and The Solar (Thermal) Solution
By Eerik Wissenz
Grid parity not the bench mark
It is often assumed that when renewables reach grid parity our energy/ecological problems are over.
This view is incorrect, to truly compete with carbon on a global scale renewables must also reach “thermal parity”.
Since it makes no sense to burn fossil fuels to make heat to convert to electricity, then transport it over an expensive distribution network, only to convert it back into heat; we tend to simply burn fossil fuels directly for our thermal needs. Though today it may be as cheap to produce electricity with gas and coal as with wind in some locations, it still remains significantly cheaper to get heat with gas or coal than with a windmill. The reason is that it generally takes 2-3 kilowatts of fossil fuel thermal energy to create 1 kilowatt of electricity, so if we just need heat it’s at least 2-3 times cheaper to simply burn the fossil fuels directly than to use an electric renewable technology that is at grid parity. In fact, since burning fossil fuels directly usually doesn’t require a boiler, turbine, generator, condensing tower, distribution grid, it’s almost always even cheaper than even this basic comparison.
Insofar as the "mixity fixity" approach to energy only concerns itself with electricity, then it simply ignores altogether the actual foundation of our civilization which entirely depends on heating stuff and melting things.
Without power to our electronics and lighting we may become very relaxed and well rested, albeit completely unable to work in the modern job. When we are away from electricity most of us are not bothered in any significant way and a large portion of humanity use electricity very little or not at all. Without access to heat on the other hand, many of us couldn’t cook most of our food, heat water and would freeze in the winter. Essentially all industry and crafts would be impossible.
So this subject shouldn’t be viewed simply in terms of consumption but also in terms of importance to our survival. Thermal energy not only represents more energy consumption but is also far more important than electricity.
The “massive scaling problem”
In terms of hard numbers, we consume about 15 terrawatts of energy globally in total but only 2 terrawatts of electricity. To make these 2 terrawatts of electricity we consume 5 terrawatts of primary energy, mostly fossil, the difference is virtually all lost. Of the 10 terrawatts left, we consume about 3 terrawatts in transportation and 7 terrawatts domestically and in industry, more than 80 percent for heating things.
So, between heating stuff and running internal combustion engines about 10 terrawatts are consumed. So, the idea of an all out, all electric mixed-renewable-nuclear-smart-grid economy to replace current fossil fuel consumption would require going from 2 terrawatts of electricity consumption to 12 terrawatts of electricity consumption, a scaling of 6 times. Is this remotely possible?
We can start out by noting that the time and costs required just to scale the electricity grid excludes this option of having any impact on declining fossil fuels or global warming. If we consider the time and costs of scaling electric renewable and/or nuclear to our present electricity consumption and then scaling that again 6 times, the whole electric plan is not just a risky bet – a bet that there’s enough economic resources and stability to make the transition, that there’s enough lithium for a shiny new fleet of electric cars, enough copper for all the wires, and that enough fossil energy will be available to build it all – it’s not just a huge risk if the necessary elements don’t fall into place, it’s just not feasible. There’s simply no feasible way to cover a significant portion of industrial and domestic heat, transportation, and current electric consumption, with any combination of renewable or nuclear electric generating technologies in any short amount of time; as in short enough to mitigate fossil decline and environmental chaos.
Now, in a purely electric economy it could be argued some processes would be more efficient, such as electric cars and displacing home furnaces with heat pumps. Both would reduce total energy needs. This is certainly so, and it is also certain that waste would decrease in an energy constrained world. However, in industry there is little room for gains in most thermal processes and the higher the temperature the less impact geothermal heat pumps can have outside volcanically active zones, and it is industry that represents most energy consumption.
But beyond the debate of how much electricity we would actually need, we should always keep foremost in our minds that world governments have put in place no plausible plan to scale renewable electricity to even current consumption in any short time frame. So whether we would need 2, 3, 5 or 7 times current total electricity production is not the question this paper poses. The question here is can any any significant fraction of total energy use be attained through electricity in a timely enough manner at all?
To this “massive scale obstacle” we also have to add the problem of actually building all the electric trains and cars that would be required for an electric transportation system. A total transformation of this infrastructure cannot be done over a fortnight. And again, the governments of the world currently have no plausible plan to accomplish it in a half century.
So, when we look at the whole energy picture, fossil fuel depletion doesn’t present us with an energy gap — or "unidentified energy projects" as the IEA likes to say — it hurtles us towards an energy canyon that no combination of electric generating technology can possibly bridge. 
To recap and emphasize this as much as possible, just the grid scaling problem would be a massive technical feat, and that’s the easiest problem to solve ... if there’s enough copper to do it.
Nuclear thought experiment
To appreciate this scaling issue it’s useful to go through the thought experiment of how many nuclear reactors would it take to completely displace carbon.
The world currently produces 14% of electricity with nuclear power whereas 69% is produced by carbon. So, to generate all current carbon derived electricity with nuclear reactors would require about 5 times more nuclear reactors, 2180 rather than the 443 in operation prior to the Fukushima disaster . But this represents only 2 terrawatts of electric consumption! To cover the 10 terrawatts of non-electric energy consumption would require about 15 000 nuclear reactors!
Considering the time, experts, equipment and danger involved in running the 443 reactors in operation pre-Fukushima meltdowns, the plan to build any portion of 15 000 reactors should be considered patently absurd. The prospect gets even worse when we realize that nuclear reactors have to be decommissioned at some point since the radiation degrades all the material involved; we can consider the reactors themselves as a sort of fuel fed into the nuclear industry (this also holds for fusion). To be with industry wishes and assume decommissioning in around fifty years, to go "all nuclear" would require building some 30 000 nuclear reactors in a century, then rebuilding them every century.
Some steam engines, on the other hand, built over a century ago are still in operation today, and renewable energy in general does not become radioactive so the parts can usually be recycled.
We should consider also that the costs in the nuclear industry are actually rising due to rising oil costs. For instance, the new generation EPR reactor being built in Finland is 4 years late and 90 % over budget . We should also note that the reactor is being built by Avera, the nuclear builder in France, the country proposed as the model nuclear state. One reason for this price rise is that it takes about a quarter of fossil fuel energy to build a nuclear reactor than it will generate; so as fossil fuels rise in price so does nuclear energy.
But the true cost of nuclear energy is not only the oil, not only the trillions in subsidies over the years, not only the waste problem, not only the health problems, and not only the environmental-social-economic impact if something goes terribly-predictably wrong (Tepco had hired a seismologist who concluded there was a serious risk of Tsunami within 50 years), but also the opportunity cost of not developing a technology that at least has a chance of making a dent in the thermal problem.
Producing some percent of today’s electricity consumption with renewables/nuclear is not addressing the world’s energy problem. Even if nuclear electricity was doubled this would be less than 4% of global energy consumption. 4 doubling times would be required to reach 30% of global energy consumption with nuclear electricity, this is not possible in the 10-20 years we have to deal with climate chaos and fossil decline (considering it can take 10 years to build a single nuclear reactor) nor advisable in any case as Fukushima should remind us.
What we need
What we need is a technology that can at least start warming the great thermal void we face and can also be built quickly, even shoddily, in a panicked attempt to deal with fossil decline, without endangering complex lifeforms such as the ecosystem as a whole and small complex parts of it such as ourselves.
In essence, our energy problems are far from being solved by quibbling over how best to produce slightly more electricity without fossil fuels in order to light up television sets and power air-conditioners in affluent countries ... and maybe, just maybe, continue on exactly as before only in stylish electric vehicles.
Our problems are profound, deadly serious, global and primarily thermal.
Why haven’t I heard of it yet?
The thermal problem has avoided the spotlight only because the developed world has mostly off-shored its industrial capacity and many people in rich countries can afford to heat and cook with electricity (though it makes no energy sense to do so), so electricity represents a disproportionate amount of energy use in rich countries and it seems plausible, from quotidian experience in these regions, that everything could be powered by electricity. It’s so convenient after all. We don’t see many factory smoke stacks in rich countries belching black coal smoke, so out of site out of mind. What we miss is all the embodied energy around us: all the heat required to make everything and get it here. However, without a feasible alternative, this off-shored industrial capacity will continue to require fossil fuels along with the transportation system to get all those products on-shore.
Facing the thermal problem
If we look at our energy options in terms of what can provide us with significant quantities of heat, what is physically possible to both develop and scale in the short term, and what would be accessible in both poor and rich countries, the list shortens significantly.
Renewables such as wind, hydro, tidal, photovoltaic, all provide electricity. Though a good idea for contributing to the relatively small amount of electricity we actually need, it is essentially impossible to face our thermal needs with these technologies in any significant way. We can say the same for nuclear, though in this case we can also note it would be a crazy, reckless hubris, risky bet on both our technical competence and the global stability of society to even try.
What is left is geothermal, biomass, and solar thermal. Only these three sources provide renewable thermal power and have been proven to work.
High temperature geothermal can only be used in sparse locations where the earths crust is thin. Otherwise it costs more energy to go down and get the energy than we get out of it.
There is also low temperature geothermal, using wells and heat pumps, but these are only useful for home heating and cooling, and have installation costs significantly higher than most people on the planet can afford.
So, though geothermal is a good idea for northern and affluent countries or those close to volcanoes, we can rule out geothermal as a potential significant source of high thermal heat for crafts and industry nor significant source of low thermal heat in poor countries (though rich northern countries should definitely drill as many heat pumps as possible instead of wonton consumption of frivolous products).
As for biomass, there is roughly 140 kilos of biomass production per person per year for all of Europe, whereas the average European consumes 2.3 tons of energy in terms of oil. Burning biomass at enormous scales would not only be insufficient but would completely degrade the land. The effort would simply make life difficult for our post-collapse descendants. This also makes intuitive sense. Fossil fuels are simply biomass accumulated over eons; is it really reasonable to expect one year of biomass will cover the tab?
How about burning books?
Burning books of course provides us with heat.
Though a completely useless idea to solve our energy problems, thinking through why burning books can’t form the backbone of crafts, industry and domestic heat is a good way to understand all the above issues.
The energy and time to make books is far more than we get out of them when we burn them, meaning the book industry couldn’t possibly survive by only burning books for its energy, much less society as a whole. Another important factor is what books represent. When we think of all the time and effort society has put into making books, burning them doesn’t make any sense. Though some people burn books, it’s generally not for the purposes of heating their homes in a sustainable way.
Lastly, even if we could generate an impressive (but ultimately insignificant) quantity of books to burn, why burn books when we can just burn the trees used to make the books? Seen as the result is the same, why go through all the effort to make the book only to burn it?
Obviously this argument can’t be overcome and we don’t commonly throw a few more books into the stove to heat our soup. With respect to books this is fairly clear.
But what we don’t so easily realize is that "burning books is to burning trees" as "burning trees is to using direct solar energy".
For exactly the same reason that it makes no sense to burn books rather than trees, it also makes no sense to burn trees rather than use solar energy directly.
It is sunlight that makes our trees, and just as it takes far more energy to make a book than we get from burning it, it takes far more solar energy to make a tree than we get from burning it. Likewise, just like it takes a lot of effort for society to make a book, and the book can (hopefully) serve a far greater purpose than being burned, life has taken an enormous amount of effort to make trees and for certain they serve a far greater purpose than being burned by us.
So for exactly the same reason we can ask “why burn books when we can burn trees?”:“why burn trees when we can use the sun’s heat directly?”
We can also say exactly the same thing about burning fossil fuels, though in these cases their greater purpose seems to be served by staying in the ground and not doing anything. Though we can note that oil seems a more ecological lubricant than whale blubber, there are also vegetable derived alternatives such as jetropha, but in any case most fossil fuels are simply burned or turned into known poisons (what could be plausibly argued are sustainable uses would be a tiny fraction).
This leaves solar thermal energy
The sun provides the earth with 174 thousand terrawatts of sunlight. About half of this actually reaches the earth’s surface where we can harness it. About 30% of this falls on actual ground and not in the ocean. So this still leaves about 26 000 terrawatts available, about 1740 times more than we use.
To place an upper limit to how much of this land-solar energy we could possibly capture: solar radiation can be absorbed at a maximum efficiency of around 80% using solar concentration. To this we have to add reflection losses (ranging from 6 to 20% loss with existing mirrors). For producing heat, reflection and focal absorption are the two main losses in high-temperature solar thermal systems, meaning about 16 000 terrawatts of thermal energy could be captured by the best solar devices covering all land. But there are of course always other losses, down time, wasted energy, and so in practice we can assume the best solar thermal systems can be about 60% efficient. So we can estimate that the practical limit of direct solar thermal energy is about 15 000 terrawatts of thermal energy.
This represents roughly 1000 times more energy than we consume today.
So, on average, for every 1000 square meters of land we must cover a single square meter with a solar thermal device to be able to produce as much energy as we consume today (about a third of a square yard per acre). This energy would be in the form of heat, the energy we actually use most, so it’s form is not a problem for the 7 terrawatts of crafts, industrial and domestic heat energy currently consumed.
Of course, a practical limit is not meant to be achieved, the devices would certainly not be all 60% efficient. So to actually capture 15 terrawatts may require some fraction more than 1 square meter per 1000 square meter. But taken as a benchmark using 0.001% of land for solar energy is a fairly small small footprint, and we can note that using solar energy directly has many knock on benefits that reduce energy needs, such as allowing the localization of production and recycling and minimizing grid and energy transport load and infrastructure as solar energy is its own distribution network. So how much solar thermal energy we would actually need is a question for another paper. Here we can simply note that even a few multiples of 1 square meter per 1000 square meters of solar device would probably still not be unfeasible nor ecological suicide. Solar collectors require no toxic or rare materials: aluminum, silica and steel is enough, all among the most abundant elements, and by tapping solar energy directly we have far less impact than removing disproportionately huge amounts of embodied solar energy from sensitive processes in the ecosystems (for instance, when we burn a tree we actually burn all the solar energy that fell on the tree, which can be hundreds of times more than we actually extract).
The next question is whether solar thermal technology exists that can actually answer to our thermal needs and be scaled rapidly without endangering the ecosystems nor dependence on either massive unprecedented international government programs nor the long term availability of cheap fossil fuels?
We can take this question from two angles: from the large scale and imagining adaptation for progressively smaller scales or vice-versa.
Large solar trough installations have already proved to be able to reach grid parity for electricity production. However, the crucial difference between solar thermal electricity and wind, photo-voltaic or hydro electricity, is that solar thermal electricity started out a significantly more thermal energy. Using a windmill or water mill as a thermal source cannot possibly compete with carbon as carbon electric generation takes 2-3 times more thermal energy, so can by definition supply more thermal energy far cheaper. Photo-voltaic can co-produce low grade thermal energy, but this can’t answer industrial or even cooking needs. Solar thermal electric generation on the other hand shares the same quality as fossil fuel generation, in that the electricity is derived from high quality thermal energy (above 350 degrees). So, if we want to use the same technology just for thermal energy there’s a far larger pool to draw from; i.e. the cost of thermal energy using the technology is far lower than the cost of electricity, and so can compete with burning carbon at the thermal level.
Now, grid parity solar thermal electric stations are enormous and must be situated in the desert to be cost effective. But, with further development it’s reasonable to assume that this technology can be made smaller and adapted to industrial needs. For instance, we can note that an important factor of scaling solar thermal electric stations to massive size is in order to minimize the cost of the turbine and generator. Not only is a big turbine and generator cheaper than many smaller ones but they are also more efficient. For purely thermal purposes, however, there is no need of a turbine and generator and so economies of scale are less important.
With respect to the “storage problem” that bedevils most renewable electric generating technologies and has yet to be effectively solved, there are many industries that require intermittent thermal energy or would greatly benefit from reducing thermal costs when the sun is there and using conventional fuels when the sun is not. This can be considered a niche market where on-location industrial solar thermal technology can develop, though this characterizes essentially all industry so is hardly a niche.
For instance, a lot of industrial processes require a constant source of hot water or steam. Heating water and making steam both are energy intensive thermal processes.
A factory that installs existing solar thermal technology benefits in two significant ways, reducing cost of conventional fuels and also insulation from carbon price fluctuations. In today’s market, if the process runs 24/7, the solar thermal device may only provide up to 50% of thermal needs, but in tomorrows market if the price of carbon increases to a point that makes running the process on carbon unprofitable, the factory with solar thermal installed can continue to function 50% of the time whereas the factory dependent on carbon must shut down. We can also assume that the factory that continues to function will be able to invest in simply doubling thermal-process capacity, whereas the carbon-dependent factory may simply go broke. Now, some carbon or electricity may be required to smooth out thermal processes things but this can be rendered nearly insignificant next to the bulk of energy supplied by solar thermal.
Already today, existing solar thermal technologies will pay for themselves through fuel savings, at both the industrial and domestic level. As carbon rises in price this simply shorten the payback period.
Large scale thermal plants are not the only existing cost effective thermal technology. Hot water heaters, solar cookers, and well designed concentrators, are already cost effective at the small scale. So just as we can imagine a scaling down of massive solar thermal power stations, we can easily imagine a scaling up of small scale technology. Most importantly, we can imagine these two scales meeting in the middle at the scale most industry exists, above 100 C but below multi-megawatt consumption.
For instance, solar hot water panels alone can save 50 % on heating fuel costs at the domestic level, even in temperate cloudy regions such as England . Far cheaper than photo-voltaic panels, solar water heaters address as big a domestic energy need. Hot water alone accounts for roughly 24% of domestic energy needs, so a fuel savings of 50% means 12% of total domestic energy consumption. Electricity on the other hand represents 15% of total domestic energy consumption. And again, if carbon continues to rise in price, a home with solar hot water heaters can ration hot water when there is no sunlight (i.e. wait for sunny days to wash laundry and take long showers) further increasing the saving from their thermal systems. Solar hot water heaters can also produce thermal energy to circulate around the house significantly reducing heating costs (which represent 56% of domestic energy consumption in Britain, see End Note 6.). The technology is cheap and can be easily deployed on a global scale.
But outside the home, there are many industries that require low-grade thermal energy, and with further improvement this sort of technology can only grow in scope of application.
Though a plan completely dependent on large government programs to potentially succeed and large indefinite subsidies to survive, such as nuclear technology, should be met with skepticism, technologies that are already viable and being adopted spontaneously can be significantly accelerated by government programs. Not only can a factory invest today to avoid shutdown tomorrow, a government can invest today to avoid shutdown of entire industries tomorrow. Since the technology is fundamentally viable, accelerating adoption can be accomplished through loan programs, orienting existing educational resources to train the know-how required, or simply talking about the issue and providing credible numbers (which costs almost nothing).
Everything already here
I have written this paper in a hypothetical sense to get people thinking about the issue and to spark debate. However, just as we would expect if these solar thermal technologies already exist and can do such things, they are already being adopted at the industrial and domestic level.
Most people are now familiar with the benefits of solar thermal hot water systems, and essentially any company dealing with solar concentration addresses both the potential for electricity and space or water heating and process thermal energy.
A few months ago I attended the solar thermal conference at the Institution of Technology in Mumbai. The presentation from the chief scientific adviser to the Indian Government insisted that the government of India viewed the solar thermal sector as crucially important, indeed an imperative, since in their view there’s simply no other choice for industry in the near future, so they have to be develop it now. They also insisted that they want to support all scales of the technology. So at least one of the largest governments on the planet is also aware of the thermal issue.
Resilient during fossil decline?
By displacing large amounts of carbon in a short time frame using simple and easily deployed solar thermal technologies, this can reduce demand for carbon significantly providing a buffer in which more carbon-dependent systems can continue to function.
For instance, melting metals with solar thermal is not yet commercially viable and solar thermal does not directly solve the transportation problem. However, the more demand for carbon is destroyed in simple areas, the more time complex areas have of adapting without significant shocks.
At a fundamental level, however, to build solar thermal collectors mostly requires thermal energy. So the collectors can supply at least a good part of the energy required to make more solar collectors. Recycling aluminum requires only 700 degrees, which can be attained by existing cost-effective solar thermal technology. The structure and reflective surface of a solar concentrator can be made of aluminum, though glass and steel are often useful, though requiring more energy to produce.
But even steel and glass are not off limits. The limit of solar concentration is 5000 degrees and there are existing experimental installations that reach this level, so melting steel and even rock with solar concentration is a proven technology, just not cost effective at the moment. With more development and scaling of the solar thermal industry such technologies can become only more and more cost-effective; in relatively short order we could see solar concentrators built using a majority of solar thermal energy. 
Solar thermal is thus perhaps the only renewable technology that could go closed loop in a relatively short amount of time (i.e. be mostly independent of carbon within the next 10-20 years). This could be done in a relatively short term with respect to recycling metals (as this is less energy intensive) but also feasible in the longer term with respect to mining. Though we should note that in the even of a carbon crunch there will be plenty of defunct material to recycle.
Though some metal will always be required to form a reflective surface, there is no reason that many structural components of a solar concentrator cannot be made of bamboo, wood or organic fiber. By growing solar collector components the technology can become even more independent of fossil fuels.
Awareness is the key
The potential for carbon savings at the domestic and industrial level through solar thermal is huge. Though there is no fundamental technological problem in massively deploying solar thermal, there is a time factor. The faster we do it the faster we can mitigate the consequences of both climate chaos and fossil energy decline. In terms of taking on a significant portion of the global energy load in the short term, solar thermal is the only option. The technology is proven, can be produced and installed at scale and addresses the 7 terrawatts of non-electric carbon energy. This would not only reduces carbon emissions, especially low grade carbon (the lower the grade the more easily solar thermal can compete with it), it would reduce the possibility of a serious carbon crunch and so reduce the possibility of a whole scale conversion of the biological sphere to fuel. Likewise, the more carbon that is currently being burned for thermal energy is replaced by solar thermal, the more carbon is available for transportation and electricity: thus the less likely these systems will face a collapse and the more time they will have to transition away from carbon.
We can’t fundamentally change the global transportation or electric situation in 10-20 years, other than through collapse, but we can fundamentally change the domestic and industrial thermal energy situation in 5-10 years: the technologies are ready to go, easy to deploy and don’t require some massive industrial transformation dependent on unproven cost-effective technology, cheap fossil and/or exotic materials.
Eerik Wissenz is a co-founder of www.solarfire.org, which develops Open Source solar concentrating systems, especially for poor countries rich in sunlight.