Conversion Technologies 65
Years Years
(a) (b)
Production Production
Figure 3.1Simple theoretical models of the combined output from a group of gas or oil fields: both
graphs assume that fields are found 1 year apart, larger fields are found earlier. (a) Field production
follows a trapezoidal profile, possibly typical of gas fields. (b) Field production follows a profile typical
of oil fields, that is, a rapid build up, followed by a slow decline. Bentley 2002 [3, 4]. Reproduced with
permission of Elsevier.
to release the energy from their chemical bonds and transform it into heat and work
and later to transform these molecules into useful materials such as plastics. Continued
utilisation of non-renewable resources on a finite planet must result in eventual resource
depletion, it is only the matter of question when. For every non-renewable deposit, the
productivity achieved from the extraction of this deposit resembles a bell-shaped curve
(Figure 3.1) called Hubbert curve. Once new deposit is found, the production quickly
rises until it reaches the peak, called Hubbert peak and then it starts dropping due to
resource depletion [3, 4].
At this point, the production needs to be replaced by another resource to maintain
the output. For individual non-renewable resources, these bell-shaped cures have been
observed not only at the levels of individual oilfields but also at national and regional
levels. It is just a matter of time when peak production is achieved on global level,
and many would argue that the peak for conventional oil has been already achieved
[5]. Once peak production is reached the inevitable shift towards alternative resource
needs to take place as the original resource will eventually become depleted. The reality
of year-by-year growth of supply will be replaced by a reality of year-by-year decline
most likely with a ‘bumpy plateau’ at the top due to buffering effects of natural gas and
unconventional oil [5]. Recent reports suggest that new additions to the fuel sector
are mainly from natural gas and non-conventional oil [6]. This may suggest that we
have already entered the ‘bumpy plateau’ at the top of Hubbert curve. The length and
shape of this plateau will depend on the efficiency of the introduced replacements to
conventional oil such as: non-conventional oil, natural gas or bio-fuels. Overall the issue
is not really when we exhaust our supplies of fossil resources but when our demand for
them will exceed the capacity to provide these resources or their replacements. Once
this inflexion point is reached, the economies and citizens will face a very different
landscape from the one we currently know and are used to. In terms of economic
impact, the ratio between the production rate and its increase or decrease and the
consumption rate and its increase or decrease is most important. To put current
situation into larger perspective, most of our current fossil resources come from
deposits discovered in the 1960s and 1970s in the Middle East, Western Siberia, Alaska
and North Sea. Many of these deposits are still rich in resources but they will inevitably
achieve their peaks in the near future. Since then, despite huge advances in investment
and technologies, only relatively small oil fields were found. Over past few decades, the
