Facts
Carbon & CO2
Emissions values are usually given in tonnes of carbon dioxide, but occasionally a value is given in tonnes of carbon (the giveaway is that the value looks surprisingly small). To convert a mass of carbon to carbon dioxide multiple by 3.67.
How is this number derived?
The atomic mass of carbon is 12. The atomic mass of oxygen is 16.
The ratio of CO2 to C is therefore 44/12 (1 × 12 + 2 × 16 / 12) or ~3.67.
To calculate the mass of CO2 released by burning a particular fossil fuel it is necessary to know how much carbon it contains. The additional mass comes from the oxygen.
CO2e
Peat
Peat is an accumulation of partially decayed vegetation or organic matter. The IPCC classifies peat as neither a fossil fuel nor a renewable fuel, and notes that its emission characteristics are similar to fossil fuels. Wikipedia
Coal
The formation of coal takes a significant amount of time (on the order of a few million years), and the first coal-bearing rock units appeared about 290-360 million years ago, at a time known as the Carboniferous or "coal-bearing" Period. As well, there are extensive coal deposits from the Cretaceous age - about 65 to 144 million years ago. Energy Education: coal formation
Oil & Gas
70% of oil deposits existing today were formed in the Mesozoic age (252 to 66 million years ago), 20% were formed in the Cenozoic age (65 million years ago), and only 10% were formed in the Paleozoic age (541 to 252 million years ago). This is likely because the Mesozoic age was marked by a tropical climate, with large amounts of plankton in the ocean.Energy Education: oil formation
Time
Geologic time
| Event | When | Notes |
|---|---|---|
| Paleozoic Era | 541-252 mya | Ancient life |
| Carboniferous Period | 359-299 mya | Its coal beds powered the Industrial Revolution |
| Mesozoic Era | 252-66 mya | Age of Reptiles and the Age of Conifers |
| Cretaceous Period | 145-66 mya | Further coal beds laid down |
| Cenozoic Era | 66 mya - present | Age of Mammals |
| Holocene epoch | 11.65 kya | Interglacial period |
Human time
A rough, and disputed timeline of human evolution.
| Event | When | Notes |
|---|---|---|
| Hominini tribe separates from Gorillini | 8-9 mya | Humans, Australopithecus, and chimpanzees separate from gorillas |
| Separation of the subtribes Hominina and Panina | 2.3-1.6 mya | Humans and extinct biped ancestors separate from chimpanzees |
| Homo habilis | 4-7 mya | Human ancestor or related species |
| Homo erectus | 2 mya | Extinct species of archaic human |
| Earliest use of fire | 1 mya | Wonderwerk Cave, South Africa |
| Earliest evidence of cooking | .5 mya | By Homo erectus |
| Last Glacial Maximum (LGM) | 120 kya | Ice sheets at their greatest extent |
| Younger Dryas | 11.7-12.9 kya | Temporary reversal of climactic warming since LGM |
| Holocene epoch | 11.65 kya | Interglacial period |
| First domestication of livestock | 10-11 kya | Fertile Crescent |
| Domestication of cereal crops | 11 kya | Fertile Crescent |
| James Watt patents his steam engine design | 1769 | Catalyses The Industrial Revolution |
Emissions
Emissions since when?
The IPCC calculates the rise in the global mean surface temperature (GMST) from the beginning of large-scale industrial activity. Their reference period (PDF) is 1850-1900.
Industrialisation had begun before this date, primarily in England (78% of global emissions). Dates for the Industrial Revolution in Europe and the United States are typically given as starting in 1760, and ending in 1820, or 1840, but emissions were low by comparison to today, just 4.96 billion tonnes, and were localised. Prior to this period humans had been burning wood, coal, and clearing land, but emissions were comparatively insignificant.
| Year | Cumulative emissions (billions of tonnes) |
|---|---|
| 1850 | 4.96 |
| 1950 | 230.21 |
| 1970 | 417.82 |
| 2000 | 1,020 |
| 2019 | 1,610 |
In 1850 cumulative global emissions were around 0.3% of what they are today.
Fuel emissions
| Fuel | Emissions kgCO2/kWh | Emissions kgCO2/GJ |
|---|---|---|
| Peat | 0.38 | 106 |
| Wood | 0.39 | 109.6 |
| Lignite | 0.36 | 101.2 |
| Anthracite (hard coal) | 0.34 | 94.6 |
| Crude oil | 0.26 | |
| Gasoline | 0.25 | |
| Natural gas | 0.2 |
Energy
Units
SI Units: Quick reference
Energy density
You can start explaining some of the limits and possibilities of everyday life or historical progress by playing with energy densities: the more concentrated sources of energy give you many great advantages in terms of their extraction, portability, transportation and storage costs, and conversion options. Vaclav Smil (PDF)
| Fuel | Energy density MJ/kg | Energy density |
|---|---|---|
| Solar | 1.5 microjoules/m3 | |
| Wind | 0.5-50 J/m3 | |
| Lithium-ion battery | 0.79 | 220-260 Wh/kg |
| Peat | 15 | |
| Wood | 16 | |
| Coal | 24 | |
| Crude oil | 44 | 35-45,000 MJ/m3 |
| Gasoline | 46 | 46 MJ/m3 |
| Natural gas | 55 | 35 MJ/m3 |
| Hydrogen | 143 | 0.01 MJ/m3 |
| Nuclear (uranium-235) | 3,900,000 |
Power density
| Power source | Power density W/m2 range* | Power density W/m2 median+ |
|---|---|---|
| Biomass | 0.5-0.6 | 0.08 |
| Wind | 0.5-1.5 | 2.02 |
| Solar PV | 4-9 | 6.6 |
| Solar CSP | 4-10 | 9.7 |
| Coal | 100-1,000 | 135.1 |
| Natural gas | 200-2,000 | 482.1 |
Horsepower
There are numerous definitions for the value of horsepower; one metric measure is defined as,
The power needed to lift 75 kilograms by 1 metre in 1 second.
Comparing horses and humans,A horse can reach a peak of ~11kW over a period of a few seconds.
A human can reach a peak of ~1kW over a period of a few seconds.
A horse can perform sustained activity at a work rate of about 0.75kW.
A human can perform sustained activity at a work rate of about 0.075kW.
A toaster uses in the range of .8 to 1.5kW of energy.
An ordinary family salon has ~120 horsepower, and an SUV ~200 horsepower.
Human power
2000 Calories / 1 day × 1 day / 24 hours × 60 minutes × 60 seconds × 4184 Joules / 1 Calories = 96.85 J/second = 96.85W ≈ 100W
Photosynthesis
Photosynthesis is an inherently inefficient energy conversion process, and production of biomass has large space requirements. Even with an intensively cultivated plantation of fast-growing trees, a wood-burning electricity generation plant would not have power densities higher than 0.6 W/m2, and for most operations the rate would be below 0.5 W/m2. Space demand for such facilities, then, would be two to three orders of magnitude (100 to 1,000 times) greater than for coal- or gas-fired electricity generation.Power density primer Vaclav Smil (PDF)