By Ted Trainer, May 4, 2014
In a recent article in the New York Times Paul Krugman tells us that the fall in the price of PV panels means that “…we can look forward to decarbonising electricity”, because “…drastic cuts in greenhouse gas emissions are now within fairly easy reach.”
There are a few things Paul seems to have overlooked.
The first is that PV cannot meet more than about 4% of world energy demand. It is generally understood that the limit for PV is around 20% of electricity demand. This is because PV modules can only produce during the equivalent of about 6 full-sun hours a day, so if they were to contribute 100% of electricity needed then during those hours it would have to be feeding in at a rate 4 times demand, meaning a) a vast amount of PV generating plant would sit idle for 18 hours a day, and b) a vast amount of other renewable plant would be needed to resort to during those 18 hours, and it most of it would all sit idle for those 6 hours. For this reason the practical limit to PV might be around 15% of the electricity required.
But only 18% of rich world energy use is in the form of electricity, so PV can’t be expected to meet more than about 20% of 18% = 4% of our energy demand.
But wait, what about storing the PV electricity to use at night? Forget it. Yes electricity can be stored, but it is very difficult and costly to do this in large quantity. Your best bet is by pumping water into dams, but even if all dams could be retrofitted for pumped storage the total generating capacity would be about 15% of demand.
Hydrogen? Round trip efficiency from PV panel to hydrogen to fuel cell or gas turbine power would be around 20%, and we would need huge quantities of energy intensive and dollar costly plant to generate, compress, store and reconvert hydrogen.
Well then, batteries? The world’s biggest grid storage battery system, at Fairbanks Alaska, can store 4 MWh, at a cost of $30 million. To store the output of a normal big power station for 24 hours would involve capacity to hold 24,000 MWh. To store this via a Fairbanks system would cost 6 times as much as the power station.
Locate enough solar thermal plant in the Sahara to supply Europe? Estimate the cost of doing that. How about storing energy in the heat tanks solar thermal stations have? They are starting to build units capable of running for 17 hours on stored heat, but that is nowhere near enough. And the recently completed Spanish Gemasolar plant with 17 hour capacity cost around $40,000/kW. A coal-fired power station costs only about $3,100.
The capacity to store very large quantities of electricity is not on the horizon. In winter Europe can suffer one or two weeks of more or less continual freezing cold, calm, and cloudy conditions. How are they going to get through these periods on renewables?
The second major point Paul seems not to be aware of is that several recent studies have found that when all relevant factors are included the ratio of energy produced by a PV module in its lifetime to the energy needed to produce it is not 10/1 as is commonly thought, or 60/1 as some advocates have claimed, but probably between 4/1 and 2.4/1.
Krugman mistakenly thinks the price of PV is the crucial factor. What matters most is its Energy Return on Energy Invested. If a PV panel produces in its lifetime only enough energy to produce three panels it can't sustain an energy-intensives society. Estimates in the literature are that the ratio must be at least 7/1 for a technology to be viable. The ER for corn-based ethanol is around 1.4. For coal it is around 20 (…but falling fast.)
A third question for Paul is, where is he going to get the other 82% of energy we use that is not in the form of electricity? The answer is not biomass; there is far too little available on the planet for that.
How about running as many functions as possible on electricity? A good idea, but that multiplies the problems involved in integrating highly variable solar and wind energy sources into grids, which means greatly increased costs for equipment, interconnectors, storage, redundant plant and dumped energy.
“But many experts are telling us it can all be done by renewables, and at negligible cost.” This is true, but there is a small but increasing number of energy researchers who think those arguments are flawed and that there is a weighty case that it cannot be done at an affordable cost, given the kinds of difficulties sketched above.
“Well let’s forget about renewables and just use nuclear reactors.” If you are going to provide present rich world living standards to 9 billion people you will need tens of thousands of fast breeders, all involving reprocessing of plutonium…and operated by humans who never ever press the wrong switch. You choose.
So, what is the answer? If the question was, how can we keep our energy-intensive, affluent, growth obsessed society going, then the answer is … you can’t. Paul Krugman, like almost all economists, politicians, journalists and business leaders, seems to be totally unaware of the now enormous literature showing that there are savage limits to growth, that we have gone through them, and that it is the over-production and over-consumption of growth and greed society that is generating the many global problems threatening to destroy us. The magnitude of the overshoot is clear in the common “footprint” figures; the average Australian or US person is using about ten times as much productive land as will be available per capita in 2050 if it is shared among all expected 9 billion people. The problems cannot be solved unless we in rich countries not only abandon the quest for economic growth but go right down to something like our fair share of world resource use.
For sixty years now increasing numbers have come to see that the pursuit of growth and affluence has been a terrible, probably fatal mistake and that global problems cannot be solved unless we achieve a historically unprecedented transition to what some of us label as The Simpler Way. This cannot be done unless some of the foundational structures, assumptions, ideas and values of Western culture are scrapped, including almost all of the current economic system, but, most problematically, also the culture of individualistic, competitive, acquisitiveness.
Paul is reinforcing the faith that we don’t have to think about such a transition, because renewable energy and other tech-fixes will make it possible for us to go on pursuing affluence and growth for ever. Well if by 2050 9 billion have risen to the living standards we will have given 3% growth, then world annual levels of production and consumption will be about fifteen times as high as they are now. No problem Paul?
A sustainable and just society would of course run entirely on renewable energy, but at far lower use rates than we have now. Small numbers of people in the Global Eco-village, Transition Towns, Permaculture, Voluntary Simplicity etc. movements are pioneering a "Simpler Way" alternative vision and we have no doubt that it could provide all people with a far higher quality of life than most people in the consumer rat race have now.
----
For the detailed case see The Simpler Way http://socialsciences.arts.unsw.edu.au/tsw/, Ted Trainer, The Transition to a Sustainable and Just World, Envirobook, 2010, and the papers at Simplicity Institute http://simplicityinstitute.org
No comments:
Post a Comment