The table below illustrates a very important principle – there is no free lunch in energy supply.
Whereas each of us has our own preferences about different energy sources, each energy source has its peculiar set of problems. Some may cause less environmental harm or harm to humans, but even these ‘softer’ technologies can cause major contention and may not be able to deliver the type of energy that is in demand.
For instance, an energy source that delivers a surplus of electricity may not be all that useful if our immediate energy problem is shortage of liquid fuels.
[Note that EROEI (right hand column) stands for energy return on energy invested.]
|Energy source||Problems||Nominal EROEI|
|Firewood||Although firewood enjoys a very high net energy return (EROEI), unregulated firewood collections has caused much habitat damage in Tasmania. Requires a firewood production regime, including firewood farming allotments. Firewood burning can also cause significant local pollution and health problems in certain environments. Note that the high net energy return (at right) applies only to burning firewood directly to create heat – not to be confused with burning firewood for electricity production, net energy return is closer to that of brown coal (8).||32|
|Hydro-electricity||Net energy return (EROEI) for hydro is very site specific, depending on construction needs, such as amount of concrete and earth fill etc. EROEI can be up to 200 for a simple run-of-river scheme, less than 30 for a remote dam built in very difficult terrain. Although a renewable energy source, its greenhouse emissions can be very high where significant vegetation or soil carbon is inundated, especially rainforests. Ecological damage can range from disruption of fish habitat, to destruction of ecosystems, to loss of wilderness, to alteration of downstream river ecology.||20|
|Geothermal||Release of polluting gases (SO2, H2S,); water requirement; groundwater pollution by chemicals including heavy metals; seismic effects; significant transmission infrastructure required for small output, most potential sites being far from where electricity is used.||8|
|Wind farms||Main problem is bird strike. Also resources to provide transmission infrastructure to dispersed sites spread over a wide area and their consequent visual intrusion of landscapes. There has also been much public opposition to despoilation of natural vistas and purported effects on TV reception and, in some sites, subtle effect on human health, resulting from noise frequency.||9|
|Solar photovoltaics||Use of toxic materials in manufacture of PV cells; delivers energy at very high cost per kilowatt-hour; visual intrusion in both rural and urban environments; all input energy is at the front end, before any power is produced…. long payback period.||7|
|Nuclear||High level of public fear; potential catastrophic accidents; radioactive waste disposal problem unresolved; potential misuse of fissile material by terrorists; potential contribution to nuclear weapons proliferation; high water requirement; at least 10 years needed for planning approval and construction.||7|
|Natural gas||Greenhouse pollution; pipe leakage; methane explosions||10|
|Coal seam gas||Greenhouse pollution; serious poisoning of aquifers and drinking water; intrusion on private lands and human rights; landscape scarring.||4|
|Coal||Serious greenhouse pollution; environmental spoliation by open-cut mining; land subsidence due to deep mining; spoil heaps; groundwater pollution; acid rain; damage to agricultural lands. The EROEI of 30 (at right) = coal burned for industrial heat as opposed to 9 = coal burned for electricity production.||9 and 30|
|Oil||Serious greenhouse pollution; world demand exceeding supply; resource wars in oil supply regions; marine and terrestrial damage from oil spills; exploitation of ethnic people in major oil regions (eg Nigeria); net energy return from oil wells now averages at only 15, as opposed to best quality oil in the world (Libya) at 100||17|
|Bio-fuels||Significant competition with food production; impacts on landscapes and biodiversity; groundwater pollution from fertilisers; use of scarce water; significant chemical pollution from burning emissions. Best source of bio-fuels is by-products from wastes and food crops, but volume of these are strictly limited.||3|
|Oil shale||Very serious greenhouse pollution; very serious local land degradation and local pollution.||3|
|Tar sands||Very serious greenhouse pollution; very serious local land degradation and local pollution.||4|
The EROEI figures given above are illustrative and derived from a number of sources. They give a general guide to the net energy return on energy invested, but this may have no bearing on total amount of potential energy available from any one source.
What about new alternative energy sources?
Although potential technologies have their hard core enthusiasts, none of them is, as yet, proven up so that they actually work and deliver a net return of energy in any particular setting. Some of them may never be. Such sources include nuclear fusion power, solar collectors in space, liquid fuels derived from ocean algae, integrated fast nuclear (fission) reactors, wave power, tidal power.
The history of development of energy technologies tells us that the forecast net energy return of new technologies tends to be overestimated (and capital costs underestimated) by a factor of two, as a result of wishful thinking on the part of enthusiastic developers. But the really core problem is that the global energy crisis is upon us now and we can’t wait for decades for solutions to be developed several decades into the future.
The aim of this summary is not to champion any energy source over any other, it is simply to illustrate that there is no free lunch in energy supply.
Pitted against all of these energy sources (many of them very costly) is a very basic strategy: using less of it. Living more comfortably with less energy wastage. Running our energy economy much more efficiently.
In nearly every situation the financial, environmental and social burden is much reduced, costs to business are lower and public acceptability is higher.
- The nine challenges of renewable energy (download – 1.5meg)
Hydroelectric dams and global warming: A little understood aspect of hydro dams is their potential significant contribution to global warming, as reported by the World Commission on Dams. Although methane emissions from Tasmanian dams are far less than those in tropical areas, this reference is included simply to provide background information on this topic.