Topic 3, titled Energy, is divided into two parts: Energy resources and Energy Module
implementation In this chapter, we're going to take a quick
look at: the great importance of energy in the development of humanity and our societies;
the current stagnation in oil production and the peak oil concept; the EROEI (energy return
on energy invested) concept and its importance; the current situation of other non-renewable
energy sources; and the challenge of renewable energy sources for filling the gap left by
the other energy sources.
The figure shows the history of energy transitions for almost 200 years.
Wood, a biomass, was the first source of energy.
With the Industrial Revolution in the mid-1700s coal began to replace biomass as the primary
source of energy.
The massive use of oil and natural gas didn’t start until the early 1900s when large reserves
were discovered, this process has intensified since the end of the II World War.
The most important observation is that “energy transition” on a global scale is additive
and not replacive.
Energy availability has a powerful influence on population growth.
The figure shows how growing amounts of available energy have boosted the number of people on
the planet... also on economic growth.
There is a correlation between global energy consumption and global GDP growth.
Energy change comes first!
But now we have a problem.
As I said before, population and economic growth depend on the energy availability of
all energy sources, and the main one, oil, is showing signs of exhaustion.
Between 2004 and 2015 the total production of crude oil plus condensates has moved around
a band of 5%.
The International Energy Agency (IEA) announced in November 2010 that conventional crude oil
production peaked in 2006, but what is peak oil?
Peak oil is the theoretical point in time when the maximum rate of extraction of petroleum
is reached, after which it is expected to enter terminal decline.
The concept of peak oil is often credited to M King Hubbert, a geologist who worked
for Shell Oil and for the USGS.
He predicted a peak of oil production from conventional oil fields in the Lower 48 states
and near shore waters to occur in 1970.
This did in fact occur, and subsequently his forecasts for both US and global production
gained a wide audience.
The Hubbert forecast was made after many decades of production using a database compiled from
a major producing company.
Hubbert had access to a reasonably complete knowledge of each region’s geology, production
techniques, and production history.
Because a similar knowledge base for the entire world does not exist it is more difficult
to forecast the global peak oil.
In the figure we can see different predictions of the global peak oil of the sum of conventional
and unconventional oil.
But conventional oil is not equal to unconventional oil as they are not valid for the same purpose,
for example, tight oil, which is a kind of light oil, is not good for making middle distillates
like diesel and jet fuel, and, also, because of their energy content and their cost of
extraction.
In the figure we can see the cost of extraction and the share of the different types of oil
that are currently exploited.
There's less and less cheap oil left.
The cost of extraction is also related to the EROEI.
Energy returned on energy invested (EROEI) is the ratio of the amount of ‘usable energy’
delivered from a particular energy resource or energy collecting system to the amount
of ‘usable energy’ used to obtain that energy resource or to build, operate and decommission
that energy collecting system.
Arithmetically the EROEI can be defined as in the figure.
The figure shows an illustration of the life cycle of an energy collecting system or energy
resource divided into three stages 1) construction, 2) operation and 3) decommissioning.
Energy inputs (in red and yellow) occur at each stage but energy outputs (in blue) will
normally only occur during the operational phase.
The EROEI, which in summary is the net amount of energy left to society is better the greater
it is.
In the figure we can see how the oil liquids that we currently exploit leave us less and
less available energy.
And since oil is going to supply us with ever less energy the key question is if any other
source of energy can compensate for this loss.
As we can see in this graph, nuclear energy does not look like it is going to increase
substantially.
As with the concept of peak oil there are peak uranium, peak coal and peak gas.
And as we can see in this figure the predictions for peak uranium are similar to those of peak
oil.
And as we can see in this figure the coal does not look like it is going to fill the
gap left by oil because there are big problems for it to continue growing.
neither are the predictions for peak coal any good, as we can see in this figure.
Gas is the only energy source that is still growing, but for how long?
most predictions are similar to those of other fossil sources, the peak will be reached in
a few years As we have seen, problems of fossil fuel supply
could well occur in the short term and the key question is whether renewable energies
can fill the gap left by fossil fuels.
This is one of the main questions to be answered by the MEDEAS model: we face the great challenge
of electrifying most of the economy and match it with the time frame of the decline of fossil
fuels.
The task is not easy because the current deployment of renewable energy is mainly to produce electricity
and the share of fossil fuels in world primary energy demand is currently 81% and transport
accounts for 29% of total world final consumption (World Energy Outlook 2018); we are now developing
and exploiting renewable energies using fossil fuels, in the future we will have to do so
using electricity; most renewable and non-conventional energy alternatives have substantially lower
EROEI values than conventional fossil fuels; not all sites with a high renewable resource
potential are likely to be used because they must be technically and economically feasible
and we cannot afford to repeat the environmental mistakes of fossil.
These last two questions, the EROEI and the potential of renewable energies, will answer
the question of what energy levels society can eventually enjoy.
Theoretical physical potential derived from natural and climatic conditions.
Geographical constrains such as mountains, glaciers, urban land …
Technical constraints.
The achievable energy output when fully proven technologies are used.
Economic constraints.
The output when costs and benefits are included.
Environmental constraints.
Long-term environmental development must be preserved.
And finally, the sustainable potential is when long-term environmental development is
not hindered.
In this chapter, we have described: the direct correlation between energy and population
and between energy and GDP (Gross Domestic Product); the peak oil concept as the time
when the maximum rate of extraction is reached.
This concept can be generalized to other energy sources; the importance of the EROEI and its
value for different oil types; the current stagnation in oil production, coal and nuclear
energy, and the doubts about future gas production; and the great challenge facing renewable energies
to fill the gap left by fossil fuels.
The next part will show how energy sources are modeled in MEDEAS.