Geothermal Energy

Florian Ion Tiberiu Petrescu

Bucharest Polytechnic University, Romania

E-mail: petrescuflorian@yahoo.com

 

Relly Victoria Virgil Petrescu

Bucharest Polytechnic University, Romania

E-mail: petrescuvictoria@yahoo.com

 

 

ABSTRACT

 Geothermal energy is heat energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. The geothermal energy of the Earth's crust originates from the original formation of the planet and from radioactive decay of materials (in currently uncertain but possibly roughly equal proportions). The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface.

Keywords: New energy, Renewable energy, Sustainable energy, Geothermal energy

 

INTRODUCTION

Geothermal energy is heat energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. The geothermal energy of the Earth's crust originates from the original formation of the planet and from radioactive decay of materials (in currently uncertain but possibly roughly equal proportions). The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface. The adjective geothermal originates from the Greek roots γη (ge), meaning earth, and θερμος (thermos), meaning hot.

Earth's internal heat is thermal energy generated from radioactive decay and continual heat loss from Earth's formation. Temperatures at the core–mantle boundary may reach over 4000 °C (7,200 °F). The high temperature and pressure in Earth's interior cause some rock to melt and solid mantle to behave plastically, resulting in portions of the mantle convecting upward since it is lighter than the surrounding rock. Rock and water are heated in the crust, sometimes up to 370 °C (700 °F).

From hot springs, geothermal energy has been used for bathing since Paleolithic times and for space heating since ancient Roman times, but it is now better known for electricity generation. Worldwide, 11,700 megawatts (MW) of geothermal power is online in 2013. An additional 28 gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications as of 2010.

Geothermal power is cost-effective, reliable, sustainable, and environmentally friendly, but has historically been limited to areas near tectonic plate boundaries. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation. Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of fossil fuels.

The Earth's geothermal resources are theoretically more than adequate to supply humanity's energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources are very expensive. Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, subsidies, plate boundary movement and interest rates. Pilot programs like EWEB's customer opt in Green Power Program show that customers would be willing to pay a little more for a renewable energy source like geothermal. But as a result of government assisted research and industry experience, the cost of generating geothermal power has decreased by 25% over the past two decades. In 2001, geothermal energy costs between two and ten US cents per kWh.

Matherials and Methods

Hot springs have been used for bathing at least since Paleolithic times. The oldest known spa is a stone pool on China's Lisan mountain built in the Qin Dynasty in the 3rd century BC, at the same site where the Huaqing Chi palace was later built. In the first century AD, Romans conquered Aquae Sulis, now Bath, Somerset, England, and used the hot springs there to feed public baths and underfloor heating. The admission fees for these baths probably represent the first commercial use of geothermal power. The world's oldest geothermal district heating system in Chaudes-Aigues, France, has been operating since the 14th century. The earliest industrial exploitation began in 1827 with the use of geyser steam to extract boric acid from volcanic mud in Larderello, Italy.

In 1892, America's first district heating system in Boise, Idaho was powered directly by geothermal energy and was copied in Klamath Falls, Oregon in 1900. The first known building in the world to utilize geothermal energy as its primary heat source was the Hot Lake Hotel in Union County, Oregon, whose construction was completed in 1907. A deep geothermal well was used to heat greenhouses in Boise in 1926, and geysers were used to heat greenhouses in Iceland and Tuscany at about the same time. Charlie Lieb developed the first downhole heat exchanger in 1930 to heat his house. Steam and hot water from geysers began heating homes in Iceland starting in 1943.

In the 20th century, demand for electricity led to the consideration of geothermal power as a generating source. Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904, at the same Larderello dry steam field where geothermal acid extraction began. It successfully lit four light bulbs. Later, in 1911, the world's first commercial geothermal power plant was built there. It was the world's only industrial producer of geothermal electricity until New Zealand built a plant in 1958. In 2012, it produced some 594 megawatts.

Lord Kelvin invented the heat pump in 1852, and Heinrich Zoelly had patented the idea of using it to draw heat from the ground in 1912. But it was not until the late 1940s that the geothermal heat pump was successfully implemented. The earliest one was probably Robert C. Webber's home-made 2.2 kW direct-exchange system, but sources disagree as to the exact timeline of his invention. J. Donald Kroeker designed the first commercial geothermal heat pump to heat the Commonwealth Building (Portland, Oregon) and demonstrated it in 1946. Professor Carl Nielsen of Ohio State University built the first residential open loop version in his home in 1948. The technology became popular in Sweden as a result of the 1973 oil crisis and has been growing slowly in worldwide acceptance since then. The 1979 development of polybutylene pipe greatly augmented the heat pump’s economic viability.

In 1960, Pacific Gas and Electric began operation of the first successful geothermal electric power plant in the United States at The Geysers in California. The original turbine lasted for more than 30 years and produced 11 MW net power.

The binary cycle power plant was first demonstrated in 1967 in the USSR and later introduced to the US in 1981. This technology allows the generation of electricity from much lower temperature resources than previously. In 2006, a binary cycle plant in Chena Hot Springs, Alaska, came online, producing electricity from a record low fluid temperature of 57 °C (135 °F).

The International Geothermal Association (IGA) has reported that 10,715 megawatts (MW) of geothermal power in 24 countries is online, which was expected to generate 67,246 GWh of electricity in 2010. This represents a 20% increase in online capacity since 2005. IGA projects growth to 18,500 MW by 2015, due to the projects presently under consideration, often in areas previously assumed to have little exploitable resources.

In 2010, the United States led the world in geothermal electricity production with 3,086 MW of installed capacity from 77 power plants. The largest group of geothermal power plants in the world is located at The Geysers, a geothermal field in California. The Philippines is the second highest producer, with 1,904 MW of capacity online. Geothermal power makes up approximately 27% of Philippine electricity generation.

In 2016, Indonesia set in third with 1,647 MW online behind USA at 3,450 MW and the Philippines at 1,870 MW, but Indonesia will become second due to an additional online 130 MW at the end of 2016 and 255 MW in 2017. Indonesia's 28,994 MW is the largest geothermal reserves in the world, and it is predicted to overtake the USA in the next decade.

Results and Discussion

Installed geothermal electric capacity

Country

Capacity (MW)2007[16]

Capacity (MW)2010[31]

Percentage of nationalelectricity production

Percentage of globalgeothermal production

United States

2687

3086

0.3

29

Philippines

1969.7

1904

27

18

Indonesia

992

1197

3.7

11

Mexico

953

958

3

9

Italy

810.5

843

1.5

8

New Zealand

471.6

628

10

6

Iceland

421.2

575

30

5

Japan

535.2

536

0.1

5

Iran

250

250

El Salvador

204.2

204

25

Kenya

128.8

167

11.2

Costa Rica

162.5

166

14

Nicaragua

87.4

88

10

Russia

79

82

Turkey

38

82

Papua-New Guinea

56

56

Guatemala

53

52

Portugal

23

29

China

27.8

24

France

14.7

16

Ethiopia

7.3

7.3

Germany

8.4

6.6

Austria

1.1

1.4

Australia

0.2

1.1

Thailand

0.3

0.3

TOTAL

9,981.9

10,959.7

 

Geothermal electric plants were traditionally built exclusively on the edges of tectonic plates where high-temperature geothermal resources are available near the surface. The development of binary cycle power plants and improvements in drilling and extraction technology enable enhanced geothermal systems over a much greater geographical range. Demonstration projects are operational in Landau-Pfalz, Germany, and Soultz-sous-Forêts, France, while an earlier effort in Basel, Switzerland was shut down after it triggered earthquakes. Other demonstration projects are under construction in Australia, the United Kingdom, and the United States of America.

The thermal efficiency of geothermal electric plants is low, around 10–23% because geothermal fluids do not reach the high temperatures of steam from boilers. The laws of thermodynamics limit the efficiency of heat engines in extracting useful energy. Exhaust heat is wasted, unless it can be used directly and locally, for example in greenhouses, timber mills, and district heating. System efficiency does not materially affect operational costs as it would for plants that use fuel, but it does affect return on the capital used to build the plant. In order to produce more energy than the pumps consume, electricity generation requires relatively hot fields and specialized heat cycles.[citation needed] Because geothermal power does not rely on variable sources of energy, unlike, for example, the wind or solar, its capacity factor can be quite large – up to 96% has been demonstrated. The global average was 73% in 2005.

Geothermal energy comes in either vapor-dominated or liquid-dominated form. Larderello and The Geysers are vapor-dominated. Vapor-dominated sites offer temperatures from 240 to 300 °C that produces superheated steam.

Liquid-dominated plants

Liquid-dominated reservoirs (LDRs) were more common with temperatures greater than 200 °C (392 °F) and are found near young volcanoes surrounding the Pacific Ocean and in rift zones and hot spots. Flash plants are the common way to generate electricity from these sources. Pumps are generally not required, powered instead when the water turns to steam. Most wells generate 2-10 MWe. Steam is separated from a liquid via cyclone separators, while the liquid is returned to the reservoir for reheating/reuse. As of 2013, the largest liquid system is Cerro Prieto in Mexico, which generates 750 MWe from temperatures reaching 350 °C (662 °F). The Salton Sea field in Southern California offers the potential of generating 2000 MWe.

Lower temperature LDRs (120–200 °C) require pumping. They are common in extensional terrains, where heating takes place via deep circulation along faults, such as in the Western US and Turkey. Water passes through a heat exchanger in a Rankine cycle binary plant. The water vaporizes an organic working fluid that drives a turbine. These binary plants originated in the Soviet Union in the late 1960s and predominate in new US plants. Binary plants have no emissions.

 

Thermal energy

Lower temperature sources produce the energy equivalent of 100M BBL per year. Sources with temperatures of 30–150 °C are used without conversion to electricity as district heating, greenhouses, fisheries, mineral recovery, industrial process heating and bathing in 75 countries. Heat pumps extract energy from shallow sources at 10–20 °C in 43 countries for use in space heating and cooling. Home heating is the fastest-growing means of exploiting geothermal energy, with the global annual growth rate of 30% in 2005 and 20% in 2012.

Approximately 270 petajoules (PJ) of geothermal heating was used in 2004. More than half went for space heating, and another third for heated pools. The remainder supported industrial and agricultural applications. Global installed capacity was 28 GW, but capacity factors tend to be low (30% on average) since heat is mostly needed in winter. Some 88 PJ for space heating was extracted by an estimated 1.3 million geothermal heat pumps with a total capacity of 15 GW.

Heat for these purposes may also be extracted from co-generation at a geothermal electrical plant.

Heating is cost-effective at many more sites than electricity generation. At natural hot springs or geysers, water can be piped directly into radiators. In hot, dry ground, earth tubes or downhole heat exchangers can collect the heat. However, even in areas where the ground is colder than room temperature, heat can often be extracted with a geothermal heat pump more cost-effectively and cleanly than by conventional furnaces. These devices draw on much shallower and colder resources than traditional geothermal techniques. They frequently combine functions, including air conditioning, seasonal thermal energy storage, solar energy collection, and electric heating. Heat pumps can be used for space heating essentially anywhere.

Iceland is the world leader in direct applications. Some 92.5% of its homes are heated with geothermal energy, saving Iceland over $100 million annually in avoided oil imports. Reykjavík, Iceland has the world's biggest district heating system, often used to heat pathways and roads to hinder the accumulation of ice. Once known as the most polluted city in the world, it is now one of the cleanest.

 

Enhanced geothermal

Enhanced geothermal systems (EGS) actively inject water into wells to be heated and pumped back out. The water is injected under high pressure to expand existing rock fissures to enable the water to freely flow in and out. The technique was adapted from oil and gas extraction techniques. However, the geologic formations are deeper and no toxic chemicals are used, reducing the possibility of environmental damage. Drillers can employ directional drilling to expand the size of the reservoir.

Small-scale EGS have been installed in the Rhine Graben at Soultz-sous-Forêts in France and at Landau and Insheim in Germany.

Geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost fluctuations. However, capital costs are significant. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks. A typical well doublet (extraction and injection wells) in Nevada can support 4.5 megawatts (MW) and costs about $10 million to drill, with a 20% failure rate.

In total, electrical plant construction and well drilling cost about €2–5 million per MW of electrical capacity, while the break–even price is 0.04–0.10 € per kW·h. Enhanced geothermal systems tend to be on the high side of these ranges, with capital costs above $4 million per MW and break–even above $0.054 per kW·h in 2007. Direct heating applications can use much shallower wells with lower temperatures, so smaller systems with lower costs and risks are feasible. Residential geothermal heat pumps with a capacity of 10 kilowatts (kW) are routinely installed for around $1–3,000 per kilowatt. District heating systems may benefit from economies of scale if demand is geographically dense, as in cities and greenhouses, but otherwise, piping installation dominates capital costs. The capital cost of one such district heating system in Bavaria was estimated at somewhat over 1 million € per MW. Direct systems of any size are much simpler than electric generators and have lower maintenance costs per kW·h, but they must consume electricity to run pumps and compressors. Some governments subsidize geothermal projects.

Geothermal power is highly scalable: from a rural village to an entire city.

The most developed geothermal field in the United States is The Geysers in Northern California.

Geothermal projects have several stages of development. Each phase has associated risks. At the early stages of reconnaissance and geophysical surveys, many projects are canceled, making that phase unsuitable for traditional lending. Projects moving forward from the identification, exploration and exploratory drilling often trade equity for financing.

The Earth's internal thermal energy flows to the surface by conduction at a rate of 44.2 terawatts (TW) and is replenished by radioactive decay of minerals at a rate of 30 TW. These power rates are more than double humanity’s current energy consumption from all primary sources, but most of this energy flow is not recoverable. In addition to the internal heat flows, the top layer of the surface to a depth of 10 meters (33 ft) is heated by solar energy during the summer, and releases that energy and cools during the winter.

Outside of the seasonal variations, the geothermal gradient of temperatures through the crust is 25–30 °C (77–86 °F) per kilometer of depth in most of the world. The conductive heat flux averages 0.1 MW/km2. These values are much higher near tectonic plate boundaries where the crust is thinner. They may be further augmented by fluid circulation, either through magma conduits, hot springs, hydrothermal circulation or a combination of these.

A geothermal heat pump can extract enough heat from the shallow ground anywhere in the world to provide home heating, but industrial applications need the higher temperatures of deep resources. The thermal efficiency and profitability of electricity generation are particularly sensitive to temperature. The most demanding applications receive the greatest benefit from a high natural heat flux, ideally from using a hot spring. The next best option is to drill a well into a hot aquifer. If no adequate aquifer is available, an artificial one may be built by injecting water to hydraulically fracture the bedrock. This last approach is called hot dry rock geothermal energy in Europe, or enhanced geothermal systems in North America. A Much greater potential may be available from this approach than from conventional tapping of natural aquifers.

Estimates of the potential for electricity generation from geothermal energy vary sixfold, from .035to2TW depending on the scale of investments. Upper estimates of geothermal resources assume enhanced geothermal wells as deep as 10 kilometers (6 mi), whereas existing geothermal wells are rarely more than 3 kilometers (2 mi) deep. Wells of this depth is now common in the petroleum industry. The deepest research well in the world, the Kola superdeep borehole, is 12 kilometers (7 mi) deep.

According to the Geothermal Energy Association (GEA) installed geothermal capacity in the United States grew by 5%, or 147.05 MW, the last annual survey in March 2012. This increase came from seven geothermal projects that began production in 2012. GEA also revised its 2011 estimate of installed capacity upward by 128 MW, bringing current installed U.S. geothermal capacity to 3,386 MW.

Geothermal power is considered to be renewable because any projected heat extraction is small compared to the Earth's heat content. The Earth has an internal heat content of 1031 joules (3·1015 TW·hr), approximately 100 billion times current (2010) worldwide annual energy consumption. About 20% of this is residual heat from planetary accretion, and the remainder is attributed to higher radioactive decay rates that existed in the past. Natural heat flows are not in equilibrium, and the planet is slowly cooling down on geologic timescales. Human extraction taps a minute fraction of the natural outflow, often without accelerating it.

Geothermal power is also considered to be sustainable thanks to its power to sustain the Earth’s intricate ecosystems. By using geothermal sources of energy present generations of humans will not endanger the capability of future generations to use their own resources to the same amount that those energy sources are presently used. Further, due to its low emissions geothermal energy is considered to have excellent potential for mitigation of global warming.

Even though geothermal power is globally sustainable, extraction must still be monitored to avoid local depletion. Over the course of decades, individual wells draw down local temperatures and water levels until a new equilibrium is reached with natural flows. The three oldest sites, at Larderello, Wairakei, and the Geysers have experienced reduced output because of local depletion. Heat and water, in uncertain proportions, were extracted faster than they were replenished. If production is reduced and water is reinjected, these wells could theoretically recover their full potential. Such mitigation strategies have already been implemented at some sites. The long-term sustainability of geothermal energy has been demonstrated at the Lardarello field in Italy since 1913, at the Wairakei field in New Zealand since 1958, and at The Geysers field in California since 1960.

Geothermal energy is the heat contained within the Earth that gives rise to numerous geological phenomena. The expression geothermal energy, however, is used nowadays to indicate the fraction of the Earth’s thermal energy that can, or could be extracted and exploited by man. Geothermal resources represent an important form of renewable and sustainable energy that is currently adopted in many parts of the world (Dickson and Fanelli, 2003). Volcanoes, geysers, thermal springs, fumaroles and other such surface phenomena will certainly have led our ancestors to suspect that parts of the Earth’s the interior was hot. However, it was only between the Sixteenth and Seventeenth century, when the first mines were excavated to a few hundred meters depth, that temperature was discovered to increase with depth.

The first temperature measurement using a the thermometer was probably that of M. De Gensanne in a mine near Belfort, France, in 1740 (de Buffon, 1778). From 1870 onwards, the Earth’s thermal regime was studied with modern scientific methods, but it wasn’t until the Twentieth century, and the discovery of the role of radiogenic heat, that such phenomena as the Earth’s heat balance and its thermal history were fully understood. All modern thermal models of the Earth must include the heat continuously generated by the decay of the long-life radioactive isotopes of uranium (238U, 235U), thorium (232Th) and potassium (40K) present in the Earth’s interior (Lubimova, 1969).

Other sources of heat, whose contribution is, however, less easy to define, include the Earth’s inherited (thermal) heat, gravitational energy and the kinetic an energy of the tides. Realistic thermal models were not available until the 1980s, when it was demonstrated that there is a lack of equilibrium between the heat produced by the decay of radioactive isotopes present in the Earth’s interior and the heat dispersed from the Earth’s surface into the atmosphere; in other words, it became clear that our planet is slowly cooling down.

In the heat balance developed by Frank D. Stacey and David E. Loper, the total heat dissipated from the Earth’s surface was evaluated at 421012W (conduction, convection, and radiation); the heat flow from the mantle alone, which represents 82% of the Earth’s total volume (see the below Fig.), was estimated at 10.31012 W (Stacey and Loper, 1988). More recent calculations, using far more data, give a surface heat flow value that is 6% higher than that reported by Stacey and Loper. Cooling of the Earth’s mantle is consequently taking place at a slightly faster pace than estimated by these authors, but our planet is, in any the case, cooling very slowly. The temperature of the mantle, approximately 4,000°C at its base, has decreased by 300-350°C at the most over three billion years. It has been estimated that the total thermal the energy contained within the Earth, assuming an average surface temperature of 15°C, is in the order of 12.61024 MJ, and that the thermal energy contained in the crust is in the order of 5.41021 MJ (Armstead, 1983). The Earth’s thermal energy is therefore immense, but only a part of it can be exploited by man. So far, its utilization has been limited to areas in which the geological conditions allow a vector (water in the liquid or vapor phase) to transport the thermal energy from deep hot zones too, or near to, the surface, creating what is commonly known as geothermal resources.

 

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Aversa, R., R.V. Petrescu, A. Apicella and F.I.T. Petrescu, 2016i. Mitochondria are naturally micro robots-a review. Am. J. Eng. Applied Sci., 9: 991-1002.

Aversa, R., R.V. Petrescu, A. Apicella and F.I.T. Petrescu, 2016j. We are addicted to vitamins C and E-A review. Am. J. Eng. Applied Sci., 9: 1003-1018.

Aversa, R., R.V. Petrescu, A. Apicella and F.I.T. Petrescu, 2016k. Physiologic human fluids and swelling behavior of hydrophilic biocompatible hybrid ceramo-polymeric materials. Am. J. Eng. Applied Sci., 9: 962-972.

Aversa, R., R.V. Petrescu, A. Apicella and F.I.T. Petrescu, 2016l. One can slow down the aging through antioxidants. Am. J. Eng. Applied Sci., 9: 1112-1126.

Aversa, R., R.V. Petrescu, A. Apicella and F.I.T. Petrescu, 2016m. About homeopathy or jSimilia similibus curenturk. Am. J. Eng. Applied Sci., 9: 1164-1172.

Aversa, R., R.V. Petrescu, A. Apicella and F.I.T. Petrescu, 2016n. The basic elements of life's. Am. J. Eng. Applied Sci., 9: 1189-1197.

Aversa, R., F.I.T. Petrescu, R.V. Petrescu and A. Apicella, 2016o. Flexible stem trabecular prostheses. Am. J. Eng. Applied Sci., 9: 1213-1221.

Mirsayar, M.M., V.A. Joneidi, R.V.V. Petrescu,    F.I.T. Petrescu and F. Berto, 2017 Extended MTSN criterion for fracture analysis of soda lime glass. Eng. Fracture Mechanics 178: 50-59.     DOI: 10.1016/j.engfracmech.2017.04.018

Petrescu, R.V. and F.I. Petrescu, 2013a. Lockheed Martin. 1st Edn., CreateSpace, pp: 114.

Petrescu, R.V. and F.I. Petrescu, 2013b. Northrop. 1st Edn., CreateSpace, pp: 96.

Petrescu, R.V. and F.I. Petrescu, 2013c. The Aviation History or New Aircraft I Color. 1st Edn., CreateSpace, pp: 292.

Petrescu, F.I. and R.V. Petrescu, 2012. New Aircraft II. 1st Edn., Books On Demand, pp: 138.

Petrescu, F.I. and R.V. Petrescu, 2011. Memories About Flight. 1st Edn., CreateSpace, pp: 652.

Petrescu, F.I.T., 2009. New aircraft. Proceedings of the 3rd International Conference on Computational Mechanics, Oct. 29-30, Brasov, Romania.

Petrescu, F.I., Petrescu, R.V., 2016a Otto Motor Dynamics, GEINTEC-GESTAO INOVACAO E TECNOLOGIAS, 6(3):3392-3406.

Petrescu, F.I., Petrescu, R.V., 2016b Dynamic Cinematic to a Structure 2R, GEINTEC-GESTAO INOVACAO E TECNOLOGIAS, 6(2):3143-3154.

Petrescu, F.I., Petrescu, R.V., 2014a Cam Gears Dynamics in the Classic Distribution, Independent Journal of Management & Production, 5(1):166-185.

Petrescu, F.I., Petrescu, R.V., 2014b High Efficiency Gears Synthesis by Avoid the Interferences, Independent Journal of Management & Production, 5(2):275-298.

Petrescu, F.I., Petrescu R.V., 2014c Gear Design, ENGEVISTA, 16(4):313-328.

Petrescu, F.I., Petrescu, R.V., 2014d Balancing Otto Engines, International Review of Mechanical Engineering 8(3):473-480.

Petrescu, F.I., Petrescu, R.V., 2014e Machine Equations to the Classical Distribution, International Review of Mechanical Engineering 8(2):309-316.

Petrescu, F.I., Petrescu, R.V., 2014f Forces of Internal Combustion Heat Engines, International Review on Modelling and Simulations 7(1):206-212.

Petrescu, F.I., Petrescu, R.V., 2014g Determination of the Yield of Internal Combustion Thermal Engines, International Review of Mechanical Engineering 8(1):62-67.

Petrescu, F.I., Petrescu, R.V., 2014h Cam Dynamic Synthesis, Al-Khwarizmi Engineering Journal, 10(1):1-23.

Petrescu, F.I., Petrescu R.V., 2013a Dynamic Synthesis of the Rotary Cam and Translated Tappet with Roll, ENGEVISTA  15(3):325-332.

Petrescu, F.I., Petrescu, R.V., 2013b Cams with High Efficiency, International Review of Mechanical Engineering 7(4):599-606.

Petrescu, F.I., Petrescu, R.V., 2013c An Algorithm for Setting the Dynamic Parameters of the Classic Distribution Mechanism, International Review on Modelling and Simulations 6(5B):1637-1641.

Petrescu, F.I., Petrescu, R.V., 2013d Dynamic Synthesis of the Rotary Cam and Translated Tappet with Roll, International Review on Modelling and Simulations 6(2B):600-607.

Petrescu, F.I., Petrescu, R.V., 2013e Forces and Efficiency of Cams, International Review of Mechanical Engineering 7(3):507-511.

Petrescu, F.I., Petrescu, R.V., 2012a Echilibrarea motoarelor termice, Create Space publisher, USA, November 2012, ISBN 978-1-4811-2948-0, 40 pages, Romanian edition.

Petrescu, F.I., Petrescu, R.V., 2012b Camshaft Precision, Create Space publisher, USA, November 2012, ISBN 978-1-4810-8316-4, 88 pages, English edition.

Petrescu, F.I., Petrescu, R.V., 2012c Motoare termice, Create Space publisher, USA, October 2012, ISBN 978-1-4802-0488-1, 164 pages, Romanian edition.

Petrescu, F.I., Petrescu, R.V., 2011a Dinamica mecanismelor de distributie, Create Space publisher, USA, December 2011, ISBN 978-1-4680-5265-7, 188 pages, Romanian version.

Petrescu, F.I., Petrescu, R.V., 2011b Trenuri planetare, Create Space publisher, USA, December 2011, ISBN 978-1-4680-3041-9, 204 pages, Romanian version.

Petrescu, F.I., Petrescu, R.V., 2011c Gear Solutions, Create Space publisher, USA, November 2011, ISBN 978-1-4679-8764-6, 72 pages, English version.

Petrescu, F.I. and R.V. Petrescu, 2005. Contributions at the dynamics of cams. Proceedings of the 9th IFToMM International Symposium on Theory of Machines and Mechanisms, (TMM’ 05), Bucharest, Romania, pp: 123-128.

Petrescu, F. and R. Petrescu, 1995. Contributii la sinteza mecanismelor de distributie ale motoarelor cu ardere internã. Proceedings of the ESFA Conferinta, (ESFA’ 95), Bucuresti, pp: 257-264.

Petrescu, FIT., 2015a Geometrical Synthesis of the Distribution Mechanisms, American Journal of Engineering and Applied Sciences, 8(1):63-81. DOI: 10.3844/ajeassp.2015.63.81

Petrescu, FIT., 2015b Machine Motion Equations at the Internal Combustion Heat Engines, American Journal of Engineering and Applied Sciences, 8(1):127-137. DOI: 10.3844/ajeassp.2015.127.137

Petrescu, F.I., 2012b Teoria mecanismelor – Curs si aplicatii (editia a doua), Create Space publisher, USA, September 2012, ISBN 978-1-4792-9362-9, 284 pages, Romanian version, DOI: 10.13140/RG.2.1.2917.1926

Petrescu, F.I., 2008. Theoretical and applied contributions about the dynamic of planar mechanisms with superior joints. PhD Thesis, Bucharest Polytechnic University.

Petrescu, FIT.; Calautit, JK.; Mirsayar, M.; Marinkovic, D.; 2015 Structural Dynamics of the Distribution Mechanism with Rocking Tappet with Roll, American Journal of Engineering and Applied Sciences, 8(4):589-601. DOI: 10.3844/ajeassp.2015.589.601

Petrescu, FIT.; Calautit, JK.; 2016 About Nano Fusion and Dynamic Fusion, American Journal of Applied Sciences, 13(3):261-266.

Petrescu, R.V.V., R. Aversa, A. Apicella, F. Berto and S. Li et al., 2016a. Ecosphere protection through green energy. Am. J. Applied Sci., 13: 1027-1032. DOI: 10.3844/ajassp.2016.1027.1032

Petrescu, F.I.T., A. Apicella, R.V.V. Petrescu, S.P. Kozaitis and R.B. Bucinell et al., 2016b. Environmental protection through nuclear energy. Am. J. Applied Sci., 13: 941-946.

Petrescu, F.I., Petrescu R.V., 2017 Velocities and accelerations at the 3R robots, ENGEVISTA 19(1):202-216.

Petrescu, RV., Petrescu, FIT., Aversa, R., Apicella, A., 2017 Nano Energy, Engevista, 19(2):267-292.

Petrescu, RV., Aversa, R., Apicella, A., Petrescu, FIT., 2017 ENERGIA VERDE PARA PROTEGER O MEIO AMBIENTE, Geintec, 7(1):3722-3743.

Aversa, R., Petrescu, RV., Apicella, A., Petrescu, FIT., 2017 Under Water, OnLine Journal of Biological Sciences, 17(2): 70-87.

Aversa, R., Petrescu, RV., Apicella, A., Petrescu, Fit., 2017 Nano-Diamond Hybrid Materials for Structural Biomedical Application, American Journal of Biochemistry and Biotechnology, 13(1): 34-41.

Syed, J., Dharrab, AA., Zafa, MS., Khand, E., Aversa, R., Petrescu, RV., Apicella, A., Petrescu, FIT., 2017 Influence of Curing Light Type and Staining Medium on the Discoloring Stability of Dental Restorative Composite, American Journal of Biochemistry and Biotechnology 13(1): 42-50.

Aversa, R., Petrescu, RV., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Chen, G., Li, S., Apicella, A., Petrescu, FIT., 2017 Kinematics and Forces to a New Model Forging Manipulator, American Journal of Applied Sciences 14(1):60-80.

Aversa, R., Petrescu, RV., Apicella, A., Petrescu, FIT., Calautit, JK., Mirsayar, MM., Bucinell, R., Berto, F., Akash, B., 2017 Something about the V Engines Design, American Journal of Applied Sciences 14(1):34-52.

Aversa, R., Parcesepe, D., Petrescu, RV., Berto, F., Chen, G., Petrescu, FIT., Tamburrino, F., Apicella, A., 2017 Processability of Bulk Metallic Glasses, American Journal of Applied Sciences 14(2): 294-301.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Calautit, JK., Apicella, A., Petrescu, FIT., 2017 Yield at Thermal Engines Internal Combustion, American Journal of Engineering and Applied Sciences 10(1): 243-251.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 Velocities and Accelerations at the 3R Mechatronic Systems, American Journal of Engineering and Applied Sciences 10(1): 252-263.

Berto, F., Gagani, A., Petrescu, RV., Petrescu, FIT., 2017 A Review of the Fatigue Strength of Load Carrying Shear Welded Joints, American Journal of Engineering and Applied Sciences 10(1):1-12.

Petrescu, RV., Aversa, R.,  Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 Anthropomorphic Solid Structures n-R Kinematics, American Journal of Engineering and Applied Sciences 10(1): 279-291.

Aversa, R., Petrescu, RV., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Chen, G., Li, S., Apicella, A., Petrescu, FIT., 2017 Something about the Balancing of Thermal Motors, American Journal of Engineering and Applied Sciences 10(1):200-217.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 Inverse Kinematics at the Anthropomorphic Robots, by a Trigonometric Method, American Journal of Engineering and Applied Sciences, 10(2): 394-411.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Calautit, JK., Apicella, A., Petrescu, FIT., 2017 Forces at Internal Combustion Engines, American Journal of Engineering and Applied Sciences, 10(2): 382-393.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 Gears-Part I, American Journal of Engineering and Applied Sciences, 10(2): 457-472.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 Gears-Part II, American Journal of Engineering and Applied Sciences, 10(2): 473-483.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 Cam-Gears Forces, Velocities, Powers and Efficiency, American Journal of Engineering and Applied Sciences, 10(2): 491-505.

Aversa, R., Petrescu, RV., Apicella, A., Petrescu, FIT., 2017 A Dynamic Model for Gears, American Journal of Engineering and Applied Sciences, 10(2): 484-490.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Kosaitis, S., Abu-Lebdeh, T., Apicella, A., Petrescu, FIT., 2017 Dynamics of Mechanisms with Cams Illustrated in the Classical Distribution, American Journal of Engineering and Applied Sciences, 10(2): 551-567.

Petrescu, RV., Aversa, R., Akash, B., Bucinell, R., Corchado, J., Berto, F., Mirsayar, MM., Kosaitis, S., Abu-Lebdeh, T., Apicella, A., Petrescu, FIT., 2017 Testing by Non-Destructive Control, American Journal of Engineering and Applied Sciences, 10(2): 568-583.

Petrescu, RV., Aversa, R., Li, S., Mirsayar, MM., Bucinell, R., Kosaitis, S., Abu-Lebdeh, T., Apicella, A., Petrescu, FIT., 2017 Electron Dimensions, American Journal of Engineering and Applied Sciences, 10(2): 584-602.

Petrescu, RV., Aversa, R., Kozaitis, S., Apicella, A., Petrescu, FIT., 2017 Deuteron Dimensions, American Journal of Engineering and Applied Sciences, 10(3).

Petrescu RV., Aversa R., Apicella A., Petrescu FIT., 2017 Transportation Engineering, American Journal of Engineering and Applied Sciences, 10(3).

Petrescu RV., Aversa R., Kozaitis S., Apicella A., Petrescu FIT., 2017 Some Proposed Solutions to Achieve Nuclear Fusion, American Journal of Engineering and Applied Sciences, 10(3).

Petrescu RV., Aversa R., Kozaitis S., Apicella A., Petrescu FIT., 2017 Some Basic Reactions in Nuclear Fusion, American Journal of Engineering and Applied Sciences, 10(3).

Petrescu, Relly Victoria; Aversa, Raffaella; Akash, Bilal; Bucinell, Ronald; Corchado, Juan; Berto, Filippo; Mirsayar, MirMilad; Apicella, Antonio; Petrescu, Florian Ion Tiberiu; 2017a Modern Propulsions for Aerospace-A Review, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, Relly Victoria; Aversa, Raffaella; Akash, Bilal; Bucinell, Ronald; Corchado, Juan; Berto, Filippo; Mirsayar, MirMilad; Apicella, Antonio; Petrescu, Florian Ion Tiberiu; 2017b Modern Propulsions for Aerospace-Part II, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, Relly Victoria; Aversa, Raffaella; Akash, Bilal; Bucinell, Ronald; Corchado, Juan; Berto, Filippo; Mirsayar, MirMilad; Apicella, Antonio; Petrescu, Florian Ion Tiberiu; 2017c History of Aviation-A Short Review, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, Relly Victoria; Aversa, Raffaella; Akash, Bilal; Bucinell, Ronald; Corchado, Juan; Berto, Filippo; Mirsayar, MirMilad; Apicella, Antonio; Petrescu, Florian Ion Tiberiu; 2017d Lockheed Martin-A Short Review, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, Relly Victoria; Aversa, Raffaella; Akash, Bilal; Corchado, Juan; Berto, Filippo; Mirsayar, MirMilad; Apicella, Antonio; Petrescu, Florian Ion Tiberiu; 2017e Our Universe, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, Relly Victoria; Aversa, Raffaella; Akash, Bilal; Corchado, Juan; Berto, Filippo; Mirsayar, MirMilad; Apicella, Antonio; Petrescu, Florian Ion Tiberiu; 2017f What is a UFO?, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, RV., Aversa, R., Akash, B., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 About Bell Helicopter FCX-001 Concept Aircraft-A Short Review, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, RV., Aversa, R., Akash, B., Corchado, J., Berto, F., Mirsayar, MM., Apicella, A., Petrescu, FIT., 2017 Home at Airbus, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, RV., Aversa, R., Akash, B., Corchado, J., Berto, F., Mirsayar, MM., Kozaitis, S., Abu-Lebdeh, T., Apicella, A., Petrescu, FIT., 2017 Airlander, Journal of Aircraft and Spacecraft Technology, 1(1).

Petrescu, RV., Aversa, R., Akash, B., Corchado, J., Berto, F., Apicella, A., Petrescu, FIT., 2017 When Boeing is Dreaming – a Review, Journal of Aircraft and Spacecraft Technology, 1(1).

History of aviation, From Wikipedia, the free encyclopedia. Retrieved from: https://en.wikipedia.org/wiki/History_of_aviation

History of ballooning, From Wikipedia, the free encyclopedia. Retrieved from: https://en.wikipedia.org/wiki/History_of_ballooning

Airship, From Wikipedia, the free encyclopedia. Retrieved from: https://en.wikipedia.org/wiki/Airship

 

 

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