Energy is integral to every aspect of life, including professional audio. Energy also has a swirling tornado of political, economic, and environmental considerations that kick up quite a cloud of confusion when trying to make sense of how to think about this important topic. For this month’s column, I have the ambitious goal of conveying an engineer’s perspective on the myriad details surrounding the production and use of energy. My hope is that, by touching broadly on a number of different disciplines, FRONT of HOUSE readers will gain a clearer perspective about the big picture surrounding the present and future of energy.
The Challenges
The human race faces a number of challenges in the near future when considering how we generate electricity, heat our homes, conduct industry, travel and otherwise use energy. The most basic challenge is that humans consume a lot of energy, and energy use worldwide has more than tripled since 1960. Even as the developed world starts using less energy through conservation, the number of people leaving poverty in the developing world and increasing their energy consumption continues to grow.
According to the U.S. Energy Information Administration, developing countries will consume 65 percent of the world’s energy in 2040. The scale of energy consumption also means that “clean” energy projects that seem large by today’s standards barely move the needle at changing the energy production methods on a global scale.
A second challenge is that a large fraction of the energy we use at present was already here on the earth in the form of resources locked within the planet. As the resources already within the planet are consumed, there exists an eventual future when all new energy storage materials will need to be created outright. In this context oil, natural gas, coal, gasoline, hydrogen, steam, lithium, etc. will function merely as different “batteries” that will need to “filled.”
With most of our existing energy sources, it’s easy to take for granted that they are already here, waiting to be unearthed. However, when oil, natural gas, hydrogen, etc. must be made from scratch, the economics of energy are far less palatable. While this future is certainly far from imminent, eventually it will have major implications.
A third challenge is energy density. This refers to the idea that certain volume or mass of energy source is capable of storing a given amount of energy, and that all energy sources are not created equal. Hydrocarbon fuels, in particular, store a huge amount of energy in a small area. It is this great energy density that enables technologies like airplanes, rockets or long-haul tractor trailers. Without high energy density sources, a number of modern conveniences, especially in transportation, would disappear.
The Environment
Looking broader, the production of energy has environmental implications. Much of the world’s energy is created through chemical reactions, and those reactions take chemical inputs and produce chemical outputs. The most-discussed chemical output is commonly referred to as “carbon footprint,” and refers to carbon dioxide. Coal, oil, and natural gas are different forms of materials primarily composed of carbon and hydrogen. During the course of combustion, carbon reacts with oxygen to form compounds like carbon monoxide (CO) and carbon dioxide (CO2). While the carbon monoxide is re-burned, carbon dioxide gets released to the atmosphere. Much is discussed about the problems of carbon dioxide, especially in the context of “climate change.” But little is explained about the actual mechanics involved.
The earth receives heat primarily from the sun, and also a small amount from the decay of radioactive elements within the earth’s crust. The atmosphere traps a substantial amount of this heat near the surface of the earth, with a lot of that stored by water vapor in the air. Water has amazingly efficient heat storage capabilities. It is the best or next best material in all the relevant thermodynamic categories. In the form of vapor, water is the preeminent greenhouse gas that keeps our planet habitable with moderated temperatures.
Water also has the unique property that it does not absorb much light in the visible band. Instead, sunlight hits the earth and is absorbed (comparatively deeply) in the oceans, or it hits the earth’s surface. Light that hits the earth’s surface gets re-radiated as infrared light. Water vapor in the air can then absorb this infrared radiation. This is the same effect that causes your car to be hot in the summer. Glass is transparent to visible light, but absorbs the infrared light that is re-emitted from the cars’ interior. Carbon dioxide, however, is good at absorbing visible light. The concern is that this additional absorbed energy will be transferred to water vapor, raising the temperature and trapping more water vapor. If water vapor is in the driver’s seat, then carbon dioxide is the brick on the gas pedal. The question now is how hard is that brick pushing down on the pedal.
Another less-discussed problem with additional carbon dioxide in the atmosphere is the effect on the pH of the oceans. With additional carbon dioxide in the atmosphere, the increased concentration in the air drives more CO2 to be dissolved in the ocean. Some of this carbon dioxide then forms carbonic acid which decreases the pH of the ocean water, making it more acidic. Decreasing the pH of the oceans could have substantial disruptive effects on the organisms living in the ocean that provide the majority of our oxygen.
An honest engineering appraisal of both the climate change and ocean pH problems is that we do not yet have a grasp on how quickly or drastically each effect will be manifested. Both issues have potential to cause large problems for humans and the planet, so we would do well to tread carefully. As those concerns play out, there is the ongoing pollution cost from fossil fuels, with coal being the most egregious offender. There is the obvious soot and smog, but also the concentration of radioactive species in the fly ash waste generated during coal’s combustion. Especially in the developing world, where coal plants release fly ash into the atmosphere, rather than scrubbing it from the exhaust, this is a major source of atmospheric radiation.
The Alternatives
Alternative energy sources are somewhat of a misnomer. Ultimately all the energy we consume is the result of gravity and nuclear power. Whether solar fusion energy trapped in the carbon of fossil fuels, or causing wind, or converted by solar panels, or radioactive decay within the earth, or fission harnessed in reactors, or gravity driving hydroelectric plants, or tidal flows, we cannot escape these two sources. And even then, the fusion in the middle of the Sun is driven by gravity. The question is really how do we utilize these two processes in a future with a different mix of energy.
While hydroelectric power doesn’t produce carbon dioxide, few would argue that it is particularly kind to the environment. This leaves wind, solar, and nuclear energy as the three most frequently mentioned ways to produce energy. All three remaining technologies have their own tradeoffs. Wind power, for instance, is mature, available today, and capable of reasonably large sized generating capacity. The challenges facing wind are encompassed by people’s willingness to put up with the footprint, and managing the fluctuating generating capacity against the needs of the electrical grid.
Nuclear power, in the form of fission reactors, is even more nuanced. Large, complicated, and potentially dangerous plants like those operating today might give way to smaller, simpler, and safer designs. There is plenty of reason to be skeptical about the scale and economics of current nuclear reactors, even as smaller designs with promise lurk in the wings. The current crop of reactors operate at elevated steam pressures and have multi-megawatt levels of heat left over to be dissipated after a controlled shutdown. Both of these factors compound the potential for accidents and make the case for the nuclear status quo less than clear.
Another thing that hampers the nuclear industry, and makes the waste problem more severe, is the ban on fuel reprocessing. Reprocessing is the chemical steps required to remove the small amount of long-lived radioactive elements from a fuel assembly composed of otherwise re-usable fuel. Reprocessing was banned by Jimmy Carter in 1979 as a gesture to the Russians at the height of the cold war. Regardless of how much you hate (or love) nuclear power, it is important to remember that radioactive decay is a random process that pays no mind to politics, policy, or nation states. As such, any prudent, forward-looking nuclear path needs to support reprocessing and include methodologies that transmute the long-lived leftovers from current reactors into shorter-lived species that don’t need storage measured in millenia. Nuclear reactor technology with different neutron spectrums is likely the most prudent approach to breaking down long-lived waste.
Restarting reprocessing activities to help in the process of speeding the breakdown of fuel should be a central feature in any nuclear policy. Some cannot seem to see the scientific need to continue with nuclear fission at least long enough to clean up the mess that has already been created. A coherent “full stop” nuclear policy should still include reprocessing and transmutation of the waste stockpile. Stopping short will make the waste problem far worse. By the time the existing waste is transmuted, the performance of transmuting reactors will be established enough that retaining or shuttering of those reactors should be clear.
An important take away from this article is the following: “If all present nuclear activity was halted immediately, things do not suddenly become all right with the spectre of existing radioactive waste.” The current unit economics and regulatory environment of nuclear energy (at least in the USA) foster a path to large plants, more waste accumulation and no serious waste reduction roadmap. We would do well to modify this trajectory.
Help from Our Friend, The Sun
So what about the prospects of using solar energy, either by direct conversion of light into electricity or solar thermal operations? Especially in solar panels, huge forward progress has been made in efficiency, performance, and cost over the last 15 years. Here, costs have been aggressively reduced — particularly by Chinese suppliers. If their cost structures are sustainable, which may not be a great assumption, they have done a great job at bringing solar energy within the ballpark of conventional generation methods. Further aiding solar are financial instruments that make installation of the product accessible to a wider range of people.
Germany is the model country for the installation of solar panels, where heavy government incentives and a coherent energy policy have resulted in almost 17 percent of their energy coming from a mix of wind and solar power. A great fraction of the German installed solar base is directly on the homes where the energy is used. Presently this is the best use case for solar, as it eliminates most of the complication of storing and distributing the generated electricity. Solar installations can store their energy in small, local batteries or return the power to the grid infrastructure.
Solar panels continue to improve, and the discussion for solar and wind will shift primarily to concerns of energy storage and distribution of generated power throughout the grid infrastructure. Distribution and storage are serious challenges to a fully “renewable” energy grid. Electrical grids have a so-called baseload power requirement. This value represents the minimum energy demand over some unit of time (e.g., a day or a year) and therefore is the required background level of electrical generation that is required.
Baseload generation is well suited to technologies like coal, hydroelectric, or the current crop of nuclear power plants on our current grid infrastructure. Processes like smelting aluminum use huge quantities of electricity in a relatively concentrated and consistent fashion. For 2014, 58 percent of worldwide primary aluminum smelting was powered using coal, and 88 percent was powered using a combination of coal and hydroelectric power. Natural gas and nuclear power compose the rest. The present reasons for this power mix are primarily economic, as coal can provide the concentrated energy needs for such processes and do so cheaply. Of course, some of the affordability of coal is that we do not quantify the external costs that coal places on humans and the environment.
For solar or wind to make sense as baseload power, one must solve either energy storage or instantaneous distribution of power, and likely a mixture of both. A generous assessment of the current worldwide solar electricity generation capacity shows that it is equivalent to less than 40 percent of the energy consumed in 2014 for primary aluminum smelting. Project that same sort of calculation across the whole scope of baseload electricity requirements and we have a very long way to go for renewable baseload energy. The sooner that energy distribution and/or storage are tackled head-on, the sooner the power generation mix can be moved in a better direction. Until then, renewables will primarily take the form of “made locally, used locally.”
Simpler is Better
While there is extensive press on things like Tesla’s wall mount battery for home solar panels, the technologies suitable to large-scale energy storage are more mundane. Batteries are comparatively expensive, have a limited number of use cycles, and have their own environmental issues. By contrast, a technique like pumping water into a water tower or reservoir during the day, and letting gravity pull it back out at night is simple, scalable and repeatable. Another take on the gravity-driven system is the work of Advanced Rail Energy Storage, which stores energy using gravity and train cars.
A further technology with appeal for simplicity is the storage of energy in compressed air. LightSail Energy, SustainX and General Compression are developing performant energy storage systems based around well-understood thermodynamics, materials and engines. These companies are greatly improving the efficiency of compression by holding the air temperature nearly constant, and then returning that heat back to the stored air upon expansion.
Conclusion
Water towers or compressed air may not be the sexiest of technologies, and thoughts of each neighborhood generating its own electricity is a big shift from the present state of how utilities operate. In the developing world, it’s likely that they will skip over much of the centralized infrastructure and move directly into power generated in smaller quantities closer to the point of usage. I personally believe it is important to focus on achievable goals that can be implemented in a reasonable amount of time. Projects with achievable and repeatable milestones will help eat the very large elephant in the room.
Germany has shown that one can kick off this process, and the world should look their way for lessons on how to drive towards ambitious renewable energy goals. It is not yet clear they will be able to meet their initiatives, but they are executing on more than rhetoric. Some combination of energy efficiency, grid flexibility, usage prediction, and installed capacity is necessary to make renewables a viable replacement. Only once we are walking the path to meaningful replacement of our generating capacity will the tough discussions on how to dis-incent fossil fuels like coal have a real alternative to stand on.
Note: Statistics cited from the U.S. Energy Information Administration, Wikipedia and the International Aluminum Institute.
Phil Graham is FOH’s regular technical contributor and resident scientist.
