Over the last several years it has become clear that there are tremendous reserves of natural gas
deep in shale deposits. Estimates indicate that there may be as much as 200 trillion cubic meters of
recoverable natural gas in these deposits around the globe.
A technique called hydraulic fracturing, or “fracking,” is now being used to access these gas
Fracking involves injecting a slurry of water, sand, and chemical additives under pressure
through a well bore drilled into the shale. This produces frac- features in the rock that
allow the gas to flow out into wells
potential contamination of groundwater, risks to air quality, and possible
mishandling of wastes associated with the process.
The composition of petroleum varies somewhat, but it consist consists mostly of hydrocar- bons
having chains that contain from 5 to more than 25 carbons
To be used efficiently, the petroleum must be separated into fractions by boiling. The
lighter molecules (hav- ing the lowest boiling points) can be boiled off, leaving the
heavier ones behind.
As gasoline became more important, new ways were sought to increase the yield of gasoline
obtained from each barrel of petroleum.
Burton invented a process at Standard Oil of Indiana called
Intensive research to find addi- the objectives that would promote smoother burning
produced tetraethyl lead, (C2H5)4Pb, a very effective “antiknock” agent.
The addition of tetraethyl lead to gasoline became a common practice, and by 1960,
gasoline contained as much as 3 grams of lead per gallon.
the use of leaded gasoline also greatly increased the amount of lead in the envi- the
environment, where it can be ingested by animals and humans.
For these reasons, the use of lead in gasoline has been phased out, requiring extensive
(and expensive) modifica- tions of engines and of the gasoline refining process.
was formed from the remains of plants that were buried and subjected to high
pressure and heat over long periods of time.