the carbon economy and the possible future role of hydrogen

how much of global energy do fossil fuels provide

~80%

carbon economy

the system that has evolved around the reality of the actions and decisions we take all have a cost in carbon

what is organic carbon a source of

oil and gas

where is carbon held in solution

oceans

where is carbon stored

plants and soils

where is carbon sequestered

in rocks in the form of fossil fuels and various minerals

what does the subsurface carbon cycle involve

organic matter burial and remobilisation as petroleum, while in the surficial cycle carbon moves predominantly as CO2

peak oil

the point in time when the maximum rate of global oil production occurs. It is followed by a terminal production decline

oil depletion

a period of time of failing reserves

peat transformations

transferred after burial to a soft, brown coal called lignite (few 100-1500 m temperatures up to 50 degrees C). At higher temperatures this becomes dull black bituminous coal (1000-5000 m, temperatures up to 150 degrees C).

At even higher temperatures it is transferred into shiny black anthracite (beyond 5000 m and temperatures over 150 degrees C)

coal is the dirtiest fossil fuel

Burning can release toxic heavy metals, sulphur dioxide, nitrogen oxides and particulates. Many countries are still building coal-fired power stations to generate electricity. A major challenge is to decrease, or capture and sequester, the greenhouse gases

coal degasification

the process of producing clean-burning gases from solid coal - produces grey hydrogen amongst other things

what do heavy oils have

high API gravity

oil sands

a loose unconsolidated mixture of sand clays and water, saturated with viscous bitumen (<1-20%)

production from oil sands

Steam is injected into the oil sands and the released bitumen is collected through lower horizontal wells beneath the injection wells

example of production from oil sands

Steam-assisted gravity drainage (SAGD) facility in Alberta

environmental issues

water requirement, waste water treatment

hydraulic fracturing

combined with horizontal drilling, this has facilitated the recent huge increase in exploration and production of tight reservoirs and especially of shale gas

methane hydrates (clathrates)

solid compounds in which a large amount of methane is trapped within the crystal structure of water ice

necessary conditions in their formation and preservation are only found in

• Polar (permafrost) settings where surface temperatures <0 degrees C

• Oceanic settings where depths >300 m, bottom water temperatures  ≤ 2 degrees C

how much of hydrogen is produced by water hydrolysis

2%

how much hydrogen is produced globally

600 billion cubic metres

hydrogen from natural gas

98% - CO2 as a by-product

current issues with green hydrogen

• Electrolyser manufacturers unable to meet demand at present

• Relatively high capital costs

• Energy loss during transitions from electricity to hydrogen and back to electricity

• Public perception of safety