Energy Harvesting challegess solutions sj

Electronics

1. Unit-2 Addressing the Power challenge: RFID, Energy harvesting, Battery based systems, Power management systems, and Power management algorithms.

2. Introduction to Power Challenges in IoT Why Power is Critical: IoT devices are often deployed in remote or inaccessible locations (e.g., environmental sensors in forests). Devices need to operate for extended periods without manual intervention. Ensuring energy efficiency and sustainability is crucial for scaling IoT solutions. Key Solutions: RFID, energy harvesting, battery-based systems, advanced power management systems, and algorithms.

3. Power requirements for IoT Devices Typical IoT devices or low-powered electronic devices require power ranging between 10 nW and 100 W

4. Power Sources for IoT Devices- Battery Environmental Energy-(Energy Harvesting) Solar energy:[Photovoltaic Cell/Solar Cell] Using photovoltaic cells to convert sunlight into electricity, often seen in outdoor IoT sensors.  Thermal energy:[Thermocouple] Utilizing thermoelectric generators to harvest heat from a temperature difference, like in industrial environments.  Mechanical energy/Kinetic Energy:[Piezoelectric Sensors] Harvesting kinetic energy from vibrations or movement using piezoelectric materials, common in wearables.  Radio Frequency (RF) energy :[Antenna] Capturing radio waves from surrounding sources to power low-power devices. (RFID)

5. The Photovoltaic cell is the semiconductor device that converts the light into electrical energy. The voltage induces by the PV cell depends on the intensity of light incident on it. The name Photovoltaic is because of their voltage producing capability. Solar Cell/Photovoltaic Cell-

6. Advantages and Disadvantages for Light Energy Harvesting by Solar Cell- Renewable energy source Reduces carbon footprint High scalability and easy to expand Long term energy production Initial Cost is high Weather dependent Semiconductor material waste

7. Thermocouple Sensor- T hermocouple can be used for thermal energy harvesting, as it is a key component of a thermoelectric generator (TEG) which converts temperature differences into electrical energy by utilizing the Seebeck effect; essentially, when a temperature gradient exists across a junction of two dissimilar metals, a voltage is produced, allowing for energy harvesting from heat sources.   Advantages and Disadvantages for this device- The thermocouple is less expensive. than RTD. It has wide temperature ranges- 270-2700 degree Celsius. It has good accuracy. It has high speed of response. As output voltage is very small, it needs amplification. The cold junction and lead compensation is essential. It shows non linearity.

8. Piezoelectric Sensor- The piezo transducer converts the physical quantity into an electrical voltage. The piezoelectric transducer uses the piezoelectric material which has a special property, i.e. the material induces voltage when the pressure or stress applied to it.  The word piezoelectric means the electricity produces by the pressure. The Quartz is the examples of the natural piezoelectric crystals, whereas the Rochelle salts is an example of the man made crystals. 

9. Advantages and Disadvantages for Piezoelectric Sensors- Small size : Easy to handle and install High-frequency response : Can quickly change parameters Flexible : Can be shaped into different sizes and shapes Rugged construction : Can withstand certain conditions Not suitable for static measurements : Can't measure static conditions Temperature sensitive : Can be affected by temperature changes Low output : May require an external electronic circuit Water soluble : Some crystals can dissolve in humid environments

10. RFID Technology and Power Efficiency What is RFID? Radio Frequency Identification (RFID) uses electromagnetic fields to transfer data wirelessly. Types of RFID Systems: Passive RFID: No internal power source; relies on the reader for energy. Example: Inventory management in retail stores where RFID tags on products track stock levels automatically. Active RFID: Battery-powered, enabling longer range and richer data exchange. Example: Toll collection systems (e.g., FASTag in India) where vehicles pass through toll gates without stopping. Benefits: Low power consumption for passive systems. Widely used in logistics, healthcare, and asset management.

11. RFID Standards-ISO 14443/ ISO 15693/EPC Gen2 ISO 14443 Components operating at 13.56Mhz Power consumption 10mW Data  throughput  is 100 kbps Operates at working distance 10 cm

12. Definition: Energy harvesting involves capturing energy from environmental sources like sunlight, vibrations, heat, or radio waves. Common Energy Sources: Solar Energy: Efficient for outdoor IoT devices. Example: Solar-powered weather stations in smart agriculture. Thermal Energy: Converts heat differences into power. Example: Industrial IoT devices that capture waste heat from machines to power sensors. Kinetic Energy: Utilizes motion or vibrations. Example: Wearable fitness trackers that harvest energy from user movement. Energy Harvesting in IoT

13. Energy Harvesting in IoT RF Energy: Harnesses ambient radio waves. Example: Battery-less sensors in smart buildings that use RF energy from Wi-Fi signals. Advantages: Enables self-sustaining devices. Reduces dependency on batteries and manual recharging.

14. Energy Sources: Energy Harvesting There are many forms of energy that can be harvested:

15. Radio Frequency (RF) Energy

16. Radio Frequency (RF) Energy

17. Hybrid Energy Harvesting

18. Wireless Power Transfer (WPT)

19. RF Energy Harvesting

20. RF Energy Harvesting

21. RF Energy Harvesting

22. Importance of Batteries in IoT: Batteries are a primary energy source for portable and stationary IoT devices. Battery Types: Lithium-Ion: High energy density, commonly used in smartphones and IoT gateways. Example: Smart home hubs like Amazon Echo or Google Nest. Lithium-Polymer: Lightweight and flexible, suitable for wearables. Example: Smartwatches like Apple Watch or Fitbit. Alkaline Batteries: Cost-effective for low-power devices. Example: Remote controls for smart TVs. Solid-State Batteries: Emerging technology with improved safety and longevity. Example: Potential use in future autonomous vehicles. Battery-Based Systems

23. Challenges: Limited lifespan and capacity. Environmental impact of battery disposal. Solutions: Combine batteries with energy harvesting. Use low-power microcontrollers to extend battery life. Battery-Based Systems

24. Battery types will be evaluated according to their suitability for different IoT applications. There are many characteristics that can be used to classify the different battery technologies. The most critical parameters are listed below: Energy density; Temperature range; Longevity; Nominal cell voltage; Safety; Cost; Energy efficiency.

25. Battery Type Nominal Cell Voltage (V) Lead–Acid 2.1 Nickel–Metal Hydride (NiMH) 1.2 Lithium–Ion (Li–ion) 3.6 Lithium–Polymer (LiPo) 3.7 Solid- State 3.7 Alkaline 1.5 Zinc–Air 1.4 Redox Flow 1.4 Supercapacitor 2.7

26. TYPES OF BATTERIES Secondary batteries can be recharged: that is, they can have their chemical reactions reversed by supplying electrical energy to the cell. Must be charged before first use. The oldest form of rechargeable battery is the lead–acid battery in an unsealed container. The sealed valve regulated lead–acid battery (VRLA battery) is popular in the automotive industry as a replacement for the lead–acid wet cell. There are two types: Gel batteries Absorbed Glass Mat (AGM) Batteries are classified into primary and secondary forms: Primary batteries irreversibly transform chemical energy to electrical energy. They can produce current immediately on assembly. These are most commonly used in portable devices that have low current drain and are usually used intermittently.

27. TYPES OF BATTERIES According to its cell, there are two types: In wet cell batteries the liquid covers all internal parts of the device. They were a precursor to dry cells and may be primary cells or secondary cells. Dry cell batteries . Unlike a wet cell, a dry cell can operate in any orientation without spilling, as it contains no free liquid, making it suitable for portable equipment

28. Lithium- ion uses a cathode (positive electrode), an anode (negative electrode) and electrolyte as conductor. The charging and discharging of a battery (a) and (b), respectively. In both cases, the negative electrode (-) is shown on the left and the positive electrode (+) on the right. The oxidation occurs at the positive electrode during charging, whereas reduction occurs at the negative electrode. The reverse takes place during discharging. Working of Battery

29. CAPACITY, CHARGE AND DISCHARGE A battery's capacity is the amount of electric charge it can deliver at the rated voltage. The more electrode material contained in the cell the greater its capacity. The rated capacity of a battery is usually expressed as the product of 20 hours multiplied by the current that a new battery can consistently supply for 20 hours at 20 °C, while remaining above a specified terminal voltage per cell. For example, a battery rated at 100 A·h can deliver 5 A over a 20-hour period at room temperature. There is a capacity loss over the number of cycles it charge and discharge

30. Limitations Requires protection circuit to prevent runaway if stressed. Degrades at high temperature and when stored at high charges. No rapid charge possible at freezing temperatures (<0°C). Transportation regulations required when shipping in larger quantities. Advantage and Limitation of Battery Advantages High specific energy and high load capabilities. Long cycle and extend shelf-life; maintenance- free. High capacity, low internal resistance, good coulombic efficiency. Simple charge algorithm. Low self-discharge (less than half that of NiCd and NiMH).

31. Lithium–Ion (Li–Ion) Batteries The lowest reduction potential and highest cell potential makes the element lithium a popular choice for batteries . Lithium–ion batteries are a popular choice of battery over a wide range of applications ranging from portable electronics to electric vehicles. This is mainly due to their energy density, low self discharge, and low memory effect when compared to the other secondary (rechargeable) batteries. In the 1970s, the development of lithium-based rechargeable batteries marked a significant milestone in the energy industry. Lithium–ion cells are made up of three main components: a cathode composed of lithium metal oxide, an anode made from graphite, and an electrolyte that contains lithium ions. When the battery discharges, the lithium ions move from the anode to the cathode through the electrolyte, while electrons flow through the external circuit, providing power to the device. This process is reversed during charging . Compared to traditional batteries, the unique structure of lithium–ion batteries provides an advantage due to their ability to generate electricity without dissolving the electrodes in the electrolyte. This is possible due to the presence of lithium in the cathode and its efficient storage capability in the carbon anode. This process helps prevent battery deterioration and increases the number of charge and discharge cycles the battery can undergo

32. Lithium Cobalt Oxide (LCO) Batteries Lithium Manganese Oxide (LMO) Batteries Lithium Nickel Manganese Cobalt Oxide Lithium Iron Phosphate (LiFePO4) Batteries Lithium–Polymer (LiPo) Batteries * Ref.: Navigating Battery Choices in IoT: An Extensive Survey of Technologies and Their Applications By- Kareeb Hasan , Neil Tom and Mehmet Rasit Yuce

33. Definition: Systems designed to optimize energy consumption and ensure efficient operation of IoT devices. Components: Power Supply Regulators: Maintain steady voltage and current. Example: Voltage regulators in drones that adjust power for stable flight. Energy Storage Units: Store energy from batteries or harvesting sources. Example: IoT-enabled UPS systems in data centers . Monitoring Tools: Track power usage and predict device energy needs. Example: Energy monitoring in smart factories to reduce operational costs. Applications: Smart homes, healthcare devices, and industrial IoT systems. Power Management Systems

34. Role of Algorithms: Manage energy allocation to maximize device lifespan and efficiency. Types of Algorithms: Dynamic Voltage and Frequency Scaling (DVFS): Adjusts processor power based on workload. Example: Smartphones reducing CPU frequency during idle times. Energy-Aware Routing: Optimizes data transfer paths to reduce energy consumption in networks. Example: Routing in wireless sensor networks for smart agriculture. Sleep/Wake Schedules: Puts devices into low-power modes when idle. Example: Smart lighting systems in smart cities that dim or turn off lights when no activity is detected. Power Management Algorithms

35. Predictive Power Management: Uses machine learning to anticipate energy needs and optimize resources. Example: AI-powered thermostats like Nest Learning Thermostat that predict and adjust energy usage. Benefits: Reduces operational costs. Prolongs battery life and enhances device reliability. Power Management Algorithms

36. Power Management Systems Dynamic Voltage and Frequency Scaling (DVFS) is a technique that adjusts the voltage (V) and frequency (f) of a processor dynamically to balance performance and power efficiency . This helps reduce power consumption, heat dissipation, and energy costs in computing systems. DVFS is widely used in mobile devices, laptops, cloud servers, high-performance computing (HPC), IoT devices, and embedded systems . Why is DVFS Important? Reduces power consumption to extend battery life (e.g., in smartphones, laptops). Lowers heat dissipation , preventing overheating and reducing the need for active cooling. Optimizes performance per watt , crucial for data centers and AI workloads . Helps meet thermal design power (TDP) limits in compact electronic devices.

37. Power Management Systems Power consumption in a CMOS circuit (such as a CPU or GPU) is determined by : P=CV 2 f *Change in voltage levels and frequency will result in change in power consumption at device Where: P = Power consumption (Watts), C= Effective switching capacitance (device-specific constant), V= Supply voltage (Volts), f = Clock frequency (Hertz) Since power consumption is proportional to the square of the voltage , reducing voltage results in power savings.

38. Power Management Systems Question 1: Effect of Voltage and Frequency Scaling on Power Consumption A processor operates at 1.2V , 2.0 GHz , and has a switching capacitance of 1.0 × 10⁻⁹ F . Calculate the power consumption at these conditions. If DVFS reduces the voltage to 1.0V and the frequency to 1.5 GHz , what is the new power consumption? Power formula: P f For 1.2V, 2.0GHz: = ( x(2.0 x ) =2.88W For 1.0V, 1.5GHz: = ( x(1.5 x ) =1.5W   Lowering both voltage and frequency reduces power consumption significantly. Here, power is reduced by almost 48% , improving energy efficiency while balancing performance.

39. Power Management Systems Question 2: Execution Time with Different Power Levels A computing task requires 10 Joules of energy. A processor has two operating modes: High-performance mode: 1.2V, 2.5 GHz , Power = 3.6 W Low-power mode: 0.9V, 1.5 GHz , Power = 1.215 W Find the execution time for the task in both modes. Execution time formula : = = = =   DVFS reduces power consumption but increases execution time. 1. In high-performance mode , the task finishes faster but consumes more power. 2. In low-power mode , the task takes 3× longer , but energy efficiency is much better, which is ideal for battery-powered devices .

40. Power Management Systems Question 3: Energy Savings in Cloud Computing using DVFS A cloud server runs at 1.2V, 3.0 GHz , consuming 5W of power. If DVFS scales the voltage down to 1.0V and frequency to 2.0 GHz , what percentage of energy is saved for a 100-second workload ? Energy formula: t 5 New power at 2.0 GHz : = 2.78W New energy consumption: = 2. Percentage energy saved: ×100 =44.4%   DVFS can save up to 44.4% of energy in cloud computing , reducing costs and heat generation while keeping performance at an acceptable level.

41. Power Management Systems Question 4: Battery Life Extension in IoT Devices An IoT device operates at 1.1V, 1.8 GHz , consuming 1.8W . The device has a 3000mAh battery at 3.7V . Calculate the battery life. If DVFS reduces power to 1.0W , what is the new battery life? 3.0 Battery life at 1.8 W : hours Battery life at 1.0W: hours   Using DVFS, battery life increases by 80% . This is essential for IoT and mobile devices , where power efficiency is critical.

42. Power management at hardware Level as well as software algorithms for route optimization are some basic techniques for power optimization.

43. Energy Management- Data Collection Low-power sensors: Hardware sensors are designed to operate in low-power modes when idle and only activate when specific thresholds are met (e.g., motion detection, temperature change). Analog-to-Digital Converters (ADCs): Efficient ADCs convert sensor data to digital signals with minimal energy usage. Duty Cycling: Sensors are powered on/off periodically rather than being continuously active, reducing unnecessary energy drain. Energy Harvesting Components: Some systems integrate solar cells or piezoelectric devices to harvest energy, reducing reliance on batteries. ________________________________________

44. . Task Scheduling Microcontroller Units (MCUs) with Power Modes: Modern MCUs have multiple power states (active, idle, sleep, deep sleep) allowing them to switch states depending on workload requirements. Asynchronous Processing: Hardware components can process tasks independently without waking the central processor. Regional Calculation • Edge Computing Devices: Instead of sending raw data to a central server, devices with onboard processing units (like microprocessors or FPGAs) perform computations locally to save transmission energy. Distributed Sensor Networks: Hardware nodes collaborate, with each node responsible for processing data from its region, reducing redundant energy expenditure. Application-Specific Integrated Circuits (ASICs): ASICs designed for specific regional computations are more energy-efficient than general-purpose processors.

45. Processing Low-Power Processors: ARM-based processors (commonly used in IoT devices) are optimized for energy efficiency compared to traditional CPUs. Voltage Scaling: Dynamic Voltage and Frequency Scaling (DVFS) adjusts the voltage and frequency of processors based on workload demand to save power.

46. Data Storage Non-volatile Memory (NVM): Flash memory and EEPROM retain data without constant power supply, unlike traditional RAM. Energy-Efficient SSDs: Solid-state drives consume less power than traditional spinning hard drives. Memory Hierarchy Optimization: Use of cache memory to reduce the need for energy-intensive data retrieval from main memory. .Data Transmission Low-Power Communication Protocols: Hardware supports energy-efficient protocols like Zigbee, Bluetooth Low Energy (BLE), and LoRaWAN. Directional Antennas: Use of smart antennas to focus energy in a specific direction, reducing wastage.

47. Mobility Management Energy-Efficient GPS Modules: Hardware that only activates location tracking when movement is detected via accelerometers or gyroscopes. * Adaptive Network Interfaces : Network hardware that adjusts connection parameters (e.g., Wi-Fi vs. LTE) based on movement and signal strength to optimize energy use. Smart Sensors: Embedded sensors (accelerometers, gyroscopes) detect motion and adjust system behaviour to save energy.

48. Adaptive Network Hardware Network hardware that adjusts connection parameters based on movement and signal strength is part of adaptive connectivity management. This approach is crucial in devices like smartphones, IoT sensors, and mobile computing platforms to optimize energy consumption while maintaining reliable network performance Devices like smartphones, wearables, and IoT sensors often operate in environments with multiple available networks (e.g., Wi-Fi, LTE, 5G, Bluetooth). Maintaining constant high-performance connections can drain battery life quickly. However, not all connections are needed at all times, and some can be more energy-efficient depending on the situation. For instance: • Wi-Fi consumes less power than LTE for data-heavy tasks when stationary. • LTE/5G might be preferable when on the move, but they typically require more power due to broader range and signal processing complexity.

49. Link Performance- Error Correction Hardware: Onboard error detection and correction circuits reduce the need for retransmissions, conserving energy. Adaptive Modulation: Hardware that adjusts data rates and power levels based on link conditions.

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