🦆Engineering and the Environment Unit 5 – Energy Systems & Sustainability

Key Concepts in Energy Systems

• Energy is the capacity to do work and exists in various forms such as kinetic, potential, thermal, electrical, chemical, and nuclear
• The law of conservation of energy states that energy cannot be created or destroyed, only converted from one form to another
• Energy systems involve the extraction, conversion, storage, transmission, and utilization of energy resources to meet human needs and support economic activities
  • Extraction refers to the process of obtaining energy resources from natural sources (fossil fuels, solar, wind)
  • Conversion transforms energy from one form to another (chemical energy in coal to electrical energy in power plants)
• Energy efficiency is the ratio of useful energy output to total energy input and is a key factor in the sustainability of energy systems
• Energy density is the amount of energy stored in a given system or region of space per unit volume or mass (gasoline has a higher energy density than wood)
• The energy mix refers to the combination of different energy sources used to meet the energy needs of a particular region or country
• Energy security is the uninterrupted availability of energy sources at an affordable price and is a critical consideration in energy policy and planning

Types of Energy Sources

• Fossil fuels are non-renewable energy sources formed from the remains of ancient plants and animals, including coal, oil, and natural gas
  • Fossil fuels currently account for the majority of global energy consumption but are associated with significant environmental impacts (greenhouse gas emissions)
• Nuclear energy is derived from the splitting of atomic nuclei (fission) or the fusion of atomic nuclei (fusion) and is a low-carbon energy source
• Renewable energy sources are replenished naturally on a human timescale and include solar, wind, hydro, geothermal, and biomass
  • Solar energy harnesses the energy from the sun through photovoltaic cells or solar thermal collectors
  • Wind energy uses wind turbines to convert the kinetic energy of moving air into electrical energy
• Biofuels are derived from organic matter (corn, sugarcane) and can be used as a substitute for fossil fuels in transportation
• Hydrogen is an energy carrier that can be produced from various sources (water electrolysis) and used in fuel cells to generate electricity with water as the only byproduct

Fundamentals of Energy Conversion

• Energy conversion is the process of transforming energy from one form to another to meet specific needs or applications
• Thermodynamics is the study of heat and its relationship to energy and work, providing the foundation for understanding energy conversion processes
  • The first law of thermodynamics states that energy cannot be created or destroyed, only converted from one form to another
  • The second law of thermodynamics states that the total entropy of an isolated system always increases over time, limiting the efficiency of energy conversion processes
• Heat engines convert thermal energy into mechanical energy by exploiting temperature differences (internal combustion engines, steam turbines)
• Power plants convert primary energy sources (fossil fuels, nuclear, renewables) into electrical energy through various conversion processes (combustion, nuclear fission, photovoltaics)
• Energy storage systems capture energy during times of excess production or low demand for use at a later time (batteries, pumped hydro, compressed air)
• Cogeneration, also known as combined heat and power (CHP), is the simultaneous production of electricity and useful heat from a single fuel source, improving overall energy efficiency

Sustainability Principles in Energy

• Sustainability in energy systems involves meeting the energy needs of the present without compromising the ability of future generations to meet their own needs
• The three pillars of sustainability in energy are economic viability, environmental protection, and social equity
  • Economic viability ensures that energy systems are cost-effective and provide reliable access to energy services
  • Environmental protection minimizes the negative impacts of energy systems on air, water, land, and biodiversity
  • Social equity ensures that the benefits and costs of energy systems are distributed fairly across society
• Life cycle assessment (LCA) is a tool used to evaluate the environmental impacts of energy systems over their entire life cycle, from resource extraction to end-of-life disposal
• Circular economy principles in energy systems prioritize the efficient use of resources, the minimization of waste, and the recovery and reuse of materials
• Decarbonization refers to the reduction of carbon dioxide emissions from energy systems through the adoption of low-carbon technologies and energy efficiency measures
• Energy justice seeks to ensure that all individuals and communities have access to affordable, reliable, and clean energy services

Environmental Impact of Energy Systems

• Energy systems can have significant environmental impacts at every stage of their life cycle, from resource extraction to energy conversion and waste disposal
• Greenhouse gas emissions from the combustion of fossil fuels are the primary driver of climate change, leading to rising global temperatures, sea levels, and extreme weather events
  • Carbon dioxide (CO2) is the most significant greenhouse gas emitted by energy systems, followed by methane (CH4) and nitrous oxide (N2O)
• Air pollution from energy systems, including particulate matter, sulfur dioxide, and nitrogen oxides, can have severe impacts on human health and ecosystems
• Water pollution from energy systems can result from the discharge of contaminated wastewater, oil spills, and the leaching of toxic substances from mining operations
• Land use impacts of energy systems include habitat destruction, deforestation, and soil degradation resulting from resource extraction and infrastructure development
• The disposal of waste products from energy systems, such as coal ash and nuclear waste, can have long-term environmental and health consequences
• Renewable energy sources generally have lower environmental impacts than fossil fuels but can still have negative effects on land use, wildlife, and local communities

Energy Efficiency and Conservation

• Energy efficiency refers to using less energy to provide the same level of energy service, while energy conservation involves reducing energy consumption through behavioral changes
• Improving energy efficiency in buildings through better insulation, energy-efficient appliances, and smart energy management systems can significantly reduce energy consumption and costs
• Industrial energy efficiency can be enhanced through the adoption of best practices, such as waste heat recovery, process optimization, and the use of energy-efficient equipment
• Transportation energy efficiency can be improved through the development of fuel-efficient vehicles, the promotion of public transit and active transportation, and the optimization of logistics and supply chain management
• Energy-efficient lighting technologies, such as light-emitting diodes (LEDs), can provide significant energy savings compared to traditional incandescent bulbs
• Energy conservation measures, such as turning off lights and electronics when not in use, adjusting thermostat settings, and reducing water consumption, can help individuals and organizations reduce their energy footprint
• Energy efficiency policies and programs, including building codes, appliance standards, and financial incentives, play a critical role in promoting the adoption of energy-efficient technologies and practices

Emerging Technologies in Sustainable Energy

• Advanced renewable energy technologies, such as organic photovoltaics, concentrated solar power, and offshore wind, are improving the efficiency and cost-effectiveness of renewable energy systems
• Energy storage technologies, including lithium-ion batteries, flow batteries, and hydrogen storage, are essential for integrating variable renewable energy sources into the grid and enabling the decarbonization of transportation
• Smart grid technologies, such as advanced metering infrastructure, demand response, and energy management systems, enable the efficient and reliable operation of modern power systems
• Carbon capture, utilization, and storage (CCUS) technologies aim to reduce greenhouse gas emissions from fossil fuel-based energy systems by capturing CO2 and either utilizing it in industrial processes or storing it in geological formations
• Hydrogen and fuel cell technologies offer the potential for clean and efficient energy conversion in a variety of applications, from transportation to stationary power generation
• Advanced nuclear technologies, such as small modular reactors and fusion power, have the potential to provide low-carbon, reliable, and scalable energy solutions
• Bioenergy with carbon capture and storage (BECCS) is a negative emission technology that combines the use of biomass for energy production with the capture and storage of the resulting CO2 emissions

Challenges and Future Directions

• Integrating high levels of variable renewable energy sources into the grid while maintaining reliability and stability is a significant challenge that requires advanced planning, operation, and control strategies
• Developing cost-effective and sustainable energy storage solutions is critical for enabling the widespread adoption of renewable energy and the decarbonization of the energy sector
• Addressing the social and environmental impacts of energy systems, particularly in vulnerable communities and developing countries, is essential for ensuring a just and equitable energy transition
• Overcoming market, regulatory, and institutional barriers to the deployment of sustainable energy technologies requires innovative policies, business models, and financing mechanisms
• Enhancing energy access and affordability for the billions of people worldwide who currently lack reliable access to modern energy services is a critical challenge that requires a combination of technological, financial, and social solutions
• Developing a skilled workforce and building capacity in sustainable energy technologies and practices is essential for supporting the energy transition and creating green jobs
• Fostering international cooperation and knowledge sharing on sustainable energy best practices, technologies, and policies is crucial for accelerating the global energy transition and achieving climate goals