Unit 2: Conventional Energy System

Unit 2: Conventional Energy System

• Finite energy resources include coal, shale oil, petroleum, and natural gas.
• These resources are concentrated solar energy from millions of years ago and are considered finite.
• Other sources are constantly being discovered, making their exact status uncertain.

2.1 Introduction

• Finite energy resources are accumulated concentrated solar energy available over millions of years.
• These resources are finite.
• Others doubt the finiteness of resources due to new discoveries.

2.2 Primary Energy

• Primary energy falls into two categories: primary fuels and primary energy flows.
• Primary fuels (coal, natural gas, and uranium) are dense energy stores consumed upon use.
• Primary energy flows (solar radiation and water flow) are natural processes with extractable energy.
• Fuels store energy, while energy flows are natural processes that have extractable energy.

2.2.1 Fuels

• Fuels are dense energy sources used for heating, transportation, and electricity generation.
• Majority of global primary energy (90-95%) comes from fuels.
• Fuels like coal and natural gas are used in power plants.
• Crude oil is processed into secondary fuels (like gasoline, diesel, and kerosene) for various applications.
• Fuels exist as solids, liquids, or gases.
• Examples of fuels include natural gas, acetylene, hydrogen, Compressed Natural Gas (CNG), gasoline, diesel, kerosene, Liquefied Natural Gas (LNG), liquefied petroleum gas (LPG), ethanol, methanol, butanol, wood, wax, coal, char, peat, charcoal, bagasse, biomass.

2.2.1.1 Properties of Fuels

• Flash point: Fuel's lowest ignitable temperature with air.
• Fire point: Sustained burning temperature once ignited.
• Cloud point: Temperature at which a sample has visible cloudiness (e.g., wax, paraffin).
• Pour point: Fuel's temperature at which it stops flowing.
• Gum content: Residue after heating and evaporating for a set time.
• Trace metal content: Presence of specific metals.
• Aromatic content: Percentage of aromatic hydrocarbons.

2.2.2 Primary Energy Flows

• Hydroelectricity, tidal power, wind power, and solar power are examples of natural energy sources.
• These processes are non-dispatchable and intermittent, meaning energy availability isn't controllable.

2.3 Fossil Fuel Life Cycle

• The increased use of oil coincided with the invention of internal combustion engines.
• Technological advancements have increased oil consumption, shown by a theoretical curve.
• The area under this curve represents the total exploitable petroleum.

2.4 Coal: An Overview

• Coal formed from buried organic material over millions of years under heat and pressure.
• The process removed moisture, increasing carbon and decreasing hydrogen and oxygen content.
• Coal types vary based on conditions of formation.

2.4.2 Types of Coal

• Lignite: Lowest rank, soft, brown-blackish, high moisture and ash content, easy gas/liquid conversion, used for electricity generation, synthetic natural gas, and fertilizers.
• Sub-bituminous: Intermediate between lignite and bituminous, dull dark-brown/black, harder than lignite, mainly used for generating electricity.
• Bituminous: Formed under higher pressure and temperature, black with bands of dull/bright material, used for generating electricity and residential/commercial heating.
• Anthracite: Highest rank, black, glossy, low moisture, used for residential and commercial heating, fine particle filters, and charcoal briquettes.

2.5 Petroleum: An Overview

• Petroleum forms from buried marine plankton remains.
• The formation, including chemical reactions to kerogen, takes millions of years.
• Petroleum is often called "crude oil," used in heating, transportation, and electricity generation.

2.5.1 Formation

• Petroleum forms from marine plankton buried under sand and silt.
• Heat and pressure transform the material into a waxy substance, kerogen.
• Catagenesis produces natural gas and oil.

2.5.2 Phases of Petroleum Industry

• Upstream: Locating and drilling for oil reserves, using seismic, gravimetric, and magnetometric surveys.
• Drilling methods include primary, secondary, and tertiary recovery, targeting different depths and pressure conditions.
• Midstream: Transporting oil, using methods like rail, barge, and pipeline.
• Downstream: Refining oil products into usable fuels, different processes (e.g., refining, conversion, treatment) yield various final products from crude oil. Current usages of petroleum products are for gasoline, agriculture, plastics, tires, and pharmaceuticals.

2.7 Lifetime of a Finite Resource

• The lifetime of a finite resource can be estimated by summing yearly consumption.
• Data parameters for this process, such as the expected growth rate of consumption, and resource reserves at various time points, can affect the overall estimations.
• The lifetime is dependent on the resource's magnitude and the rate of consumption.

2.8 Summary

• Energy efficiency and conservation are essential solutions to the energy dilemma.
• Finite resources combined with increasing population pressures necessitate a shift towards sustainable solutions.

2.9 Thermal Power Plants

• Thermal power plants produce electricity from heat sources, and essential components include boilers, turbines, condensers, pumps, and superheaters.
• Thermal power cycles generally include fossil steam, nuclear, simple cycle gas turbine, and combined cycle, with coal-fired steam power being common.
• The Rankine cycle, relevant to power plant operations (diagram) details the processes in the system.

2.9.3 Power Plant Efficiency

• Ideal thermodynamic efficiency (formula available) is calculated, considering input/output temperatures (T₁ / T₂), where T₁ is the input and T₂ is the output temperature.

2.10 Environmental Effects of Power Plants

• Thermal pollution is a significant effect of power plants.
• Air pollution (e.g., ash, CO, NOx, SOx, and CO₂) is another key effect associated with power plants and combustion.

2.11 Waste Heat Recovery

• Waste heat is released into the environment, although it could repurposed for economic purposes.
• Waste heat sources vary with temperature (high, medium, and low).

2.11.1 Waste Heat Recovery Applications

• Waste heat can be transferred from one fluid stream to another using industrial heat exchangers.
• Heat exchangers, such as recuperators, regenerators, waste heat steam generators (WHSGs), condensers, and heat wheels, facilitate these transfers.
• This allows waste heat to be efficiently reused.

2.12 Micro-CHP Systems

• Micro-CHP systems offer an alternative by capturing otherwise wasted heat for domestic use.
• By using a combustion engine and/or associated generator, the system produces both electricity and hot water.

2.12.2 Efficiency of Micro-CHP Systems

• Micro-CHP efficiency is determined by comparing various components, such as electrical output, thermal output, and overall efficiency over a unit fuel input.