Module 35, 36, and 37 Notes
Measuring energy
BTU: British thermal unit: energy required to raise the temperature of one pound of water by 1 degree F
Joule (J): unit of energy
Gigajoules (GJ): 1 billion joules
Exajoule (EJ): 1 billion gigajoules or 1 billion billion joules
1 EJ is almost equal to 1 Quad (1 Quadrillion BTUs)
1 Quad = 1.055 EJ or 1.055 J = 1 BTU
Renewable energy vs. Nonrenewable
Fossil fuels = nonrenewable
Timber = potentially renewable
Nonrenewable if not obtained sustainably
Renewable if obtained sustainably
Nuclear fission = nonrenewable
Nuclear fusion = could be virtually inexhaustible
Difficult to do without an explosion with net energy gain
Solar = renewable
Resources to build solar could be considered nonrenewable
Wind power = renewable
Resources used
Hydropower = nondepletable on a large scale, depletable on a short-term scale
Hubbert Curve
Idea: oil production will reach a maximum until about half used up then slowly decline
Normal curve
Energy Efficiency vs. Energy Conservation
Two ways to reduce energy consumer
Increase energy efficiency
Getting the same job done with less energy
Decrease energy used (energy conservation)
Minimizing energy-consuming tasks
Energy Return on Energy Investment (EROEI)
Energy subsidy with food except in this metric, a higher number is better
Ex.
Oil sands EROEI is estimated at 5
Traditional oil reserves have had EROIE of 18-43
Hydropower = 110
Wind = 20
Solar = 9 - 34
ethanol from corn = 1.3
Many of these numbers are estimates with high situational variability
Modern Cabro vs Fossil Carbon
Modern cabin use as fuel could the carbon nur teal if the ecosystems it came from are able to fully regenerate and restore that carbon
Te qualifiers are important
Coal
Plant material in swamps and bogs that gets compressed
Peat → lignite → bituminous → anthracite
Increasing order of more heat and pressure (peat = less, anthracite = more)
Easy and cheap
Pros:
Energy-dense
Plentiful
Little to no refining is needed
“Easy” to extract (low-tech)
Useful for generating electricity
Useful for generating heat for industry
Steel
Cons:
High sulfur content (a major air pollutant)
Especially in bituminous coal
coal ash is a hazardous waste product
Releases more carbon dioxide per unit of energy than gas or oil
Subsurface mining is hazardous
Oil
Crude oil comes right out of the ground
Distill crude oil to refine it using a furnace
There are different levels of distillation
Pros:
Energy-dense
Easier to transport
Immediate energy output
Useful to power transportation
Less carbon dioxide, sulfur, and particulate pollution than coal
Cons
Leashes and spillage during extraction and transport
Even more, spills from land runoff
Still release carbon dioxide, sulfur, and particulates in significant amounts
Determine energy efficiency (Water Heater example)
Electric
99% efficient
Cannot be 100%
Law of entropy
not guaranteed to be greener
Where does it get the electricity from?
Gas
60-80% efficient
Origin of coal and oil
Oil and natural gas: come from algae and animals in the ocean
As they become part of the sediments they can form into oil and natural gas
Coal: plant and land-based
Natural gas
Pro
Emits much less postulates and sulfur than coal and oil
Releases less CO2 than coal or oil
Recent technology making more reserves available major resources in US
Cons
Still releases carbon dioxide
Leaks during extraction, transportation, and use consists mostly methane
25 times more potent greenhouse gas than CO2
Difficult and dangerous to transport except by pipeline
Risk associated with fracking
Fracking
Hydraulic fracking
Send high-pressure water into impermeable rock to crack the rock and release the gas
Problem
Contaminants that water
Consumes a lot do water
A lot of other chemicals that need to be put underground
Potential to get into groundwater storage
VOCs (Volatile Organic Compounds)
Many sources (both biological and anthropogenic)
Many types of varying concern
Like to bond with stuff
Likes to vaporize
Organic because they are carbon-based
Electricity
Secondary royce of energy
Must concert form a primary source
Always a loss of energy
2nd law of thermodynamics (entropy)
Nonrenewable energy resources are finite and important:
Fossil fuels: fuels derived from biological material that became fossilized millions of years ago
Coal, oil, and natural gas are fossil fuels derived from biological material that became fossilized millions do years ago
When they are combusted, they release fossil carbon that has been stored for millions of years into the atmosphere
Nonrenewable energy resource: an energy source with a finite supply, primarily fossil fuel and nuclear fuels
Because a fossil fuel cannot be replenished once it is used up it is known as a nonrenewable resource
Renewable energy resources are infinite and becoming more important:
Renewable energy resources: sources of energy that are infinite
There Are two categories of renewable resources
Biomass energy resources are potentially renewable because those resources can be regenerated indefinite if they are not consumed too quickly
Solar, wind, geothermal, hydroelectric, and tidal energy are non depletable
Nondepletable: an energy source that cannot be used up
Potentially renewable: an energy source that can be regenerated indefinitely as long as it is not overharvested
Trends in energy use are changing around the world and in the United States:
Worldwide Patterns of Energy Use
Commercial energy sources: energy sources that are bought and sol, such as coal, oil, and natural gas
Subsistence energy source: energy sources gathered by individuals for their own immediate needs including straw, sticks, and animal dung
Worldwide, oil, coal and natural gas are the three largest energy sources and comprised of 80 percent of total energy use
Renewable energy comprised of 15 percent of global energy use
Hydroelectricity is the largest source of renewable energy
Energy use is highly variable in countries around the world
Patterns of energy use in the UNited States:
In The united states, total energy use is 79 percent fossil fuel, 9 percent nuclear fuel, and 12 percent renewable energy resources
Quantities of fossil fuels in the united states and worldwide
Energy intensity: the energy use per unit of gross domestic product (GDP)
The Hubbert Curve: a graph that represents oil use and projects both when world oil production will reach a maximum and when world oil will be depleted
Fossil fuel combustion: the chemical reaction between any fossil fuel and oxygen resulting in the production of carbon dioxide, water, and the release of energy
Peak oil: the point at which oil extraction and use would increase steadily until roughly half the supply had been used up
The future of fossil fuel use:
Energy conservation: methods for finding and implementing easy to use less energy
Energy conservation is finding and implementing easy to use less energy while energy efficiency is the ratio of the amount of energy expended in the form you want to total amount of energy that is introduced into the system
Energy efficiency: the ratio of the amount of energy expended in the form you want to the total amount of energy that is introduced into the system
By avoiding the use of energy resources, conservation and effcientlabare actually sustainable energy “sources”
Based on reserves and projected consumption rates estimates can be prepared for the number of years remaining for a particular fossil fuel
These estimates are uncertain because of new energy sources and reduced demand for current resources
Different forms of energy
As anthropogenic increases in atmospheric greenhouse gas concentrations are causing global climate change, ther reaction from fossil aulas to other energy sources has become even more important
Quantifying energy efficiently:
Energy return on energy investment: the amount of energy we get out of an energy source for every unit do energy expended on its production
EROEI = energy obtained from the fuel / energy invested to obtain the fuel
100 J EROEI = 100 J / 5 J = 20
The Sun is the ultimate sources of many of the fuels we use:
Biofuels: a liquid fuel such as ethanol or biodiesel creed from processed or refined biomass
Modern carbon versus fossil carbon
Modern carbon: carbon in biomass that was recently in the atmosphere
Fossil carbon: old carbon contained in fossil fields
Carbon neutral: an activity that does not change atmospheric CO2 concentrations
The sun is the source of energy contained within fossil fuels and is also the energy source for many renewable fuels including biomass, solar, wind, and hydro
We call the carbon in biomass modern carbon, in contrast to the carbon in fossil fuels, which was recently in the atmosphere, fossil carbon has been buried for millions of years
Each fuel has specific optional applications:
Wood
Wood is used in much of the developing world as fire-wood and charcoal
Coal and peat
Coal: a solid field formed primarily from the remains of trees, ferns, and other plant materials that were preserved 280 million to 360 million years ago
Peat and three different types of coal are derived from fossil plant material and are used in electric generation, industrial processes, and heating
Peat: a precursor to coal, made of partially decomposed organic material, including mosses
Lignite: a brown coal that is a soft sedimentary rock that sometimes shows traces of plant structure
It typically contains 60 to 70 percent carbon
Bituminous coal: a black or dark brown coal that contains bitumen, aka asphalt
It typically contains 80 percent carbon
Anthracite (hard coal): it contains greater than 90 percent carbon
It has the highest quantity of energy per volume of coal and the fewest impurities
Natural gas: a relatively clean fossil fuel containing 80 to 95 percent methane (CH4) and 5 to 20 percent ethane, propane, and butane
Natural gas is composed of mostly methane and is used for electricity generation, industrial processes, and home use such as heating interior living spaces and making hot water
Crude oil: a mixture of hydrocarbons such as oil, gasoline, kerosene as well as water and sulfur that exists in a liquid state underground, and when brought to the surface
Crude oil can be extracted from the ground as oil or as tar sands
Tar sands (oil sands): slow-flowing, viscous deposits of bitumen or asphalt, mixed with sand, water, and clay
Oil can be distilled into a variety of products such as kerosene, aviation fuel, and gasoline
Different fuel types are best suited for specific purposes
Fossil fuels have specialized uses for motor vehicles and electricity:
Hot water heaters
Electric hot water heaters contain a resistance coil that generates what is inside the tank of water and are very efficient
But generating electricity can have a variety of efficiencies so the overall process may be less efficient
Natural gas heaters are less efficient, but their overall efficiency may be greater
Fossil fuel choices and transportation
Different modes of transportation use different fuels and have different efficiencies
In general,one person alone is more energy-intensive than more people in a car, or in public transportation
Generation and cogeneration convert fuels to electricity:
Natural gas and coal are two fuels used to generate electricity
Energy carrier: an energy source such as electricity that can move and deliver energy in a convenient, usable form to end users
The process of electricity generation
Efficiency of electricity generation
Combined cycle: a feature in some natural gas-fired power plants that uses both a steam turbine to generate electricity and a separate turbine that is powered by the exhaust gases from natural gas combustion to turn another turbine to generate electricity
Capacity: the maximum electrical output of something such as a power plant
Capacity factor: the fraction of time a power plant operates during a year
Cogeneration (combined heat and power): the use of a fuel to both generate electricity and deliver heat to a building or industrial process
Cogeneration is a process where the heat from fuel combustion is used to generate electricity and heat buildings
It's a more efficient process than conducting these activities separately
Fossil field and ore distribution around the globe depends on the geology of the region:
Fossil fuel distribution around the world depends on the geology of the region
Organic matter that will eventually become coal or oil must be buried quickly without being exposed to air
This typically happens in tropical locations
Oil and natural gas are also dependent on geologic events related to tectonics that create geologic domes underground
Over time, oil and gas migrate to the top of these structures
Fossil fuels have many advantages and disadvantages:
Coal, oil, and natural gas each have their advantages and disadvantages
All three decrease heat energy and carbon dioxide with differing amounts of pollutant release from each
Advantages of coal
Disadvantages of coal
Advantages of oil
Disadvantages of oil
Advantages of natural gas
Disadvantages of natural gas
Fracking: short for hydraulic fracturing, a method of oil and gas extraction that uses high-pressure buildings to force open existing cracks in rocks deep underground
Fracking has increased the availability of natural gas in the United States and has led to groundwater contamination and a suspected increase in earthquakes
Also causes the release of category of air pollutants from both fracking fluid and from the machinery used at the fracking site
Volatile organic compounds: a type of organic compound air pollutants that evaporate at typical atmospheric temperatures
Fuel is converted to electricity and releases carbon dioxide and heat energy:
Turbine: a device that can be turned by water, steam, or wind to produce power such as electricity
Electrical grid: a network of interconnected transmission lines
Coal to electricity and transport of electricity x light bulb efficiency = overall efficiency
Energy quality: the ease with which an energy source can be used to do work