In 2013, a momentous, revolutionary change, decades in the making, came to pass, almost unnoticed. Silicon solar photovoltaic energy became cheaper than coal in much of the world. Consequently, the majority of world marketed energy will be solar by around 2020–2026, and the problems humanity has to face will be completely different thereafter. Many things we think of as problems today will no longer be problems, and many things we don't think of as problems yet will be problems.
The cost of energy, particularly for power plants, is tricky to calculate because the investments are long-term and often have unforeseen consequences. But energy utilities do these calculations on a regular basis, depreciating investments in physical generation infrastructure over XXX years and including cost of labor and fuel.
By these calculations, XXX in many parts of the world, utility-scale solar photovoltaic energy is now cheaper than fossil-fuel energy. This is new as of 2013. It was never true before.
The major reason for this has been the precipitously dropping price of silicon photovoltaic cells, due to an explosion of new low-cost photovoltaic manufacturers in China.
In the case of solar energy plants, the fuel is free; the vast majority of the cost of the energy is just the cost of building the plant, much of which is the cost of the solar cells that went into it.
One of the significant expenses in photovoltaic cell production is energy. But cheaper photovoltaic cells will lower the price of solar energy, which will lower the price of photovoltaic cells further. The ultimate limit is the cost of the raw materials and the depreciation of the capital equipment needed to produce the cells in a lights-out plant. As explained below, the cost of the raw materials is extremely low.
Some people have published calculations claiming that the embodied energy of photovoltaic panels — that is, the amount of energy consumed in their production — is greater than the amount of energy that the panels produce over their lifetime, and therefore using fossil-fuel energy to produce panels is just a waste. This was probably correct up to the 1980s, but the current energy payback time on photovoltaic panels is probably around one year, while the panels are designed to last 30 years, but in practice usually last longer.
The "solar constant", the amount of sunlight that reaches Spaceship Earth, is about 1400 watts per square meter above the atmosphere. At ground level, it's about 1000 watts per square meter, due to clouds, dust, and air absorption at some wavelengths. But that's a square meter at right angles to sunlight, not parallel to the ground. Tropical latitudes receive more sunlight because they're closer to being at right angles to the sun, while areas near the poles receive the least.
The total amount of sunlight striking the earth is XXX
Total world marketed energy consumption is XXX
You could imagine that even if the total amount of energy available is very large, limitations on manufacturing capacity or raw materials will limit us to harvesting a small fraction of it, as they have for the past several million years.
Indeed, many solar energy technologies do have some limitations. Thin-film panels invariably need indium, gallium, or both, although in small amounts; these metals are already more precious than silver, and they're mostly produced as a byproduct of zinc mining, so their supply is very inelastic — the prices will have to go up a lot more before people start opening indium and gallium mines. (Substantial amounts of indium could be recovered from discarded LCD panels if they can be efficiently separated from the garbage stream.) And germanium and other exotic semiconductors used in high-end multijunction solar cells are also rare.
But silicon photovoltaic cells, the current mainstream solar panel technology, do not suffer from these problems. They are principally made of silicon, with aluminum conductive traces, and then doped with trace amounts of group III and V elements such as phosphorus and arsenic — all among the most common elements in Spaceship Earth's crust. Given sufficient energy and equipment, you could make silicon photovoltaic panels out of almost any random rock, although perhaps at a somewhat higher cost than using the currently popular ores.
Entire panels contain some additional elements: aluminum frames, copper or aluminum wires, and tempered glass, which is made from calcium, silicon, sodium, and oxygen, using fairly inexpensive processes.
There's still the risk that, even if the raw materials intentionally included in the solar panels are cheap, the capital equipment needed to convert them into solar panels might be expensive. For example, parts of the manufacturing process involve melting silicon, which requires very high temperatures, and typically platinum-iridium crucibles. Even if silicon is abundant, platinum and iridium are not. I don't know enough to know if this risk will materialize, but if it does, there is a lower-tech alternative: concentrating solar power.
The first solar power plant was built in 1908 (XXX?) in Egypt, and used trough-shaped mirrors to focus sunlight on pipes, boiling water to drive a steam engine. This project ended when abundant oil was discovered in the area, providing a cheaper source of energy, but now that we've used up most of the oil, there are a number of similar projects.
Steam engines do not need any scarce materials, either in the finished engine or the factory to produce it, although they can be substantially more efficient, up to 40%, if made using modern alloys. And the mirrors for a concentrating solar power plant can be made from aluminum and glass. Current mirrors are made using a vacuum-deposition process which makes them almost as cheap as plain glass. It's also possible to use Fresnel lenses molded from cheap transparent plastic.
CSP doesn't gather sunlight on cloudy days, but it has the great advantage that it is practical to use it to produce electricity at night, by storing the gathered heat in tanks of molten nitrate salts.
An in-between option is what the famous Solyndra was pursuing: by concentrating sunlight with mirrors or lenses, you can use a tiny fraction of the photovoltaic cells that you'd need to gather the same power directly from the sun, which in today's world may allow you to use high-end multijunction cells with up to 40% efficiency, but in a hypothetical world where platinum shortages limited photovoltaic production, could substantially increase the installed power. Solyndra went bankrupt because, at the moment, simple photovoltaic cells are too cheap to compete with using complicated machinery that needs to make back R&D costs.
Utility-scale solar photovoltaic installed capacity is currently doubling every year in the US; recently worldwide capacity was doubling every 22 months, but in early 2013 I saw figures that said the doubling time had shortened to 8 months, presumably as a result of the much lower costs.
I don't have any numbers for non-utility scale solar (e.g. on rooftops) or other forms of solar energy (e.g. thin-film solar and concentrating solar power), but I think it's safe to say that, for now, utility-scale silicon photovoltaic has won the race and will remain the cheapest way to harvest solar energy for the foreseeable future. The other forms are much smaller.
Specifically, Intersolar reported in July that new solar energy installations (worldwide, I presume) would go from 30 GW of new installed capacity in 2013 to 100 GW in 2014. This represents a doubling time of 8 months.
My prediction that this exponential growth will continue for another decade and beyond is apparently a lunatic-fringe opinion; everybody else I can find making plans or predictions about solar-energy growth rates seems to be expecting something more like linear growth, to a double-digit percentage of electric power supply only by the mid-2020s.
Much has been said about the worldwide shortage of fresh water, with predictions of wars being fought this century over it. But salt water is abundant, and production of fresh water from salt water can be carried out straightforwardly with large energy inputs: either via distillation, the traditional way, or by reverse osmosis, which uses less energy. XXX Reverse osmosis plants do require significant investment in equipment, but the majority of the cost of their water is the cost of the energy they consume; and they are already cheap enough to produce water to irrigate farmland, water pure enough that it can reverse the problem of progressive salinization that has desertified many previously-fertile lands that have been irrigated by slightly salty water.
In short, fresh water is only scarce because energy is scarce. Abundant energy will eliminate water scarcity and the risk of water wars, except perhaps for landlocked countries.
Since Andrew Carnegie and his competitors exploited the Bessemer process to make steel the mainstream material in the late 19th century, our society has been girded with steel: steel railroad tracks collapsing the price of transport, steel rebar holding our buildings and bridges together, steel boats carrying our goods from port to port, steel automobiles ferrying us from steel-framed building to steel-framed building, where we can be shot by people with steel guns.
But the Hall-Héroult process, discovered in Carnegie's heyday, made aluminum (previously a precious metal) into a lightweight, inexpensive substitute, and it's displaced steel in some uses: airplanes, drink cans, bicycles, engine pistons, and so on. It's lighter than steel for the same strength, and it doesn't rust. Aluminum, however, is still more expensive than steel per pound and even for a given strength, so we continue using steel.
Most of the cost of the Hall-Héroult process, though, is the cost of the energy it consumes to electrolyze the molten aluminum ore, an ore which is abundant. Abundant energy will make aluminum abundant too, and it will displace steel in most applications; it will even displace plastic in some.
Many of today's buildings, especially here in Argentina, are expensive to inhabit because they were built in an age of energy abundance — from the 1940s to the 1970s — and so are built with little concern for efficiency of climate control, since operating air conditioners was cheap at the time. Many other buildings, like those in the world's slums, are unpleasant and dangerous to live in because they don't have adequate air conditioning or heating, and are not built with sufficient resources to enable passive climate control. (Vinay Gupta's Hexayurt design is a possible alternative that provides passive indoor climate control with much less resources than traditional designs such as meter-thick adobe walls.)
Abundant energy makes it possible to heat and air-condition easily.
Current electrical energy production is carried out in centralized power plants, either because it's hydroelectric and therefore not portable, because it's steam and therefore experiences great economies of scale, or because it's nuclear and therefore is dangerous to distribute widely. About a third of it is then lost between the power plant and the consumer, and sometimes inadequate infrastructure maintenance results in widespread power outages, which are deadly. This is okay if you have good governance, but in places with shitty governance (like any slum, war zone, or refugee camp), it sucks. It also sucks if you have shitty self-discipline and blow your paycheck on smack and booze instead of paying the electric bill.
Photovoltaic panels are portable, do not experience economies of scale in use, and are not particularly dangerous. They can substantially ameliorate the problems of inadequately maintained electrical transmission and distribution infrastructure, fragility in the face of attack, and poor governance.
Much of the cost of transportation, especially air transportation but even bus transportation, is the cost of the energy needed. This cost makes traveling an unachievable dream for much of the world's population.
Airplanes, intercity buses, long-distance trains, and ships universally use liquid fuel rather than batteries because of its much higher energy density. This has led to suggestions that solar energy cannot replace fossil fuels for transport. This is a mistake. Liquid fuels can be produced synthetically from CO₂ and water; it just takes energy, and it's an inefficient process, so it won't happen until electrical energy is much cheaper than fossil-fuel energy.
Global warming is caused by releasing fossil fuels into the atmosphere, either burned or unburned, and by releasing carbon dioxide from calcite in the production of cement. With sufficiently-cheap energy, cement production can be reoriented to magnesium cements derived from seawater with no carbon emissions, and we can build plants to actively remove carbon dioxide from air, either to sequester it back underground or to reduce it into combustible material, as suggested in the previous section.
Dependence on energy suppliers; concentration of power in the hands of those who control energy production.
Pollution.
Lack of menial labor.
We can expect that a greater and greater proportion of our land area will be consumed by solar panels, because building them on land is easier than building them at sea. At first, much of this will take place in deserts, but eventually anyplace that gets sunlight will be fair game.
Calories are a measure of energy; a food calorie is about 4200 joules. The price of a joule in the form of food is similar to its price in the form of electricity. But solar panels are reducing that price, and they turn a larger fraction of sunlight into usable energy than natural photosynthesis does. Typical silicon solar cells convert 16% of incident sunlight into electricity, while the most efficient plants convert 7% of incident sunlight into biomass energy XXX, which then must be burned in a heat engine to recover some 2.8% of the original energy. So in the limit, an acre of solar cells will produce some five times the usable energy of an acre of sugar cane.
So we can expect food crops, as well as nature reserves, to compete with photovoltaic cells for land once the tropical deserts are used up. However, even with yearly doubling times, that won't happen until the 2030s. Before that, it will probably make more sense to plant crops in the shadows of solar panels. (Current practice, which I hope stops, seems to be to concrete over the entire area to be populated with solar panels.)
Historically, we have carried out only fairly small-scale semiconductor fabrication, because it's an expensive process and because integrated circuits can be very useful while still being small. XXX These small-scale processes nevertheless produced staggering amounts of toxic waste, contaminating numerous sites around the world. To convert the world energy infrastructure to photovoltaic, we will produce semiconductor wafers by the hectare, with a correspondingly large possible increase in toxic waste.
While we won't have water wars, we probably will have wars for access to tropical areas with low cloudiness, such as the Sahara and the Atacama.
It hardly seems worth mentioning, but the Economist predicts that European utility companies may go bankrupt when solar energy lowers the price of energy below the cost of operation of their existing fossil-fuel and nuclear plants; as a result, their market capitalization has already dropped by half a trillion dollars. (!)
As I mentioned above, current solar panels can collect some five times the usable energy from sunlight that biomass and agriculture do.
More tropically. England's kind of fucked, as eloquently calculated by David MacKay in Sustainable Energy without the Hot Air, while North Africa is sitting on a gold mine — but geopolitically lacks the power to keep it from being exploited by other powers.
XXX
Yes, both because right now much of our energy produces CO₂ by burning fossil fuels, causing global warming, and because energy is expensive. Miners and drillers die to bring coal and uranium to your power plants and gasoline to your cars.
No. Marketed energy will become abundant in the mid-2020s. An efficiency investment that saves a dollar a year now will turn into saving an inflation-adjusted dime or penny a year then.
Some people will do it anyway. Here in Buenos Aires, I hear people making arguments about how conserving fresh water is important, while the Rio de la Plata a couple of kilometers away discharges 22000 cubic meters per second of fresh water into the salty Atlantic (which is to say, 600 000 liters per day per inhabitant of Buenos Aires), and every construction pit in the city needs a sump pump to constantly pump fresh groundwater out into the street. They seem to be inspired by the virtue of asceticism more than any actual knowledge about the issues.
But in an energy-abundance regime, it will make as much sense to try to conserve electricity by not using it as to try to conserve sunlight by sitting in the shade instead of out on the beach.