Wednesday, May 30, 2012

Base Load and Clean Energy

A commonly stated claim by advocates of business as usual is that renewables cannot provide base-load power generation. In the industry, base load is the minimum that has to be continuously available. With large coal-fired plants, keeping them running at a constant rate of output is a lot cheaper than reducing or increasing output – provided you want all the power generated:it isn’t cheap to produce something if it’s wasted.

Power utilities attempt to balance demand around the clock to keep it reasonably constant. That’s why for example your electric hot water system has a ripple relay, a switch that can be turned on or off remotely by varying the usually regular AC sine wave. During times of low load, all the hot water systems on the system are turned on; when load starts to get high, they get turned off. This works because you are storing energy in the form of hot water.

For renewable energy systems to work so that you can flick a switch whenever you want power, they need to work even when the underlying energy source is not there, e.g. at night if you are using solar power, or on a windless day if you use wind turbines. The argument is that these systems cannot provide base-load power because they only supply power when their energy source is available.

We’ve already seen that a coal-powered system relies on energy storage of a sort to smooth out demand in the form of storing hot water. This is a remarkably inefficient way of storing energy. To start with, a coal-fired power station loses up to 70% of the energy it consumes as waste heat. Of the remaining 30%, about 10% is lost in transmission. Then when you heat hot water using electric resistance, that’s also a remarkably inefficient use of electricity – and you are turning it back into heat, which is what you started with. Finally, since the water tank has to store energy across periods when the ripple relay is turned off and even when that’s not the case, it has to store enough energy that taking a bath doesn’t make the water too cold for the next use, you need to heat – and keep hot – a lot more water than you actually use for any one purpose.

The massive losses inherent in a fossil-fueled power grid are to some extent masked by the fact that coal is relatively cheap. However, coal is a depleting resource and will become more expensive over time – even if we don’t count the environmental costs of mining and burning coal.

To work this all out properly, you need to work out the available energy and costing. What I offer here is an idea of how a clean energy system could work.

First, a solar thermal (or concentrating solar) system an provide base load, if a sufficiently large store of heat is included. The way these systems work is by heating a salt mix past melting point, and using that stored heat to produce steam for a turbine. Heat storage on these systems can potentially extend their use over more than a day of low sun. What if you need to extend use even longer, if there’s an extended period of low sun? A solar thermal plant has to have a way of heating the salt mix initially, usually using gas. An option is to use excess power generating at off-peak times to create hydrogen by electrolysis, then burn the hydrogen when the sun is not hot enough to maintain the temperature. A system like this combined with wind could work well. When there was sufficient wind available, the wind power could provide base load and top up the stored hydrogen if there was any excess. On less windy days, the solar thermal plant would provide more of the power.

Is it not wasteful having all these alternative power sources? A conventional grid does this anyway. The large base-load power stations are backed up by smaller generators that can be turned on and off quickly, but at a higher cost per unit of electricity. Making all this work will require some hard engineering, but describing clean base-load as impossible is wrong. Hard, not impossible. So why should we bother? Because coal will not last forever, and because coal is dirty. Coal mines are massively polluting, coal transport is energy-inefficient and coal emits many harmful substances including heavy metals when burnt.

All of these would be good reasons to look for alternatives even without climate change. Add that in, and we need to start working seriously on these options. In Australia, there’s a 100% renewables campaign and the Beyond Zero Emissions group has researched clean base load power extensively. If South Africa could beat Australia into the lead position on the Square Kilometre Array telescope project, what’s our excuse for being so backward on clean energy?

Thursday, May 17, 2012

Sceptics or deniers?

In Mail&Guardian, I had a letter published in response to a claim that it’s wrong to label people as AIDS deniers. Here it is:
Here we go again (“‘Denialist’ label just as deadly”, Sam Ditshego, letters 3 May). The pseudo debate about HIV and AIDS is not unique. Science denial occurs in many fields: the link between tobacco and health problems, the ozone hole, climate change and evolution. If Sam Ditshego doesn’t want his position to be considered denial then he shouldn’t argue like a denialist. There is nothing wrong with being a sceptic. All good scientists are sceptics, and check claims made by other scientists, and indeed their own work, for errors and inconsistencies. When this sort of attack on science occurs, practising scientists face a damned if you do, damned if you don’t dilemma. Take on the denial case and you give it additional publicity, with the serious problem that refuting it comprehensively requires airing science that cannot be explained in full to the non-expert. Ignore it, and it appears that it can’t be refuted.
Here are the key properties of a denial campaign that distinguish it from healthy scepticism:
  • Gish gallop – a debating technique invented by Duane Gish, an evolution denier, who evidently saw no contradiction in being a fundamentalist Christian and lying. The technique is to spew out apparent facts scatter-gun style. It takes only a few words to lie; it may take a lengthy, carefully constructed argument to refute the lie, giving the liar a huge advantage in any debate format with limited space (letters to the editor) or time (a public debate)
  • repeating discredited arguments – a denial campaign is not concerned with arriving at the truth (or the closest we can get to the truth in the face of uncertainty) and therefore recycles old arguments, no matter how the field has advanced; a sceptic would happily concede error if proved wrong
  • accepting contradictory positions – a true sceptic would not accept any argument to support a cause. If some were contradictory, a sceptic would be forced to thin down the range of positions to those that were mutually consistent
  • argument from authority – a whole slew of eminent people support the case therefore it has to be right. Never mind that some of them made their claims a decade or more ago, and may have died before their claim turned out to be false, or that they are not all experts in the field. A few genuine experts of course may put themselves out on left field but the fact that they are isolated fuels the conspiracy theory mindset. That doesn’t mean these people are right. Someone who’s at the top of their field who makes a mistake has a big investment in their position and may find it hard to back down – especially if their error cost hundreds of thousands of people their lives
  • reducing science to a matter of opinion – science, unlike politics or religion, is not a matter of opinion. It’s a matter of evidence. A scientific theory stands or falls by evidence. If after several decades of expressing doubt about a theory, “sceptics” are repeating the same claims that have been refuted many times, they are no longer practising science, but some sort of religion or political ideology, and rightfully deserve the “denier” label
  • accusing the other side of the very flaws in their own argument – a genuine sceptic should be able to make a case purely based on the evidence. There is no need to accuse others of politicising their science, turning science into a pseudo-religion based on belief rather than evidence or chasing research funding by predicting disaster. It is very hard to argue against this sort of tendency without appearing yourself to be attacking the messenger rather than the evidence, which is why I leave this point to last.
Let’s contrast this all with a genuine case of scientific scepticism that took on a mainstream view: the 1982 discovery by Barry Marshall and Robin Warren that stomach ulcers are caused by bacteria. They had a tough job convincing the scientific community that they were right against the conventional view that bacteria couldn’t survive in the highly acidic environment of the stomach; they produced the evidence to overturn the mainstream view and were rewarded with a Nobel prize.

The real question we should ask ourselves is why certain areas of science attract this sort of dogged faux controversy. There are many other areas of science where there are conflicts between scientific integrity and economic or political interest, and these conflicts are generally resolved in the scientific literature – but these conflicts do not generally imply major society-wide changes in human behaviour if the science is correct. HIV is an outlier because there is no obvious commercial interest in traducing the mainstream. Climate change, tobacco and the ozone hole are all areas where the science threatened commercial interests (denying evolution in a sense supports a commercial interest, because there is big money in organised religion).

What is clear though is that it’s very hard for members of the public without a scientific education to see through this sort of thing, which puts a huge onus on journalists to spot and deflate this sort of campaign. Remember the old adage: fool me once, shame on you. Fool me twice, shame on me.
Why do I quote this here? Climate change and many other environmental causes like the ozone hole are also subject to this sort of fake “scepticism”. The pattern of argument is always the same. Many people argue that it’s the fault of scientists that they cannot win against this sort of fake attack on science. I argue that it’s really a failure of journalism. The mainstream news media do not follow the markets report with a Trotskyist rebuttal. We do not follow the weather report with a witch doctor throwing the bones and giving a different answer. Why do some stories require “balance” and not others? The pattern of this sort of anti-science campaign is so depressingly familiar that I immediately saw the similarity between the anti-climate science campaign and the pro-tobacco campaign; I’ve since discovered there is just such a link.

If the mainstream science in any of these area is truly flawed, a scientist who works with the evidence will unearth this fact. That most of the argument against a particular area of science is couched in emotional terms, attacks the personal motives of scientists and uses bogus debating tactics has to tell you something.

If climate change is really not going to happen, that would be a huge relief, so I’ve studied the contrarian literature extensively. Sadly, none of it fits the evidence nearly as well as the mainstream. I say “sadly” because, as the tobacco industry revealed, this sort of attack on science can delay effective policy change by decades. And as many studies have shown, the longer we delay, the higher the cost.