A roadmap to net zero

THE INTERNATIONAL ENERGY AGENCY (IEA) has presented what it claims as world’s first comprehensive study of how to transition to a net zero energy system by 2050. The outcome should be a “clean, dynamic and resilient energy economy dominated by renewables like solar and wind instead of fossil fuels”. The report also examines key uncertainties, such as the roles of bioenergy, carbon capture and behavioural changes in reaching net zero.

In his foreword to the report IEA executive director Dr Fatih Birol said the gap between rhetoric and action had to close, and “Doing so requires nothing short of a total transformation of the energy systems that underpin our economies”.

Noting that cheaper renewable energy technologies give electricity the edge in the race to zero, IEA says: hydropower and nuclear, “provide an essential foundation for transitions.” But by 2050, almost 90% of electricity generation comes from renewable sources, with wind and solar PV together accounting for nearly 70%.

The report looks at CO2 emissions and energy supply and use, based on scenarios. The Stated Policies Scenario (STEPS) takes account of specific policies and the Announced Pledges Case (APC), assumes that all announced national net zero pledges are achieved in full and on time, with or without specific policies. The Net-Zero Emissions by 2050 Scenario (NZE) describes how energy demand and the energy mix have to evolve and examines the implications and the major milestones on the way.

With respect to nuclear, IEA says that under STEPS, nuclear energy grows by 15% between 2020 and 2030, mainly reflecting expansions in China. Under APC nuclear power increases steadily, maintaining its global market share of about 10%, led by increases in China”.

The energy mix in 2050 in the NZE is much more diverse than today, IEA says. Renewables provide two-thirds of energy use, including bioenergy, wind, solar, hydroelectricity and geothermal. “There is also a large increase in energy supply from nuclear power, which nearly doubles between 2020 and 2050.”

An increasing share of hydrogen production comes from electrolysers. “Electrolysers are powered by grid electricity,  dedicated renewables in regions with excellent renewable resources and other low-carbon sources such as nuclear power,” says the report.

It says that by 2050, hydrogen production in the NZE is almost entirely based on low-carbon technologies. “Electrolysis absorbs close to 15000TWh, or 20% of global electricity supply in 2050, largely from renewable resources (95%), but also from nuclear power (3%) and fossil fuels with CCUS (2%).”

IEA says nuclear power makes a significant contribution. In the electricity sector in the NZE, “its output rising steadily by 40% to 2030 and doubling by 2050, though its overall share of generation is below 10% in 2050”.

At its peak in the early 2030s, global nuclear capacity additions reach 30GW a year, five-times the rate of the previous decade. In advanced economies, lifetime extensions for existing reactors are pursued in many countries, while new construction expands to about 4.5GW a year on average from 2021 to 2035, with increasing emphasis on small modular reactors. “Despite these efforts, the nuclear share of total generation in advanced economies falls from 18% in 2020 to 10% in 2050. Two-thirds of new nuclear power capacity in the NZE is built in emerging market and developing economies, mainly in the form of large-scale reactors, where the fleet of reactors quadruples to 2050. This raises the share of nuclear in electricity generation in those countries from 5% in 2020 to 7% in 2050.” Nuclear also meets 4% of commercial heat demand.

From 2011 to 2020, an average of 6GW of new nuclear capacity came online each year. By 2030, this increases to 24GW a year in the NZE. “Failing to take timely decisions on nuclear power and CCUS would raise the costs of a net zero emissions pathway and add to the risk of not meeting the goal by placing an additional burden on wind and solar to scale up even more quickly than in the NZE.”

The World Nuclear Association said the IEA’s NZE scenario “puts too much faith in technologies that are uncertain, untested, or unreliable and fails to reflect both the size and scope of the contribution nuclear technologies could make”.

It adds, “Given that more than 60% of the world’s electricity is currently generated by fossil fuels, if we are to eliminate them in less than 30 years, the IEA’s assessment of the role of nuclear is highly impractical.”

WNA notes that, in addition to electricity, nuclear energy can generate zero-carbon heat. “This is an opportunity that the IEA’s report barely touches on.”

WNA also criticises IEA for depending so heavily on expanding wind and solar, and “relying so heavily on as yet unproven at scale modern bioenergy, battery storage and hydrogen to cover for this intermittency”.