Week 1 (Lec 1-4) - Physics of Renewable Energy Systems PDF

E L P T N PHYSICS OF RENEWABLE ENERGY SYSTEMS Prof. AMREESH CHANDRA DEPARTMENT OF PHYSICS, IIT KHARAGPUR Module 1 Basics of energy systems Lecture 1: Introduction and relevance of the course CONCEPTS COVERED Basic introduction...

E L P T N PHYSICS OF RENEWABLE ENERGY SYSTEMS Prof. AMREESH CHANDRA DEPARTMENT OF PHYSICS, IIT KHARAGPUR Module 1 Basics of energy systems Lecture 1: Introduction and relevance of the course CONCEPTS COVERED Basic introduction E L T Renewable and non-renewable energy sources P – Basic definition N Relevance of renewable energy sources to India Limitations of renewable energy sources Need for alternative energy storage devices KEY POINTS E L T ⮚ Defining Mtoe P ⮚ Need for energy N ⮚ Renewable, non-renewable, primary and secondary sources of energy  PHYSICS SYSTEMS a) ‘The science of matter, motion a) We will consider mostly the physical and energy.’ and engineering systems. RENEWABLE ENERGY L b) The laws can be expressed using b) Comprises of a set of interacting mathematical formulations. elements, components (mechanical, E c) The physical experiments and electrical, …), which together a) Energy comes from a natural and perform a desired task by following T theory models are used persistent flow of energy that complementary for obtaining a a set of rules in a designated order. occurs in the environment. P consistent framework. c) It can be severely influenced by its b) A term, which is closed associated d) But the subject is continuously environment or boundary conditions. with renewable sources, is: N evolving! ‘sustainability’. e) Therefore, a law can be modified, if ‘new’ observations and experiments makes it necessary. The way we will proceed? In most of the discussions, we will addressing the following: 1) Why? (2) What? (3) Where? (4) When? (5) How? Examples: E L T 1) Why do we need to move towards renewable based energy systems? P 2) What are renewables? 3) Where do we use renewables? N 4) When should we use renewable based energy systems? 5) How do me make renewable based systems? and so on… Lets start… E L P T N Why is the course relevant in the present scenario? L Let is look into a very recent document, published in 2020, by the NITI Aayog (India) i.e.: Towards a Clean Energy Economy: Post-COVID-19 Opportunities for T E P India’s Energy and Mobility Sectors N Available at RMI India: www.rmi-india.org/insight/india-stimulus-strategy-recommendations-towards-a-clean-energy-economy/ Some of the major statements from the documents are: 1) India’s transport sector can save 1.7 gigatonnes of cumulative carbon dioxide emissions and avoid about 600 million tonnes of oil equivalent (Mtoe) in fuel demand by 2030 through shared, electric, and connected passenger mobility and cost-effective, clean, and optimized freight transport. L 2) Significant savings are also achievable in the power sector through the adoption of renewable energy, E energy storage, efficiency, and flexibility. T 3) In the power sector, major opportunities include improving electricity distribution business and operations, P enabling renewables and distributed energy resources, and promoting energy resilience and local N manufacturing of renewable energy and energy storage technologies. 4) The following principles can help guide initiatives and investments in India’s clean energy future at this time: (i) invest in least-cost energy solutions (ii) support resilient and secure energy systems, (iii) prioritize efficiency and competitiveness, and (iv) promote social and environmental equity  Mtoe and World energy scenario 2020 in Mtoe DEFINITION: Mtoe ≡ Megatonne of oil equivalent According to the International Energy Agency, L 1 toe = 11.63 megawatt-hours E = 41.868 GJ T = 10 Gcal NP Ref: Global Energy Statistical Yearbook 2020  Energy Consumption and Available Resources 1) Energy is indispensable and essential for our lives. L Question: Why: E Our bodies need energy to function. Required for lighting, heating, communication, transport, manufacturing, and the list can go on… P T Therefore, let us consider the general characteristics of energy sources and the N need or way by which one form of energy can be transformed to other? Question for the class: can you estimate the energy a normal adult consumes in a 24 hour period and where does this energy come from? [Hint: chemical energy stored in food] Another example: Power consumption by household appliances E L P T N A typical all India daily load curve Ref 1: DOI 10.1016/j.enbuild.2018.06.034 Ref 2: http://www.iitk.ac.in/npsc/Papers/ NPSC2016/1570293957.pdf https://letsavelectricity.com/wattage-power-consumption-of-household-appliances/ BUT, please remember: ❖ No source of energy is cheap. ❖ They all have some E Lform of T environmental impact. ❖ N P Therefore, consumption in an efficient manner is absolutely essential.  WHAT ARE: E L P T N The energy sources listed are also called as “primary energy sources”. Electricity is described as a “secondary energy source”, as it is derived from the conversion of energy from a primary source. Non-renewable energy sources A non-renewable energy sources are finite stores of energy, come from naturally occurring resources, which get depleted on consumption and cannot be replenished at a L speed comparable to its consumption. Therefore, they are not sustainable in the longer E term. T Renewable energy sources N P A renewable energy sources are naturally available, ensure persistent/ continuous flow of energy, while ensuring compatibility with the term: ‘sustainability’ EACH HAVE THEIR OWN ADVANTAGES AND DISADVANTAGES! Question to the class: Can you list some of them?  1. Electricity is India’s largest greenhouse gas-emitting sector, accounting for 34 percent of total emissions in 2016–2017 (Ref. 1,2). 2. Coal continues to dominate India’s electricity supply, L accounting for 55 percent of installed capacity and 72 percent of generation in 2019–2020 (ref. 3) E 3. Renewables installed capacity has seen rapid growth (see T adjacent figure). 4. In India, solar and wind have become the lowest-cost P electricity sources, even without subsidy. N 5. Comparing countries, the cost of solar in India has consistently been among the lowest in the world. 6. The government has established a national renewable energy target of 175 GW of solar and wind by 2022 and 500 GW by 2030. Figure: Compounded Annual Growth Rate (CAGR) for Various Energy Sources, 2011–2019. References: 1) NITI Aayog Document 2) “CAIT—Country Greenhouse Gas Emissions Data,” World Resources Institute, accessed 20 May 2020, https://www.wri.org/resources/data-sets/cait- country-greenhouse-gas-emissions-data 3) Executive Summary on Power Sector, Government of India, Ministry of Power, and Central Electricity Authority, March 2020, http://cea.nic.in/reports/ monthly/executivesummary/2020/exe_ summary-03.pdf Another factor, which is indicated: NEED FOR ENERGY STORAGE L Energy storage technology will play a key role in the overall clean energy transition. E Renewable energy’s intermittence requires that it be connected to energy storage to compete directly with fossil fuels. T These two markets will drive substantial demand for energy storage systems in India P over the coming decade. India’s energy storage market in 2030 is expected to be worth Rs 1 lakh crore across N the electric vehicle, stationary storage, consumer electronics, rail, and defence sectors. As India’s battery manufacturing capacity grows, 60 percent or more of the total economic activity of domestic battery cell demand can be captured within the country, “despite limited domestic reserves of raw materials”. THEREFORE, IN THIS COURSE, WE WILL ALSO DEVOTE SIGNIFICANT TIME ON UNDERSTANDING ENERGY STORAGE DEVICES, USEFUL FOR INDIA. Summarizing Brief introduction to the subject was presented. L The relevance of the course, in context to India, was discussed. E T Renewable and non-renewable energy sources were also defined. P The requirement for energy storage devices, in renewable based N future energy landscape, would have become clear. REFERENCES E L P T ⮚ “Physics of Energy Sources” by George C. King N ⮚ “Advance Renewable Energy Systems” by S. C. Bhatia. ⮚ “Physics and Technology of Sustainable energy” by E. L. Wolf ⮚ www.rmi-india.org/insight/india-stimulus-strategy-recommendations-towards-a- clean-energy-economy/  E L P T N  E L P T N PHYSICS OF RENEWABLE ENERGY SYSTEMS Prof. AMREESH CHANDRA DEPARTMENT OF PHYSICS, IIT KHARAGPUR Module 1 Basics of energy systems Lecture 2: Energy sources In the first lecture, we covered the following points: 1) Introduction to the course E L T 2) Renewable and non-renewable sources P 3) Definition of Mtoe and its usefulness N 4) Need for energy storage devices CONCEPTS TO BE COVERED IN THIS LECTURE L ⮚ Classification of energy sources, according to their nature. E ⮚ Introduction to: T ✓ P Thermal energy sources N ✓ Mechanical energy sources ✓ Photovoltaic sources KEY POINTS ⮚ Renewable energy sources are essential for sustainable energy growth. E L T ⮚ Reducing production cost of renewable energy conversion processes P would make them economically viable. N  The main sources of energy, which are available to us Fossil Fuel Geothermal E L Nuclear Waves and tides P T Solar Hydroelectric Wind N Biofuels EACH HAVE THEIR ADVANTAGES AND LIMITATIONS Lets us see the advantages and limitations of few of the earlier mentioned resources: EXAMPLE 1: FOSSIL FUELS [ As we know, these are obtained from the decomposition of the remains of plants L and animals] E ADVANTAGES: Highly standardized infrastructure and technologies already exist, which facilitates large scale use. T The energy density of the petroleum based fuels, in terms of volume and mass, is superior to most of the P alternative energy sources. Presently, they continue to be more commercial, economical and also allow decentralized use. N LIMITATIONS: o They are not SUSTAINABLE. o The efficiency of conversion of fuel energy into mechanical energy continues to be ~ 30% (±). o The resulting heat and gaseous emissions raise environmental concerns. o The energy supply and associate security has geopolitical issues. o The extraction of fossil fuels add to complications. EXAMPLE 2: GEOTHERMAL ENERGY [ harnesses the heat energy present underneath the earth] ADVANTAGES: Is becoming economically viable is some areas. The cost of installation/ implementation/ deployment is low. L High uptime; can run continuously day and night. Low maintenance cost, after installation. E The associated power stations are smaller in comparison to hydroelectric or tidal plants. T Does not lead to air or water pollution, if operated/ utilized correctly. N P LIMITATIONS: o Can extract small amounts of minerals such as sulphur. These must be removed before the feeding the turbine and reinjecting the water into the injection well. o Require locations that have suitable subterranean temperature within 5 km of surface. o During the construction of power stations, geological instability may occur, which can have serious consequences. EXAMPLE 3: HYDROELECTRIC ENERGY [ harnessed from the ENERGY in WATER. Mostly, the downward flowing river is forced to a single location with a dam or a flume. This concentrated pressure and flow can be utilized to operate turbines or water wheels, which are connected to electrical or mechanical converters] L ADVANTAGES: E Can lead to significant increase in the full capacity. T By maintaining water flow, electricity generation process is stable and nearly constant. Once installed, the power stations lead to low pollutions. P Is renewable and sustainable. LIMITATIONS: o Cannot be installed everywhere! N o Construction leads to serious socio-, political-, economical and environmental issues. o Failure of containment areas can have catastrophic consequences. o Requires long transmission lines. EXAMPLE 4: SOLAR ENERGY [uses solar radiation as the primary source] ADVANTAGES: Imparts no fuel costs, is renewable and sustainable. Large scale implementation (both grid and off-grid) L Many different types of applications. E Cost of steadily falling. Has seen lot of science and technology development. LIMITATIONS: P T N o Intermittent. o Requirement of a DC to AC converter; leads to energy loss. o Energy payback time is still limiting large scale use, without subsidy. Similarly, other energy sources have their E L T own advantages and limitations…! N P  L Broad classification of energy sources T E N P According to the kind of energy they deliver, the sources can be broadly classified as: Thermal Energy Sources E L T Mechanical Energy Sources N P Photovoltaic Sources  E L T Thermal Energy Sources N P  Thermal energy sources These are sources, which store chemical energy in a form of potential energy associated with the chemical bonds of the molecules of a fuel. The burning the fuel breaks the bond and release energy, mostly in L the form of thermal energy. T E Reference: Silva et al. Environmental performance assessment of For example, building products based on Life Cycle Assessment. a) Nuclear fission reactions release potential energy stored in the P nuclei that undergo fission and convert it into thermal energy in the N core of the reactor. b) Conventional coal fired power plants. The conversion of thermal energy into mechanical energy is governed by the laws of thermodynamics. The efficiency is controlled by the conversion process.  E L Mechanical Energy Sources P T N  Mechanical energy sources L These sources deliver mechanical energy directly E (eg. wind turbine). P T N ❖ The thermodynamic limitations of thermal to mechanical energy conversion are avoided. ❖ The efficiency can be significantly higher than other processes.  E L Photovoltaic Sources P T N Photovoltaic sources A photovoltaic system can directly convert sunlight into electrical energy. E L T Immediate consequence: able to avoid the thermodynamic limitations of thermal to P mechanical energy. N However, there are a large number of other factors that limit the efficiency of the solar based - systems and conversion processes, which we will see later. CONCLUSIONS 1) There are a large of energy sources, which can be useful to us. 2) Each of the energy sources have their own advantages and limitations. L 3) The energy sources can be broadly: T Thermal Energy Sources E N P Mechanical Energy Sources Photovoltaic Sources REFERENCES L ⮚ “Physics of Energy Sources” by George C. King E ⮚ “Advance Renewable Energy Systems” by S. C. Bhatia. P T N  E L P T N  E L P T N PHYSICS OF RENEWABLE ENERGY SYSTEMS Prof. AMREESH CHANDRA DEPARTMENT OF PHYSICS, IIT KHARAGPUR Module 1 Basics of energy systems Lecture 3 : Solar Radiation CONCEPTS COVERED E L ⮚ Solar energy and spectrum P T N ⮚ Scattering of solar radiation ⮚ Important parameters to explain the incident solar radiation ⮚ Examples of solar based devices KEY POINTS E L T ⮚ Solar energy – Classic example of renewable source. P ⮚ Solar spectrum N ⮚ Solar energy available at a point/ surface  L Our main source E T of energy – N Ref: Google images P The SUN Our main source of energy – The SUN E L P T N  Solar Radiations E L P T N 99% of the energy of solar radiation of contained in the wavelength band: 0.15 to 4 µm. The electromagnetic radiations received from SUN include radio-waves, infrared, visible, ultraviolet, X-rays to gamma rays. Ref.: https://serc.carleton.edu/download/images/3786/e-m_spectrum.gif THERMOSPHERE 90km As solar radiation passes through the Earth’s atmosphere, ‘depletion’ occurs. 80km L MESOSPHERE 70km A E L 60km T T I 50km T P U 40km D N STRATOSPHERE E 30km 20km 10km TROPOSPHERE  Depletion in solar radiation occur due to the simultaneously occurring processes viz., (i) Selective absorption by molecular oxygen, ozone, CO2, L water vapour. E (ii) Rayleigh scattering molecules of different gases. (iii) Mie scattering T Nearly half of the scattered radiation is lost to space; the P remaining move towards the earth’s surface from N different directions as diffuse radiation. Considerable depletion can also occur in a cloudy atmosphere.  Few related but useful information 1) The fraction of the total solar radiant energy reflected back to space, due to the reasons discussed previously, is called albedo of the earth-atmosphere system and has L a value of ~0.30 for the earth as a whole. E 2) Depending upon latitude, altitude and season, the mean monthly value of direct solar T radiation, normal to the solar beam, which is received in India at 12 noon varies from P 0.51 to 1.05kW/m2. N 3) The solar radiation intensity falling on a surface is called irradiance or insolation and is measured in W/m2 or kW/m2. 4) The total amount of solar radiation energy is called irradiation (J/m2). It is denoted by H. 5) At the surface of the Sun, intensity of solar radiation is ~ 6.33 x 107 W/m2. Ref. Book - Adv. Ren. Ener. Sys. (Part I) by S C Bhatia, WPI Press (2014) Let us consider an imaginary surface, which is perpendicular to the sun rays reaching the earth. The solar constant (Isc) defines the average radiation that falls on such a surface. L The value is 1367 W/m2. I (W/m2) 0 Normal from Sun’s to earth’s centre Sun T E N PParallel sun’s rays Plane perpendicular to sun’s rays Question: Is the solar constant (Isc) really a constant? Ref. Book - Adv. Ren. Ener. Sys. (Part I) by S C Bhatia, WPI Press (2014)  1420 Using solar constant, we can calculate the irradiance on any day of the year. 1400 L I0 (W/m2) 1380 Isc E 1360 T 1340 P 1320 N 1300 1 2 3 4 5 6 7 8 9 10 11 12 Months 𝑛 𝐼0 = 𝐼𝑆𝐶 1 + 0.034 cos 2𝜋 365.25 I0= incident extraterrestrial irradiance (W/m2); ISC=Solar constant, n=the day of the year Can we make some estimate of the solar energy available at a surface? What is the area of the disc? 1367 W/m2 𝜋𝑅2 684 W/m2 What is the average irradiance on unit area facing the Sun? L 𝐼𝑆𝐶 𝑥 𝜋𝑅2 This value is then divided by half the surface area of the earth, which gives the value E R 684 W/m2. T What is the value of albedo, that we discussed earlier? P 0.30 Earth N What would be the H i.e. irradiation/ unit area; lets say for a 12 h day? 𝐻 = 0.7 𝑥 684 𝑥 12 = 5.75 𝑘𝑊ℎ/𝑑𝑎𝑦 ❖ Now, suppose the Sun has appreciable strength for 6 h, what will be the value of H? ✓ Can you now clearly understand why there is variations in the yearly profile of mean solar radiation at different locations? ✓ The solar cells are calibrated that there is 1000 W/m2 available.  With this brief knowledge, let us start mention some of the SOLAR DEVICES Solar Solar Most of them will be discussed in this course water L water heater E pumps Solar Solar T cells Solar Solar fans Solar lights street P ingots lights N Solar Solar lanterns Solar Solar coolers ACs Solar power cookers plants These are just a few of the examples…! You will also see that the following three phenomenon will play an important role in most of the mentioned devices: Radiation E L P T N Conduction Thermal Convection Summary of lecture 1. Introduction to solar radiation was given. L 2. Few of the relevant parameters, associated with solar radiation were E introduced. T 3. It must be clear that the solar radiation falling on the surface in not P constant and can vary owing to various factors, which were also N introduced. 4. Some of the devices based on solar energy, that would be discussed in the course, were finally mentioned.  E L In the next lecture, we will start our discussions on ‘Solar Photovoltaic Systems’ P T N REFERENCES L ⮚ “Physics of Energy Sources” by George C. King E ⮚ “Advance Renewable Energy Systems” by S. C. Bhatia. P T N  E L P T N  E L P T N PHYSICS OF RENEWABLE ENERGY SYSTEMS Prof. AMREESH CHANDRA DEPARTMENT OF PHYSICS, IIT KHARAGPUR Module 2 Solar energy Lecture 4 : Solar Photovoltaic Systems CONCEPTS COVERED E L ⮚ Introduction to photovoltaic cells P T N ⮚ Types of solar cells ⮚ Need for materials development KEY POINTS 1) Use of solar energy E L T 2) Classification of solar cells P 3) Basic functioning of solar cells N 4) Use of semiconductors in solar cells 5) Importance of materials development for solar cell technology In the earlier lectures, we saw the energy sources can be broadly classified as: Thermal Energy Sources E L T Mechanical Energy Sources N P Photovoltaic Sources  Edmond Becquerel discovered the photovoltaic A major increment in the performance came in effect in 1839. 1950s, by the studies in Bell laboratories, L where G. Pearson, D. Chapin and C. Fuller, Photo - Ref.: https://en.wikipedia.org › wiki › Edmond_Becquerel using doped silicon reported a solar cell with E In 1894, probably, the 5.7% efficiency T first true solar cell was P reported by Charles Fritts. Efficiency (~ 1%) N In 1875 , William Grylls Adam and Richard Evans Day, using selenide as a solid material, showed that light can be used to generate electricity. We are now in 2021! Lot of work still needs to be done and are being done  Photovoltaic Classifications 1st Generation d > 100 µm 4th Generation?? (Efficiency ~ 25% (±)) (Efficiency ~ 28% (±)) L Crystalline and d < 1 µm Polycrystalline silicon E Perovskite Solar cells T 2nd Generation P d> 1 µm N (Efficiency ~ 22% (±)) 3rd Generation Amorphous silicon d < 1 µm for organic solar CdTe, CdS, GaAs cells CIGS d > 1 µm for DSSC (Efficiency ~ 12 % (±)) * CIGS (Cu-In-Ga-Diselenide) * DSSC (Dye sensitized solar cells) Comparing photovoltaic effect L with T E photoelectric effect N P Photoelectric effect Clear understanding will help to understand UV Light photovoltaic effect, as there are few similarities. Evacuated quartz tube Einstein’s equation that describes L photoelectric effect: E e- T 𝑬𝒎𝒂𝒙 = 𝒉𝝑 − 𝝋 ❖ 𝒉𝝑: Photon energy ❖ 𝝋: Work function of the metal NP Metal Surface Direction of A Work function for metals is ~ 5 eV. Conventional Can you calculate the wavelengths, Current, i which will lead to photoelectrons? Comparing with photovoltaic effect, where p-type n-type you consider a p-n junction L Direction of electron flow 𝒉𝝑 E Semiconductors T p-type n-type Ecp N Depletion region P Ecn EF EF Evp Evn Photovoltaic effect 𝒉𝝑 Grid electrode n-type region The process occurs L in or close to the E depletion layer Depletion layer Load P T electron-hole pair More details about the construction and characterization will N Back electrode p-type region be explained is next few lectures  Conduction band Photon absorption at a p–n junction ❖ When a photon is incident upon a semiconductor Energy band material, an electron may be promoted from the 𝒉𝝑 gap, Eg L valence band to the conduction band if the photon has an energy 𝒉𝝑 that is greater than the band gap E Eg. P T ❖ 𝒉𝝑 > 𝑬𝒈 Valance band N ❖ In terms of wavelength 𝝀 𝒉𝒄 𝝀< = 𝝀𝒄 𝑬𝒈 Working principle ❖ Generation of electron-hole pairs by the incident photons in or close to the depletion layer. L ❖ Inbuilt electrical field across the depletion layer E Result - electron move towards the n-type, while the holes move towards the p-type material. P T ❖ The generated electrons can flow around the external circuit from n- to the p-type, N where they combine with the hole. ❖ Consequence – ‘electrical power is delivered to an external load’. Some parameters used to explain solar cells Voc (b) isc (a) p n p n E L (a) A solar cell in the short-circuit mode with short- circuit current isc. (b) A solar cell in the open-circuit mode with T open-circuit voltage Voc. P RL (c) N p n (c) solar cell connected to a load of finite resistance RL. The current flowing through the load is less than isc and the voltage across the load is less than Voc.  CONCLUSION E L 1. The basic introduction to solar photovoltaics was given. P T 2. There are some similarities between photoelectric and N photovoltaic effects, which were presented. 3. The way the field of solar photovoltaics is developing was also discussed.  REFERENCES E L T ⮚ “Photoelectrochemical Solar Cells” by Suresh Chandra (Gordon and Breach Publishers, 1985). P T Singh, T Miyasaka; Advanced Energy Materials 8 (3), 1700677 (2018) N S Mishra, S Ghosh, T Singh; ChemSusChem 14 (2), 512-538 (2021) ⮚ “Physics of Energy Sources” by George C. King ⮚ “Advance Renewable Energy Systems” by S. C. Bhatia  E L P T N