Our Renewable Future

Chapter 7. What About . . . ?

This book is essentially a thought exercise designed to explore some of the issues involved in transitioning our economy to 100 percent renewable energy. Some readers may chafe at the boundaries of this exercise. Why rely so much on wind and solar, rather than envisioning a more diverse mix of low-carbon energy sources? We chose our framework because it was simple and clear, and because this is a future that is indeed being widely proposed. The state of Vermont, for example, has announced the official goal of sourcing 90 percent of all its energy (not just electricity) from renewable sources—mostly solar and wind—by 2050. Moreover, studies have been published purporting to show that a 100 percent wind, solar, and hydro energy regime is both possible and affordable,[1] and prominent climate-oriented environmental organizations are now calling for that goal.[2] Further, we ourselves believe that a full transition to renewables is necessary and achievable, provided society is willing to accept adjustments, both profound and minor, to the ways it uses energy.

As we have seen, relying entirely on renewable energy entails some hefty challenges. We have discussed at some length the problem of source intermittency and the need for energy storage, grid redesign, and capacity redundancy; the environmental and land use challenges of installing very large numbers of solar panels and wind turbines; electrification and the revamping of energy-consuming equipment; and the requirements for very high levels of investment. The conclusion we have reached so far is that, realistically, a mostly wind-and-solar future will likely provide less energy overall, less mobility, and less manufacturing capacity. This conclusion is likely to be unwelcome to many readers, again leading to objections regarding the study’s narrow boundary assumptions. This chapter addresses three of the most likely of those objections.

Nuclear Power

We cursorily explained our reasons for not including nuclear power in our “renewable future” energy mix in the introduction. The main reason is simply that nuclear fuel is not renewable. Some readers will nevertheless disagree with this decision, since (excluding mining, transport, enrichment, plant construction, and plant decommissioning) the nuclear fuel cycle generates no carbon emissions. For this reason there are many environmentalists and climate activists—including former National Aeronautics and Space Administration climate scientist James Hansen—who argue that nuclear has to play an expanded role as part of the energy transition away from fossil fuels. Therefore it may be helpful for us here to provide a more detailed discussion of nuclear power.

Nuclear electricity is reliable and relatively cheap (2.9 cents per kilowatt-hour) once the reactor is in place and operating. In the United States, while no new nuclear power plants have been built in many years, the amount of nuclear electricity provided has grown during the past 15 years due to the increased efficiency and reliability of existing reactors.

However, uranium, the fuel for the nuclear cycle, is a depleting resource. The peak of global uranium production rates is likely to occur between 2040 and 2050, which means that nuclear fuel is likely to become more scarce and expensive over the next few decades.[3] Already, the average grade of uranium has declined substantially in recent years as the best reserves have been depleted.[4] Recycling of fuel and the employment of alternative nuclear fuels are possible, but the technology has not been adequately deployed.

Nuclear power plants are so costly to build that unsubsidized nuclear plants are not economically competitive with similar-sized fossil-fuel plants. Government subsidies in the United States include those from the military nuclear industry, as well as nonmilitary government subsidies including artificially low insurance costs. New power plants also typically require many years for design, financing, permitting, and construction.

The nuclear fuel cycle entails substantial environmental impacts, which may be greater during the mining and processing stages than during plant operation, even when radiation-releasing accidents are taken into account. Mining entails ecosystem removal, dust, large amounts of tailings (equivalent to 100 to 1000 times the amount of uranium extracted), and radioactive particles leaching into groundwater. During plant operation, accidents causing small to large releases of radiation can impact the local environment or much larger geographic areas, potentially making land uninhabitable (as with Chernobyl and Fukushima).

Storage of radioactive waste is highly problematic. High-level waste (like spent fuel) is much more radioactive and difficult to deal with than low-level waste and must be stored on-site for several years before transferal to a geological repository. The best-known way to deal with waste, which can contain lethal doses of radiation for thousands of years, is to store it in a geological repository, deep underground. Yucca Mountain in Nevada, the only site that has been investigated as a repository in the United States, was ultimately rejected. More candidate repository sites will need to be identified soon if the use of nuclear power is to be expanded in the United States. Even in the case of ideal sites, over tens of thousands of years waste could possibly leak into the water table. The issue is controversial even after extremely expensive and extensive analyses by the Department of Energy.

Nearly all commercial reactors use water as a coolant. Heat pollution from coolant water discharged into lakes, rivers, or oceans can disrupt aquatic habitats. In recent years, a few reactors have had to be shut down due to water shortages, highlighting a future vulnerability of this technology in a world where droughts are becoming more common due to climate change. During the 2003 heat wave in France, several nuclear plants were shut because the river water was too hot.

Reactors must not be sited in earthquake-prone regions due to the potential for radiation release in the event of a serious quake. Nuclear reactors are often cited as potential terrorist targets and as potential sources of radioactive materials for the production of terrorist “dirty bombs.”

Hall et al. reviewed net energy studies of nuclear power that have been published to date and found the information to be “idiosyncratic, prejudiced, and poorly documented.”[5] The largest issue is determining what the appropriate boundaries of analysis should be. The review concluded that the most reliable energy returned on energy invested (EROEI) information is quite old (it showed an EROEI in the range of 5–8:1), while newer information is either highly optimistic (10:1 or more) or pessimistic (low or even less than 1).

The nuclear power industry is shrinking in most of the older industrial nations; only in China and India are substantial numbers of new reactors being planned. Hopes for a large-scale deployment of new nuclear plants rest on the development of new technologies: pebble-bed and modular reactors, fuel recycling in fast reactors, and the use of thorium as a fuel. However, each of these new technologies is problematic for one reason or another. The technology to extract useful energy from thorium is highly promising but will require many years and expensive research and development to commercialize. The only breeder reactors in existence are closed, soon to be closed, abandoned, or awaiting reopening after serious accidents: BN-600 (Russia, end of life 2010); Clinch River Breeder Reactor (United States, construction abandoned in 1982 because the United States halted its spent-fuel reprocessing program, making breeders pointless); Monju (Japan, potentially coming online again after a serious sodium leak and fire in 1995); and Superphénix (France, closed 1998). The ultimate technological breakthrough for nuclear power would be the development of a commercial fusion reactor. However, commercial deployment of fusion still appears to be decades away and will require much costly research.[6]

China now has about 20 GW of nuclear capacity online, with a target of about 70 GW by 2020 (a target it is likely to miss), and envisions about 250 GW by 2050. The nation is already a net importer of uranium. Chinese nuclear plans don’t foresee alternatives to the standard uranium cycle, such as improvements to the nation’s own native pebble-bed reactor design, until after 2035 at the earliest. Therefore, realistically, most nuclear power plants constructed in the short and medium term worldwide will be only incrementally different from current designs.

In order for the nuclear industry to grow sufficiently so as to replace a significant portion of energy now derived from fossil fuels, scores if not hundreds of new plants would be required, and soon. The enormous investment requirements for such a build-out would probably preclude a simultaneous large-scale build-out of solar and wind generators. But more realistically, given the expense and long lead time entailed in plant construction, the industry may do well merely to build enough new plants to replace old ones that are nearing retirement and decommissioning.

In short, we do not see a nuclear renaissance as a realistic alternative to a massive shift toward renewable energy in addressing the climate dilemma.

Carbon Capture and Storage

If stopping climate change is our main goal, isn’t it possible to do this without completely phasing out fossil fuels by capturing and burying carbon emissions? That way, we could continue burning coal to generate cheap electricity (and use that electricity to power automobiles and an increasing share of industrial processes), while simultaneously reducing the release of carbon dioxide into the atmosphere.

For years, Americans have seen billboards and TV commercials touting “clean coal,” while politicians from both major parties have extolled its promise. The technology to capture carbon emissions from coal-fired power plants has been tried and tested. Yet today almost none of the nation’s coal-fueled electricity-generating plants are “clean.”

Why the delay? The biggest problem for clean coal is that the economics don’t work. Carbon capture and storage (CCS) is extremely expensive. That gives the power industry little incentive to implement it in the absence of a substantial carbon tax.

Why would implementing CCS be so expensive? For starters, capturing the carbon from coal combustion is estimated to consume 25 to 45 percent of the power produced, depending on the approach taken.[7] Add to this the energy costs for transport, injection, and storage management. The result would inevitably be not only higher prices for coal-generated electricity but also the need for more power plants to serve the same customer base. Other technologies designed to make carbon capture more efficient aren’t commercial at this point, and their full costs are unknown.

Capturing and burying just 38 percent of the carbon released from current US coal combustion would entail the manufacturing and installation of pipelines, compressors, and pumps on a scale equivalent to the size of the nation’s oil industry, requiring tremendous energy expenditures.[8] And, although bolting CCS technology onto existing power plants may conceivably be possible, it would be exceedingly inefficient. A new generation of plants capturing carbon dioxide prior to coal combustion would do the job much better—but that means replacing roughly 600 current-generation power plants. Altogether, the US Department of Energy estimates that wholesale electricity prices with the initial generation of CCS technology would be 50 to 80 percent higher than current coal-based power.[9]

Thinking long term, the economics of coal—and natural gas, for that matter—are likely to get worse, with or without the vast investment required for CCS implementation. After all, coal and natural gas are nonrenewable, finite in quantity, and therefore subject to depletion. Rates of production of coal from most regions of the United States are in decline. And as depletion forces the mining of lower-quality resources, production costs will rise because of the need for more-sophisticated extraction technologies. Declining output is inevitable sooner or later.

The only thing that keeps coal-based electricity cheap today in relation to power from renewable energy sources is the industry’s ability to shift the hidden costs—environmental and health damage—onto society. If, as climate regulations inevitably kick in, the coal power industry adopts CCS as a survival strategy, the task of hiding from the market the real and mounting costs of coal can only grow more daunting. Any lingering economic advantage over wind and even solar will disappear.

On top of all this, CCS doesn’t address the full range of coal’s impact on society. It won’t banish high rates of lung disease, because it doesn’t eliminate all the pollutants from the combustion process or deal with the coal dust from mining and transport. It also doesn’t address the environmental devastation of “mountaintop removal” mining.

This is not to say that clean coal has no future whatever. Coal plants with CCS will likely be built in situations where captured carbon dioxide can be used to generate extra income—for example, by using it to stimulate old oil wells or make cement. But even a dramatic increase in such uses would put only a small fraction of carbon from coal to work.

A full transition of today’s coal power industry to CCS is extremely unlikely unless the economics substantially change for some currently unforeseeable reason. And other technological advances, like more-efficient coal-fired plants, can only slow the growth of harmful emissions at best.[10]

In all likelihood, the real future of carbon sequestration lies elsewhere—with reforestation and agricultural methods that build topsoil. Atmospheric carbon levels are currently at 400 parts per million (ppm) of carbon dioxide, while a consensus has emerged that a “safe” level would be below 350 ppm. One ppm is equal to 2.125 gigatons (Gt) of carbon; thus we need to safely sequester 106.25 Gt of carbon in order to return to a safe climate regime. Is there sufficient potential absorptive capacity in forests and soils to accomplish this?

Society has removed 136 Gt of carbon from soils through agriculture and land use. There is the potential to reverse the trend by minimizing tillage, planting cover crops, encouraging biodiversity, employing crop rotation, expanding management-intensive pasturing, and introducing biochar to soils.[11]

Deforestation has also contributed significantly to the historic increase in atmospheric carbon dioxide. It makes sense therefore that reforestation could diminish atmospheric carbon. Unfortunately, climate change is putting pressure on forests, even as we want them to recover. Nevertheless, a recent study shows large regional potential for sequestration, especially in the tropics.[12]

Massive Technology Improvements

Some readers may feel that we have failed to take into account the possibility of extraordinary new developments in energy research. In the computing world, Moore’s law describes a trend of rapidly declining cost and increasing functionality regarding transistors. During recent decades, the number of transistors that can be crammed into a square inch of integrated circuit has doubled approximately every two years. Memory capacity, computer processing speed, and the number of pixels in digital cameras have shown the same trend. Why shouldn’t renewable energy technology achieve a similar pace of improvement in output and efficiency?

Surely we can and should expect improvements to solar panels and wind turbines, and technological refinements are in fact occurring. As just one example, translucent photovoltaic modules are now feasible.[13] However, there are inherent physical limits to all processes and materials. Microprocessors have offered a unique opportunity for rapid technological advancement that may not be replicable in other fields. Areas of technology that involve massive infrastructure that is expensive to build and replace understandably evolve more slowly. Our energy infrastructure is in that category.[14]

What about entirely new energy resources? News reports occasionally inform us of experiments with cold fusion that purport to show high levels of anomalous energy output; or with artificial photosynthesis, which promises to be far more efficient than natural photosynthesis.[15] Couldn’t the development of one or both of these technologies constitute a “black swan” event capable of changing the energy game overnight?

It’s unlikely. In any case, it would have been pointless for us to try to factor black swans into our future energy scenarios. We don’t know what the actual costs for these possible future energy devices would be, nor do we know their scalability or their EROEI, so no useful analysis is possible.

Even in the best case, it will take time to get from the point of discovery of a new energy process to the commencement of build-out of commercial devices. During this period, perhaps a decade or two, development and testing of products would occur. The build-out of those products to replace current energy production technology would likely take even longer, probably another two or three decades.

Vaclav Smil, author of Energy Transitions: History, Requirements, Prospects, tells us that an energy revolution takes 40 years at minimum.[16] Since we will need to have the renewable energy revolution largely completed 40 years from now in order to avert catastrophic climate change, that means we will have to count mostly on technologies that have already passed through the research and development stages. Solar and wind have done so; supporting policies (such as feed-in tariffs) have been tested; and investment capital is already flowing toward the build-out of these technologies. Substantially different and more efficient energy technologies may emerge later this century, but for the foreseeable future the fates of our economy and of the global climate appear to hang largely upon the success or failure of our adoption of solar and wind power, and on a wide range of technological adaptations to intermittent energy at lower overall levels of supply.

Much the same must be said for massive efficiency improvements in energy consumption technologies. We have tried to identify and factor in the advantages of existing technologies such as air-source heat pumps, LED lighting, passive-house design, electric cars and bicycles, and public transit options like streetcars and light rail. We did not attempt to estimate the likely contribution of technologies at a very early phase of adoption, such as 3-D printing and the “Internet of Things” (though the latter is discussed briefly in chap. 3).[17] Though extravagant claims have been made for how these technologies could reduce the need for product transportation and increase energy efficiency, there simply isn’t enough real-world data to tell whether such claims are realistic or overblown.

*          *          *

In a nutshell, there is good news and bad news for society’s efforts to transition away from reliance on fossil fuels and to instead adopt renewable energy technologies.

The good news is that most of what we currently do with fossil fuels can be done with renewables: solar and wind can generate electricity, cars can be battery powered, solar thermal can heat water for our homes (at least during summer months), biofuels can power heavy transport. It is possible to use solar concentrators or hydrogen (produced from renewable electricity) to run high-heat industrial processes, and biofuels could conceivably even power ships and a much-reduced global fleet of airplanes.

The bad news is that some of these substitutions will be very expensive, some will not scale up easily, and most will require considerable research and development. In some cases, higher investment requirements will probably be ongoing as a result of higher materials and process costs.

This may be a good place to reemphasize the fact that only about 20 percent of the energy we use daily is in the form of electricity. That means 80 percent of all energy services today need to be electrified or we need to find a renewable alternative, preferably a drop-in substitute, requiring massive research and development expenditures for developing both the substitutes themselves as well as new process technologies. This may also a good place to point out once again that half of the energy we use today is essentially “wasted.”

We citizens of industrialized nations will have to change our consumption patterns. We will have to use less overall and adapt our use of energy to times and processes that take advantage of intermittent abundance. Mobility will suffer, so we will have to localize aspects of production and consumption. And we may ultimately forgo some things altogether. If some new processes (e.g., solar or hydrogen-sourced chemical plants) are too expensive, they simply won’t happen. Our growth-based, globalized, consumption-oriented economy will require significant overhaul.

Though the prospect is daunting, this doesn’t mean the renewable energy transition should not be attempted. As we wrote at the very beginning of this book (and will repeat again in part 3), the transition is both necessary and inevitable: maintaining our current fossil fuel–based energy system for much longer is simply not an option. However, this does mean that an all-renewable energy economy will have drawbacks as well as advantages (from our current perspective), and we should try to be realistic about both.

The advantages we will reap from an all-renewable energy economy will include the absence of financial and social costs associated with extracting, refining, transporting, and burning depleting fossil fuels—costs that will only increase as extractive industries have to drill deeper into lower-grade deposits; and the absence of the environmental externalities from burning those fuels—health and climate costs that would otherwise balloon to the trillions of dollars per year by midcentury. If we have fewer consumer products, they will likely be ones that are more durable and of higher quality. Because there will be tangible advantages to using energy when nature offers it, we are likely to feel more integrated into the rhythms of the natural world.

Perhaps it is helpful to maintain a long-term and philosophical view of our historical moment. Fossil fuels have enabled a temporary overshoot in human population levels and consumption patterns. Nevertheless, the planet is finite, and our energy use and population levels will inevitably be constrained—either voluntarily or otherwise. The renewable energy transition offers an opportunity to adapt to planetary limits more on our terms, preserving the best of what we have accomplished during our brief fling with nonrenewable energy sources. In a way, the renewable energy transition of the twenty-first century is a return of sorts. After all, for more than 99 percent of our species’ history, we lived entirely on renewable sources of energy. Our challenge now is to learn to live within planetary limits while preserving the best of what we achieved during our brief, fossil-fueled binge of overconsumption.


previous      next