Harald Heinrichs · Pim Martens Gerd Michelsen · Arnim Wiek Editors

3.3 Limits to (Growing) Fossil Energy Supply and the Role 
of Unconventional Resources
Global energy consumption is constantly rising, but fossil fuel resources, notably 
oil, are limited. This is an obvious fact that has led to a debate on whether the world 
will soon reach a peak in global oil production and subsequently also peaks of natu-
ral gas, uranium and coal production. However, fossil fuel resources are more than
sufficient to fuel dangerous climate change well beyond the target to limit average 
global warming below 2 °C.
While it is undeniable that fossil resources are limited – as the world and the 
amount it contains are finite – the estimates of which fossil resources are 
( economically) recoverable and which are not are relatively uncertain and changing 
over time. Increasing fossil fuel prices and technology developments (e.g. spurred 
A very concrete example is solar lanterns (with PV cells, batteries and LED 
lamps) that can provide high-quality efficient lighting and simultaneously 
reduce reliance on purchased fuel for kerosene lamps.
S. Lechtenböhmer and L.J. Nilsson

---

237
by high price expectations) make it profitable to extract fossil resources that were 
previously un-economical to exploit. Such factors postpone the point at which 
global fossil energy production will de facto not increase anymore (this is assuming 
that extraction will not be limited by environmental concerns).
The recent development of unconventional gas production in the USA is a good 
example of this effect. Declining domestic gas production resulted in increasing gas 
prices and expectations of significantly increasing import dependence. At the same 
time, drilling techniques including the technology of hydraulic fracturing (“frack-
ing”) to better exploit existing unconventional gas were developed. Together with 
reduced environmental restrictions and a couple of other favourable factors, this 
made domestic unconventional gas production economic and led to the “shale gas 
boom” in the years 2010–2013. This boom significantly reduced gas (and subse-
quently other energy) prices and made the USA the largest producer of gas world-
wide (cp. Boersma and Johnson 
2013
).
Fig. 19.4
Global greenhouse gas emissions in 2010 by source (estimated)
19 Sustainable Energy Systems

---

238
However, unconventional energy resources come at a price. Often their extrac-
tion is not only more expensive but also more harmful to the environment than that 
of conventional fossil resources. One example is shale gas which is highly debated 
due to environmental threats to groundwater resources but also possible large green-
house gas emissions. Another is the oil extraction from tar sands, mainly in Canada,
which among other things consumes huge amounts of energy and water 
(Lechtenböhmer and Altmann 
2013
).