Alternative Sources of Energy
At present, the practical large-scale sources of global energy are coal, oil and gas and nuclear power with some additional remaining hydroelectric resources yet to be exploited.
While Australia has significant reserves of uranium, these are not as plentiful as coal and impose other problems. There are obvious risks involved in encouraging the proliferation of nuclear power in third world countries. India acquired nuclear weapons within a few years of gaining their first reactor and even the Soviet Union has proven to be an unreliable manager of nuclear power plants.
There are many potential sources of energy appropriate to the domestic energy needs of small regions or communities, including hydroelectric power, geothermal power, tidal power and wind power.
Most of the World's energy use is consumed by industry manufacturing and moving materials[10]. At the current level of technology, only nuclear power provides an alternative source of energy to fossil fuels on sufficient scale to be able to meet the world's energy requirements. But nuclear power poses other threats, already identified above.
There are many that propose that solar power or perhaps wind energy can contribute in a substantial way to the world's energy needs. But this is not possible in many locations using present mechanical or electrical technology. Energy balance analysis shows that, in many parts of the globe, the energy used to manufacture the materials used in energy collectors exceeds the energy that those collectors could collect within their expected lifetime. The use of solar and wind collectors will result in net energy consumption if their production energy can't be collected within their practical lifetime.
Domestic solar hot water provides an example. Although modest sized solar units can provide an energy boost to the average family home by supplementing hot water, the CO2 equivalent the materials used in their manufacture is significant. Energy collected is small. It is typically many years before the CO2 equivalent of the energy usefully collected by these units exceeds carbon dioxide generated in their manufacture, transportation and erection. In many locations and aspects, break even may not be achieved in their lifetime. Where this is the case the use of these units will increase global CO2 production above that which would have resulted if conventional fossil fuels had been used.
If there was significant investment passive solar hot water units, global world CO2 production would be driven up by the energy demands of solar unit production and sufficient savings in energy may never result to “pay back the debt”. Further, because solar units collect energy at a non-peak period for electricity generation, they increase the “lumpiness” of electricity demand and have potential to adversely affect the efficiency of the electricity grid and the utilisation of generation equipment. If they became commonplace, there would be a hidden additional energy cost to the electricity generation system, which would also translate to additional CO2 production.
Photovoltaic solar collectors are far more promising. Costs of production are falling and new materials may result in lower materials and fabrication energy costs. While photovoltaic solar collectors have a significant and growing place in communications, domestic and building energy supplies, particularly in rural Australia and other dry temperate climates, they will never be a replacement for large-scale high intensity industrial or transport energy sources for much of the world.
Most of the world's population is concentrated in high latitude countries or in tropical countries with high levels of cloud cover.
Maximum theoretical energy conversion efficiency for a solar collector is only about 40% and less than 20% is typical in practice. Total solar incidence is already exceeded by energy consumption in several large northern industrial cities of the world. That is, even at 100% conversion efficiency and total coverage, there is not enough sun to meet existing energy needs in those areas. As a British Steel scientist once remarked, “it would be very cold and dark under the collector”.
Wind generators may many years to generate the energy consumed in their manufacture[11]. Wind generators can theoretically run night and day. But in reality few locations have continuous winds of over 55 km/h[12]. Below his level, or at very high wind speeds, present commercial wind generators will not deliver full output.
The energy required to make the materials and to build the solar collectors or wind generators is predominantly obtained from fossil fuels and is required at the outset, whereas the energy received is collected over an extended period. A large expansion of solar collector or wind generator manufacture world wide would therefore result in a substantial additional net energy drain on the planet's fossil energy resources while growing “green” energy needs were being met.
At present levels of technology of the energy produced by some so called “green power” sources may be insufficient, simply to replace the fossil energy consumed in their manufacture and installation, let alone fuel the system's own expansion.
Similar problems confront tidal and wave power and geo-thermal collectors. Biological solutions including bioengineered fuels and biomass could provide transport and industrial fuel in the future but these require further technological development.
The solution lies not just in finding new energy sources but also in solving the problems caused by the existing sources.