Solar Power: Sci-Fi or Future?
As much as people depend on chemical fuels, such as oil, gas, and coal, for their day to day power needs, many would be surprised to learn that these are not real sources of power from a global perspective. Each are little more than chemical batteries, collecting power harvested from plants and organisms over billions of years, which they themselves harvested from more fundamental sources. Solar radiation is primary among these sources from which all of Earth’s energy is gathered, and without it life, and by extension fossil fuels, would be non-existent. Other sources of global power include geological temperature and pressure, radioactivity from various earth minerals, tidal motion from the Sun and Moon, and even power from the electric field of the Earth itself, which is generated via the motion of the molten iron core at the center of our planet. Even sources of energy such as wind, and heat, are direct products of solar radiation. The Earth intercepts 200 million billion watts of solar energy on average over the course of a year, over 80 thousand times the amount of energy generated by all the countries in the world combined (Wolfram). If we were to power the planet entirely by solar energy, at 100% efficiency in the Sahara desert, the space required would only amount to an area of 98 square miles (a square with an edge length of only 9.9 miles) (McKay, 2014). Of course, 100% efficiency is unrealistic. Inefficiencies and deficits in panel production, energy generation, and power transportation exist which limit solar power from becoming the great hit to the market that many hope one day it will be. However, none of these challenges are insurmountable, and the future is bright on solar power’s eventual success.
California just connected the largest solar power plant in the world, generating up to 550 megawatts, capable of powering over 160,000 homes, and reducing global CO2 emissions by 377,000 tones each year. It spans 9.5 square miles in California’s Carrizo Plain. However, its title is soon to be overturned by a larger project, rating in at 579 MW, in the same part of the world. Cheap land prices, high intensity sunlight, and low panel costs make each of these 500MW plants only $2.4 billion, and that cost is only going down (Knight, 2014). Take a moment to consider these numbers: 377 kilotonnes is a weight comparable to the mass of the entire empire state building, yet nearly 33 billion metric tons of CO2 are released into the atmosphere yearly. Still, calculating from global power consumption, which averages 2.3 terawatts yearly, the world would require 4,182 of these plants to entirely replace global power generation, spanning 39,729 square miles (a square with an edge length of 200 miles). Clearly, space is not an issue; the world has upwards of 51 million square miles of land available, much of which is covered in isolated, untapped deserts, which are well suited to solar power generation. However, solar panel supply is not yet sufficient to meet this demand, as direct duplicates of this current power plant, even without accounting for increased cost of production based on demand, would cost close to 10% of global GDP to completely eliminate conventional power generation (Wolfram). Efficiencies and material alternatives are likely to reduce this cost in a relatively short amount of time, as the cost of organic fuels are likely to soar given that we continue to quickly drain our supply at ever increasing rates.
Groundbreaking research is being done in high efficiency solar panels which could greatly reduce the amount of space required for full global power conversion. A power conversion efficiency of 44.7% is currently the record for high efficiency cells, achieved in September of 2013 under intense lighting conditions (Dimroth, 2014). The cell was created by using four high efficiency semiconductors which react to light of differing spectrums. Each of the cells are semi-transparent, and layered together in order to capture the entire spectrum, and convert it into electricity. This is twice as efficient as the average cost-effective solar panel on the market today, which usually runs around 20% efficiency. By creating high efficiency solar panels, not only can we cut down on the space requirements for high power solar arrays, we can also create gadgets and cars which can be efficiently recharged with the power of the sun, greatly reducing the demand on batteries to carry the entire load of each device. Hopefully such panels will become a cheap power solution in the near future.
Increasing cell efficiency is only one of two ways in which we can reduce the cost of solar panels. The most important metric concerning the solar market is cost per watt, which means that decreasing cost for existing technologies can be just as effective for market growth as more power efficient cells. One of the factors which most heavily contributes to the cost of solar panels today is the supply of its primary production material, silicon. Silicon exists primarily in China, where lax labor regulations, and poor working conditions, make mining and processing of silicon an ethically questionable industry (Mulvaney, 2014). The centralization of silicon production existing in China, as well as China’s incredible need for environmental rehabilitation, explains why China is currently the world leader in solar power (Duggan, 2014). Ironically, this makes an industry which is meant to help save the environment overall, a potential risk to China’s local environment. Luckily, the mining of silicon may soon be unnecessary for all electrical products, replaced with graphene, a 2D lattice material made purely of carbon, the fourth most abundant element in the universe. Graphene is the only non-semiconductor material with the conductive properties capable of producing gate arrays (which allow the creation of transistors necessary in computers, and the creation of solar cells). Graphene is lighter, stronger, and more conductive than silicon, allowing for much smaller transistor sizes, bordering on the molecular scale. Solar panels made primarily of graphene already exist at up to 15% efficiency (Quick, 2014). However, production has not yet been invented capable of make graphene into large sheets at market prices. Graphene production is being heavily researched, and soon it is very likely that graphene will beat out silicon almost entirely in the production of integrated circuits, capacitors, and eventually solar panels.
Another of the many challenges that face solar power generation is storage and transportation. Solar power can only be generated during the day and only under certain weather conditions, it also fluctuates in intensity wildly depending on a number of factors. As such, solar undergoes a number of steps in order to ensure that it is able to supply the power grid 24/7. Household solar systems vary, but generally solar power is directly fed into a battery under DC, which is then charged by the panels and connected to an inverter which takes DC power and converts it to AC. This AC power is then available to power the home, and the battery is available to keep appliances running all night long. Some systems are also connected to the power grid, and then have an option of feeding current backwards into the system, earning each household money which generates excess power.
For state-wide power systems, however, the process is more complex. Batteries have a high cost and size relative to capacity, as well as introducing storage inefficiency into the system. Occasionally, non-conventional batteries are used in high power systems, such as kinetic batteries which increase a spinning object’s rotational velocity to store energy, superconducting magnetic coils, air temperature and pressure, and high power capacitor banks, which are high efficiency, and allow for very quick charge and discharge. Often, instead of using batteries to store power overnight and during inclimate weather, they are simply used for short term storage, taking on rapid fluctuations in demand faster than power generation can accommodate the change. In the near future, electric vehicles parked in people’s garages may serve the power grid as a form of distributed long term power storage, again allowing an individual or family to run sell power back into the power grid when the system requires their temporary services.
Once power fluctuations are detected on the grid, conventional power generators undergoes a process called cycling in order to take on the demands of non-optimal conditions for renewable energy, or an extra load on the system. Conventional generators and power plants monitor the power deficit in the system, and “cycle up” or “cycle down” the power output of their plant in order to compensate. This demand can usually be predicted, as it is regularly correlated with the time of day (due to artificial lighting), and time of year (due to heating and air conditioning demands). Increased cycling does increase the inefficiency of the power system, and thus the cost of operation for conventional power plants, but the cost and inefficiencies are marginal (DOE/National Renewable Energy Laboratory, 2013).
One of the paradoxes of solar power is that electric lighting, a necessity at night, ideally would be powered by natural lighting, generated during the day by the Sun. Several systems have attempted to alleviate the pressures and the paradox of this demand, by ensuring that lighting systems are no longer strained to generate power for electric lights during the day while natural light is available. One such systems, known as hybrid solar lighting, uses fiber optic cables and a reflective dish on the roof of a building or house to reflect and redirect natural light into all lighting fixtures in a building, compensating for the variance in intensity throughout the day with a set of artificial lights in each fixture, which themselves are controlled by computer (Lapsa, “Hybrid Solar Lighting Illuminates Energy Savings for Government Facilities”). By feeding excess light into a solar panel array, and monitoring its output power as it feeds into a battery, the computer system can vary the artificial light intensity inverse to the output power of the solar panel, allowing the system to store up power for lighting needed at night during the day. In this way, solar panels can be used not only as a source for power generation, but also as a sensor in measuring light intensity for computer systems and smart grids. This system eliminates the inefficiencies of both solar panels and electric lighting during the day, greatly reducing power usage, and therefore reducing the space and cost required for a complete solar system.
An alternative to this type of design, one which affects buildings which have not yet been built rather than already established structures, might be a movement towards smart architecture, which, as past generations of architects utilized, facilitates natural lighting from windows and other architectural placements which allow sunlight to enter a room. Other structural renovations, including better insulation, and air-flow capabilities, allow for the elimination of the need for significant heating and cooling, greatly reducing power consumption. Such simple designs as these might be the future of high efficiency living, which is essential for our move away from wasteful and destructive energies.
It is important to our civilization, as well as to our environment, to highly restrict, if not eliminate altogether, the use of fossil fuels. Though we have no way of predicting when our technology for oil extraction might limit our ability to tap untapped resources buried deep in our planet, it is undeniable that one day oil will become far too expensive to be economical as an energy source on which to base our entire society. The same is not true of solar, which is only becoming more efficient, and less expensive by the year. At some point, these two technologies will pass each other on the economic price curve, and that day is not too distant. A solar plant already has one advantage over coal power plants in that coal costs money over time to mine and supply, whereas solar is completely free once built, apart from routine maintenance which plagues both systems. The Washington Post points out that in many countries, including Germany, Spain, Portugal, Australia, and the Southwest United States, residential solar systems are already more cost efficient than buying power off the grid, a status they call “grid-parity.” Eventually, we will reach a state of grid-parity within the industrial and state arenas, at which point it will suddenly become impractical to build non-renewable power plants over the renewable options available. The only potential to keep this from happening would be policy, which even now seeks to reduce coal and oil prices at the detriment to our switch to cleaner energies (Wadhwa, 2014).
Might we wish to make the switch to solar before it becomes economical, in order to prevent a runaway greenhouse effect? It seems both necessary and practical. From a purely economic perspective, one of the primary problems with America’s gas prices is that they don’t reflect the true cost of burning a gallon of gasoline: Health risks, natural disasters, animal extinction, and water pollution are all costs which, were they included in the price of purchasing a gallon of gasoline, might drive alternatives to already be cheaper. These types of hidden costs are called externalities, which are defined by Merriam-Webster Dictionary as “a secondary or unintended consequence <pollution and other externalities of manufacturing>” In the end, in order to incentivize the populace to switch to alternative fuels, prices will need to be cheaper than for conventional fuel usage, such as gasoline powered vehicles, and on-the-grid living. Unfortunately, tax incentives and policies are working toward make gasoline cheaper, and expand its production, whereas relatively minor contributions are made towards R&D for alternatives. Oil tycoons, currently the richest demographic in human history, will work as hard as they can to keep themselves from becoming obsolete and losing their market. Even as fuel efficiencies rise, the growth of our population, and the number of cars per household insures that global greenhouse emissions continue to rise at greater and greater rates. No one individual can fix the problem; we will require global policy changes in order to create any meaningful lasting effect on our planet, at least until our oil wells dry up, which by then the damage will have already been done.
In order to solve the problem of global greenhouse emissions within a shorter time window than projected it will be necessary not only to decrease the cost of alternatives, but, rather controversially, to increase the cost of conventional fuel sources. By this I do not mean to propose that we unethically inflate the cost of fossil fuels past their market price merely as an incentive, but rather to square the perceived cost of fossil fuels with their real cost, forcing people to truly feel the costs of burning fossil fuels with their wallets. The profits of such programs can then be funneled into alternative sources, and into environmental repair for those areas which have been destroyed by such misuse of our natural resources. Equally controversial is the necessity to create global policy on carbon emissions, as emissions from each country affect all others equally (Goddard Media Studios, “A Year In The Life Of Earth’s CO2"). We all share the atmosphere; we live on a planet where our actions locally can affect others globally, and as such it is our duty to hold one another accountable for those actions..
As we debate global policy on carbon emissions, and research how best to meet global power production requirements, new technologies, previously the realm of science fiction, are being planned for the very near future. Countries which do not traditionally have much land available to them, such as Japan, are considering the use of orbital solar platforms, capable of beaming energy to Earth from geosynchronous orbit, greatly increasing lighting on the panels even compared to the hottest deserts, and eliminating the cycles of night and day that plage land-based systems (Sasaki, 2014). Cheap, lightweight, and multi-spectrum solar panels are all essential to the future of this endeavor, all of which hinge on independent research in many of the areas previously discussed.
Solar is an infinitely expandable resource, with a nearly limitless supply here on earth, and near infinite availability from extraterrestrial sources. Land which previously had no other use such as deserts will quickly become our most valuable resource. Future alternatives for solar power generation featuring carbon based cells will be as cheap as graphite, supplies greatly exceeding even our wildest projections for demand. Lighter than any material known to man, graphene and other forms of molecular carbon have the potential to create affordable space based platforms for solar generation, beaming energy via laser to earth based platforms continuously. Not only is solar energy competitive, and clean, it is the one source of power which we can depend on lasting the entire span of our civilization, harnessing the very source that life has depended on for the past 4.5 billion years, the power of the Sun itself.
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Ryan Peach, written for Dr. Joe Austin, October 27, 2014