Renewable energy has come a long way in the last 60 years. A major influencer was the OPEC crisis which led the U.S. government to a drastic change in energy policy. In general, carbon dioxide emissions are responsible for ocean acidification and an increase in global temperatures. The environmental impact of these emissions motivates investigating carbon free or neutral energy sources. This is energy which releases no carbon dioxide in the former or the carbon dioxide released is harvested or stored in some way in the latter case. Currently, 11% of U.S. electricity comes from renewable sources: predominantly wind, solar, geothermal, and hydroelectric power. This represents a 4% increase from 2006. After the drastic decrease in silicon solar cell prices, integration of solar energy into electricity production has become attractive even without environmental motivation. Despite this progress in renewable energy’s competitiveness and economic attractiveness, complexity surrounding the incorporation of renewables into the current energy market exists. Economic competition, energy storage, and environmental considerations dominate the field of renewable energy.
Because fossil fuels have existed for hundreds of years, the heavy price of infrastructure has already been paid, which makes any new rival energy disadvantaged to market success. An underappreciated aspect of economic competition in the energy market is the dynamics of government funding for different energy sources. Various industries may receive different levels of financial support from the government. Understanding the nuances of a country’s budget is difficult, and this adds an entirely different level of complexity to the picture. In the U.S. in 2016, $1.9 billion was spent on fossil fuel research and development with tax credits and direct subsidization. This does not account for many other programs that support the infrastructure itself: pipelines, mining, and pay for disabled coal miners. Alternatively, renewable-tax-funded support totaled $5.7 billion in 2013. Comparing these numbers might seem like a good start; however, ignoring the unaccounted-for fossil fuel values, which have become integrated into most of our energy budget, these credits represent a market for renewable energy that is not independent of government aid.
With DOE funding having been cut by almost 40% in 2016, which supports most of the renewable energy research, breakthroughs in renewable energy technology will become more difficult. What’s more, the present field of renewable energy that stands on incentives in the form of tax credits and stipends can be viewed as dependent on political favor rather than economic clout. Based on the extreme cuts to the DOE from 2013 to 2016, U.S. support systems for renewable energy may quickly fall short. Fortunately, the solar market, which only composed ~1.2% of all U.S. energy in 2016, has become much more economically feasible, with energy costs approaching $0.37/W, which is comparable to the cost of coal generated electricity.
Most of the renewable energy research, breakthroughs in renewable energy technology will become more difficult. What’s more, the present field of renewable energy that stands on incentives in the form of tax credits and stipends can be viewed as dependent on political favor rather than economic clout. Based on the extreme cuts to the DOE from 2013 to 2016, U.S. support systems for renewable energy may quickly fall short. Fortunately, the solar market, which only composed ~1.2% of all U.S. energy in 2016, has become much more economically feasible, with energy costs approaching $0.37/W, which is comparable to the cost of coal generated electricity.
While the production of sustainably sourced electricity is great, nature does not always align its energy output with the energy usage of your local city. For example, a field of solar panels may produce excess energy one Sunday morning in the summer when very little energy is being consumed. Thus, energy storage is a major concern. On December 25th, 2017 in Germany, prices went negative for two days as a result of high energy output, as the grid had so much energy that transformers and other components could be severely damaged. Citizens were paid to use electricity as a result of this risk. Since then, Germany has developed several strategies for excess energy storage, also known as energy harvesting. Strategies to use excess energy have been developed since. One strategy pumps water uphill to later be used for subsequent hydroelectric power. Another strategy is to distribute “virtual power plants” in which homes are equipped with large batteries where excess energy can be stored and later used by neighboring homes. While battery storage mitigates the need for active fossil fuel burning when renewable energy sources cannot be used, they use either cobalt oxide or nickel manganese as cathode materials for the most energy dense batteries. These metals have been shown to be toxic and mechanisms for how they might become available to wildlife have been explored. Additionally, batteries do not store energy as efficiently as liquid fuels such as gasoline.
Alternative uses for excess energy should be explored, and prior to implementation, the environmental impact must be assessed. One long sought avenue has been the production of high energy, dense fuels which could be stored and later used. A popular molecule to exploit has been hydrogen due to abundance (water can be used as the supply) and easy reversibility (simply converts back to water after either burning or use in a fuel cell whereas most carbon-based molecules convert to carbon dioxide or have less predictable behavior). A major concern with hydrogen-based energy is the storage of flammable gas. Metal organic frameworks (MOFs), an extremely porous class of materials which can bind and release molecules, have become increasingly effective at gas storage. In a similar vein, frustrated lewis pairs have the capacity to similarly bind and release hydrogen using more abundant phosphorous and boron based compounds. Thus, safe and high-density hydrogen storage may very well become available.
The problem with energy production are waste streams; one of which is heat. The best solution for efficient energy production is likely synergistic. That is, the connection of the waste of one process to the necessary input of another. In a solar cell, waste heat is produced from light that heats the panel because it is not absorbed and converted to electricity. One might envision a regime where that excess heat is used for another beneficial purpose. In a recent review on desalination, a simple graphene layer over wood was reported to achieve desalination efficiently with 86% energy converted into distilling water. Solar cells overlaying a similar setup may serve as both a radiator for waste heat for photovoltaics and clean water. This type of cooperative energy production can turn the waste of one process into the driving force of another, and this is the mentality that should frame our energy frontiers.
The history of renewable energy in the U.S. began primarily with the motivation to obtain energy independence. Since then, global climate change has become an increasing concern. At the same time, concern over the health of the natural environment has grown as a result of both economic and altruistic motivations. To ensure the future of many industries which rely on the health of biomes, climate change must be mitigated and this can only begin with renewable energy. Solar energy has risen as an affordable alternative in recent years for electricity. To such an extent, that at peak operation, some solar fields are producing more than is needed. This opens the capacity for renewable energy to produce stored forms of energy such as hydrogen fuel or a charge in a battery. Safely and compactly storing hydrogen is becoming more possible with current research. Batteries as a storage option for excess energy must be strictly regulated to minimize heavy metal waste reaching the environment. Renewable energies have adopted a strong economic role in the market where a few decades ago a solar panel was considered fairly niche in terms of applications. This can be seen in the drastic drop in price and the production of massive solar fields. Similarly wind has grown, with China having nearly 200 gigawatts of wind energy installed. However, we should not place our faith solely in solar energy, wind, or hydroelectric, but attempt to optimize each while finding ways that one process might help another. By reframing the way our world produces and uses energy, we can obtain an energy market which effectively sustains itself with repairs being the only cost.
Peer edited by Jessica Griswold and Mikayla Armstrong.
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