Natural resources energy
Energy Resources
Definition of Energy: Energy is defined as the capacity to do work.
Energy Resource: Matter that has the capacity to:
Produce heat.
Power muscles.
Generate electricity.
Move machinery.
In its material form, an energy resource is referred to as a fuel.
Energy stored in chemical bonds is essential for fueling life.
Many geological materials are recognized as energy resources.
Human Energy Consumption
Growth of Human Energy Consumption: Human energy consumption has seen a steady increase.
Comparison to Early Humans: Americans consume 110 times more energy than early humans.
Areas of Energy Consumption:
Various sectors of energy consumption include:
Feeding livestock.
Agriculture.
Transportation.
Mining.
Manufacturing.
Indoor comforts.
Exploration and conquest.
Moving and treating water.
Data storage and electronic media (E-media).
Sources of Energy
Five Fundamental Sources of Energy:
Energy stored in chemical bonds.
Nuclear fusion (as seen within the Sun).
Energy generated within the Earth’s interior.
The gravitational pull.
Nuclear fission.
Photosynthesis
Process of Photosynthesis: Photosynthesis is the process that converts solar energy into chemical energy via chlorophyll molecules.
Chemical Reaction: The reaction can be summarized as:
6CO2 + 12H2O + ext{light}
ightarrow C6H{12}O6 + 6O2 + 6H_2OThis reaction results in glucose (sugar) and oxygen as byproducts.
Release of Energy: Energy is released when the bonds in sugar are oxidized during organic respiration (the breakdown of food by organisms) and through rapid thermal oxidation (combustion).
Energy from Chemical Reactions
Types of Reactions:
Exothermic reactions: These reactions release energy in the form of heat, light, or explosions.
Energy from Fossil Fuels:
Oil, natural gas, and coal are derived from living organisms and contain energy stored in hydrocarbon (H-C) bonds.
These hydrocarbons are created by photosynthesis, thus referred to as “fossilized sunshine.”
Many types of hydrocarbons exist and they typically occur as complex mixtures. Refining is required to separate hydrocarbon compounds.
Genesis of Oil and Gas
Origin of Oil and Gas:
Oil and gas are primarily derived from plankton and marine algae.
Dead plankton and algae accumulate offshore, forming fine mud.
Under anoxic conditions (absence of oxygen), this organic material is preserved.
Lithification: Over time, the material undergoes lithification to form dark shale, which serves as a petroleum source rock.
Heating Process:
The shale is buried and subjected to heat, causing organic matter to break down into waxy kerogen.
Kerogen-rich source rocks are designated as oil shales. The process continues with heating decomposing kerogen into oil.
Temperature Ranges for Oil and Gas Formation:
Oil and gas: 90^ ext{o}C to 160^ ext{o}C.
Gas only: 160^ ext{o}C to 250^ ext{o}C.
At temperatures exceeding 250^ ext{o}C, further decomposition occurs producing graphite and water.
Hydrocarbon Systems
Oil and Gas Preservation: Oil and gas preservation is geologically rare. A known supply of oil is defined as an oil reserve, which is geographically limited.
Statistics on Reserves:
Approximately 60% of the world’s reserves are located in the Persian Gulf.
New potential exploration areas include the South Atlantic deep water and the Arctic region.
Features of Oil and Gas Reserves
Creation of an Oil or Gas Reserve: Requires four distinct features:
Source Rock: Usually an organic-rich shale.
Migration Pathway: Facilitated through fractures or bedding porosity.
Reservoir Rock: Needs to be permeable or capable of being fractured.
Trap: Contains both the reservoir rock and the seal rock system that retains oil and gas.
Reservoir Rocks: These rocks are integral for storing and transmitting oil and gas.
Definitions:
Porosity: Refers to the open spaces in rock that can store fluids.
Permeability: Determines the ease of fluid movement through the pore space.
Low permeability indicates small well yields.
High permeability entails large well yields.
Migration and Trapping of Oil and Gas
Migration: Oil and gas migrate upward from the source rock, aided by factors such as:
Porosity and permeability.
Pressure gradients.
Density and buoyancy differences.
Fluid Layering in Reservoirs: Typically, gas overlaps oil, which in turn overlaps water.
Traps and Seals: It is within these traps that oil and gas reserves are formed.
Seal: A low-permeability rock that prevents the upward movement of oil and gas.
Trap: A geological formation that includes both reservoir and seal rocks to contain hydrocarbons.
Types of Traps
Anticline Trap: A structural arch trap for oil or gas within a permeable bed such as sandstone.
Salt-Dome Trap: Formed by the buoyancy and plastic flow of salt disrupting nearby rocks.
Fault Trap: Occurs due to displacement that juxtaposes rocks of varying permeability.
Stratigraphic Trap: Created by depositional features (e.g., sand narrowing between shales).
Birth of the Oil Industry
Early Use of Oil: Oil has been utilized from seeps for millennia.
First Oil Well: The first oil well was drilled in Titusville, Pennsylvania in 1859, marking a significant industrial advancement.
Impact of Oil Wells: Wells allowed for rapid extraction of oil, leading to increased availability and consumption.
Oil Exploration Techniques
Seismic Reflection Profiles: Utilize sound waves to study layers and discontinuities within the Earth, helping geologists identify potential traps without needing to drill.
Diamond-Coated Rotary Bits: These are utilized to grind through rock with the help of rapid circulation of high-density drilling mud.
Benefits of Drilling Mud:
Lifts cuttings to the surface.
Cools the drill bit.
Reduces risks associated with blowouts.
Processes of Oil Production
Drilling Process: Once a reservoir is reached, drilling is halted. Steel casing is used to prevent the collapse of unstable rocks into the hole.
Testing and Pumping of Wells: After capping with steel casing, the well is tested, and oil is pumped.
Recovery Methods
Primary Recovery: Utilizes natural reservoir pressure and pumps to extract oil (typically recovers about 30%).
Secondary Recovery: Involves the introduction of fluids (e.g., steam or CO2) to heat, thin, and push oil, recovering an additional 20%.
Hydraulic Fracturing: This method artificially increases permeability to enhance extraction.
Refining of Crude Oil
Process of Refinement: Crude oil is refined by distillation that separates mixtures based on weight.
Lighter molecules rise to the top of distillation columns, while heavier molecules remain at the bottom.
Alternative Hydrocarbons
Natural Gas: Short-chain hydrocarbons including methane, ethane, propane, and butane, formed just above the oil window.
Abundance: More abundant than oil and generally cleaner as a fuel source. Currently being drilled from shale using directional drilling and hydraulic fracturing techniques.
Oil Shale: A type of shale rich in kerogen, which transforms upon burning into liquid hydrocarbons.
Geographic Abundance: Found in locations such as Wyoming, China, Russia, Scotland, and Estonia.
Tar Sands: Heavy residual petroleum found in sand; too viscous to be pumped directly.
Process of Extraction: These must be mined and processed. Significant deposits are located in Alberta and Venezuela.
Gas Hydrate: Methane found within a “cage” of ice formed by bacterial decomposition of organics.
Formation Conditions: Occurs in cold water depths exceeding 300 m and has the potential to store more carbon than all other reservoirs combined. Recovery is not yet feasible.
Characteristics of Coal
Definition: Coal is defined as a black, brittle, carbon-rich, low-silica sedimentary rock.
Formation: Result of the burial and heating of vegetation.
Environmental Impact: Important global energy source and a significant emitter of CO2. Notably formed only after the evolution of land plants (~420 million years ago).
Carboniferous Period: Approximately 60% of the world’s coal reserves formed during this period (354–286 million years ago), characterized by:
Warm climate.
Broad epicontinental seas.
Tropical deltaic wetlands.
Coal Formation Process
Vegetation must accumulate within anoxic (oxygen-poor) environments that slow organic decay. Common depositional environments yielding coal include:
Marine deltas.
Tropical coastal wetlands.
Transformation: When the sea level rises, deposited vegetation gets buried under clastics. Compaction transforms plant debris into peat (~50% carbon); with further burial, heat alters peat, expelling H, N, and S gases, while increasing carbon content until it converts into coal at ~70% carbon content.
Rank of Coal
Classification of Coal: Based on the carbon content, higher ranks yield more energy when burned.
Material | % Carbon | Energy Content | Rank |
|---|---|---|---|
Peat | 50 | 1500 kcal/kg | low |
Lignite | 70 | 3500 kcal/kg | low |
Bituminous Coal | 85 | 6500 kcal/kg | Mid |
Anthracite Coal | 95 | 7500 kcal/kg | High |
Conversions: 1 kcal = 1000 calories; 1 kg ≈ 2.2 lbs.
Coal Mining Techniques
Geologists use specific sedimentary sequence analysis to find coal in shallow marine, coastal, fluvial, and deltaic environments.
Coal must be:
Not too deep,
Have a minimum thickness of >1 meter.
Global Coal Deposits
Vast quantities of coal are prevalent in the U.S. and Canada, consisting largely of bituminous and lignite coals, accessible via:
Strip mining (open pit).
Underground mining.
Strip Mining Process
Mechanics of Strip Mining:
Drag-line buckets remove overburden (spoil), which is stockpiled for sale or reuse in restoration.
Coal is extracted, with efforts made to backfill excavated areas with soil and replant.
Hazard: Potential acid mine drainage exists.
Underground Mining Dangers
Tunnel and shaft systems used for extraction pose several hazards, including:
Tunnel collapse.
Methane gas risks leading to asphyxiation or explosions.
Black lung disease from excessive dust exposure.
Coalbed fires are difficult to extinguish and render areas uninhabitable.
Energy from Nuclear Fission
Nuclear Fission Process: This process allows certain radioactive atoms to be split apart, yielding tremendous amounts of energy.
Nuclear power plants primarily utilize the fission of uranium to generate electricity.
Mechanics of Fission: Neutrons collide with nuclei of fuel molecules to trigger fission, generating further neutrons to facilitate additional fission events, resulting in heat production.
Most reactors utilize fuel rods made of uranium oxide pellets.
Characteristics of Nuclear Power
Nuclear Energy Output: Nuclear power can produce electricity and emits no greenhouse gases.
Power plants maintain a balance between neutron generation and absorption to sustain the reaction.
Control rods absorb neutrons to moderate fission rates.
Geology of Uranium
Occurrence of Uranium: Naturally present in all rocks, but the concentration varies significantly.
Uranium is leached from minerals and transported, potentially solidifying in fractures and veins.
Isolation of Isotopes: Not all uranium isotopes are suitable for fission:
238U: Constitutes 99.3% and is non-fissionable.
235U: Comprises 0.7% and is fissionable.
Enrichment Requirements: Enrichment processes are necessary for 235U to increase fissionability, requiring complex and energy-intensive mining operations.
Nuclear Power Production
Energy Generation Cycle in Reactors:
A closed reactor loop creates high-pressure steam which is transferred to an external water loop, allowing steam to spin turbines and generate electricity.
Proper design and construction of reactors are critical for safety.
Incidents such as Fukushima (2011) raised concerns regarding the safety of nuclear plants in geologically active locations.
Nuclear Power Issues
Storage Concerns: Used reactor cores are often stored in spent fuel pools cooled by circulating water to prevent radioactive release, as seen in the Fukushima disaster.
Waste Management Problems:
Mining often leaves behind radioactive tailings and leachates, while fission creates long-lasting radioactive wastes which pose health risks.
Managing radioactive waste is a complex societal issue, highlighted by historical incidents such as Three Mile Island (1979), Chernobyl (1986), and Fukushima (2011).
Economic Concerns of Nuclear Power
Cost of Nuclear Plants: Building nuclear plants is a large financial investment, and safety concerns post-Fukushima have diminished public acceptance in the West.
Potential reactor meltdowns risk releasing radioactivity and necessitate robust management of spent fuel policies.
Geothermal Energy
Sources: The internal heat of the Earth derives from:
Radioactive decay of naturally occurring isotopes.
Residual heat from Earth's formation.
This geothermal energy has implications for tectonic movements and heat accessibility through the Earth’s crust.
Utilization of Geothermal Energy
The geothermal gradient indicates that Earth’s temperature increases with depth, ranging between 15°C/km to 50°C/km.
Applications of Geothermal Energy:
Hot water can be pumped from the ground for building heating.
Steam can drive turbines to generate electricity. Notably, Iceland generates all its power from geothermal energy apart from fossil fuels for vehicles.
Energy from Gravity
Mechanics of Gravity in Energy Production:
Gravitational forces exerted by the Moon create tides on Earth, and tidal flows can be harnessed to generate electricity.
The downward movement of water generates energy via turbines, and complex fluid motion allows for energy extraction from both air and ocean currents.
Hydroelectric Power
Kinetic and Potential Energy Utilization: Running water embodies kinetic energy (KE), which can be converted to potential energy (PE) through dams that store water above sea level.
Conversion Process: Water is released, converting PE back into KE, which flows through turbines to produce electricity. Tidal fluxes are sometimes used in dams as well.
Advantages and Disadvantages of Hydroelectric Power
Positive Aspects:
Reduces flood risks.
Stores water for drinking, irrigation, and recreational uses.
Provides a renewable energy source (hydrothermal electricity).
Does not generate hazardous waste or CO2.
Negative Aspects:
Alteration of ecosystems and landscapes due to damming.
Reservoir filling can induce geological activity.
Interrupts sediment flow downstream leading to delta and beach destabilization and necessitating dredging to restore reservoir capacity.
Wind Energy
Overview of Wind Energy Production: Wind farms are experiencing renewed interest, utilizing wind to drive turbines for electricity generation, which is a renewable and CO2-free energy source.
Challenges:
Turbine blades pose risks to bird populations.
Maintenance costs of turbines can be substantial, with some facilities being rendered inactive due to financial burdens.
Public opinion can be influenced by aesthetic concerns of wind farms.
Energy from Fusion
Solar Energy Generation: Energy produced by nuclear fusion within the Sun emits heat and light, with only a fraction of that output reaching Earth.
Human Utilization: Solar energy can be harnessed through photovoltaic cells or direct heating; however, fusion processes cannot be controlled on Earth.
Solar Power Characteristics
Abundant Energy Source: Solar energy is the plentiful energy source available on Earth’s surface, considerably more available than hydrocarbons.
Challenges for Wider Adoption:
Solar energy is diffuse, necessitating efficient collection and conversion practices.
Solar power generates no CO2 during operation.
Energy Usage Problems
Trends in Global Energy Use: There has been a significant increase in global energy consumption, driven by industrialization and population growth.
Oil remains the dominant energy source but is perceived as diminishing in availability.
The Oil Crunch
Projected Oil Depletion:
Experts warn of potential oil extinction occurring between 2050 to 2150.
The era of oil may be viewed by historians as a two-century phenomenon, and we are approaching the peak of global oil production.
Societal changes will be necessary as oil resources diminish.
Renewable vs Nonrenewable Energy
Definitions:
Renewable Energy: Resources that can be replenished quickly include solar, wind, hydroelectric, and geothermal energy sources.
Nonrenewable Energy: Resources requiring hundreds to millions of years for replenishment include oil, natural gas, coal, and uranium ores.
Biofuels can straddle the line between being classified as renewable or nonrenewable depending on their methods of production.
Environmental Impact of Energy Sources
Fossil Fuel Impact: Production and consumption of fossil fuels considerably harm the environment, notably through:
Oil Spills: Such as the Deepwater Horizon spill in the Gulf of Mexico.
Coal Mining Practices: Including strip mining that causes acid drainage.
Shale Gas Extraction: Related to groundwater contamination from hydraulic fracturing techniques.
Nuclear Energy Concerns: Following radiation releases and the destruction of facilities like Fukushima and Chernobyl.
Air Pollution and Climate Impact
Sources of Pollution from Fossil Fuels:
Unburned hydrocarbons increase photochemical smog.
Emission of sulfur dioxide (SO2) contributes to acid rain issues.
Burning coal releases toxic metals and soot into the atmosphere.
Increased CO2 levels from fossil fuel combustion are driving global warming and climate change.