Health or junk?

In developed countries, the obesity pandemic is spreading. The US, UK and Australia are vying for top spot in a race where the Americans had a big head start.

It’s no coincidence that English-language countries have this the worst. They have a common approach to food marketing, even if the details differ. As illustrated in the movie Food, Inc., the US has turned food production into a factory from start to finish, with a very small number of core ingredients. Cows are fed an unhealthy diet of grains (for which they are not adapted) in feedlots to fatten them up, with a cocktail of drugs to stop them getting ill. Large-scale production-line slaughterhouses are an incipient disaster that occasionally turns real.

The logic of factory food is hard to shake: it’s inexpensive, so the poor can’t do without it. Yet if you look at the consequences of the obesity pandemic, can the poor live with it? We are seeing young children developing diabetes, and the US, the epicentre of the problem, has the world’s highest per capita health expenditure with some of the worst results in the developed world.

Obesity is an addiction. You can only deal with it effectively if you treat it as such. Junk foods are designed to prime the addiction by desensitising your taste to extreme levels of sugar and salt. That makes healthy food unsatisfying. Then you are on the junk slippery slide. Sugar and other easily absorbed carbs throw your metabolism out of kilter because a rapidly absorbed carb results in an insulin spike that over-corrects, pulling your blood sugar down. And that makes you feel hungry again. Artificial sweeteners are even worse because they can totally confuse various metabolic signals (with differing effects for differing sweeteners).

Junk food companies are the new drug lords. We should recognise them as such, though we should not repeat the mistakes of the war on drugs in the way we take them on. Prohibition and criminalising an existing popular but unhealthy practice generally leads to massive profits for a mafia that takes over the trade.

The solution? A wider range of health warnings on food. Anything with sugar above a reasonable level e.g. 5% should be labelled as high sugar, and similar warnings can apply to salt. Many products sold as “health” foods would be exposed by this sort of labelling. Public service advertising warning of the dangers of junk food would be good too. These could be funded out of a tax on sugar. A few cents per kilogram would raise a lot of advertising revenue.

There may be better ideas than mine. But to ignore the problem is to inflict massive health costs onto society, premature loss off loved ones and – for those for whom logic excluding a dollar sign does not signify – needless loss of productivity.

And for those who understand the problem: the solution can start with you. Minimise your intake of obvious junk. This doesn’t mean you have to refuse a chip at a party. It does mean you don’t eat them every day. Try to cook from scratch and from fresh as much as possible. The time cost is not as high as you may think: I do this all the time and still have time for many other things (this blog, lecturing to students, writing papers and grant proposals, going to movies, etc.). And I very seldom get sick, a big time saver in itself. Another good rule: read product labels. If you don’t know what the ingredients are, give it a miss. If your head can’t process it, there’s some chance your gut can’t as well.

Finally, what makes this a green issue? Green is not only about the natural environment but about the human habitat. Quality of life is an important part of that concern, and avoiding unnecessary health problems follows from that.

Fuel from air or just hot air?

From a few sources, I’ve had a story about a UK company that claims they can make petrol out of air and water (actually hydrogen extracted from water and carbon dioxide extracted from air).

I perused their web site and one critical figure is missing: energy return on energy invested (EROEI: which has to less than unity because a hydrocarbon fuel made from hydrogen and CO₂ is an energy store, not source; plants consume solar energy to do this trick). If you make a hydrocarbon fuel any other way, it costs energy, but I have my doubts that this can be better than e.g., using a feedstock like biomass because CO₂ density in the atmosphere is so low, about 400ppmv (and biomass starts from chemicals closer to what you want, created with the aid of photosynthesis – so there’s some chance of over-unity EROEI).

Here are some numbers: petrol has an energy density of about 35MJ/litre which is about 10kW-h/litre. They claim they can produce:

1,200 litres of liquid hydrocarbon fuel per day using approx 3 MW (nominal installed capacity) of renewable electricity

Be generous and assume this is in only 8 hours, which means they are using 24000kW-h of electricity to produce a fuel with total capacity of 12000 kW-h so they their energy cost is double the energy out (EROEI = 0.5). If their plant actually takes all day to produce this amount of fuel, EROEI is much worse (0.17, or less than 20% of the energy put in). Add in the inefficiencies of internal combustion engines (as I recall, about 5% of energy produced gets on the road) and this is not terribly exciting.

The only way it can make any sense is if you use up waste energy, e.g., if you have a wind farm that’s producing electricity at a time when you don’t need it. If you are going to do that I would rather just make hydrogen. Hydrogen can be used to operate a fuel cell, and can also be burnt directly as a fuel. While the energy density of hydrogen is much lower (especially in terms of energy per unit volume) than a hydrocarbon fuel, a large vehicle like a bus can operate efficiently off a hydrogen fuel cell, and hydrogen could also be a useful fuel in stationary applications.

The most promising alternative to fossil liquid fuels currently is algal biofuels. Algae use photosynthesis efficiently to produce biomass; that makes a lot more sense to me than this proposal.

Hypocrisy Exposed

You have to admire the chutzpah.

The fossil fuel industry has a track record of funding professional science deniers to undermine public confidence in climate science and global warming. Climate change, we were led to believe, was "junk science" (along with other science that predicts effects harmful to an industry, like the ozone hole, and harmful consequences of tobacco and asbestos). Now that a predicted effect, the rapid decline of Arctic sea ice, is happening on schedule, if not a little faster, fossil fuel companies are rushing to exploit the new opening of lower-cost exploitation of Arctic reserves.

Clearly, if fossil fuel execs do not believe that the climate is changing to a warmer phase, they cannot plan on Arctic waters being increasingly accessible through summer. Such improved access is critical to economic viability. While a large part of the Arctic will still ice over in winter, easy access during summer radically reduces costs of supplying operations and shipping out gas and oil over water.

Part of the rush to exploit these reserves can be explained by growing demand and depletion of other reserves. Even so, fossil fuel companies have to have increased confidence that costs will be lower than previously to find the prospect of tapping into Arctic reserves appealing. If what climate deniers claim is true, the current low in Arctic sea ice is a temporary blip, and we have summers ahead when ice will return to former levels.

I can think of only two explanations for the industry's confidence in the profitability of exploiting the Arctic: there is some natural phenomenon someone has modelled accurately that predicts a continuing decline in Arctic sea ice, or the industry accepts the mainstream climate models that predict human-caused climate change will continue to radically reduce Arctic summer sea ice. If the former applies, no one has published such a model and, given the huge interest fossil fuel companies have in deflecting action on climate change, it would be bizarre if they had such a model and didn't publish.

There is only one conclusion that fits the evidence:

fossil fuel companies accept the mainstream science and are using it to predict the future viability of Arctic fossil fuel extraction

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If you previously believed climate change was a hoax, this is a good time to stop conning yourself. The fossil fuel industry clearly does not believe their own propaganda, so why should you?

The Ice Thermometer

On 27 August 2012, the US National Snow and Ice Data Center announced that the Arctic sea ice extent had broken through the minimum set in 2007. Why is this significant? First, loss of sea ice is a directly measurable consequence of a warming planet. Second, the greater the sea area exposed to incoming solar radiation, the greater the warming effect because ice is highly reflective. Ice loss is one of the key amplifiers of any initial form of warming, whether orbital perturbations leading to the start or end of an ice age, or changes to the atmosphere such as is happening in the modern industrial era.

Minimum sea ice extent. Each grey line represents area of sea ice (areas with at least < 15% ice cover are added to the total) over a year; the red line the current year. Graph drawn using R software by Rasmus E. Benestad, posted at RealClimate, from data at the National Snow and Ice Data Center.

At time of writing, the area of sea ice was still trending down; we will only know the actual minimum when it starts to increase again. Why should the sea ice extent have hit a new minimum this year? Data so far for the year does not indicate it will be unusually warm by standards of the last few years. None of the short-term natural effects should have a significant impact on temperature averages this year. We have not had a big El Niño, and the solar cycle remains one of the lowest on record, though we are on the higher side of the cycle.

Sea ice volume anomaly

The key to understanding this is that the area of ice takes a long time to change, even if the volume of ice is changing fast, because the permanent ice over the Arctic is multi-season ice. If conditions warm sufficiently to melt multi-season ice, it does not melt in one season. Instead, it progressively becomes thinner.

If we look at the long-term trend of sea ice volume, it becomes clearer what’s going on. Total sea ice volume has been trending down steadily, with a sharp increase in the trend in recent years, breaking out of two standard deviations (the grey area) from the trend.

How can this be happening if temperatures are not increasingly sharply?

First, there’s my point about long-term ice being lost. Once it’s gone, it takes that much less energy to thin the ice further next summer. Also, about 90% of incident solar energy is absorbed by the ocean [Levitus et al. 2001], and ocean heat transport is a significant factor in governing the temperature of the planet. El Niño and La Niña events occur when some of that energy is either released to the atmosphere, or the oceans absorbed a little more than the average amount of energy in the system. Increasing the energy content of the oceans is the big sleeper in climate science: the thing the public doesn’t pay attention to because the numbers look small compared with temperature increases in the atmosphere. The relevance of all this is that a relatively small shift in where that extra energy ocean goes could have a big impact on sea ice.

Measuring ocean heat content is very complex because the effect of currents including thermal transport between depths has to be taken into account, and measurement is in a relatively harsh environment, meaning instruments have to be changed frequently, with potential for calibration error. You can’t just stick a thermometer into select parts of the ocean and measure for a few decades as you can on land. But guess what: Arctic ice is turning out to be a pretty damn good thermometer.

For more, go here for another interesting article.

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September 2012 minimum

Update

On 19 September, NSIDC announced that sea ice had appeared to bottom out at 3.42-million km². I’ve redrawn the graph (22 September 2012 data); it appears to have taken another small dip to 3.37-million km², 19% below the previous minimum of 4.17-million km². The script reports the previous low as 4.16-million km². Possibly NSIDC is rounding the numbers differently, or smoothing the data they report (they generally report numbers averaged over the last 5 days). Either way the difference is slight; the latest record represents nearly 20% below the previous record.

Contrast the current situation with a 2006 paper that was widely misrepresented as an alarmist prediction that sea ice would be all but gone by summer 2040 [Holland et al. 2006]. The focus of that paper in fact was demonstrating that a very rapid drop in sea ice is possible over a few years. In the scenario where the Arctic summer was almost ice-free in 2040, it would have taken until about 2030 for sea ice to drop as low as it has this year – and then only as a consequence of one of the abrupt drops the authors claim is possible.

Holland et al fig 1(a) compared with 2012 minimum

In this graph (based on Holland et al fig. 1(a)), based on an ensemble representing seven models (grey bars are the range of values, the black line is representative of the ensemble, the light blue line is smoothed using a 5-year running mean, the red line is real measurements smoothed with a 5-year running mean), the 2012 level of ice has arrived 20 years early – and this is a paper that attracted controversy at the time as being “alarmist”. I compare reality with the smoothed data (light blue line); models like this are not intended to predict annual data accurately. Since the grey bars represent the range of values from different models, you could say that 2012 matches the lower edge of a prediction (one of the grey bars touches my 2012 line at about the right time), but that’s more accuracy than the models should claim. I’ve marked on the graph the 2012 minimum and the point where it intersects the model graph.

Note also that the ice level we see today would only have happened in the smoothed Holland et al. ensemble of models after an abrupt drop in ice extent (the grey area of the graph), something that hasn’t happened yet. If their models are correct, and there is a scenario when sea ice extent falls rapidly, the 2040 “prediction” might yet prove to be conservative.
There are some who take comfort for the fact that a model such as this is not 100% correct. I don’t see why. There is enormous pressure on scientists in a field where findings have major economic impact not to be “alarmist”, which has a dampening effect on publishing results that predict disaster. If disaster is likely, I’d rather know in advance and have the option to head it off.

Those attacking the science, on the basis that it’s not 100% accurate and that the margin of error in predictions includes the possibility that nothing “alarming” can happen, miss miss the rather obvious point that the margin of error includes the possibility that reality will turn out more alarming than predicted. Worse, as reality unfolds on the worse side of modelled outcomes, they continue to deny.

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References
Sydney Levitus, John I. Antonov, Julian Wang, Thomas L. Delworth, Keith W. Dixon, and Anthony J. Broccoli. Anthropogenic Warming of Earth’s Climate System, Science 13 April 2001, 292 (5515): 267-270
Marika M. Holland; Cecilia M. Bitz; Bruno Tremblay. Future abrupt reductions in the summer Arctic sea ice. Geophysical Research Letters 2006, 33(23): 217. 25

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?

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.

Solar hot water or heat pump?

Basics

With the growing price of electricity and increased awareness of climate change, increasing numbers of people are turning to solar hot water or heat pumps.

The way solar heating works is obvious: you have an energy collector on the roof that picks up energy from the sun, and heats your water. A few details may be less obvious, like why you still get hot water after dark with minimal electricity use, and how it can work on a cloudy day.

A good solar system can heat the water in the tank to up to 95°C, and reduces the temperature at the tap by using a tempering valve, which mixes in cold water to keep your hot tap water down to a safer level. You store energy in effect by heating the water more than you need to when the sun is out. What then about when the sun’s obscured by cloud? Some energy obviously still gets through because cloudy days are mostly warmer than cloudy nights. A good modern solar hot water system can at least maintain temperatures on all but the cloudiest days, and even increase the temperature if it falls as a result of using hot water. Wikipedia has a detailed discussion of different types of heat collectors, and their advantages and disadvantages.

What of heat pumps then?

A heat pump is based on a law of physics: the ideal gas law, which says that temperature is a direct function of pressure, if nothing else changes. One effect of this is that if you increase the pressure of a gas it gets hotter; another is if you drop its pressure it gets cooler. The picture on the right illustrates the principle of a heat pump. If you have a fixed amount of gas and pump it in a fixed-sized container from one side to the other, with a valve that can be closed to allow the pressure to be high on one side but not the other, you make the high-pressure side hot. If you then vent some of the gas to the low pressure side, while keeping the pressure lower than on the other side, it cools. You can use this principle to make a fridge or air conditioner, by routing the high-pressure side of the container through a radiator on the outside of the space you need to cool, and let it cool a bit, before releasing it at lower pressure to the cold (low pressure) side of the system.

A heat pump (or for that matter, a reverse-cycle air-conditioner working as a heater) reverses the role of the two sides. You use the hot side and radiate out the cool side to the outside world.

The key to understanding the whole thing is that the side you don’t want (the hot side of a fridge or aircon, the cold side of a hot water system or heater) has to be able to get rid of its unwanted temperature differential to the outside environment. A fridge or aircon does this simply by radiating away heat; a heat pump may need to be more aggressive in getting rid of unwanted cold with a fan.

A heat pump is a far more efficient process for heating than using electrical resistance to create heat.

Benefits

How much more efficient?

When I used to live in Australia, I had the benefit of a dual electricity meter, with a separate one for water heating because we had the option to pay a lower off-peak rate for electricity. I was able to observe the benefit of changing to a heat pump directly (picture at  left, note the fan to expel cold air; some models are split in two parts, with the heat pump machinery separate from the tank): a drop of 80% in electricity usage for hot water.

That sounds dramatic, but remember it’s 80% of only one component of electricity usage, and this was in a two-person household with relatively light water use. The benefits you see may vary depending not only on your usage pattern but the efficiency of the system (for example, if the heat exchanger is not well sited, you will get a lesser saving). Solar systems with electric backup reportedly save 90% of hot water electricity usage.

Which type?

So, the bottom line: should you get solar hot water or a heat pump?

It depends. A heat pump, while slower than a traditional resistance heater to fully reheat a large water tank, can top up lost heat overnight even when there is no sunshine. A good design can take heat out of the air at a temperature as low as -10°C. If you use a lot of water overnight, you may find this better overall than a solar system – though a solar system with a bigger tank may still come out ahead. The best case for a heat pump is when you don’t have a roof on which to install the solar collector (e.g., if you are in a ground floor flat). In Brisbane, I installed a heat pump because I wanted my roof space for solar power – we could feed our solar power into the grid and earn a premium price of almost 3 times the retail price for excess electricity, not yet an option here.

For my house here, I decided to go for a solar collector because I have plenty of roof space – and because it works even if the electricity is out. So far, it’s been pretty good. It took a few days (including some that weren’t too sunny) to build up to full heat but since then the water has been pretty hot even on cool cloudy days. The only problem I’ve had with mine is that the installer promised that a fibreglass resin odour in the water would dissipate quickly, but it lingered for months. It’s hard to compare before and after electricity bills because I wasn’t in the house long enough before installing it, and other electricity use may have changed, so I am not going to make any specific claims.

Thinking long term

As the price of electricity goes up, solar hot water or a heat pump should become standard in new dwellings and when replacing existing systems. It’s great that solar hot water is being installed free of charge in poorer communities (even if the target of 3,000 houses in Makana looks low). Many of these households would never have been able to afford hot water otherwise: even if they could scrape together the money for a system, they would battle to find the cost of the extra electricity. And if we are serious about climate change, we need to make it easy for those who already have a low carbon footprint to stay that way without being disadvantaged.