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Getting to Net Zero: The Technologies Needed

Copyright © 2021 Energy Intelligence Group

Some see the International Energy Agency's (IEA) net-zero report as just an extreme intellectual -- or political -- exercise (NE May20'21). It is indeed one pathway among many, but it confirms that reaching net-zero by midcentury is achievable with mostly proven technologies. The report -- which has been a lightning rod for criticism and debate -- also finds that net-zero is still possible even in the face of stumbling blocks, for example if carbon capture doesn't take off. The agency insists it is "the most technically feasible, cost-effective and socially acceptable" net-zero scenario. It is more ambitious than the Paris Agreement, which is not calling for carbon neutrality in 2050 but for limiting global warming to 1.5°C, a goal scientists see as feasible if neutrality is achieved later, in 2060-70 (NE Apr.29'21). But net-zero by 2050 is the goalpost a growing number of governments are chasing and "we've just translated this to real life," says IEA Executive Director Fatih Birol. Proven Technology To build their net-zero emissions (NZE) scenario, IEA experts refrained from using too much unproven or controversial technology. The scenario confirms that net-zero is possible using known technologies: About half of them are already in the market while the other half -- for example, direct air capture (DAC) -- are "at the demonstration or prototype phase." The IEA also made the "explicit decision" not to rely on non-energy offsets such as forestry projects, says the agency's chief energy modeler Laura Cozzi (NE Mar.11'21). While oil companies such as Royal Dutch Shell and Eni are counting on large amounts of them to achieve their climate goals, such offsets are socially questionable. Influential investor groups such as the $37 trillion strong International Investors Group on Climate Change (IIGCC) are very reluctant about them. "Investors should not allow the use of external offsets as a significant long-term strategy for achievement of decarbonization goals by assets in their portfolios, except where there is no technologically or financially viable solution," the IIGCC states in its recent Net-Zero Investment Framework (PIW Apr.16'21). The IEA also limited bioenergy in the NZE "so it doesn't interfere with food production and maintains a certain level of biodiversity," Cozzi tells Energy Intelligence. The NZE involves no significant amount of bioenergy production from existing cropland or forests but relies a lot on using waste to produce biogas, plus marginal forest or land, Cozzi explains. Total bioenergy supply would grow from the current 62 exajoules to just over 100 EJ in 2050. If no new land at all was to be used for energy crops, bioenergy supply would be reduced by some 10% to 91 EJ in 2050, the IEA found. This would imply an extra 5% need in solar and wind power. No Constraints on Capture Other than cost considerations, there was no constraint on carbon capture and storage (CCS) or DAC, Cozzi emphasizes. The NZE leads to almost 7 billion tons of carbon dioxide captured with CCS in 2050, plus 1 billion tons with DAC. This is less than in most of the scenarios considered by the Intergovernmental Panel on Climate Change in its 2019 report on the 1.5°C goal, but many of the scenarios it used are now three years old or more. Climate economic models have been increasingly criticized in recent years for the huge quantity of carbon capture they involve (NE Nov.19'20). The NZE's 8 billion tons indeed amount to 200 times the current CCS capacity, or 40 million tons per year. It is also equivalent to the total amount of hydrocarbons the oil and gas industry is currently producing. Caroline Le Meaux, head of sustainability research at French asset manager Amundi, recently told Energy Intelligence that companies should focus on reducing emissions and keep carbon capture "very marginal" (NE May20'21). Negative emissions technologies such as bioenergy with CCS (BECCS) and DAC are mostly needed in the model to "buy time" for aviation as "we're not yet quite sure how to fully decarbonize it," Cozzi notes (NE Apr.1'21). Similarly, one of DAC's key roles would be to provide carbon for sustainable aviation fuels. CCS, by contrast, would hardly be needed in power. "There are cheaper options, including low carbon sources of flexibility such as geothermal energy, hydrogen and batteries," Cozzi says (NE May13'21). The main applications for CCS would be hard-to-decarbonize industries such as cement production and, "importantly," blue hydrogen production from natural gas. While green hydrogen from renewable electricity is expected to grow "very quickly," blue hydrogen has a role to play, particularly in the current decade (NE Mar.11'21). It would account for 46% of total low-carbon hydrogen production in 2030 and 38% in 2050. What if CCS Doesn't Take Off? The IEA cautions that a rapid scale-up of CCS would be "very uncertain for economic, political and technical reasons." With this in mind, the agency tested a low carbon capture variant of the NZE relying on no new fossil fuel-based CCS projects beyond those already approved are constructed. This reduces the amount of captured CO2 by around 3.5 billion tons from the base NZE in 2050, although it still leaves a substantial 4 billion tons still to be captured from industrial processes, BECCS, DAC and the already-approved or constructed fossil fuel CCS projects (NE Nov.26'20). Those would capture a mere 150 million tons of CO2 by 2050. The gap in emissions reductions would be met by more electrification, which would include electrifying industrial processes instead of capturing emissions at those facilities. Hydrogen would also be leaned on more heavily, but only the green variety. The base NZE's blue hydrogen production, which involves 1.4 billion tons of CCS by 2050, would need to be fully replaced by green hydrogen. Because the low CCS scenario would rely on more electrification, power demand would increase by 24% from the base NZE and wind and solar capacity by 31% to a huge 30 terawatts in 2050. That's up from 23 TW in the base NZE and 13 TW in the IEA's sustainable development scenario, which would achieve carbon neutrality around 2070. This might look overly optimistic compared to current global wind and solar capacity of just 1.5 TW, but critics such as Carbon Tracker's Kingsmill Bond argue it is overly cautious. Falling renewable energy costs could arguably support a deeper and even more rapid uptake of renewables.The NZE was built with a 20% learning rate assumption for solar photovoltaic (PV) -- or the rate at which capital costs decline every time capacity doubles. This is in line with long-term trends but PV cost savings seem to have accelerated in the past decade, which would allow for faster growth in the future (NE May13'21). Philippe Roos, Strasbourg

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