When Science Upends Wishful Thinking: Can Renewables Alone Ensure 1.5 Degrees?

Cherry Picking Consensus

Climate activists are fond of talking about the “scientific consensus” that stands behind the idea that climate change is real and the burning of fossil fuels is primarily responsible. But there is another consensus that does not get the attention it deserves; that is, achieving 100 percent renewable energy will confront a series of formidable technical challenges and may, in fact, not be possible. And even if these challenges might eventually be overcome, full conversion to renewables would still not be anywhere near enough to limit global warming to 1.5 degrees.

. . . [A]chieving 100 percent renewable energy will confront a series of formidable technical challenges and may, in fact, not be possible.

The IPCC has for a long time asserted that the electrical power sector—currently the leading single contributor to greenhouse gas emissions—should undergo “deep decarbonization.” But the IPCC consensus is that decarbonization will also require carbon capture and storage (CCS) and lots of new nuclear power. And to stay within safe limits of warming, there needs to be massive advances in energy efficiency to suppress demand. The IPCC has also explored the need for carbon dioxide removal (CDR) technologies.

For the left in the United States and internationally, it is important to interrogate the scientific basis of these various scenarios and their implications. Yes, we must strive to understand what needs to be done—but we must also have a clear grasp of what can be done given what we know about the various methods and technologies that currently exist or are being developed. Implementing “climate solutions” at the necessary speed and scale will involve decisions that must take technical matters into consideration. We have no choice but to meet this challenge head on.

The Potential of Renewable Energy

Significantly, the most recent IPCC report again calls into question the possibility that renewable energy, on its own, can meet global energy needs—however, these needs may be defined. Clearly, if one of the goals is to get to a point where renewable energy provides electricity to the 1.3 billion people who currently have none at all (mostly rural dwellers in South Asia and Sub-Saharan Africa), and to also electrify various transport modes as well as domestic cooking and heating, and so on, then it is very likely that, based on today’s technologies, the technical potential of renewables will be pushed to the absolute limits. ⁴

The IPCC’s “renewables can’t do it all” approach has, however, been challenged by Stanford University’s Mark Z. Jacobson. ⁵ He and others have argued that renewable energy can provide almost all of the world’s energy needs by 2050 at the latest—without CO2 capture and recovery technologies or new nuclear power. ⁶ But other scientists strongly disagree. ⁷ A paper challenging Jacobson’s claims referred to, among other things, the undeveloped state of storage technologies that will need to be routinely available to overcome the problems created by the variable nature of wind and solar power. ⁸ A recent MIT study focused on the levels of storage that would be needed should the continental United States reach a point where wind and solar power provide 80 percent of the country’s electricity. The study’s conclusions deserve to be taken seriously. Aside from the enormous costs, and the levels of lithium required in the mass production of batteries, the technical challenges posed by the need to store renewable energy at levels that can guarantee reliable energy supply are formidable to say the least.

It is understandable that many progressives would like to think Jacobson’s assessment is more or less correct, and may be inclined to look no further. But the scientists that challenged his conclusions are, along with Jacobson himself, also highly credible professionals. ⁹ It is, therefore, important to try to understand the basis for these contrasting assessments regarding the potential for renewable energy and to examine the data without prejudice.

Another major challenge concerns how to integrate significant-to-large quantities of variable renewable energy (VRE) into existing grids. Among scientists, there is no clear consensus with regard to how to deal with technical and system-balancing challenges posed by so-called “source intermittency.” But in countries that have deployed significant wind and solar power, problems have occurred, especially in sunless periods during winter when the wind may also not be blowing. Germany, for example, overcomes this problem by importing nuclear power from France and hydropower from Norway—but both of these back up sources are geographically close by. Other countries may not be as favorably situated.

Some regard VRE as a relatively easy problem to solve (with the right investments in storage and interconnectors) while others regard it as virtually insurmountable. For the latter, there is no way to avoid the need for “base load” power generation that can be relied upon 24/7 and every day of the year. Most people on the left oppose nuclear power, and they seek the end to coal and gas as sources of energy. Therefore, we have a clear stake in the debate around the “true potential” of renewable energy and related technologies, a debate that will grow considerably more intense in future.

Escaping Capture

In an important recent volume titled “Radical Realism and Climate Justice,” the Heinrich Böell Foundation (which has links to the German Green Party) recently presented a collection of fact-based essays that address how to decarbonize key sectors of the economy. ¹⁰ One of the motives behind the Radical Realism project is to interrogate the IPCC’s conclusion that restricting warming to 1.5 degrees will be impossible without more nuclear power coupled with the development and large-scale deployment of carbon capture and storage as well as CO2 removal technologies. ¹¹ For the IPCC, CCS and nuclear energy are already considered to be “essential mitigation options” and CO2 removal is well on its way to achieving the same status.

CCS involves the chemical separation and removal of as much as 90 percent of CO2 generated by power plants and industrial processes that require the use of coal or gas. According to the IPCC, the International Energy Agency (IEA), and others, CCS is needed because “clean coal” and “clean gas” are established technologies and can help solve the problem of intermittent supplies of wind and solar power. Furthermore, renewables are not yet capable of supplying certain industries that require intense and consistent heat (steel, cement, pulp and paper, refining, and petrochemicals).

But how much CCS is needed? A lot, apparently. ¹² Prior to the Paris Agreement, the IPCC was counting on CCS to contribute at least 14 percent of “avoided” CO2 emissions between 2014 and 2050 to stay within two degrees Celsius of warming. ¹³ This would require a “capture” rate of around 7 gigatons (GTs) of CO2 per year, which itself is pretty massive. With the more ambitious 1.5 degrees Celsius target, the IEA estimates that capture technologies would need to account for as much as 36 percent of the projected reductions between now and 2050. ¹⁴

However, according to the IPCC’s current models, there is a distinct possibility that—even with CCS routinely deployed—cumulative emissions could exceed “safe” levels (so-called “emissions overshoot”), in which case the removal of CO2 from the atmosphere will sooner or later need to become a priority. Scientists have investigated the potential of removal technologies of various kinds. Some ideas for carbon dioxide removal (CDR) sound pretty far out, such as Direct Air Removal (DAR) where carefully positioned machines suck CO2 out of the atmosphere. The technologies are experimental, but advocates of CDR say companies could be paid to remove CO2 at a specific dollar amount per ton (for the good of the planet, of course). Then, the CO2 that has been removed can be sold as an industrial product for making concrete or cement. ¹⁵ (Nice work if you can get it.)

But other CDR ideas are attracting more serious and sustained attention. For example, advocates of bioenergy with carbon capture and storage (BECCS) say that the growing of bioenergy (trees, for example) removes CO2 from the atmosphere (wood is essentially carbon, roughly 50 percent of which comes from the surrounding atmosphere). The tree then becomes a source of fuel for power stations and industry. If equipped with CCS, burning the tree prevents the CO2 going back into the atmosphere, but the heat generated can be used for energy in the same way as occurs when burning coal and gas. According to the IEA, “BECCS is able to do this because it uses biomass that has removed atmospheric carbon while it was growing, and then stores the carbon emissions resulting from combustion permanently underground.” ¹⁶

Rage against the Machines?

Many in the various social movements have opposed carbon capture and storage in traditional power plants on the basis that it perpetuates our collective dependence on fossil fuels.And no one has yet figured out where to “store” (read “dump”) billions of tons of carbon in a way that is both safe and relatively economical. And research has estimated the enormous potential negative impact of BECCS, particularly in terms of the extremely large areas of arable land that would likely be used to generate the biomass feedstock for bioenergy—land that will need to be cultivated to meet rising global food demand. Using vast amounts of arable land in this way would impose an intolerable burden on hundreds of millions of people. ¹⁷ Nuclear energy is also rejected as a low carbon option but for different reasons.

Many in the various social movements have argued to oppose carbon capture and storage in traditional power plants simply because it perpetuates our collective dependence on fossil fuels.

These objections are often grounded in solid research, but this does nothing to alter the fact that, if nuclear power, CCS, and CDR are taken out of the equation, then reducing emissions to “safe” levels will be a lot more difficult. And it is clearly not enough to state, without substantiation, that more renewable energy, by itself, resolves the climate crisis. The decarbonization of energy clearly presents challenges. To overcome these challenges, we need to first know what they are—and be part of the search for solutions, social as well as technological.

Enough Energy Already

Most important, the IPCC, the IEA, and others acknowledge that energy efficiency can potentially contribute up to 40 percent of the reductions in energy-related emissions required by 2050. ¹⁸ In this scenario, reaching 1.5 degrees Celsius will require that energy demand by mid-century be “around today’s level due to extensive energy intensity improvements.” ¹⁹ Such a scenario, says the IEA, is “technically feasible.” In fact, both the IPCC and the IEA are pinning a lot of their hopes on it becoming a reality.

A recent study by a team of scientists led by Arnulf Grubler goes even further. The study argues that it is possible—based on existing and likely technologies—to reduce final energy demand as much as 40 percent from today’s levels by 2050 without unduly impeding progress toward the U.N.’s Sustainable Development Goals (SDGs). ²⁰ Grubler’s lower energy demand (LED) scenario “meets the 1.5°C climate target as well as many sustainable development goals, without relying on negative emission technologies” (CDR). ²¹

. . . [I]f nuclear power, [carbon capture and storage] and [carbon dioxide removal] are taken out of the equation, then reducing emissions to “safe” levels will be a lot more difficult.

Shifting attention toward energy demand reduction will not solve all of the supply-related problems discussed earlier, but it is fairly obvious that “downsizing the global energy system dramatically improves the feasibility of a low-carbon supply-side transformation.” ²² In plainer terms, less demand will require less supply, making it easier (at least in principle) to create an energy system based on 100 percent renewable sources.

Clearly, the task of controlling and then dramatically lowering energy demand lies at the heart of the fight for climate protection. This will be an enormous challenge. Energy demand has been rising between 2 and 3 percent per year on average for several decades, and the global economy is expected to be three times larger in 2050 than it is today. ²³ This means that the IPCC and IEA’s “flat energy demand” scenario is already completely at odds with the projected increases in energy use. And the far more ambitious 40 percent demand reduction presented in the LED scenario is, needless to say, even more so. As Gruber’s paper notes, “Ultimately, LED’s low energy demand outcomes depend on social and institutional changes that reverse the historical trajectory of ever-rising demand.” ²⁴ Indeed they do.

The Best Laid Plans

The poet Robert Burns was right. The best laid plans often go awry. But leaving the plans to decarbonize the global political economy in the hands of men in black suits who hire men in white suits to produce “science” is today a far bigger danger. Their plans went awry a long time ago.

. . . [T]he task of controlling and then dramatically lowering energy demand lies at the heart of the fight for climate protection.

But scenarios have their place. And in these discussions, there is a lot to learn, and not all of the solutions being discussed should be dismissed out of hand. Motivated by the desire to build a truly sustainable future, we must try to understand—collectively and with openness—what can be done to limit warming to 1.5 degrees Celsius and what barriers (technical as well as political) stand in our way. There are many scientists who will join us in this great endeavor. But first we must know what we do not know, and be willing to get beneath the skin of our own slogans. And the quicker we get to work, the better our chances of success.