Alternative Energy Sources
For the sake of simplicity, I have been looking at the state of conventional
oil. But what of unconventional oil (whatever that is)? Or gas and coal,
or nuclear, or renewable fuels such as wind and solar? You may have heard
that hydrogen is the answer for the internal combustion engines. Unfortunately,
all of these sources have problems which prevent them being the panacea
we need. Some are running out like oil, others are unsuitable, and some
are not usable within the period that we are looking at. They are all
important aids in the effort to avoid disaster but aids only. I shall
look at each and explain.
The Other Fuels
The graphs below show some of the reasons why oil is so
difficult to replace. E2 shows one reason why coal and other solid fuels
are unsuitable replacements: to replace your petrol tank with plant biomass,
for instance, it would require two and a half times the mass (rather simplified,
E3 shows one of the problems we would face if we switched
to producing our electricity from coal instead of natural gas nearly
70% more carbon dioxide emissions with all the pollution and cleansing
The main problems with the alternatives to oil and gas are
- they are generally only of use for heat and electricity, not the multitude
of uses that oil in particular has (eg. transport and plastics)
- they each have their own forms of pollution
- even by increasing them to their maximum potential, they would find
it hard to compete with the present day requirements
This last point is shown in Chart E4. Taken from Janet Ramage's book
"Energy: a Guidebook" (1997), it shows that the alternative
fuels would only just match the present fossil and nuclear fuels if they
were expanded to their maximum. But this would involve many decades and
enormous costs (wind power, for instance, would have to increase by 900,000
As noted above, all of the alternatives have their own pollution problems
and this is summarised below (again from data in "Energy: a Guidebook".
Pollution Problems of Renewables
||Global warming; air pollution by vehicles; acid rain; oil spills;
oil rig accidents
||Global warming; pipe leakage; methane explosions
||Global warming; environmental spoliation by open-cast mining; land
subsidence due to deep mining; spoil heaps; groundwater pollution;
||Global warming (despite what they say); radioactivity (routine
release, risk of accident, waste disposal); misuse of fissile material
by terrorists; spread of nuclear weapons
||Effect of landscape of and biodiversity; groundwater pollution
due to fertilisers; use of scarce water; competition with food production
||Displacement of populations; effect on rivers and groundwater;
dams (visual intrusion and risk of accident); seismic effects; downstream
effects on agriculture
||Noise; visual intrusion in sensitive landscapes; bird strikes;
||Destruction of wildlife habitat; reduced dispersal of effluents
||Release of polluting gases (SO2, H2S,
etc); groundwater pollution by chemicals including heavy metals;
||Sequestration of large land areas; use of toxic materials in manufacture
of PV cells; visual intrusion in both rural and urban environments
EROEI and EPR
An important element in comparing fossil fuels with other forms of energy
generation goes by the unfortunately unmemorable acronym of EROEI
"energy returned on energy invested". An alternative version
of this is the EPR Energy Profit Ratio. To produce any energy,
whether it is pumping oil out of the ground, or building and operating
a wind turbine, you need to use some energy in the process. If the energy
returned is less than the energy you produce, it is generally not worth
producing it (but see below).
As a simple example, imagine a (very small) car whose fuel tank holds
1 liter of petrol. The car's fuel efficiency is 20 km per liter.
If the nearest petrol station is 5 km away, fine you wait
until the tank is quarter full then drive there to refill (positive EROEI).
If it is 10 km away, you have gained nothing (and lost money)
by the time you have refuelled and driven home, you only have enough fuel
left to return to the station to fill up again. And if the station is
15 km away, once you have filled up and reached home, you would not
have enough left to get back to refuel again. You would be better off
staying at home and simply using up the existing petrol for other journeys
This example is mainly about fuel consumption rather than EROEI but
the analogy holds: if you think of taking petrol from the station
as extracting oil from a well, and the petrol used to drive to and from
the station as the combined energy used to extract oil (manufacturing
materials, building roads and pipelines, operating the well), you can
see the principle.
The EROEI is calculated by taking the energy content of your energy (in
whatever units you wish) and subtracting the energy used in producing
the energy. The result will be a number either negative, positive or zero.
The higher the number, the better.
The EPR is similar but the energy content is divided by the energy to
produce: the answer will be a ratio where 1 is equal to the zero if EROEI,
and less than 1 is equal to a negative.
As an example, if it takes the equivalent of 1 MJ of energy to extract
oil which, when burnt, can produce 10 MJ, then the EROEI is 101 = +9
and the EPR is 10/1 = 10. If it took 15 MJ of energy to
extract the oil, the answers would be 5 and 0.7.
The only time when negative EROEI can be worthwhile is if the energy
produced is in a more useful form than the energy used. For example,
can be used not only for energy generation but to make petrochemicals
whereas wind-generated electricity cannot. So it could be more worthwhile
using some wind-electricity to pump oil-energy out, even if the EROEI
is negative. Using the car analogy above, if the journey to the 15 km
petrol station was also used to deliver some goods to sell, you would
gain elsewhere even if you lost out on the petrol. But negative EROEI
is only acceptable if you have ample supplies of the one form and it
looks likely in the future that we will be struggling for all.
Individual Fuel Links
For more information on individual fuels, click the links below. EPR
values (see above) are given on the pages according
to information in Richard Heinberg's book "The Party's Over".
For comparison oil and gas has dropped from 100 (in the 1940s) to 8 for
discoveries in the 1970s.