kinetic energy produced by the force of the wind and converted into mechanical or electrical energy. Our country is located in the temperate zone, where excellent wind conditions prevail, while the terrain is favorable for the utilization of wind energy. Greece's wind potential is one of the best in Europe. The country's total exploitable wind potential can cover a large part of its electrical needs, especially those of the islands.
3. Geothermal
Geothermal fluids, in addition to their therapeutic properties, can also be used for energy purposes. Geothermal energy is a mild and relatively renewable energy source, which with today's technological data can cover a significant percentage of the country's energy needs.
The possibilities of energy utilization of geothermal fluids are not well known to the inhabitants of many regions of Greece. Excluded is the use of geothermal fluids for heating greenhouses, an application that is relatively widespread in our country, particularly in regions of northern Greece and on the islands of the northern Aegean, where over 150 acres of geothermal greenhouses have been installed.
Other applications besides the use of geothermal energy in heating greenhouses are district heating, fish farms, drying of agricultural products, desalination of water (seawater or even geothermal) and others.
4. Hydraulic energy
Uses waterfalls with the aim of producing electricity or transforming it into absorbable mechanical energy. Taking into account the significant hydropower advantages of Greece, hundreds of locations scattered throughout the Greek territory await the installation of small hydroelectric projects, in the direction of exploiting the local renewable potential.
According to relevant research, the country's theoretical hydro potential is in the order of tens of billions of kilowatt hours per year and it is possible to install hundreds of small hydroelectric projects in small or large watercourses that will utilize a part of the total untapped Greek micro-hydroelectric potential. The supremacy of the micro-hydropower potential is highlighted, mainly of the mountainous arc of Epirus - Macedonia - Thrace and the mountain range of Pindos, which starts from Macedonia and Thessaly and reaches Sterea, but also the great potential of the mountainous masses of the Peloponnese and Crete .
5. Biomass
It is the result of photosynthetic activity, which transforms solar energy through a series of processes of plant organisms of terrestrial or aquatic origin. There are two forms of biomass: any kind of remains of plant or animal origin and biomass derived from plants cultivated for this purpose (energy crops).
The remains are divided into two categories:
- a. Residues remaining in the field or in the forest after the main product has been taken, such as grain stubble, cotton stalks, branches left in the forest after the timber has been taken, etc.
- b. Residues remaining in factories processing agricultural and forestry products, such as heartwood, sawdust from sawmills, etc. To these should be added the garbage of the cities, which to a large extent consist of biomass residues. In Greece, the utilization of residues (straw, cotton stalks, forest residues, etc.) for energy production could save 1.6 million tons of oil equivalent. While today biomass covers only 5% of the country's energy needs, with the utilization of agricultural and forest residues the percentage would rise to 13%. Therefore, the utilization of agricultural and forest residues left in the fields and forests can provide three times more energy than all the hydroelectric plants of the country give us today.
However, the amount of biomass from residues is definitely limited, both at the European and Greek level. On the other hand, where there are huge margins is in the utilization of "energy crops" and biomass plants in general. It has already been reported that 200 million hectares remain fallow every year in the EU, while significant areas are cultivated and their products end up in landfills. All these areas could easily be used with the above plants.
Energy crops are plants grown for the production of liquid, gaseous or even solid fuels. Typical cases are the cultivation of sugar cane in Brazil, maize in the USA, sugar beet in France and rapeseed in various European countries for the production of liquid fuels (Table 9-1).
ENERGY TECHNOLOGY IN AGRICULTURE Table 9-1
Source: Center for Renewable Energy Sources (K.A.P.E.) In addition to the above, both in Europe and globally, many other plants are being examined and tested, such as sweet sorghum (for alcohol production from its stems), the mischanthos (for energy production, chipboard manufacturing and maybe paper pulp making), wild artichoke, reed (energy plant, chipboards and paper pulp) etc. (Figs. 9-4, 9-5, 9-6). |
Use of Energy Sources
Usually the use and application of innovative technologies has positive as well as negative effects in various sectors of society. Indicatively, the use of automation and robotics technologies in various applications, in addition to the positive consequences, also has negative ones as it destroys some jobs, which before the introduction of these technologies were necessary to carry out some tasks. The mechanization of the first textile units in England during the first industrial revolution, resulted in the substitution of many manual workers by machines, resulting in the development at that time of the Luddite movement. In recent decades we have seen the IT and internet revolution, which has resulted in the elimination of many jobs that were previously required to process information and communicate between people, machines and businesses.
But the use of renewable energy sources, in contrast to the use of fossil fuels and nuclear energy, has mainly positive consequences as shown below.
Overview of Renewable Energy Sources
Renewable energy comes from natural and virtually inexhaustible sources such as the sun, wind, water and plants. Any energy source considered "renewable" cannot be used up or depleted and must be renewed frequently (within an average human lifetime) and naturally.
Furthermore, renewable energy is not the same thing as clean or green energy. While many renewable energy sources are considered clean energy, this term specifically refers to the environmental impact of an energy source. This is why nuclear power can be considered, in some circles, clean (but not green).
Green energy is actually a subset of renewable energy, representing the most environmentally beneficial resources. Includes:
- Solar power
- Wind power
- Geothermal energy
- Biogas energy
- Biomass energy
- Low impact hydropower
Renewable energy sources that are not considered green include:
- Large scale hydropower
- Energy from the combustion of solid waste
Renewable energy sources reduce the carbon footprint
We are all more aware of how our actions affect the environment. It's more than straws and sea turtles. From the clothes we buy and the food we eat to the electricity that powers family movie night, nearly every choice we make affects the environment. We just might not know it.
These daily decisions make up the carbon footprint, a metric used to calculate environmental impact. As you might have guessed, using renewable energy in your home reduces your carbon footprint by "offsetting" or replacing the need for fossil fuel emissions with zero-emission energy sources like wind and solar power.
So rethinking your home's energy source is an important way to reduce your carbon footprint.
Renewable energy sources reduce harmful air pollutants
When fossil fuels are burned to create electricity, they react with oxygen to form nitrogen oxide, or NOx, a dangerous greenhouse gas. Not only can the gas create smog and acid rain, it reacts chemically to produce ground-level ozone, a harmful air pollutant. Stratospheric ozone, known as the ozone layer, protects us from harmful UV rays emitted by the sun. However, ground-level or tropospheric ozone can cause a variety of health problems, including:
- Cough
- Throat irritation
- Inflammation of the airways
- Decreased lung function
- Damaged lung tissue
Ground-level ozone is created by a combination of heat, sunlight, and volatile organic compounds (especially man-made chemicals used and produced in the manufacture of paints, pharmaceuticals, and refrigerants).
Renewable energy sources do not release nitrogen oxides when they generate electricity. So not only do renewable energy sources not release greenhouse gases, but they also reduce our carbon footprint and help offset the need for fossil fuel energy that can contribute to excessive air pollution in urban areas
ENVIRONMENTAL BENEFITS FROM THE USE OF RES
In the era of sustainable development and climate change that we live in, the use of renewable energy sources reduces the addition of greenhouse gases (mainly carbon dioxide) to the atmosphere that are released from the burning of fossil fuels. At the same time, air pollution with particles, soot and gaseous pollutants such as sulfur dioxide and nitrogen oxides is reduced. The thermal pollution of the atmosphere and water resources caused by the use of fossil fuels and nuclear energy is avoided by the use of renewable energy sources.
At the same time, the use of exhaustible natural resources such as oil, coal, natural gas and Uranium, which are finite on the planet, is avoided and renewable and inexhaustible energy resources are used instead.
The extraction of fossil fuels and uranium results in the degradation of the environment in the areas where the mining takes place, as one can see with a visit to the lignite mines of Kozani, Ptolemaida or Megalopolis Arcadia. At the same time, there is the risk of a major environmental accident, and a relatively recent case is the BP subsea oil rig disaster in the Gulf of Mexico, which created a major environmental disaster. Similar environmental disasters have been created by marine accidents of ships carrying oil.
ENERGY BENEFITS FROM THE USE OF RES
The energy benefits from the use of RES for a country like Greece, which bases its production of energy and energy products on domestic but polluting lignite and imported oil and natural gas, are many and specific.
Any dependence that exists on imported oil and natural gas is reduced by their gradual substitution by domestic renewable energy resources, thereby reducing the country's energy dependence. The increased energy dependence makes the country more insecure, but also vulnerable to geopolitical upheavals and changes that happen every day.
Therefore, the substitution of imported fossil fuels with domestic renewable energy resources improves the country's energy independence and security. At the same time, PPC's needs for investments in new electricity generation facilities from fossil fuels are decreasing.
FINANCIAL BENEFITS FROM THE USE OF RES
The use of renewable energy sources for the production of energy and energy products creates many economic benefits that include:
a) The increase of investments in facilities for the utilization of renewable energy sources.
b) The creation of new businesses in these sectors, but also in the production of biomass for its energy utilization.
c) The improvement of the country's trade balance due to the reduction of fossil fuel imports.
d) The possibility of small and medium enterprises and private investors operating in the production of energy and energy products which was previously not possible as in these sectors and especially in the production of electricity from fossil fuels, large companies were traditionally active.
e) The promotion of regional development by the creation of many small and medium-sized energy production companies in various remote areas of the Greek region.
F) The increase of the gross national product due to the production of energy from RES.
SOCIAL BENEFITS FROM THE USE OF RES
The use of renewable energy sources entails many social benefits that include:
a) The creation of new jobs for the construction, operation and maintenance of energy production facilities and energy products from RES. This is especially important today when unemployment in the country is at very high levels.
b) The creation of businesses utilizing RES in remote areas with few alternative ways of development. Usually the utilization of RES is done in areas far from the urban centers of the country.
c) The creation of companies for the production, processing and standardization of biomass for energy use in areas far from urban centers where people are employed and where there are not many alternative ways of employment.
CONCLUSION: Renewable Energy Sources are Surprisingly Profitable in Southern Europe but Surprisingly Unprofitable in Northern Europe
TECHNOLOGICAL BENEFITS FROM THE USE OF RES
The utilization of renewable energy sources and the creation of businesses in these sectors promotes innovation and the development of new technologies in the energy sector.
The creation of businesses in the field of A.P.E. it contributes to the increase of research in these fields, to the activity of more scientists and engineers in new energy technologies and ultimately to the increase of innovations in the field of RES.
At the same time, the promotion of investments in new energy technologies results in the technological upgrading of the country's production potential with the creation of technologically modern renewable energy production facilities.
Therefore, the use of renewable energy sources has multiple benefits at local, regional and national level. Given that the disadvantages of the use of RES are minimal, their further development in Greece is currently the only way forward. It remains only to find the optimal distribution of the burdens that will be shouldered by the various social groups at least for as long as financial support from the state is required for the promotion of certain new energy technologies.
The main advantages of Renewable Energy Sources (RES) are the following:
- They are practically inexhaustible sources of energy and contribute to reducing dependence on exhaustible conventional energy resources
- They are domestic sources of energy and contribute to strengthening energy independence and the security of energy supply at the national level
-They are geographically scattered and lead to the decentralization of the energy system, making it possible to cover energy needs at local and regional level, thus relieving infrastructure systems and reducing energy transmission losses
-They offer the possibility of rational utilization of energy resources , covering a wide range of users' energy needs (e.g. solar energy for low-temperature heat, wind energy for power generation)
-They usually have low operating costs that are not affected by the fluctuations of the international economy and in particular the prices of conventional fuels
- RES exploitation facilities are designed to meet the needs of users and in small-scale applications or large-scale, respectively, they have a short construction period, thus allowing a quick response of energy supply to demand
- RES investments are labor intensive , creating a significant number of new jobs, especially at the local level
-They can in many cases be a nucleus for the revitalization of economically and socially degraded areas and a pole for local development, by promoting similar investments (e.g. greenhouse crops using geothermal energy)
-They are friendly to the environment and people and their utilization is generally accepted by the public
The Chernobyl nuclear accident took place on April 26, 1986, in reactor no. 4 of the Chernobyl Nuclear Power Plant of the Soviet Union, which today is located on the territory of Ukraine.
The accident was in the category of the maximum predicted accident on the International Nuclear Event Scale, seriously disrupted the economic and social conditions prevailing in the surrounding areas and had significant environmental and health impacts.
As a result of the accident, 2 of the station's workers died on the spot. Within four months, 28 firefighters who rushed to the scene died from radiation and heat burns, and 19 additional deaths were recorded up to 2004.
In addition, it is estimated that the health of hundreds of thousands of people was affected due to environmental radiation exposure. . Percentage increases in cancers were over 15% in exposed populations, with thousands of cancer and leukemia deaths linked to the accident.The devastation caused by the accident was seen in its aftermath: the site was evacuated, there was a large radioactive leak, many people were exposed to radiation, and workers left their workplaces.The media later referred to the incident as a large-scale disaster, referring to it as a nuclear accident, and also estimated that the damage caused to Chernobyl had catastrophic consequences for the rest of Europe as well.
It took two full months after the start of the Fukushima nuclear crisis for the management company Tepco to finally admit that the partial core meltdown in reactor 1 occurred just 5 hours after the earthquake and tsunami on March 11, 2011, followed by a total core meltdown 16 hours later. The situation at the Fukushima nuclear power plant is currently ranked at the upper levels of the impact scale.
Japan's nuclear crisis is worse than Three Mile Island. Both the Japanese and French nuclear safety authorities confirm that the radiation leak was significant. The French nuclear authority (ASN) rates the accident a 5 or 6 on the International Nuclear and Radiological Events Scale (INES), instead of a 4 as originally announced. An accident with "local consequences" is classified as category 5, while an accident with "wider consequences" is classified as 6. The Chernobyl accident was a level 7, "major accident" and the most serious in the history of nuclear power.
What Happened at Fukushima
It all started on Friday, March 11, 2011, when Enceladus struck about 70 kilometers northeast of the coast of Japan, with one of the five strongest earthquakes recorded in modern times, measuring 9 on the Richter scale. The earthquake triggered a powerful tsunami, with waves reaching a height of 40.5 meters and sweeping away everything in their path. Sixteen thousand Japanese lost their lives, 6,000 were wounded, 3,500 are still missing. Roads, ports and railway lines suffered enormous damage, fires broke out in many areas, a dam collapsed. About 4.4 million households were left without electricity and 1.5 million without water.
The worst thing was that the nuclear threat "awakened". The tsunami severely damaged the Fukushima Daiichi nuclear power plant and set off a race against time to prevent the meltdown of three of its seven nuclear reactors. Contamination was eventually contained but not avoided: the radioactivity released was equivalent to a Chernobyl, and hundreds of thousands of citizens evacuated the area within a radius of 80 kilometers.
The most expensive natural disaster of all time, with a cost of 181 billion euros, took place in just 24 hours.
Last October experts from the International Atomic Energy Agency traveled to Japan to help clean up extensive areas around the Fukushima nuclear power plant contaminated by radiation. Specifically, a group of 12 international experts and IAEA members led by Juan Carlos Ledijo, responsible for radiation protection at the Spanish Nuclear Safety Council, visited Japan from October 7 to 15, responding to a request from the Japanese authorities.
The intervention of the IAEA is an indication of the difficulty of cleaning up the area around the Fukushima nuclear power plant. IAEA director Yukiya Amano said last month that Japan "doesn't have enough experience" to carry out the task.
According to the Japanese Ministry of the Environment, the extent of the contaminated areas can reach 2,400 square kilometers.
Ten months after the accident, the Japanese, armed with determination and an emergency financing of 120 billion euros, have already repaired two-thirds of the damage.
The... insecurity of nuclear reactors
According to the company's announcement, the temperatures inside reactor 1 reached 2,800°C, the fuel melted and collected at the bottom of the pressure vessel where cracks were created. As a result, the radioactivity that leaked from the core spread to the ground and the sea with the cooling water.
“The delay in finding out exactly what happened in the reactor after the earthquake and tsunami demonstrates once again the complete failure of the nuclear industry to face the seriousness of the situation and the inherent dangers of nuclear power. Tepco should have known that the water pumped into Reactor 1 would be contaminated with high levels of radioactivity. It is infuriating that the company did not do more to prevent massive amounts of radioactive water from leaking into the sea. The result is that long-lived radioactive pollution has spread to the east coast of Japan, exposing the marine environment to serious and long-term risks," said Jan Beránek, head of the anti-nuclear campaign at Greenpeace International.
Greenpeace scientists measure radioactivity in Namie, 30 kilometers from the Fukushima Daiichi nuclear plant, on March 26, 2011. (photo by Christian ijlund / Greenpeace)
“The nuclear industry claimed that incidents like the one at Fukushima could not happen in this type of reactor, following the experience gathered from previous incidents. The Japanese authorities were too slow to admit they were wrong. In the face of Tepco's new admissions, the nuclear industry's claims about the safety of nuclear reactors are crumbling. It is now clear that we cannot leave our safety and public health in the hands of the nuclear industry," added Beránek.
What was wrong?
Press questions: 'Is Japan to blame for the accident?' or "Did the accident happen because the reactors are old or poorly built in a seismic zone?" it is reasonable for them to arise after such an accident. Before assigning blame, we should realize that nuclear technology is inherently dangerous, associated with unavoidable risks and accidents are very serious and have long-lasting effects. Nuclear power will always be prone to accidents related to human error, design failure and natural disasters. There are much better, safer, economical and reliable solutions. Nuclear power is simply not worth the risk.
Despite the fact that Japan has some of the best engineers and nuclear scientists in the world, and despite the fact that its reactors are believed to be designed to withstand earthquakes, the accident was not avoided. However, the regulations regarding site selection for a nuclear power plant have changed since Fukushima was built.
We remind you that Japan has 54 reactors in 18 nuclear power plants. The total installed capacity is 47,000MW which for 2010 covered 29% of electricity generation.
Four nuclear power plants are located on the east bank near the epicenter: Onagawa (3 reactors), Fukushima-Daiichi (6 reactors), Fukushima Daini (4 reactors) and Tokai (1 reactor). These reactors use Boiling Water Reactors and were commissioned in the 1970s and 1980s. The nearest station is Kashiwazaki-Kariwa (7 reactors) located on the opposite (west) shore of Honshu Island (the largest island of Japan – this is where Tokyo is located). There are many nuclear power plants with similar technology in Europe and America.
We note that of Japan's total of 54 nuclear reactors, only ten are now operational.
• The accident at the Mayak nuclear fuel processing station in Russia in 1957 (INES category 6), the effects of which are still being felt today, more than half a century later.
• The accident at the Three Mile Island nuclear power plant, in the USA in 1979 (INES category 5).
• The Tokaimura nuclear power plant accident in 1999 (INES category 4) where two workers died from excessive radiation exposure.
• The 1977 Bohunitsa nuclear power plant accident (INES category 4) which was kept secret by the Soviet authorities for decades.
• The near meltdown of one of the reactors at Sweden's Forsmark nuclear power plant in 2006 (INES category 2)
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