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.

Atomic mass or atomic weight?

Example calculation using weight and moles.

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.

Cumulative emissions

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

*Solar energy has a density over twenty quadrillion times less than oil

Energy Education | Energy density

An Energy Primer for the AP Environmental Science Student

Vaclav Smil | Power density primer (PDF)

A comparison of energy densities of prevalent energy sources in units of joules per cubic meter | Bradley E. Layton Drexel University

Wikipedia | Comparison of commercial battery types

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

*Power density primer Vaclav Smil (PDF)

+The spatial extent of renewable and non-renewable power generation John van Zalk, Paul Behrens

Volker Quaschning

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.

Over time,

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.

Everyday power requirements,

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

Energy Education | Power Servant

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)