Solar
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"Resolution occurs not by attacking the negative but by fostering the positive."
- David Hawkins
In the 1920s refrigerators utilized ammonia, chloromethane, propane, and sulfur dioxide as refrigerants. Despite their effectiveness these compounds were toxic, flammable, or explosive to various degrees which could lead to serious injury or death in the event of a leak. To address this issue, the General Motors Research Corporation assembled a team led by the mechanical engineer and chemist Thomas Midgley to come up with a suitable replacement compound, and Midgley delivered (1). By incorporating flourine into a hydrocarbon, he and his team synthesized dichlorodifluoromethane, or Freon, one of the first of the organic compounds known as chlorofluorocarbons (CFCs). Since they were nontoxic, nonflammable, and chemically stable, CFCs were touted as "miracle" compounds (2). By the 1960s CFCs had widespread industrial applications, not only in refrigerators but also in other products such as aerosol spray cans, air conditioners, and asthma inhalers (2).
In 1974 it was suggested that CFCs were damaging the Earth's ozone layer, a very small yet vitally important layer of the atmosphere containing high concentrations of trioxygen (O3) that protects people, animals, and plants by filtering out most of the sun's harmful ultraviolet (UV) rays (3). Several countries acted on this to reduce their CFC emissions, but it was not a serious effort until the shocking 1985 discovery of the ozone hole, a marked ozone depletion that occurs every springtime over Antarctica, by a trio of British Antarctic Survey scientists (4) - actually, the ozone hole is not really a hole, it's more of a depression; the ozone gets thinner but it does not disappear. Still, the discovery of annual reductions in the ozone layer of up to 70% over Antarctica provided a wake-up call for many people (4). The ozone hole was a serious problem, and human CFC use was clearly responsible.
The prospect of increasing rates of skin cancer and cataracts from an increase in unchecked UV radiation prompted countries to act quickly. In 1987 the representatives of 43 nations signed the Montreal Protocol, an international treaty that aimed to gradually phase out virtually all CFCs and other substances responsible for ozone depletion (5). There was some initial industrial resistance, yet this subsided after it soon became apparent that finding CFC substitutes would be relatively easy (6). Moreover, it was projected that banning CFCs would result in a significant long-term profit from the avoidance of UV damage to fisheries, agriculture, and outdoor materials (6).
It worked - the idea became reality and culminated in an environmental success story. The depletion of the ozone layer is now slowing and it is expected to recover to 1980 levels by the middle of the 21st century (6,7,8). Likewise for the ozone hole over Antarctica (6,7). As long as we don't pump appreciable amounts of CFCs into the atmosphere anymore, the ozone problem is solved.
This excellent result happened through a combination of political will (which was high enough that governments decided to make CFCs a priority resulting in legislation) and economic inventive (which was high enough that industries were able to use viable alternatives to CFCs resulting in long-term profits). Both political will and economic incentive were crucial factors; just one of them probably would not have been sufficient to reach the tipping point for change.
Fundamentally, there's no reason this strategy can't be applied to fossil fuels. There's just not enough political will or economic incentive to do it yet.
Let's talk about fossil fuels.
Fossil Fuels
Fossil fuels are buried, combustible geological deposits formed from decayed plants and animals that have been converted to crude oil, natural gas, or coal by hundreds of millions of years of enormous heat and pressure (9). Currently, about 80% of the world's energy is derived from fossil fuels (10). There's a wide degree of variation - for example, Israel relies on them for 97% of its energy whereas Iceland only relies on them for only 11% of its energy, making up the remainder with geothermal and hydroelectric power (10). Yet overall, the world reliance on fossil fuels is about 80%.
There are two major problems with fossil fuels - they are not renewable and they are not clean.
(1) Fossil fuels are not renewable.
Two billion years worth of accumulated fossil fuel reserves gave a nice kick-start to the industrial revolution that arguably started in 1769 when James Watt patented the first truly efficient steam engine design (11). Since then, fossil fuel use has increased such that humans in 2015 consume 93 million barrels of oil per day; to make that number somewhat digestible, that's well over 1,000 barrels of oil per second (12). Moreover, as long as oil remains a primary energy source this number will continue to grow since global oil consumption is expected to increase by 30% by 2040 (13). Most of the demand for oil and energy in general is from the west - the typical US citizen consumes as much energy as two people from Europe, ten people from China, or twenty people from India (11,14). How long can this trajectory continue? Estimates vary, yet even if we go by some of the more optimistic estimates provided by the Swedish environmentalist Bjorn Lomborg in his book The Skeptical Environmentalist (6), it may be likely that humans run out of oil by 2040 and natural gas by 2060; there's a lot more coal, enough to make it past 2200, but the take-home message is that at some point during this century oil and natural gas will likely run out. The energy problem can be delayed by reducing consumption, but reducing consumption directly won't solve it - fossil fuels need to be replaced with something that is renewable.
(2) Fossil fuels are not clean.
It is now recognized that there are planetary limits to human activities and that some of them are being pushed as recently illustrated by the Swedish environmentalists Johan Rockstrom and Mattias Klum in their book Big World, Small Planet (15). This is of particular concern when it comes to the issue of climate change. Burning fossil fuels produces "greenhouse gases" that absorb infrared radiation thereby trapping and holding heat in the atmosphere; collectively, the most influential heat-trapping greenhouse gases are carbon dioxide (CO2) followed by methane (CH4) (6). Since James Watt's steam engine was patented in 1769, atmospheric greenhouse gas levels have been increasing and there is little doubt that human activities are responsible (6,11,15). Energy use produces 74% of all greenhouse gas emissions (11) and since fossil fuels provide 80% of the world's energy, fossil fuels are the overwhelming source of greenhouse gas emissions. The biggest greenhouse gas emitters are in the west - per capita, the top three major CO2 emitters currently are Australia, the US, and Canada (per capita, China's rate of emissions is actually lower than the world average) and the top three major CO2 emitters of all time are the US, the UK, and Germany (11). How long can this trajectory continue? Since the late 1800s, the best estimate shows that the Earth's surface temperature has risen by 0.4-0.8 degrees Celsius (6,16); a supercharged debate rages as to whether this temperature rise is largely due to natural fluctuations in the Earth's atmosphere as opposed to human-induced greenhouse gas emissions. Most people on both sides actually agree that greenhouse gas emissions do play a role in rising temperatures - the only question is how big a role, and therefore how urgently greenhouse gas emissions should be reduced or eliminated. Climate change models are not very good at answering this question, but it's generally predicted that a 2 degrees Celsius temperature rise could be catastrophic for at least some countries, and that greenhouse gas emissions must be reduced by at least 70% by 2050 if this is to be avoided (12,17). Regardless of the uncertainty, even if there is a small chance that greenhouse gas emissions could result in catastrophic climate change for a handful of countries, it's still too much of a risk considering that the whole situation is avoidable. Moreover, addressing greenhouse gas emissions with stop-gap measures such as carbon taxes might delay the problem for a while, but won't solve it - fossil fuels need to be replaced with something that is environmentally clean.
Tactics involving reduced energy consumption and greenhouse gas emissions will only result in limited success as long as fossil fuels continue to burn. The source of the problem must be uprooted - at some point, fossil fuels have to be replaced by energy sources that are renewable and clean.
Solar Energy
There are many renewable, clean energy sources already in use to varying degrees around the world including geothermal, hydroelectric, wave, tidal, wind, nuclear, and solar energy. Each of these options has its pros and cons, but if humans are to replace fossil fuels then the alternative must not only be renewable and clean, it must also be able to generate enough energy to power most of the world. Geothermal, hydroelectric, wave, and tidal energy can provide adequate energy for a few countries with the right geology or location, but on a global level they cannot deliver nearly enough energy to replace fossil fuels for most of the world (11). Wind energy could conceivably power much of the world, but onshore wind farms would require country-sized areas of land to make any difference whereas offshore wind farms would not only require country-sized areas of water, they would also have to be regularly replaced at enormous cost as a result of sea water damage (11). Nuclear energy can deliver enough power to replace fossil fuels, but accidents like Three Mile Island and Chernobyl have undermined confidence in this energy source; it also produces waste materials that remain radioactive for thousands of years (6). Out of all these options the only one that really meets all of our criteria is solar energy.
The sun continuously provides the Earth with a huge amount of renewable, clean energy possessing more than enough capability to replace fossil fuels in powering most of the world (14). Solar energy is the most renewable energy source in existence as long as the sun continues to shine. It is also one of the cleanest as it offsets vast amounts of CO2 and other greenhouse gases compared to fossil fuels (18). In terms of replacing fossil fuels, solar energy delivers far more power than any other renewable energy source - a whopping 6,000 times as much energy to the Earth as humans currently consume (19,20).
Solar energy can be used to make energy using natural photosynthesis, artificial photosynthesis, converting it into heat, or converting it into electricity. Taking advantage of natural photosynthesis involves either growing plants and burning them to make heat and electricity, or growing specific bacteria, algae, or plants and converting them into biofuels like bioethanol and biodiesel (21). While using artificial photosynthesis to make fuel and electricity is a field that is still in its infancy (14), it holds great promise - in 2011, the US chemist Daniel Nocera and his team developed the first-ever artificial leaf; it's the size of a poker card and it is approximately ten times more efficient than natural photosynthesis, and it can make hydrogen fuel (22,23). The process of solar heating involves using the sunshine for direct heating of buildings or water (11). Generating solar electricity involves converting sunlight into electricity; since solar electricity can currently supply the most power and therefore replace most of the fossil fuels in the near future (11), it will be our main focus here.
Sunlight may be converted into electricity either directly using photovoltaics, or indirectly using concentrated solar power.
(1) Photovoltaics.
Converting sunlight into usable energy with photovoltaics involves using solar cells, devices that convert sunlight into a supply of electrons via the physical and chemical phenomenon that is the photovoltaic effect (11,21). The US inventor Charles Fritts built the first working selenium-based solar cell in 1883, but it was only 1% efficient in its conversion of sunlight into electricity (24). Today's silicon-based solar cells are much more efficient - the best commercially available solar cells are now over 20% efficient, and research-based multijunction solar cells are over 40% efficient (25). The world's photovoltaic capacity is growing at an impressive rate of 50% or more per year (26).
(2) Concentrated solar power (CSP).
Converting sunlight into usable energy with CSP involves using mirrors or lenses to concentrate a large area of sunlight into a small beam, which is in turn used to heat up a working fluid, which in turn may be either stored as thermal energy or used to drive a heat engine or an electrical power generator (11,27). There are five different major CSP designs - parabolic troughs, enclosed troughs, linear Fresnel reflectors, solar towers, and dish Sterlings (11,27,28). In all of these designs, the mirrors or lenses of the CSP system "track" the sun so as to focus the sunlight into a beam in the most efficient way possible. One of the biggest advantages of CSP is that the energy can be stored, which means that it can provide electricity on demand without fluctuations in the energy supply; energy supply fluctuations are a problem inherent in most of the other renewable technologies, including photovoltaics. The world's capacity for CSP is growing rapidly, with parabolic troughs accounting for 90% of CSP plants (26). Interestingly, Spain has the highest CSP capacity of any country in the world (26).
For reasons that will now be explained, CSP is the best long-term option for replacing fossil fuels as the world's primary energy source.
Solar Energy - The Bigger Picture
Solar energy currently supplies about 1% of the world's energy consumption and yet it has the potential to provide 6,000 times as much energy as humans currently consume (19). How can we turn this potential into reality?
Logically, any strategy involving solar energy on a global scale would require the construction of massive CSP plants over enormous tracts of land. In his book Sustainable Energy - Without The Hot Air (11), the engineer and scientist David Mackay outlined how solar energy could be utilized on a global scale to provide much of the energy needs of humanity by building CSP plants in the world's sunny deserts. Sunny deserts are ideal as they provide maximal sunlight and the loss of habitat for native plants and animals is minimal (29). Using today's technology, a single CSP plant built in the Sahara desert covering an area of 1,000 km by 1,000 km could power the entire world (11). Realistically, the world would not be powered by one huge CSP plant but by numerous smaller ones (11). This strategy would provide all the energy ever needed for countries with sunny deserts, and the generated electricity could be sold and transported to countries with vast electricity demands and inadequate sunshine using high-voltage direct current (HVDC) transmission lines; typical losses due to electrical resistance, voltage, and AC/DC conversion in these lines amount to only 3% per 1,000 km (11,28). Since 90% of the Earth's population lives within 3,000 km of deserts, the overall energy losses would be very low (30).
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Take a look at Figure 1, which shows that - from the point of view of land sustainability and sunlight - every significantly populated continent in the world with the exception of Europe contains enough suitable sunny desert to provide the bulk of its energy needs with CSP plants (31). Australia and Africa are particularly blessed, but North America, South America, and Asia possess more than enough sunny deserts to power themselves (29). The only continent that would have to purchase and import energy generated by CSP from other countries would be Europe, and it would have to get it from the closest area to it which is the Sahara desert of Africa. As a matter of fact, this concept is already taking form through the DESERTEC initiative, a collaborative project between Europe and Africa that aims to generate power from northern Africa and transport much of it to southern Europe (30). The DESERTEC concept integrates all types of renewable energy, but it would rely primarily on CSP plants (28,30). DESERTEC has a long way to go yet, but it's a start.
The idea of supplying most or all of the world's energy needs with enormous CSP plants in sunny deserts is already technically feasible - the problem, of course, is that a political and economic paradigm shift will be required before this idea can be actualized on a global scale (28). Let's briefly look at some of the technical, political, and economic challenges that currently impede humanity from powering the world with solar energy.
(1) Technical challenges.
For an idea as massive as replacing the world's fossil fuels with solar energy derived from CSP plants in sunny deserts, monumental technical challenges are to be expected - some of the largest ones include cooling, heat storage, and the environmental impact to plants and animals. With regards to cooling, the CSP power plant condensers require a lot of cooling water, and in sunny deserts there's not a lot of water to spare (28). However, water cooling can be replaced with dry cooling which can reduce water consumption by 93%; this is associated with a modest 2-4% reduction in electricity production due to the parasitic power requirements of the additional dry cooling equipment (28). Regarding heat storage, a suitable medium capable of storing the thermal energy, which can get up to nearly 1,000 degrees Celsius, has been a problem until recently (28). However, the Crescent Dunes facility in Nevada recently bypassed this issue by being the first CSP plant in the world to use molten salt as a heat storage medium - the concentrated solar energy heats the salt, which flows to a storage tank where it can be used to produce steam and electricity; using this strategy, the molten salt can continue to generate power for up to ten hours, even during evening hours or when direct sunlight is not available (32). Since Crescent Dunes has only been operating since September 2015 this is a very recent accomplishment, but a significant one. With regards to the environmental impact to plants and animals, any large CSP plant obviously impacts on the ecological system by removing a large chunk of sustainable habitat for plants and animals, and one of the biggest problems is that birds get killed when they fly through the focal point where the energy from all the mirrors and lenses is concentrated (33). However, it must be emphasized that CSP plants can only be built in sunny deserts where the impact to plant and animal life is minimal compared to any large shopping mall, and as for the bird issue when it was found that birds were inadvertently flying into their concentrated area of solar energy resulting in hundreds of bird deaths, the engineers at the Crescent Dunes facility fixed the problem by spreading the energy out over a much larger area, resulting in zero bird deaths afterwards (33).
(2) Political challenges.
Perhaps the greatest political challenge to the idea of replacing the world's fossil fuels with solar energy derived from CSP plants in sunny deserts is that it would require a great deal of political negotiation between nations in order for it to work. The greatest example of this would be the degree to which Europe would be politically dependent upon North Africa for its major supply of energy (34). However, it should be pointed out that a heavy reliance between many nations on others for their fossil fuel needs already exists - for example, the European Union already imports a large percentage of its oil and natural gas from abroad, with some European countries virtually 100% reliant on other nations (particularly Russia) for their oil and natural gas (35). Regardless of whether it is fossil fuels or solar energy, political negotiation between countries is the only sustainable way for regions such as the European Union to ensure a reliable supply of energy. The alternative is to ensure a constant energy supply by exerting military force, but this option never has been and never will be truly sustainable. In this light, it is interesting to examine how much the world currently spends on "defence" compared to investments in renewable energy - in 2012, the world spent a total of 1.756 trillion (that's 1,756 billion) US dollars on defence compared to only 10 billion US dollars on research and investment into renewable energy (36,37). That's an incredible disparity - imagine what could happen if the countries of the world relied more on political negotiation and less on military force to achieve their energy needs; even a fraction of the money spent annually on the military would be enough to replace the world's dependence on fossil fuels with solar energy from CSP plants in sunny deserts.
(3) Economic challenges.
If the idea of replacing the world's fossil fuels with CSP plants in sunny deserts is to succeed, there has to be a significant return on the investment for whomever pays for it. Photovoltaics are already competitive and the cost is dropping so rapidly that by 2025 they may even be cheaper than fossil fuels in many parts of the world (6,28,38). By comparison, although CSP is still currently a relatively expensive investment (28), it has the long-term economic edge compared to fossil fuels and the other renewable energy sources - including photovoltaics - when we factor in energy storage, economies of scale, and the declining costs of building and running CSP plants. First, the ability of CSP plants to store energy in a thermal medium is a huge advantage that allows CSP plants to meet peak energy demands just as well as fossil fuels; the other renewables such as photovoltaics and wind energy cannot do this (11). The ability of CSP plants such as the Crescent Dunes facility to store thermal energy with molten salt negates much of the apparently cheaper costs of more fluctuant energy sources (39) and at present there are efforts underway to create even more efficient and cost-effective thermal energy storage mediums such as calcium-based sorbents (40). Second, although the initial cost of building a CSP plant is substantial, economies of scale apply - with CSP, as plant size increases, capital costs decrease (29). This is an enormous economic advantage over other energy sources given that gigantic CSP plants would have to be built in order to power most of the world. Third, although it is not declining as rapidly as photovoltaics, the cost of CSP is still declining every year and it has been estimated that the levelized cost of electricity for CSP will be competitive with electricity from fossil fuels in a number of market segments by as early as 2025 (28).
Powering most of the world with CSP plants in sunny deserts would not be without its problems there are significant technical, political, and economic barriers that would have to be overcome. However, these barriers are not insurmountable - it can be done!
Last Words
Humans can create an energy success story with fossil fuels - in fact, it's going to have to happen at some point given that fossil fuels will run out and that may be putting humanity in a tenuous position in relation to the environment. Harvesting solar energy with CSP plants in the sunny deserts of the world could provide the outline to this success story - it's renewable, it's clean, and it has the capacity to be global.
The major obstacles to this happening are not technical, they're political and economic. Right now, a substantial increase in the political will to fund research and development into renewable energy sources such as solar energy is needed so that CSP technology can become more efficient and cheaper. In turn, this will increase the economic incentives of CSP technology such that at some point, building CSP plants in sunny deserts will become financially competitive with other energy sources, particularly fossil fuels.
Since the west - especially Australia, the US, and Canada - consumes more energy per capita than anyone else in the world the political and economic responsibility, not to mention the moral imperative, lies with the western nations to start fixing the problem now. There are already a few CSP plants out there and more are planned for construction, but with even a fraction of their military spending the western nations could have this problem whipped before fossil fuels even run out, and before humanity finds out how serious the environmental impact of climate change might really be.
It took the discovery of the ozone hole over the Antarctic before the world really acted to solve the CFC problem - do we really need to wait for concrete evidence that we are out of energy, or that climate change is serious, before we act to replace fossil fuels?
Solace (inspired by Tim Phillips).
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