Carbon can take many forms depending on how the individual atoms are arranged, one of the most familiar being graphite (pencil lead). Graphite is made up of stacked layers of graphene. In graphene, the individual carbon atoms are arranged in connected rings of six atoms each, forming a structure that looks like honeycomb or chicken wire when viewed under a microscope. Graphite is a fairly brittle material, but when isolated, the individual sheets of graphene are incredibly strong — as much as 200 times stronger than steel.
Graphene can be isolated from naturally occurring materials but can also be synthesized and was isolated for the first time in 2004. Strength is not the material's only benefit; it is extremely flexible and has excellent thermal and electrical conductivity. Because of these properties, a wide variety of industries, including computing and energy storage, medicine, aerospace and desalination, could see benefits from graphene or graphene derivatives. However, many of the remarkable qualities of graphene are dependent on the quality of the substance. Defective or impure graphene may not be as strong or as conductive as a purer counterpart. In order to reach its full potential, the pure synthesis of graphene still needs to be achieved on a commercial scale, since so far significant defects often occur during synthesis or isolation.
Graphene still must overcome significant manufacturing hurdles to become a cost-effective and viable solution to advance in any number of sectors. There are multiple methods in various stages of development to either isolate or synthesize graphene, but they are not all created equal. Lower-grade graphene, which can be used in composites such as protective coatings and paints, can be chemically and mechanically isolated from bulk material like graphite on a large scale, but this method does not necessarily produce graphene of a quality high enough to be used in all potential applications. Producing high-quality graphene is often difficult to scale up and frequently requires high temperatures and harsh conditions that demand large amounts of energy, which can reduce the cost effectiveness of the manufacturing process. But the industry as a whole is getting closer to a solution.
Large corporations and small startups alike are developing methods to make the manufacturing process more cost-effective and industrially scalable. In 2013, a collaboration between two Chinese companies announced plans to start the first mass-produced graphene film intended for use on 15-inch touch screens to increase the durability, transparency and flexibility of the screens. More recently, academic labs at the University of Illinois in collaboration with South Korean researchers developed a production technique that uses a supersonic spray system to disperse a low-grade graphene solution onto a surface, creating a higher-grade product. And in April, a team of researchers from Ireland and the United Kingdom published a solution-based isolation method that showed great potential for scalability. But each application of graphene or graphene derivatives cannot necessarily be directly transferred between different products, and a range of manufacturing processes will likely still need further development.
Graphene is part of a larger family of nanomaterials, often referred to as 2-D materials because they all are sheets that are only one atom thick. Graphene, while it does have amazing conductive properties, can be difficult to control for some computing purposes, where it could be used to improve the performance of computer chips and is sometimes suggested as a replacement for silicon. Researchers at Lawrence Berkeley National Laboratory recently developed the first field-effect transistor (an essential electronic component that enables current to be sent through devices) made entirely of 2-D materials, including graphene. In the future, the field is poised to expand further, using other elements such as phosphorous, silicon and germanium, to create the 2-D nanomaterials phosphorene, silicone and germanene. Those could theoretically be used instead of or in combination with graphene when it comes to computing applications as well as other sectors. However, these materials come with their own limitations; they are often difficult to synthesize, let alone manufacture on a large scale, and some can be unstable when exposed to the air.
Graphene remains the most studied and advanced of the 2-D nanomaterials and as manufacturing methods continue to improve, the likelihood that graphene could be a material of geopolitical importance increases. While graphene has the potential to affect a number of different fields, two specific examples of graphene's potential impact are in desalination and energy storage.
There are numerous areas around the globe that currently face significant stress on water resources, and the level of stress is expected to increase in the near future. Many regions already facing these problems, including India and the Middle East, will experience increasing populations and rising urbanization over the next 20 years. Other areas, such as China, will experience increased pressures on domestic water resources from a growing middle class and economic policies geared to promote increasing domestic consumption. Desalination will be an important contributor to closing the gap between water supply and demand, especially in coastal urban centers.
Some countries, mostly in the Middle East, already use desalination. However, the energy and cost barriers are still too high for more widespread use. Desalination by filtration or osmosis requires high pressures to force water through the membranes currently in commercial use, which requires large amounts of energy. Graphene has the potential to solve this problem. Filters using graphene or graphene derivatives are several orders of magnitude more permeable than traditional materials, meaning the water can pass through more easily, allowing for reductions in pressure. Some estimates predict that graphene filtration could use 99 percent less energy than current reverse osmosis plants and could eventually reduce overall costs by as much as 20 percent. While we may see initial implementation over the next couple of years as proposed pilot projects from companies such as Lockheed Martin are set to start, the widespread use of graphene-based desalination is likely further in the future, at least five to 10 years away (and possibly longer for new-build plants). As water stress continues to increase in the large population centers over the next couple of decades, however, technological improvements in new water resources will become increasingly important.
Some regions will be experiencing rising population and urbanization rates, but much of the developed world, including Japan and much of Northern Europe, will be faced with the challenge of an aging population. Improvements in energy storage technology will be key in adapting to both of these demographic trends in the coming decades. Large-scale energy storage will be needed if renewable energy sources, especially wind and solar, are to make up a greater percentage of electricity production. We expect electricity demands to increase as both populations increase and the growing middle class shifts consumption patterns to become more energy-intensive. For countries that have to import energy, renewables such as solar and wind could be good alternatives, but those require improved storage capabilities. Energy storage can also stabilize electricity distribution grids and defer the need to update infrastructure — something that would be beneficial to countries that are struggling to meet growing electricity demands.
Improvements in small-scale energy storage will become increasingly important, not just for hand-held electronics but also for mobile robotics, which we expect will be significant for sustaining economic output as populations age over the next several decades. As populations decline, robotics can be used to replace parts of the workforce, enabling a country to maintain economic output even as the workforce declines. Improvements in battery technology will be necessary in order to see greater incorporation of robotics.
While there are a number of alternative energy storage technologies, including compressed air energy storage and pumped water storage for electrical grid storage, that are already in use or have the potential to advance over the next couple of decades, graphene's potential impact is in advancing electrochemical storage (e.g., batteries and supercapacitors). The properties of graphene can allow for greater reactivity and increased energy and power densities. Lithium ion batteries already widely utilized have greater energy densities than many of their counterparts, but there are still limitations with existing technology. Using graphene as an electrode is one possible method for improving lithium ion batteries beyond their current performance ceiling. Incorporating graphene has also been shown in the laboratory to double both the power and energy density of commercially available supercapacitors.
Batteries, with advancements, have the potential to affect the full spectrum of future energy storage needs, from miniaturization and wearable electronics to robotics, electric vehicles and electric distribution grid storage. There are numerous avenues of research that are being explored; graphene is one of many. In general, technological advancements in the field as a whole will become increasingly important as demographic pressures increase in the coming decades.
Graphene, though often touted as such, may not necessarily be a miracle material, but it could still play an important role in the coming years. While an exact timeline will depend on the technology, we will likely see incorporation first in consumer electronics, followed by possible use in other sectors, including computing, desalination and energy storage more gradually over the next 20 years or more. New applications and derivatives are still being discovered. We will continue to watch for advancements in industrially scalable manufacturing and decreasing costs — the most important hurdles to overcome. There will continue to be more support for technologies that can mitigate the ramifications of increasing resource scarcity and demographic pressures. As a result, we will likely see continued and even growing investment in the coming years in both graphene-based advancements and competing technologies.