1) So far, what did we talk about in this class regarding Geothermal Energy and
ID: 118097 • Letter: 1
Question
1) So far, what did we talk about in this class regarding Geothermal Energy and Resources. Summarize it with 2-3 sentences. 2) Is there any difference between heat and temperature? If so, what is it? 3) There are three ways of heat transfer in the subsurface Name them and explain one of hem. 4) Use the term "Larderello" in two sentences. 5) Please explain these two units: MW and mW/m. 6) What are the top 5 countries of the world you think they have high installed geothermal electricity generating 7) How and where do we use geothermal water in non- 8) Where do we see the locations of geothermal power 9) High temperature (TC>150) geothermal resources are capacity? electric applications? plants in the world? generally used fo purposes. 10) Give me one example of high temperature geothermal resource power plant name What are the two main types of high temperature geothermal resources? 11) What is principle of "heat pumps"? 12) What is the principle of "binary power plant"? 13) How is the relation between geothermal energy production and the environment? 14) What are the surface manifestation of geothermal water resources?Explanation / Answer
A - Geothermal energy is derived from the heat generated within the earth.It is used either for heating purposes or for generating electricity. This heat is produced by radioactive elements and earth’s core that transfers it to the surface by convection processes. Geothermal energy is called a renewable energy source because the water is replenished and the heat is continuously produced by the earth.
2 – Difference between Heat and Temperature
A – Heat - It is the amount of energy that flows from an object at a higher temperature to a lower one.
Temperature – It is the measurement of the amount of heat.
3) 3 ways of Heat transfer in subsurface
A – 1) Conduction
2 – Convection
3 – Radiation
RADIATION – Heat is emitted by the decay of Radioactive elements like Uranium, Thorium and transferred to rocks. The heat is transferred to neighboring rocks either by conduction or convection.
4- Use the term ‘ Lardarello’ in two sentences
A – Lardarello is a volcanically active province in Northern Italy. The heated metamorphic rocks and the fluids circulating in them make Larderello a prominent location for Geothermal energy production
5) Explain MW and mW/m2
A – MW – MegaWatts – A unit of power in SI system measured as 1 X 106 Joules/second amount of work done in joules per second.
mW/m2 – milliwatt per sq meter – a measure of power density or amount of power per unit volume
6) Top 5 countries
A –
7) How and where do we usegeothermal water in non-electric operations?
A – Where – Heating purposes - in spas or to heat buildings, grow crops, warm fish ponds. In Iceland and in France geothermal heat is used for heating public buildings, schools, and homes. In the United States, geothermal heat pumps are used in 45 states to heat and cool homes and buildings. Idaho, Oregon, Nevada, and some other states use geothermal energy to heat entire districts. Heat from geothermal resources is also used to dry ceramics, lumber, vegetables, and other products.
How – Use of Heat pumps (mechanism explained below)
8) Where do we see Geothermal plants in the world?
A – They are mainly located in regions experiencing active faulting, volcanic action (Iceland, Alaska-valley of 10000 smokes), active plate boundaries (Ring of fire region -b ounded by Japan, the Philippines, the Aleutian Islands, North America, Central America, and South America.)
9) High temperature Geothermal resource (>150 C) are used for GENERATING ELECTRICITY
10) One example of high temperature Geothermal resource power plant
A – Nesjavellir Geothermal power station, Iceland
What are the two main types of high temperature Geothermal resources?
11) What is the principle of “heat pumps”
A - A geothermal heat pump transfers heat to or from the ground. Earth is used as a heat source in winter and a heat sink in summer. It reduces operational costs of heating and cooling systems in geothermal energy set-up.
12) What is the principle of binary power plant?
A – Binary power plants uses two sources of power generation. In geothermal plant, Binary cycle power plants transfers heat from hot water which is at a lower temperature(100°–300°F) than the conventional hot springs to another fluid. This fluid (isobutene isopentane) has a lower boiling point than water. The secondary fluid vaporizes, turns the turbines and drives the generators. The remaining secondary fluid is recycled. The geothermal water is condensed and returned to the reservoir.
13) How is the relation between Geothermal energy and the environment?
A – If hotwater is drawn from deeper source, then it releases gases like CO2, H2S, Ch4, NH3 which are greenhouse gases. However, appropriate emission exhaust systems reduce the outflow of these gases.
In addition to dissolved gases, trace amounts of toxic elements such as mercury, arsenic, boron, and antimony are also found in hot water. As the water cools down, these chemicals precipitate and released to the environment. Today however, the fluids are pumped back inside the earth to reduce environmental damage. But pumping inside the earth may pollute Groundwater.
Geothermal systems run on pumps and compressors. If they are fuelled by Geothermal energy itself then it is environmentally friendly. But if a fossil fuel is used for this purpose, then it damages the environment.
Also there are chances of land subsidence where Geothermal energy plants are located. Hydraulic fracturing for induced heat transfer may cause minor earthquakes in future.
Therefore Geothermal energy, although a clean source of energy, produces damaging effects on the environment.
14) What are the surface manifestations of Geothermal water resources?
A – 1) Hot-water springs,
are surface manifestations of Geothermal water resources.
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