Why Wind & Solar Power Options Fall Short of Viability
In seeming defiance of the second law of thermodynamics, living organisms on Earth actually organize energy. More specifically, they concentrate energy and leave it in a concentrated form after they have died. Of course, this is not an abrogation of the second law or anything hyper-impossible like that because living things burn more energy throughout their lives than they organize, so there is net disorder.The universe is a very orderly bookkeeper of its disorder.
Nearly all life on Earth derives its energy from the Sun but exists in a diurnal world in which there is a super abundance of radiant solar energy during approximately half of each day, and an absence, even a net loss, of energy for the other half. Because every single organism must be alive for the entire day, each day of its journey through its living existence on Earth, it is a pre-requisite that organisms must husband some of the solar energy harvested during daylight hours to keep themselves going overnight – even if only at a reduced metabolic rate. Even plants don’t die overnight.
The solar energy harvested by living things is converted into chemical energy through that most spectacular miracle of organic chemistry known as photosynthesis. In photosynthesis, the sunlight is stored in a chemically reducing environment in the form of a carbohydrate. Such organisms which manufacture their own food using solar energy are known as autotrophs.
The fact that organisms must store energy for later use provides for another strategy of being alive, known as heterotrophism, in which some organisms live on the energy harvested by others by eating them. Heterotrophs in turn store a portion of the same energy through chemical oxidation of the carbohydrate made possible by respiration. And that energy, if not used by the heterotroph for its own metabolism, is harvested still later by a special type of heterotroph known as a carnivore (or a scavenger). Heterotrophs need to concentrate the energy more than the autotrophs; the heterotroph lifestyle requires more energy because individual heterotrophs must roam around the world searching for the energy stored in autotroph bodies. If the heterotrophs are to live at any size below that of preposterously gigantic (dinosaurs had a different strategy not dealt with here), the energy must be stored in a more concentrated form than in plant tissues – tissues which are called muscle tissue which is a concentrated form of energy – protein.
So, in summary, radiant energy (Sunlight) is converted to chemical stored energy (photosynthetic fabrication of chemically reduced carbohydrate), which is consumed and oxidized to release energy, AND to store some in the form of concentrated protein energy.
This is the balance of nature viewed from a strictly energy consumption perspective.
As it happens, and fortunately for us, not all organisms are eaten or scavenged when they die, so their organized energy (literally, their bodies) is not passed on to a subsequent heterotroph, whether the latter might be a wolf, a vulture, a hyena, a maggot, or a bacterium. In fact, the whole food chain and balance of nature thing is a bit of a sham from an energy perspective, because nature tends to be extremely profligate in distributing its largess in the form of available energy; there is a super-abundance.
The problem is that the excesses in energy availability are distributed so unevenly across time and space, that the energy is not always available in the form needed by a particular heterotroph, or it is simply not available at a time when a heterotroph might need it most. So a lot of energy goes unused – and a lot of heterotrophs perish from hunger.
But nature, in its infinite wisdom, is not done with energy even if the living world loses it. Much, if not most, of that concentrated energy which is not consumed by heterotrophs continues to be concentrated further and further after the plants which concentrated it the first time are dead. Vegetation not consumed is washed with rains into lakes and oceans, where the energy, in the form of the organic effluvia of vast land areas, is concentrated further into relatively small volumes; natural compost heaps, if you will. Those compost heaps are really accumulations of organic matter in deep water where they become isolated from the oxygenated surface world (reducing chemical conditions again – always necessary so some collection of wee beasties doesn’t eat it).
The zones become buried and are exposed to the heat of the Earth’s interior. Chemical reactions drive off oxygen bound in the structure of lipids in the matter, driving chemical conditions even more into the reducing. Deep burial also compresses the matter into smaller and smaller volumes, driving out water, salts and other impurities. The result is that, after plants have used sunlight to concentrate energy for storage and later use, but the use was never realized, the Earth takes that energy pool, moves it, concentrates it in one place – an energy deposit account, so to speak – isolates it chemically, buries it, heats it up and concentrates it even more both chemically and physically.
This is, of course, the generation history of fossil fuels, in their various manifestations: peat, lignite, bituminous coal, anthracite coal, petroleum oils and natural gas, the latter including natural gas liquids. It is this doubly concentrating processes of plants-animals and the Earth itself which make the modern world possible.
With just a little thought, it is easy to see that any viable energy source, in order to be useful at all, requires power generation from a concentrated form of energy. What is not as evident is that that concentration can come in two basic ways. The amount of energy available from any source, and consequently the amount of work which can be done with it, is a direct function of the magnitude of the concentration and it does not matter which form of concentration was in effect.
The two basic ways in which living organisms concentrate sunlight is that the sunlight is harvested/stored over long periods of time or across large geographic areas – concentration over time and concentration over space. In many instances, both types of concentration work together, with the result that the most energy packed fuels are those into which energy has been concentrated from a large geographic area over a long period of time. The more concentrated the energy is within a given volume of fuel, the more energy dense that fuel is (D = M/V). A given volume of fuel with high energy density can deliver more power than the same volume of a lower density fuel; for example: diesel fuel packs about 15% more energy into the same mass of fuel.
With the exception of nuclear, and geothermal, all sources of energy are ultimately solar-powered. That includes wind, water, solar (all three being direct sources of solar power), wood, bio-fuels and fossil fuels. Nuclear and Geothermal are not solar power sources, but are viable only because they have been concentrated by tectonic forces at work in the Earth over long periods of time and gathered from large geographic areas).
Human societies have naturally gravitated toward the more energy dense fuels over time, which means that we have progressively moved to more concentrated forms of energy storage. That is, all human societies with the exception of the sub-set of modern western societies who adhere to the anti-fossil fuel school of environmentalism. This group of retrogressive, anti-civilization zealots is fervently campaigning, with too much success, for humans to revert to the power sources with the lowest concentration of energy of all those available.
The one thing which distinguishes humans from all other species is energy use; in particular, the use of concentrated sources of energy. Other species can and do use tools – many of them do. Therefore tool use is not a distinguishing characteristic.
Civilization took its first halting steps from absolute uncivilized existence when humans began using sources of concentrated energy to improve their ability to survive. In particular, when humans first harnessed the power of fire by burning wood.
At the root, firewood, no less than coal or petroleum, is a concentrated form of solar energy. In the case of wood, the concentrating autotrophs, trees, concentrated excess sunlight over a lifespan of a few decades, and the sunlight was harvested within the areal space encompassed by the large sunlight-gathering surface area presented by the trees’ leaves within the footprint of the tree’s individual canopy; a large area compared with the size of an average human.
Accordingly, firewood contains the concentrated excess solar energy from a modest area of a few thousand square feet collected over a period of decades and stored in the carbon-based cellulose wood fibres. The amount of energy available from the wood can not be more than the excess energy harvested and so stored. As a result wood produces heat sufficient to warm small living spaces, to cook food, boil water and provide similar domestic energy needs. Wood does not have the higher concentrations of energy which would, in more recent time, provide the power needed to accomplish more demanding tasks of traction, motive and mechanical power.
The next big step in the harnessing of energy occurred probably very near in time to the taming of fire, and that was the domestication of animals. This one seems a little odd because the power is supplied by an organism which is still alive. This is the use of draft animals for traction, motive and mechanical power. Draft animals do, of course, concentrate energy, which was the point of that bit, above, about heterotrophs. Draft animals are herbivorous quadrupeds which harvest sunlight from large areas of land through their grazing, or from the large land areas farmed to provide the food for them.
The energy concentrated in the muscle power of draft animals provided much of the power of the world until the 18th Century and well into the 19th Century. From time immemorial through the American Revolution, people, news and goods traveled at the same rate of speed as they did in ancient Babylon – the speed of a horse cart; heat was provided by low energy density wood; and the construction of the edifices and machines of civilization was completed with manual labor augmented by draft animal power. Greater than human power by many times though draft animal power is, it is still limited to the amount of solar energy which can be concentrated by the plants which are consumed by an individual animal within any particular period of work, with an ultimate limitation set by how much equivalent land area that specific animal consumes within one growing season. That is the sum total of available energy.
Even the relatively small concentration of energy from plant to animal increased productivity enormously and the draft animals increased crop yields far more than they depleted crops via their own consumption. The real advantage of draft animal power was that the plants they consumed were NOT the target plants of human agriculture, so there was less competition for the human food supply to feed the draft animal. What was necessary was that about one third of the arable land had to be set aside each year to provide the grazing ground for the draft animal to concentrate its energy to produce the work needed to make anything beyond subsistence farming possible. A huge advance beyond former tilling and reaping methods but a full 33% of productive land was, at any time, OUT of production.
It is uncertain which was the next innovation in the struggle to add more power to civilization’s ability to do work: Wind or Water. These two forms of solar power are deceptively complex in that they seem to be relatively simple and straight-forward, but they are not. Of the two, wind has the least potential as a meaningful energy source on the scale of civilizations so it will be addressed first.
The change which resulted in modern civilization involved the generation and distribution of power, rather than the passive and local exploitation of available energy sources. This involves the collection of an energy source, conversion of the energy in that source to some other form of energy, and distribution to a wide network of end users. The significant point is that concentrated forms of energy are concentrated further at centralized locations where power can be generated (energy conversion) and from which it can be distributed. It is this centralization which brings the efficiency which makes abundant energy affordable and the basis of an industrial-commercial society. In the remainder of this essay, the various forms of concentrated energy are examined in terms of the degree of their respective energy densities.
For virtually all of human history wind power has been one of the principle energy sources. It has been used in two fundamental ways. First, and perhaps most ubiquitous, it has been used for motive power in the form of sailing vessels and second, as a source of mechanical power in the form of wind mills. The curious thing about wind power is that the presence of wind is only a secondary manifestation of the actual energy input into the Earth-Atmosphere system and is not a primary or direct effect of solar energy transfer; i.e., solar energy does not directly generate wind but, rather, produces wind as an effect of another phenomenon which IS caused directly by the input of solar energy.
Wind is caused by the collective movement of air molecules from areas dominated by high atmospheric pressure to areas dominated by low atmospheric pressure. The relatively large areas of high and low pressure result from the uneven heating of the Earth’s surface by incoming solar energy: areas of low pressure are caused where air near the land surface is heated and rises through the atmosphere; areas of high pressure are caused where cooler upper level air subsides to take the place of warmer rising air. the globally distributed patterns of such rising and falling air masses is the ultimate cause of our wind and weather and is the vehicle by which the uneven heating of the Earth’s surface by the Sun is distributed around the globe.
So, the wind itself is not the carrier of solar energy, but it is the mechanism whereby warm and cool air masses are distributed around the globe. Having made that fine distinction, there actually is a substantial amount of solar energy tied up as kinetic energy in the winds and that very real energy was the driving force for many uses in pre-industrial civilizations.
The reason wind was not as important a source of energy as water over the millennia is that it is not as concentrated, either in time or in space, as water. Consequently, the energy density of wind power, is not as great as that of water. Moreover, for even more obvious reasons, wind energy is also much more sporadic than water energy and, even when relied upon as the only available power source, was not reliable for either motive power (sailing vessels which could be stilled for days or weeks) or for mechanical energy (windmills which could not grind or turn the wheels of equipment).
In essence, the amount of wind energy available to a wind mill is limited by the area of the circle described by the rotating blades of the fan – the longer the length of the blades, the larger the cross sectional area exposed to passing wind, the more energy can be harvested. So, at any time, the area of concentration of each individual wind mill is limited by the size of the fan structure. In addition to that limitation set by the area of energy concentration, there is also the limitation resulting from the time of concentration of the energy available in wind. Wind is very transient and the energy within any air mass has not been concentrated over a long time of solar radiation insolence. In consequence, solar energy is both concentrated and dissipated rapidly in air masses, which is the causative factor as to why it was, and is, a notoriously unreliable source of energy. The concentration area of wind can be relatively large even though the time is short, which accounts for the great strength of wind in short bursts, such as tornadoes or thunderstorms.
In the modern manifestation, the ability to harvest the wind using a rotating fan to turn a mechanism is now used to turn an electricity generating turbine rather than a cog to power a mechanical device such as a mill stone or a fulling hammer attached to a rotating cam or a pump to lift water from a well or out of a mine shaft. Modern wind turbines (the turbine is actually the internal mechanism and not the fan blades themselves) are as limited as their predecessors in the ability to harvest solar energy from the wind. The utility in a modern wind farm lies only in the ability to site as many wind turbines in close proximity as possible. This increases the area of concentration from the size of a single fan structure to the collective size of multiple turbines.
Using statistics from the Energy Information Administration (US Federal Government) a single modern large-scale wind turbine can provide the domestic energy needs of approximately 330 residences, if operating at an above median capacity, which rarely is the case. Using a spacing factor of ten times blade area diameter for turbine spacing, each wind turbine in a farm requires approximately 50 acres of dedicated land (these are the BIG turbines). So, for a population of about 100,000 people, and assuming median generating capacity consistently, around 100 wind turbines would be needed to provide a portion of the energy needs (remember the intermittent and unreliable portions of the generating curve of wind, so they can not provide power all the time) by concentrating wind energy over a land area of 5,000 acres or about 8 square miles – the size of most small to medium townships.
In more tangible terms, that same population of 100,000 would drive, at a minimum, an average of 125,000 miles per day (one out of four people making a round trip of only five miles). Using an efficient modern electric American automobile the generating power capacity of FIVE of those wind turbines would be completely consumed, so that would reduce the number of people actually served in their homes by that wind farm by 5,000 or so.
So when a tiny fraction of the actual travel enjoyed by modern Americans is factored in to this simplified thought exercise, the number of residences which could be served decreases by about 5%. Travel consumes a lot of energy and requires a concentrated source of energy, which wind is NOT. That is intuitive.
Imagine it this way: the energy which would be required for the wind to push a car any distance from a standing stop in neutral gear on a flat road is precisely the amount of energy which must be harvested by a wind turbine, transmitted to a distribution network and tapped at an outlet by an electric car owner in order to move that same car a similar distance.
Add in lawn mowing, municipal infrastructure needs, commercial power demand and the number of homes served decreases further and further – or, conversely, the number of wind turbines (and the size of the land required to house them) increases further and further.
In terms of motive power, apart from the example above, wind was used for millennia for sailing. This is no different than harnessing wind power in stationary locations such as wind mills because the limiting factor for the total energy available is the area of concentration. The more sails which can be hoisted to catch the wind, the more energy is available for motive power. The limitation being the size of the sail area, and, consequently, the practical size of the sailing ship.
And, of course, that other little, nagging problem that the wind can simply abandon one. If you are on land and the lights go out it is damned inconvenient. But if you are at sea, you are stranded.
Finally, the efficiency of wind turbines within a wind farm is a function of pylon spacing and the size of the farm. except in situations in which the pylons can be arranged in a line, as in the photograph above, there are interference and energy loss effects for any farm in which the spacing is in a two-dimensional array.
There is a finite amount of energy available in wind and the conversion of that kinetic energy into electrical current via a turbine reduces that finite total. The result is that there is a continual energy loss in the downwind direction with less energy available to downwind turbines. More recent wind farm designs attempt to account for that effect, but there is no escaping the physical limitation that there is less energy available in downwind sections of any 2-D array than in the upwind end and that that differential will result in a loss of efficiency in downwind turbines. So, if wind use were to increase over time and land use requires more pylons per square mile, there will be a loss of efficiency of the total farm output. In other words, the already low energy density of wind would be decreased even more.
Water contains a higher concentration of solar energy than wind does and it provides a more reliable, more highly concentrated source of both mechanical power (in the past) and electricity generation in the present. Water was used for centuries to turn mechanisms to do a variety of tasks. Water contains a higher concentration of energy because there is a longer concentration time, a large concentration area, and the water itself is the carrier of solar energy (rather than being a kinetic manifestation of the storage of solar energy as temperature in air) so, unlike wind, there actually is a concentration area for the energy contained in water.
The energy in water is potential energy which is imparted to each molecule of water by the energy required to lift that molecule in the form of water vapor from sea level to the elevation of the clouds in which it is condensed and from which it ultimately rains. The energy is released during the fall of each drop back to sea level. The difference between the ascent of water vapor and the subsequent fall of rain is that the latter is not direct when rainfall is over continental areas. The available energy contained in each raindrop is released in small amounts with every millimeter of elevation loss as the drop flows over and through the landscape on its vertical way back to sea level.
The power tapped by generations of humans derives from the concentration of solar energy over time and space. It might seem as though the time of concentration of the energy in water is similar to that in wind, but in fact, it is much longer, typically on the order of years to decades. Only a portion of the water which falls as rain either runs off the land directly into streams and back to the oceans, or evaporates shortly after rainfall or is taken up by plant roots for growth and photosynthesis. The remaining water seeps into the ground and slowly flows through pore spaces until it discharges into a stream channel and then flows back to the ocean. From infiltration areas to discharges into perennial streams, groundwater concentrates the collective energy of water from decades’ worth of solar energy input. The energy contained in the water at any point along its journey back to the ocean is inversely proportional to the elevation above sea level at that point.
What people have done for centuries is to dam up a reach of a perennial stream to stop the flow – when the flow stops, the water ceases to lose energy. So a dammed mill pond is an energy storage vessel, and that energy is released at the mill race where it can turn a water wheel or a turbine. The mill pond is a concentrator of energy because it stops the flow and, consequently the loss of energy, over some distance, equivalent to a vertical drop in the steam bed. The storage in the reservoir is of the energy which is collectively stored in every particle of water concentrated from the entire area of the upstream stream drainage area, and concentrated over the time it takes for the volume of water in the reservoir to collect. That entire energy budget is released onto a water wheel at a specific point. The amount of energy lost as the water moves through the race and over a water wheel (turbine) is directly proportional to the difference in elevation from the water surface of the mill pond (reservoir) to the contact point with the water wheel at the lower stream elevation, and is equal to the amount of energy each particle of water would have lost over that same horizontal and vertical distance in the absence of the dam and reservoir. It is not quite that amount but it can not be more than that, because the particle of water is still above sea level and, consequently, still contains some portion of the original energy to expend on the remainder of the downstream journey.
In the modern synthesis, water from a large geographic area is impounded behind a dam in a reservoir many hundreds of feet deep and many square miles in area, and which collects water (and consequently concentrates energy) from a large sub-drainage area. The vast energy reserved in the water is concentrated into a narrow feedstock pipe and onto the blades of a turbine. This system works because the streams which are impounded are perennial, which means they receive groundwater discharge year-round.
That in turn, means that the water feeding the impoundment derives from years’, or decades’ worth of rainfall which is slowly accumulated as groundwater and released into the stream. The concentration period of the stored energy is years to decades and the concentration area is the entire watershed land area upstream of the dam – typically many hundreds of square miles. The amount of energy in each water molecule is small, but collectively , the concentrated energy is enormous. In fact, in terms of power to mass ratios, this is one of the most energy dense systems of power generation and is probably the most efficient.
Any discussion of solar-based energy sources would be incomplete without including the modern day poster child for Green-based transportation schemes: bio-fuels. These fuels have an energy density which is equivalent to regular liquid petroleum fossil fuels. The difference is that the bio mass is concentrated by humans using another form of energy, and the concentration time is eliminated because it is only one growing season. The loss in concentration time is compensated by a large concentration area – vast acreages of land are harvested to concentrate bio mass into a processor to essentially expedite the generation of petroleum process. So, even thought the actual fuel itself has a high energy density, its generation is energy intensive – more so than in other fossil fuels – so there is a net decrease in energy density compared with other fossil fuels (see below). The reasons for that conclusion will become clear after all the fossil fuels are discussed in the ensuing sections.
Following on the discussion of wood energy, the natural progression is to Peat. Peat is compressed woody matter in which the concentration of combustible matter is more densely packed than in wood. Peat is the first step in the step-wise formation of coal from woody plant detritus. Whereas wood is the plant tissue in its original, unaltered form, peat is a compressed woody tissue alteration product in which the energy concentration is higher than that of wood because the formation of peat involves compression of wood and the concentration of carbon to approximately 20% – 25%. Peat forms over time periods spanning hundreds to thousands of years, over which time multiple forests’ worth of wood accumulated where the trees fell. So the concentrating effect is one to two orders of magnitude greater than wood.
Because peat represents plant material deposited from multiple generations, energy has been concentrated both over time and spatially. Peat has been used effectively for domestic heating and cooking in a manner similar to wood for centuries. However, it suffers the same limitations as wood, but has the advantage that a smaller volume of peat produces the same energy value as a much greater volume of wood, for the simple reason that the energy content of wood has been concentrated in peat so the energy density, and hence the energy value on a per-weight basis, is much higher in peat.
Left un-harvested and buried geologically, peat can be further compressed into low-grade brown coal known as Lignite which has a carbon concentration in the 25% to 30% range, slightly higher than peat. Lignite, however, is essentially the first grade of coal and comprises a large percentage of actual coal use in many countries.
Energy concentration in Lignite is quite high because it is a compact energy source which contains the carbon residues of plants which accumulated over periods of time long enough that, for the first time in this essay, can be referred to as ‘geologically long’ periods. Again, and similar to peat, because the time periods are so long, the lignite at any location consists of the accumulation of multiple forests’ worth of organic matter. Accordingly, the long time concentration is attended by a large spatial concentration by default because it is the aggregated area of the forest canopy at any location many times over.
The large spatial and time concentration of energy in lignite makes it the first of the fossil fuel category of concentrated energy with a high enough energy density that it is adequate to power industrial societies – nearly half of all Germany’s electricity is provided by lignite-fired generating stations.
Following the progression from wood to peat to lignite comes the various ranks of real coal: sub-bituminous, bituminous and anthracite. In these, the formation mechanism is basically the same as peat and lignite, but the percent carbon in each increases up to anthracite in which the carbon comprises over 90%. The result is that in each progressive stage the energy density increases. This is because the energy concentration increases in each.
The real issue is that, in the cases of the upper ranks of coal the energy concentration times are VAST – literally millions of years, so the concentration areas, following the same rationale as for peat and lignite, are similarly vast. Coal contains energy in such a concentrated form that even small hand-sized lumps pack the energy equivalent of decades’ worth of stored excess sunlight gathered over fairly large areas. It is this kind of energy concentration which is needed to generate gigawatts of electric power on a daily basis. The concentration of energy is so great that, even after two hundred years of coal use, at ever-increasing rates, and many decades of use at the gigawatt generating capacities we see now, there is still enough coal to last many scores of years at the current consumption rates. Because the energy density, the power to mass ratio, is so high in coal and a lot of energy is packed into small volumes, it is also transportable, so it is feasible to move the volumes needed to run large industrial societies to the places where the power is needed.
Until the time of coal, motive power was dependent on animals or the wind and mechanical power was based almost wholly on water and wind energy. Wood and peat were used to small degrees, but the power to mass ratios are too low to make them portable, severely limiting things like wood-fired locomotives to relatively short runs between re-fueling stations. Coal, however, was portable enough to carry in locomotives and powerful enough to move the trains, large trains, long distances – the distance limitation was the water to put into the boilers more so than the coal. Coal was also portable enough to load train cars, MANY train cars, and deliver it to factories and electric generating stations all over the country.
But coal had more than that. Coal could be separated into component parts to provide for lighting and the manufacture of a plethora of chemicals and pharmaceuticals which made the modern world, beginning in the latter 18th Century, possible. And all of those myriad other products could be made at will because coal contained enough concentrated energy to manufacture, heat, generate and move the goods and services of the first truly industrial societies on large scales. And all that was possible using resources gathered from very small source areas; i.e., much as modern environmentalists raise a hue and cry that coal mining wrecked the landscapes in some areas, with some justification, the fact remains that industrial societies blossomed in the western world using the coal mined from a very small aggregate footprint.
Whereas eight square miles of land are needed for wind power to provide just the domestic electric use for a relatively small population of 100,000, the ENTIRE power needs of that same population and all of its commercial, industrial and municipal infrastructure needs can be provided by the coal from a single coal mine – with excess power to spare.
The discussion has been moving up the scale of energy density within the spectrum of solar based fuels, so it is now time to move up to the heavy hitters – petroleum. The term literally means “Rock Oil”, but it includes natural gas as well as liquid petroleum.
It is not an exaggeration at all to state that modern civilization is a civilization of petroleum. That is bold and it will likely anger some people who like to think it would be a simple thing to shut off the pumps and close the pipelines and live a ‘renewables’ lifestyle. This is not an essay about the many ways in which we rely on petroleum – the bold statement at the head of this paragraph is meant only to emphasize that civilization has naturally gravitated to the fuels with the highest energy densities which are hydroelectric, coal and petroleum. Petroleum has the advantage over the other two sources of concentrated energy in two principle ways; 1). it is portable so it is the best source for motive power because it can be transported compactly within the transportation vehicle; 2). Almost anything can be synthesized from this versatile substance which has provided for the democratization of affordable goods and services.
Petroleum is the fossil fuel power house because its energy was concentrated from expansive geographic areas over colossal spans of geologic time. Unlike peat, lignite and coal which form where the plants and trees fell, the organic matter which is the source of petroleum is transported from its areas of origin to the location which will become the source rock. The source of much petroleum was the perennial leaf litter which is washed by rains into ocean basins, breaking down into small fragments of organic matter along the way. It is no coincidence that much of the world’s petroleum reserves derived from the geologic time periods which also saw the evolution of deciduous plants. That type of continental organic detritus combines with the countless microscopic, marine organisms, the corpses of which create an unending rain of organic matter on sea floors.
The source areas of the organic matter which will someday become petroleum are geographically immense; the excess sunlight is integrated from continent-scale areas. The time over which accumulation occurred is reckoned in millions of years. A lot of unused solar energy gathers on the sea floors in the form of organic muck – even today.
With continued sedimentation and burial, the organic matter is heated and changed: first into kerogen, then into the varieties of oil and, at the highest temperatures, natural gas. At each stage, the volume occupied by the organic matter decreases and the energy content on a per volume basis increases – it becomes more energy dense. Because petroleum is a liquid, it typically moves and accumulates into zones from which it can be readily retrieved.
On a scale greater by degrees of magnitude than any other solar energy fuel, petroleum is the concentrated energy from the excess sunlight which fell on millions of square miles of land integrated over millions of years, accumulated and compacted into relatively small zones from which it can be readily retrieved. The result of that spatial and temporal concentration is a power to volume ratio which is astounding. Petroleum has the added advantage that it can be put in containers to power vehicles and can be delivered directly to homes and businesses, so it has become the fuel of choice for transportation and heating.
By simply considering the degree of concentration of energy, it becomes patently obvious why our ancestors abandoned wind power for the generation of mechanical energy and motive power. Apart from the fact that it is as unreliable as… well, as the wind, it is not a viable power source because of its low energy density. This can be gleaned by considering the concept of energy concentration in the reverse: Energy distribution density. Put simply, how many users can be served by any single unit of generation? Considering that wind is capable of providing electricity for normal domestic use with an unacceptably high land consumption ratio and is not a concentrated enough source to provide the full range of community power demands, its energy distribution density is very low.
Similar to wind, the distribution density of solar is very low and it has an unacceptable land use footprint. And solar is not a concentrated enough, or a reliable enough source to provide power for all uses – only domestic or minor commercial electricity needs. Moreover, like wind, solar power is extremely variable and, consequently, unreliable. The reason solar is not viewed as a leading contender in the energy market is….. the absence of energy density. There is no energy concentration in direct solar energy; the area covered by solar panels is the area over which direct sunlight is gathered. Because the panels can not capture all sunlight, the energy actually converted to electricity via the photovoltaic effect represents only a portion of the available energy, so, rather than a concentration of energy, solar represents a dilution of the incoming radiant energy. Moreover, there is no concentration over time – solar energy is used within the time period over which it is collected, with the exception of very limited battery-based storage.
Centralized solar farms are being built to serve multiple residences – it takes about 32 acres of solar panels to run the domestic electricity of 1,000 homes. Allowing for half-acre residential lots and the additional area for sidewalks and streets, there is a land use loss of approximately 3%; that much land is needed to power domestic energy needs. And additional power is still needed to run cars, lawnmowers, street lights, water supplies and sewage treatment, etc. So, the energy density is very low because there is no concentration in either time or space and the energy distribution density is low because there is a large land use loss factor.
Wood and peat are adequate sources of heat for individual dwelling structures, but the energy concentrations are not high enough to make them feasible as regional, multi-use power sources.
The only solar-powered fuels with any real capability for power production on any meaningful scale are hydro-electric, coal and petroleum, including natural gas. That might seem like the obvious to you and that this lengthy thought exercise has resulted in nothing new under the Sun. And you would be correct to reach that conclusion.
However, the real point is to look at energy from a different perspective so we understand WHY the energy use practices of civilization have evolved as they have and so we can actually answer the multi-part question:
Can we abandon fossil fuels and mothball our hydro-electric projects in favor of wind and solar, and will wind and solar ever be meaningful components of an integrated energy strategy?
The answer, for the foreseeable future is “No!” Ultimately, in a long time, we will have to decrease our reliance on fossil fuels, but wind and solar will never be a replacement. Unless we either develop a tolerance to losing large areas of landscape and useable land to power generation; or decrease our population and return to a life style on a par with the 18th Century when the entire energy spectrum consisted of wind, wood, animals, small water mills and that most detestable source of energy concentration – human slavery.
At best, wind and solar will fill the role they do now – a supplement to more reliable sources of base load production, which will have to include hydro-electric, geothermal and nuclear as the only sources, apart from coal and petroleum, with energy concentrations high enough to provide for all energy needs. A position that the concentrated solar energy is not a long-term solution because the reserves are finite whereas so-called renewables are virtually infinite is a specious argument. The renewable energy sources touted (wind and solar) are sustainable for only a fraction of today’s population existing with a much-reduced standard of living; i.e., there is a trade-off in which society abandons actual human lives never lived and the living standards of those who do, in return for long term energy availability for a far smaller population.
To sum it up, it is a fool’s errand to set one’s self up to be a prognosticator of doom and gloom. Such persons invariably end up being false prophets, just like everyone who asseverates that some thing will or will not definitely happen. There is no limit to the greatest resource of all: human intelligence and creativity. What we can count on is that at some time, perhaps just beyond the foreseeable future, a new idea or development will change the entire picture painted here. The only thing which is certain is that the first and second laws of thermodynamics must be satisfied. After all is said and done, it takes just as much energy to shift a load from Point A to Point B whether the power source is electricity, diesel, gasoline, natural gas, or wind. So whatever idea or innovation comes about to utilize energy in more efficient ways, the ultimate source of the power itself must have a high enough density as a result of the concentration of energy to provide the absolute power needed to run an industrial-commercial civilization.
As Francis Bacon said: “Nature, to be commanded, must be obeyed.”
Our greatest resource is our ability to think and adapt.
So, CONCENTRATE, PLEASE!