May 09, 2011
Energy: A Sense Of Loss
Whenever electricity is transmitted from one place to another a certain amount is simply lost. In older grids, energy is wasted overcoming resistance in the lines themselves. In extremely high voltage lines, so-called corona discharge losses [as shown in the image above] can offset the lower resistance losses.
Whether system-wide electricity losses amount to three or 65 per cent across the system as a whole is a matter of heated debate. Corona discharge is just one of the arcane variables that are contested when optimistic energy scenarios are subject to the fabled 'closer inspection' of experts.
Such has been the fate of the World Wildlife Fund's Energy Report, which was published in February. It asserts that the world's energy needs could be met by wind, solar, geothermal, hydropower and sustainable forms of bio-energy — and by 2050.
My immediate concern about the WWF scenario was it took "global energy needs" as a given, added up how much renewable energy would be required to meet them — and then ignored the true costs of deploying such an infrastructure.
These concerns have not diminished as experts have examined those costs in more detail. Ted Trainer, for example, an Australian energy analyst, calculates that the amount of solar thermal, wind and PV plant needed in the WWF plan would cost about 10% of 2050 world GDP -or 14 times the present fraction of world GDP that is invested in energy supply. How likely are those kinds of sums to be available?
Trainer also raises questions about electricity storage and a 'redundancy problem' in the WWF Report.
Without a satisfactory way of storing electricity in very large quantities, the intermittency of solar and wind energy sets severe limits on the proportion of total demand they can contribute. What are we to do when winter calms set in across the whole of Europe for a week? If the answer [as proposed by WWF] is draw on solar thermal farms in North Africa, it means having to build enough solar thermal plant to substitute for all the wind and PV plant, only to have much of it sit idle most of the time.
The WWF Report suggests that biomass would plug these potentially huge gaps. But Trainer questions whether any land at all should be used for biomass energy production. Such use depletes soils over time, and depends on large amounts of water. More worrying is the impact of biomass production on biodiversity. "The holocaust of extinction we are causing is due primarily to the taking of so much habitat by humans. We should be returning very large areas to natural state, not contemplating the taking of more".
If the costs of implementing the WWF Report would be unbearably high, what are the alternatives?
The answer is as simple as it is hard to embrace: use less. Using less energy, less resources, less stuff of every kind is 'the hallmark of any serious response to the predicament facing industrial civilization'.
Line loss, in that context, is just a detail.
Posted by John Thackara at May 9, 2011 06:52 AM