Energy: Sources, Consumption, and Environmental Impacts
Electricity
An electrical generator is a spinning coil of wire within a magnetic field. As the generator turns, the coils spinning through the magnetic field generate a voltage along the loop. The voltage is determined by the number of loops in the coil.
AC current moves back and forth with the changing magnetic field. As the coil of wire spins through the changing magnetic field, it produces a voltage going one way, but when the coil is 180 degrees from its initial starting point, it goes back and forth. AC is like a sine wave and vibrates back and forth, where DC current travels only in one direction. DC=batteries.
Once electricity is generated at a power plant (5000V), it first goes to a transmission substation where the voltage is stepped up by a transformer (500,000V). Electricity is stepped up to very high voltages because it is much more efficient to transmit electricity across long distances; the losses of energy are lower.
Typical voltage for long distance transmission is 500,000V, and typical voltage in our homes is 120V/240V.
For the electrical transformer, a”Step u” transformer increases the voltage (more coils on the output side v.s. the input side), and a”Step dow” transformer decreases voltage.
Energy Consumption
For a typical western developed economy, the categories are:
- Car – 40 kWh/day
- Jet Flights – 30 kWh/day
- Heating and cooling – 37 kWh/day
- Lights – 4 kWh/day
- Gadgets – 5 kWh/day
- Food, farming, fertilizer – 15 kWh/day
- Stuff – 48+ kWh/day
- Transporting stuff – 12 kWh/day
- Defense – 4 kWh/day
Driving, flying, heating and cooling, and just overall stuff has the most significant effects on energy consumption. About 30% of the total energy use in the US is used for transportation. About 40% of the total energy in the US is used for electricity production.
Other principal uses of energy include Residential, Commercial, and Industrial purposes.
Embodied energy is the energy consumed by all the processes associated with making a product [mining, processing, manufacturing, assembly, construction, transportation etc.]. LCA is important because it allows us to analyze/estimate the amount of energy a product consumes- Electric Car and LED Light bulb.
Transportation
Criteria for viable fuel: availability, cost, efficiency, ignition point, burning rate.
Refined petroleum performs best- made into gasoline and diesel.
Energy density = the amount of energy stored in a given system, substance, or region of space per unit volume.
Energy for transportation depends on both energy density by mass and energy density by volume.
Hydrogen has the highest energy density, followed by Petroleum fuels (Gas, Diesel, Kerosene), Coal, and Batteries.
Petroleum is a non-renewable resource which means at a certain point the resource will run out bad bc of the pollution associated with petroleum, C02 emissions etc.
Two solutions: Electric/Hydrogen:
- Clean, Renewable energy, abundant availability.
- Cons: Limited Range, Charging/Fueling Network.
- Hydrogen is very expensive.
- Electric pros: Emissions can be reduced if the electricity is generated using renewable energy, Electricity is cheaper than gas.
- Electric cons: Little/no positive change in emissions if the electricity used to fuel the car is generated using coal. Not suited for long distances.
- Hydrogen pros: Almost no emissions, Incredibly efficient [Refills much faster than Electric].
- Hydrogen cons: Very little infrastructure for hydrogen technology. Expensive.
Electric vehicles: If it’s a renewable and clean energy source, the manufacturing cost will be a much greater percentage of its overall emissions, but if it’s fossil fuels or coal, etc, it would make up less of an overall percentage.
Hydrogen fuel is the energy created from merging H2 molecules with Oxygen [producing water as well]. H2 fuel can be produced by steam-methane reforming [the process of heating CH4 +2H2O -> CO2 + 4H2] and electrolysis [putting electrical currents in the water and extracting H2].
H2 fuel is often used for refining petroleum, treating metals, producing fertilizer, and processing foods. When extracting H2 there is some carbon emission as a byproduct when utilizing the steam-methane method, however electrolysis produces none [it’s just highly inefficient].
H2 fuel makes up a very small portion of the transportation market due to the fact that other alternatives are much cheaper to produce, but there are cars like the Hyundai Nexo that utilize h2 fuel cells and we may see more being produced as an alternative to electric cars as the process becomes more streamlined.
In most spaces, we do not have a majority of renewable energy sources, meaning that most of our electricity will come from fossil fuels. This means that even if electric cars are using electricity instead of fossil fuels, the fossil fuels used to create said electricity may make the environmental impact negligible compared to a place that uses a majority of renewable energies.
In CA, a state that has a good amount of renewable energy sources, switching to an electric car would be beneficial compared to a gasoline powered car.
Transportation must respond to density.
Big Picture Energy Use
Correlation isn’t causation, but the better the economic situation is in a certain area, the higher the energy usage consumption and output is.
GDP: There tends to be a positive correlation between energy consumption and economic output, as energy is a fundamental input for most economic activities.
Developing countries often have a steeper trajectory of energy consumption growth relative to GDP growth compared to developed nations. This is because developing economies are typically undergoing rapid industrialization and urbanization, leading to increased energy demand.
While energy consumption is a significant input for economic activity, other factors such as technological innovation, policy interventions, demographic changes, and global economic conditions can also influence both energy consumption and GDP.
Physical Definitions
Power is energy exchanged per unit of time [Watts].
Energy is the capacity to do work. [Joules].
Work is the application of a force over a distance W = F x d, F = force applied, d = distance over which force is applied.
EX: Pushing something over some distance [Moving furniture around a room, Pushing a car].
Force is equal to Mass times acceleration (i.e., push or pull – capable of moving).
Gravity exerting a downward force on you.
The floor exerts an upward force on a ball during its bounce.
A car seat exerting a forward force on your body when you accelerate forward from a stop.
The seat you’re sitting in now is exerting an upward force on you (can you feel it?).
You exert a sideways force on a couch that you slide across the floor.
A string exerts a centrally-directed (centripetal) force on a rock at the end of a string that you’re twirling over your head.
The expanding gas in your car’s cylinder exerts a force against the piston.
Scientific Notation
Ex: 45,000→ 4.5*10^4 and 7.6*10^-4→ 0.00076.
Fossil Fuels
Hydrocarbon: organic compound containing. Hydrogen (H) and Carbon (C) – store chemical energy in C-H bonds – different hydrocarbons make up oil vs gas vs coal.
Simplest Hydrocarbon: Methane (CH4). Energy can be released when bonds are broken (e.g., by combustion). By adding more carbons, we can create different hydrocarbons. Natural Gas: light hydrocarbons (i.e methane C1 through pentane C5). Gasoline: hexane C6 through C12 Lubricants: C 16 And up. Photosynthesis: CO2 + H2O + light CH2O + O2. Carbon dioxide + water + light carbohydrate + oxygen. Carbohydrate: simple sugar, simplest representation of the building blocks of living organisms. Carbohydrate (CH2O) and Hydrocarbon (CH4). Hydrocarbons formed by loss of Oxygen (O) from carbohydrates – occurs naturally through baking at high temperatures (and sometimes high pressure) for long periods of time. Since C-O bonds store less energy than C-H bonds, energy density increases in transformation to hydrocarbons). Start with photosynthesis – energy coming from sunlight, carbohydrate is cooked and loses oxygen – resulting in hydrocarbon such as CH4 (Hydrocarbons can form without sunlight; deep sea bacteria use dim light from hydrothermal vents, some microbes use chemical energy (fe-oxidation), some form inorganically but we think most fossil fuels are ultimately from photosynthesis). Methane: CH4, Methane combustion reaction: (Extracting energy from hydrocarbons, harnessing energy by burning and releasing this as heat and light i.e., combustion) CH4 + 2O2 CO2 + 2H2O (+ energy). CH4 + 2O2: more energy in the bonds in these molecules…CO2 + 2H2O: than in the bonds in these…so that energy is released during reaction. Natural gas: mostly methane (CH4). “Sour gas”: high H2S – very undesirable (removed by “sweetening”) “Wet gas”: high heavy hydrocarbons (including possible oil) Natural gas is a literal gas. Automobile gas is liquid petroleum (crude oil), which is completely different from natural gas *Petroleum is a complex mixture of hydrocarbons. Molecules range greatly in size and are separated into fractions based on boiling point (“refining”). Petroleum is made from 4 chains of hydrocarbons, while Natural Gas is just Methane (one hydrocarbon). *Smallest to largest, complexity of chemical composition. Natural gas, automobile gasoline, unrefined crude oil, coal. Coal: cheap, dirtiest, high emissions – CO2, mercury, sulfur, Gas: little processing, cleaner to burn, 50% of CO2 of coal, only 10% energy loss in combustion, less pollution from unburned molecules, difficult to transport/transportation, drilling pollutes, dangerous to extract, leaked CH4, Oil: easily transported, clean (refining) compared to coal, CO2 emissions, oil spills, nitrogen oxide from internal combustion engines, energy security. Coal forms→Organic material (peat) is buried into an anoxic (no oxygen) state + time/pressure/heat -> Lignite/brown coal -> Subbituminous -> Bituminous -> Anthracite (Hard Coal) As these progress, the more carbon content they contain and the higher heating intensity they output. Coal is often found in the same layers as fossil forests. This leads paleontologists to believe that the majority of coal was processed in what were originally swamps due to the terrains ability to submerge organic matter (an anoxic state) and transposing it into peat. Breakdown of organic material to CO2 in presence of O2 As rocks are buried, O2 is consumed, and aerobic decay no longer possible (sediments become “anoxic”) and organic material is turned into coal. Sedimentary rocks: the source of coal. “Sediments”: made of mineral and/or organic particles. Usually layered horizontally, and can then be deformed’, Formed by the deposition and subsequent cementation of sediments. (Typically in oceans or river floodplains). Pangea: Case Study in Coal Formation: The Illinois Coal Basin, Carboniferous: about 300 million years ago, following evolution of plants, Near-equatorial Illinois was characterized by Carboniferous swamp forests (giant insects because of high O2 in the atmosphere) Tree trunks preserved during intermittent floods would bury the forest, alternating with coal-rich layers. Anoxia is defined by a complete lack of oxygen supply, and is important to the creation of fossil fuels because it preserves the dead material from being broken down and encourages the formation of peat or oil. 40% of our energy comes from petroleum.Chemical reactions: release of energy from H2 fuel • photosynthesis= CO2 + H2O + light -> CH2O + O2, Photosynthesis – reaction between carbon dioxide and water and energy in sunlight to create carbohydrate and oxygen. Carbon dioxide + water + light carbohydrate + oxygen, (Carbohydrate: simple sugar, simplest representation of the building blocks of living organisms) Carbohydrate (CH2O) and Hydrocarbon (CH4). Hydrocarbons formed by loss of Oxygen (O) from carbohydrates – occurs naturally through baking at high temperatures (and sometimes high pressure) for long periods of time. (Since C-O bonds store less energy than C-H bonds, energy density increases in transformation to hydrocarbons) Start with photosynthesis – energy coming from sunlight, carbohydrate is cooked and loses oxygen – resulting in hydrocarbon such as CH4 (Hydrocarbons can form without sunlight; deep sea bacteria use dim light from hydrothermal vents, some microbes use chemical energy (fe-oxidation), some form inorganically but we think most fossil fuels are ultimately from photosynthesis). Combustion of a simple hydrocarbon (e.g., methane) CH4 + 2O2 -> CO2 + 2H2O (+ energy). Hubbert Curve: peak oil in 70s and new peak of oil because of fracking, understanding and preparing for the eventual peak in oil production will be crucial for ensuring energy security and transitioning to alternative energy sources. Peak Oil and Unconventional Fossil Fuels: peak oil: the hypothetical point in time when the global production of oil reaches its maximum rate in which we then expect a terminal decline – it becomes too expensive to extract little oil. Oil sands: bitumen mixed with sand, high production costs, water consumption, habitat destruction, SAGD helps. Shale Gas: trapped in shale rock formations, requires fracking, increased seismicity, water usage. Keystone Pipeline: facilitate the transportation of oil from the oil sands(highly carbon intensive process) of alberta to refineries in the gulf coast of the US, Conventional oil – middle east, russia, parts of south america, unconventional oil (like shale oil) – US, canada, china. Conventional Natural gas- russia, iran, qatar. Fracking: used to extract natural gas and oil from underground rock formations, particularly shale rock. Process: Fracking involves injecting a mixture of water, sand, and chemicals into a wellbore at high pressure to create fractures in the rock formation, The pressure from the injected fluid opens up existing fractures and creates new ones, allowing the trapped natural gas or oil to flow more freely to the surface for extraction. History: The basic concept of hydraulic fracturing has been around for decades, with early experiments dating back to the mid-20th century, The modern technique of fracking evolved in the late 20th and early 21st centuries, combining hydraulic fracturing with horizontal drilling to access previously inaccessible shale gas and tight oil reserves, Fracking gained prominence in the United States in the early 2000s, particularly in regions like the Barnett Shale in Texas and the Marcellus Shale in Pennsylvania. Increased Use: Fracking has seen a major increase in use over the past decade due to several factors: Technological advancements: Innovations in horizontal drilling and fracking techniques have made it possible to access previously inaccessible shale gas and tight oil reserves more economically. Bad- water contamination/usage, air pollution, habitat disruption, climate change (methane leaks). Permeability:refers to the ability of a rock to allow fluids, such as oil, gas, or water, to flow through it. In unconventional reservoirs like shale, the permeability is typically very low, meaning that the rock does not naturally allow fluids to flow easily through it. Fracking is used to increase the permeability of these low-permeability reservoirs by creating fractures in the rock formation. During the fracking process, high-pressure fluids are injected into the rock, causing it to crack and fracture. These fractures create pathways for oil and gas to flow more freely through the rock, allowing for improved extraction rates. In essence, fracking enhances the permeability of the reservoir by artificially creating pathways for oil and gas to move from the tight rock matrix into the wellbore and ultimately to the surface for production. Without fracking, the low permeability of unconventional reservoirs would severely limit the flow of hydrocarbons, making extraction economically unfeasible. (slickwater). Environmental and other costs of fossil fuels: