151: Lateral thoughts #7 - the problems with wind power

Fig. 151.1: Wind turbines.

There are many claims that are made about wind power, not least that it is cheap. It isn't. In fact it costs almost the same as nuclear.

A nuclear power plant costs about £10bn and delivers 1GW of power almost constantly over a lifetime of up to fifty years. So that is £10 of capital cost per watt of output.

A 1MW wind turbine costs about £1.25m (offshore turbines cost even more). So that is only £1.25 of capital cost per watt of nominal output, much less than nuclear. But wind turbines rarely deliver their maximum or nominal output because they cannot operate in high winds for safety reasons, and at normal wind speeds (v) the output varies as v³. So a drop in wind speed of 50% results in the output power dropping to an eighth of its previous value (see Fig. 151.2 below). 

 

Fig. 151.2: The observed power output of a 1.5MW wind turbine.

 

But there is another problem, and that is that wind speeds are weighted in their frequency of occurrence towards lower values (see Fig. 151.3 below). The result is the power output is both highly variable and weighted towards low values, and so most turbines struggle to deliver more than 33% on average over time of their nominal output. So the true capital cost of a wind turbine is about £3.75 per watt of output. But if we also factor in the 25 year lifetime of wind turbines (i.e. half that of nuclear), then the true capital cost relative to nuclear is going to be about £7.50 per watt. So wind is only marginally cheaper, and remember, offshore wind is even more expensive.

 

Fig. 151.3: The observed frequency of wind speed.

But this is not the biggest problem with wind power. That is the energy storage or backup dilemma. What do we do when the wind doesn't blow?

This was the problem in December of last year. The UK experienced a cold snap with temperatures dropping below -10°C. This is not unusual: it happens every year and is caused by an area of high pressure sitting over the UK. So, just as the UK needed more power for extra heating in the cold weather in mid-December, there was no power coming from the UK's main renewable source: wind power. But this is not just a winter problem. A similar phenomenon is seen during heatwaves in summer. In both cases the wind across most of the UK drops to almost zero for days, or sometimes even weeks on end. So how do we compensate for this?

Well, there are two options. We can either build extra wind turbines to generate surplus electricity in times of plenty and store the excess energy, or we can build backup generators using different and more reliable energy sources.

The problem with the energy storage route is the sheer amount of storage required. The cold snap described above lasted about a week but could have lasted up to twenty days. According to Worldometers, the UK generated 318,157 GWh of electricity in 2016, or about 870 GWh per day. That is 3132 TJ per day, or the energy equivalent of exploding fifty Hiroshima-sized atomic bombs every day. So twenty days of storage would require the equivalent energy storage of over one thousand atomic bombs. And if we want to completely de-carbonize our energy and transport systems that number could easily double. That would require an awful lot of batteries and so is totally unrealistic. It cannot be done.

So what about backup alternatives? Well the issues here are cost and reliability. Because wind is unreliable the backup source needs to be very reliable and immediately accessible. But it also needs to be green. So the obvious candidate is nuclear. But nuclear is more expensive than wind power, so using it as a backup means adding its capital cost to that of wind power when it is rarely going to be used. That makes no sense economically. If we are going to build enough nuclear power stations to satisfy all our electricity needs when the wind isn't blowing, then we may as well use them continuously all the time rather than keeping them idle as backups. If a backup is only going to be used sporadically then its capital cost needs to be much smaller than that of the primary generator it is backing up otherwise it is just an unnecessary additional cost. That leaves only two viable options for backup energy sources: coal and natural gas.

Coal and gas powered generators are up to ten times cheaper than the equivalent-sized nuclear station or wind farm, so their capital costs are negligible in comparison. They are also reliable, but they are not green. That said, they would only be used intermittently so their carbon emissions would be low.

So here is the dilemma. If we stick with wind power then we will need to compromise and allow some fossil fuels to be used as backup supplies in times of need. This will still massively reduce our CO₂ emissions but it will not make us carbon neutral. The only alternative is to abandon wind power and go nuclear.

126. Lateral thought #6: Is plastic a form of carbon capture or a pollutant?

 

Climate change and environmentalism can be confusing. They can also be contradictory. As an example consider this.

 

Climate change

We are told that fossil fuels are bad for the environment because they produce carbon dioxide (CO₂).

We are told that this CO2 stays in the atmosphere and adds to the greenhouse effect. This in turn increases downwelling radiation which causes global warming.

We are told that we need to prevent global warming by putting less CO₂ into the atmosphere. This means either less use of fossil fuels or removing CO₂ from the atmosphere. As using less fossil fuels is difficult to achieve economically, then maybe we need to look at CO₂ removal.

One suggested removal method is carbon capture. This involves removing the CO₂ from the atmosphere and storing it underground in perpetuity. One way to achieve this could be to turn fossil fuels into a compound of carbon that does not degrade or decompose. Well we have such a set of compounds - they are called plastics. So plastic is a form of carbon capture. So plastic is good, yes?

The environment

Well no, because we are also told that we are polluting our environment with unnatural materials.

One of the worst of these is plastic because it does not decompose. So the trend now is to make plastic biodegradable so that it does decompose. But if it does decompose then it will just add to the carbon in the carbon cycle (see Post 36), first in the soil and then it will add to the amount of CO₂ in the atmosphere.

So biodegradable plastic is good for the environment but bad for global warming. 

Bio-plastic or non-bio?

So there is the dilemma. Plastic could help to permanently store unwanted carbon and prevent it entering the atmosphere, but it could damage the environment instead.

But if we prioritize protecting the environment by making plastic biodegradable, then we will just add the carbon in those plastics to the atmosphere in the form of CO₂.

It appears that there are no easy solutions.

90. Lateral thought #5: Without fossil fuels there would be no Champagne

 

Yes, amazing as it seems, without coal we might not have Champagne. Well, possibly.

This tale arises out of the English energy crisis in the early 17th century (see here). After over one hundred years of shipbuilding for the new Royal Navy the country ran out of wood. There were of course other reasons such as population growth and increased urbanization that were equally to blame, just as they are today. But the net result was there were just not enough trees. So much for renewable energy.

In response a worried King James I banned the use of wood for non-essential purposes. And one of the areas to feel the heat was glass-making. In response they switched to using coal, which had previously been considered a dirty and ungodly fuel even though it was abundant. Yet needs must when the Devil drives. And there was an unexpected bonus, as there often is when the Devil is in play. By using coal English glass-makers were able to achieve higher kiln temperatures. This meant they could make glass bottles that were thicker and stronger - just what you need to make Champagne. Otherwise the bottles have a tendency to explode.

So, three cheers for fossil fuels. And yet another reason why the French love the English.

Of course this does raise an important philosophical question. Can you be a Champagne socialist and still fight for climate justice? I don't know. And until I do I'll probably stick to the Château Haut-Brion.

80. Lateral thought #4 - COP26 and keeping 1.5 alive

For the last two weeks politicians from all over the world have been gathering and meeting in Glasgow in order to formulate an agreement to cut the use of fossil fuels by mankind. The target has been to keep the maximum extent of global warming below 1.5°C and so avoid a catastrophic warming of over 2.8°C by the end of this century. This may be very laudable, but in my opinion most of the measures agreed or demanded are unworkable and unnecessary.

My first critique is with regard to the current temperature rise and its projection. The received wisdom is that current warming relative to pre-industrial times (i.e. before 1750) now stands at 1.1°C. In contrast, the real temperature records, as outlined on this blog, show that this is unlikely to be true. Over the last sixteen months I have analysed the land-based temperature records of virtually the entire Southern Hemisphere, plus those of the USA, Europe and southern Asia. None show a warming of over 1°C since 1750 that correlates with increases in anthropogenic carbon dioxide emissions. The only consistent warming is seen after 1980, and this is only about 0.5°C in magnitude. Given that 70% of the Earth's surface is water and that the oceans heat up by less than half the amount compared to land, it is impossible to get to a 1.1°C average warming globally unless one postulates that land temperatures have increased by over 2°C everywhere, as Berkeley Earth does (see Fig. 80.1 below). But the reality of the raw data that I have analysed so far is that there is virtually no country or continent that I have investigated so far where this has happened. So the real temperature increase so far is likely to be less than 0.5°C. And as I showed in Post 14 and Post 29, much of this 0.5°C could be due to urban heat island effects.

Fig. 80.1: Land and ocean global average temperature anomalies since 1850 according to Berkeley Earth.

My biggest criticism, though, is reserved for the proposed countermeasures. The one consideration that has been completely omitted from discussions of carbon reduction policies has been the economics. While a lot of time has been devoted to discussing financial aid to small developing countries that are supposedly at risk from climate change, none has been directed to considering the financial impact on producers and consumers. 

One of the main aims of COP26 was to "keep 1.5 alive" - namely to enact measures that would prevent the global temperature rise from exceeding 1.5°C. This, we are told, requires a 50% reduction in fossil fuel use by 2030, and a move to net-zero by about 2060. The question, then, is how do we reduce fossil fuel use by 50% by 2030, or 5% per year? At COP26 all the emphasis appeared to be on reducing fossil fuel demand rather than supply. Yet both are problematic, and both will cause economic hardship to many.

The current political strategy appears to revolve around getting as many countries as possible to cut their usage of fossil fuels, but this policy has two flaws. Firstly, it requires over 180 countries to agree to do something that none really want to do. That means it is highly unlikely to succeed (think: herding cats). But if it does there is the second problem. It will devastate the economies of many oil producers. What is striking is the callous disregard many climate activists have for the people of these countries.

Countries like Iran, Iraq, Azerbaijan, Russia, Libya, Nigeria and Venezuela are almost entirely dependent on the revenues from oil and gas to feed their people. They are economic monocultures. Nor do they have large sovereign wealth funds to fall back on like Norway, Saudi Arabia or Kuwait. So what happens to their economies when demand for oil and gas runs out, or the sale is banned by international treaty? The impact will be cataclysmic.

The alternative strategy is hardly much better, but will create a different set of losers. Rather than trying to regulate demand, the UN could instead try to regulate supply by getting the producers to cut supply by 5% per year and thus force the consumer nations to adapt. This strategy has two advantages. Firstly it requires the agreement only of the producers who are much fewer in number, and secondly any cut in supply would result in spikes in price which would largely protect the incomes of the producers. Instead the consumers would suffer, and with them the global economy. The result would be oil and gas shortages, high prices, fuel poverty and global economic collapse. So, not a great choice!

65. Lateral thought #3 - when analogies go wrong

 

About six years ago Professor Steven Koonin wrote a guest post for Judith Curry's blog site Climate Etc. entitled "Are human influences on the climate really small?" The post was a follow-up to an article Prof. Koonin had written for the Wall Street Journal (WSJ) about six months earlier entitled "Climate science is not settled." The general thrust of these articles was to argue that many effects of man-made climate change were too small to be significant when compared with natural variabilities and climate uncertainties.

Needless to say both articles provoked a heated response from lot of climate scientists and their supporters. One such came from Andrew Lacis. His response was posted on Judith Curry's blog, and then again on Skeptical Science, and it began as follows:

Physicists should take the time to understand their physics better.

Only 1% to 2% . . . that may sound small and insignificant . . . but it isn’t.

It is well known that the normal human body temperature is about 310 K. Furthermore, it is also well known that a seemingly small change (up or down) in absolute body temperature by only 1% (3.1 K, or 5.6 F) would make one sicker than a dog, and, that a 2% change in body temperature (up or down by 6.2 K, or 11.2 F) will virtually guarantee a dead body. From this, it should be sufficiently clear that, when viewed in absolute energy terms, the viable margin between life and death in the Earth’s biosphere is remarkably narrow – so much so that a seemingly insignificant 1% to 2% change in the total energy of the global environment will invariably result in serious disruption of the established infrastructure of life in the biosphere.

 

The full response from Andrew Lacis ran to over twenty paragraphs and extended to other issues such as changes to atmospheric water vapour concentrations and other climate feedbacks. I am not going to consider the rest of his arguments in detail as they are not pertinent to the main thrust of this post. What I am going to consider is the above quote, minus the rather condescending first line, and ask, is the human body a good analogy for global climate? My considered answer is, no!

The attraction of the above analogy is, I think, two-fold. Firstly, both the normal temperature of the human body (310 K) and the generally assumed mean surface temperature of the Earth (288 K) are fairly similar in magnitude (the difference is only about 7%). Secondly, both the human body and the Earth are highly complex systems regulated by multiple feedback mechanisms, but which at the same time appear to be extremely stable. So, it could be inferred that what is true for one could, or should, be true for the other. In which case, according to the analogy, if a change in body temperature of 1°C in a human is of profound importance to their health and well-being, then the same should be true for the biosphere of the Earth with regard to the interdependence of its own mean temperature and its long-term survival.

Except, that it is not.

Because the mean temperature of the human body does not change by ±10°C or more every twelve hours. Nor does the mean daily temperature of the body change by over 10°C over the course of a month, or in many cases even a week, or by over 50°C from January to July. Nor is there a permanent temperature difference of over 100°C between different points on the body such as the head and the feet. Because if it did do any of this, then a mean temperature rise of only 1°C due to a mild fever would be undetectable. And that is the key point! Yet that is what climate science is trying to measure in respect of a mean global temperature, and then claim that a) the measurement is statistically significant, and b) that the consequences will be so catastrophic that the system will be unable to cope.

You might ask, why should we care now about what a few physicists, climate scientists and commenters wrote over six years ago? The main reason is that those who oppose the Steven Koonin viewpoint, or his right to articulate it, continue to republish quotes like the one above to support their own arguments.

So, thank you to Andrew Lacis for the above analogy. It is indeed a very useful and illuminating analogy.

36. Lateral thought #2 - does human respiration cause carbon dioxide levels in the atmosphere to increase?

Does breathing contribute to a build-up of carbon dioxide in the atmosphere? This was the subject of an article on the Skeptical Science website that I came across recently that claimed to be debunking a climate myth. That supposed myth was that breathing contributes to a build-up of CO₂ in the atmosphere.

The article is not new: it was first published ten years ago. The central point of the article was to refute claims supposedly made by climate sceptics that breathing by humans adds carbon dioxide to the atmosphere, and so contributes to global warming. But after reading the article and many of the comments I realized that not only was the entire article wrong, so too were most of the comments. 

The motivation for the article appears to be a throw-away comment by Australian academic Professor Ian Plimer, Professor of Mining Geology (University of Adelaide) and Emeritus Professor of Earth Sciences (University of Melbourne), in an ABC radio interview regarding his latest book. The comment was a response to claims made in a green paper by Australian Climate Minister and Senator Penny Wong regarding the threat of climate change where she claimed carbon was a pollutant. In reply Professor Plimer said:

"If Senator Wong was really serious about her science she would stop breathing because you inhale air that's got 385 parts per million carbon dioxide in it and you exhale air with about ten times as much, and that extra carbon comes from what you eat."

I'm still not sure why that statement riled the people at Skeptical Science so much, other than it came from a climate sceptic attacking a supporter of global warming. To me it just seems like a statement of fact and a reference to the carbon cycle. It is therefore doubly puzzling that those same people at Skeptical Science then chose to use the carbon cycle to refute a claim that was not explicitly made, namely that breathing contributes to a build-up of CO₂ in the atmosphere. The argument outlined in the rebuttal by Skeptical Science basically came down to saying:

"Therefore, when we breathe out, all the carbon dioxide we exhale has already been accounted for. We are simply returning to the air the same carbon that was there to begin with."

The problem is this is not quite true. Actually, it is not true at all. In fact I will now explain why breathing by humans may have actually contributed to a build-up of CO₂ in the atmosphere over the last 100 years.

 Fig. 36.1 The carbon cycle.

The first problem with invoking the carbon cycle is that there is no such thing. There is no single carbon cycle. Instead there are multiple interlocking cycles as illustrated in Fig. 36.1 above. I've listed three possibilities below.

Atmosphere  ==>  plants  ==>  soil (bacteria)  ==>  atmosphere.

Atmosphere  ==>  plants  ==>  animals  ==>  atmosphere.

Atmosphere  ==>  ocean plants (algae)  ==>  oceans (bacteria)  ==>  atmosphere.

So the CO₂ doesn't just go round in a circle, as is claimed: it goes around multiple circles. 

The second problem is that the carbon cycle only describes the steady state. So you can’t use it to prove that human respiration isn’t increasing CO₂ levels in the atmosphere because the human population has grown exponentially over the last 100 years. It has almost quadrupled since 1920. That is not a system operating in the steady state or at long-term equilibrium.

In essence, the carbon cycle describes five competing carbon reservoirs or sinks (vegetation, animals, soil, the ocean and the atmosphere) all of which also act as carbon pumps. Moreover, these five reservoirs are all interconnected, and the pumping capacity of each depends on their size. Generally, the bigger they are, the more carbon they will pump. That interconnection means that changing the size of one will change the size of all the others in order to a) balance the pumping rates, and b) to ensure that the law of conservation of mass, as applied to the amount of carbon in the system, is never violated. These changes will happen as the system seeks to find a new equilibrium position or steady state. 

So in principle, any change to either the pumping rate or the size of a reservoir will have knock-on effects throughout the rest of the carbon cycle. That means that any increase in the human population will affect everything else. We can, however, estimate what some of these changes might be based on what we know about the change in human population over the last 100 years.

As the average 70 kg person generates about 1 kg of CO₂ per day, that means they transfer 100 kg of carbon to the atmosphere every year. This carbon comes from the food they eat. With nearly 8 billion people on the planet that equates to about 0.8 GtC per annum (GtC = gigatonne of carbon) being transferred into the atmosphere.

But that is not all. The average person probably eats their own bodyweight in meat every year. So the growth in the human population since 1920 must be reflected in a similar percentage growth in the number of farm livestock. If we assume there is about 2 kg of livestock per 1 kg of human (i.e. a 2 year supply of meat in production), then the overall CO₂ production from both will be about 2.4 GtC per annum. This is about a quarter of our fossil fuel CO₂ output so it is not insignificant. But is this directly increasing atmospheric CO₂ levels as some climate change deniers might claim (although I'm not entirely sure which)?

Some people have suggested that the increases in human and livestock CO₂ emissions are offset by increased crop production. Their argument is that, as all the carbon we breathe out comes from crops, any increase in the CO₂ produced by the human population will be offset by a commensurate increase in crop production required to feed the extra humans and their livestock. That in essence is the core of the original rebuttal from Skeptical Science outlined above. The problem is that this is not true either.

Increased crop production comes at the expense of other types of vegetation (e.g. forests). The total area under human cultivation may increase, but the total amount of land and vegetation won’t. All available fertile land is already fully occupied with vegetation, so any increase in farmland will be at the expense of wild countryside. Changing usage from one to the other does not increase CO₂ uptake because both types of land are already doing this. For example, deforestation in the Amazon region driven by the desire to grow crops and farm cattle does not increase the rate of CO₂ capture in the region. If anything, it decreases it. Forests, so we are told, are the best carbon dioxide scrubbers.

Also, increasing the number of animals does not increase the amount of vegetation or its growth rate. Instead it decreases the amount of carbon going into the soil. Animals eat plants before those plant can die and before they can decay in the soil. This means that animals replace the CO₂ producing capacity of the soil. That is where the substitution occurs. And if the pumping efficiencies of both animals and the soil were the same then nothing much would change as the animal population increases. But they aren’t the same. 

The carbon pumping efficiency of the soil is only 4%. As Fig. 36.1 indicates, the soil contains 1580 GtC globally but emits 60 GtC per annum. Humans store only 0.1 GtC but emit 0.8 GtC per annum. That is an efficiency of 800%. If we include livestock, the efficiency will be broadly the same (800%) but the size of the carbon reservoir and CO₂ emissions will both be about three times greater, for the reasons outlined above. This also means that the increase in CO₂ production from humans and livestock is the same as that produced by about 4% of the Earth’s soil. The consequence of this is that the volume of the soil must reduce by 4% over time as its pumping capacity is replaced by human and their animals, and the amount of carbon entering it from dead plants declines. 

So 63.2 GtC will be lost from the soil while only 0.3 GtC will be transferred to storage in humans and animals, and none to plants. There is only one other place that most of the 62.9 GtC can go: the atmosphere. This 62.9 GtC will increase the atmospheric CO₂ concentration by about 25-30 ppm. So the human population increase could have increased atmospheric CO₂ levels by up to 30 ppm over time, and about 20 ppm since 1920.

Fig. 36.2: A schematic illustration of the carbon cycle on land.

 

To understand this more fully consider the schematic diagram in Fig. 36.2 above. This represents the part of the carbon cycle involving exchange of carbon between the air and land in the case where initially there are no animals in existence. The terms T₁-T₄ are the flow rates of carbon between the three reservoirs, with the size of each reservoir indicated in parentheses. The four flow rates represent carbon capture in plants by photosynthesis (T₁), respiration from plants and animals (T₂), the transfer of dead plant and animal matter to the soil (T₃), and the decay of organic matter in the soil to release CO₂ back into the atmosphere (T₄).

In equilibrium the flow rates into and out of each reservoir must balance. So 

T₁ = T₂ + T₄

(36.1)

 

T₁ = T₂ + T₃

(36.2)

and

T₃ = T₄

(36.3)

Only two of these equations are independent. In addition, the total amount of carbon in the system must remain constant at 2940 GtC (=1580+610+750).

Now suppose the ecosystem outlined in Fig. 36.2 initially contains only plants and bacteria in the soil. Then we introduce some animals. The effect of animals is to eat some of the plants and emit CO₂. This means respiration (T₂) must increase by an amount x and the amount of plant matter entering the soil (T₃) must decrease by the same amount in order for Eq. 36.2 to balance. For the case of the addition of humans and livestock we have already estimated that x = 2.4 GtC per annum. 

The problem is that both Eq. 36.1 and Eq. 36.3 now no longer balance. Only Eq. 36.2 remains balanced. So the soil will lose 2.4 GtC per annum and the atmosphere will gain 2.4 GtC per annum. There is a mass transfer of carbon from the soil to the atmosphere. This will only stop when the emission of CO₂ from the soil (T₄) decreases, as it will do gradually due to the slow and gradual reduction in its volume. When that happens both Eq. 36.1 and Eq. 36.3 will once more balance and the mass transfer will stop. That will happen when T₄ has also decreased by x. As T₄ was initially about 60 GtC per annum, this requires a 4% reduction in T₄, and therefore a 4% reduction in the volume of the soil, i.e. 63 GtC (the rate of decay of the soil and its rate of emission of CO₂ must be proportional to the soil volume). That amounts to a total mass transfer of approximately 63 GtC to the atmosphere, the same as in our preliminary calculation above.

Is this an upper estimate? Yes, probably. It assumes that the growth in the human population and farming livestock is a net gain in terms of animal numbers and that they do not merely substitute for the loss of other species. But we know this is not true. Humans and their livestock do displace other creatures to some extent. This analysis also omits any additional loss of CO₂ to the oceans and changes to vegetation volumes through loss of soil (down 4%) and increasing growth rates due to increased CO₂ levels in the atmosphere (up by 8%). But what it does demonstrate is that when the human population changes, everything else changes. 

 

Conclusion

What we have shown here is that changes to the ecological balance between plants and animals changes the concentration of CO2 in the atmosphere. So respiration by humans and other animals can contribute to a build-up of carbon dioxide in the atmosphere.

29. Lateral thought #1 - suburban heating

Question

How much does the average home heat up its environment?

This is really a question that ties in with what I wrote on Post 14. Surface Heating, but I think it illustrates the point at a level that most people can relate to.
 

Answer

Well, we know from Trenberth et al. that the average power of solar radiation incident on the Earth's surface is approximately 161 W/m² (see Fig. 14.1). We also know that this leads to a mean surface temperature for the Earth of about 288 K. We also know from Post 12 (black body radiation and Planck's law) that the emitted surface radiation density scales as T ⁴, where T is the absolute temperature of the surface measured in kelvins, and the emitted radiation must balance the incoming radiation. In other words, both incoming and outgoing surface radiation densities will be proportional to T ⁴. For the outgoing radiation the constant of proportionality will be the Stefan-Boltzmann constant, while for the incoming radiation it will be the Stefan-Boltzmann constant divided by the feedback amplification factor. It therefore follows that if the mean surface temperature were to increase by 1 K to 289 K, then the quantity T ⁴ must increase by 1.40 %. And there are two main ways that this could be achieved. 

The first is to increase the feedback or radiative forcing through an increase in the strength of the Greenhouse Effect. This is what most climate scientists concentrate on, and what they believe is responsible for any temperature changes. But the second possibility is to increase the radiation power absorbed by the surface before the feedback amplification occurs. This could happen if the strength of the Sun's output changes, but more realistically it will happen whenever extra heat is liberated at the surface of the Earth. The amount of heat required to do this will be 1.40 % of 161 W/m², or 2.25 W/m². So an increase of 2.25 W/m² in the incident surface energy density will result in a 1 °C temperature rise (see Post 13 - Case 2).

As I pointed out in Post 14, a major source for such additional heat liberation at the Earth's surface is energy generation and consumption by humans, often for industrial needs. This leads to direct anthropogenic surface heating (DASH) that can raise the temperature of whole countries by as much as 1 °C. But it is not just industry that can significantly heat the local environment.

Consider a typical home. The average household in the UK uses at least 10,000 kWh of energy per year. That equates to an average rate of usage of energy of 1.14 kW throughout the year.

The average land area of homes in the UK is at most 500 m². Most modern housing developments have more than 30 new homes per hectare (see PPG3 guidance paragraphs 57-58); older suburban developments are generally a lot less dense than this; inner city flats and terraced houses are clearly a lot more.

All of this means that the power density for heat escaping from homes will be at least 2.28 W/m² (i.e 1140 ÷ 500). In other words, the energy used by a typical household is more than sufficient to increase the local surface temperature by more than 1 °C. And remember, all this heating has got nothing to do with CO₂ emissions. Nor does this calculation include the energy consumption of commercial buildings, industry or transport.


Conclusion

The energy used by the average household in the UK each day raises the temperature of their local environment by at least 1 °C compared to pre-industrial levels. That will be true irrespective of the source of the energy. Renewables will not help. Nor will cutting your level of CO₂ emissions. This is all down to heat, entropy and thermodynamics.