A dramatically more energy-efficient global economy can decarbonize electricity and emit no net carbon by 2050, deliver 50% odds of keeping average global warming to 1.5°C, and require “significantly less” negative emissions than other low-carbon models, under a new “backcasting” scenario released late last month by consultants at Ecofys.
The study comes on the heels of a paper in the journal Nature Climate Change that suggested for the first time that the 1.5°C target may be achievable with little or no reliance on a controversial and unproven negative emissions technique, Bioenergy with Carbon Capture and Storage (BECCS). That increasingly mainstream approach has raised apprehension and controversy across the climate community that will likely reach a crescendo later this year, with the Intergovernmental Panel on Climate Change due to release a special report on 1.5°C pathways ahead of the UN climate conference this December in Katowice, Poland.
Ecofys suggests a broader menu of decarbonization strategies to keep the 1.5°C goal within reach, relying only on less invasive contentious emission options like afforestation and agricultural carbon sequestration to draw down emissions that overshoot the target. Despite brisk population and economic growth, it foresees global primary energy demand declining 8% from 2014 to 2050, to 442 exajoules (EJ, or one quintrillion joules, equivalent to about 275 terawatt-hours), nearly a 50% improvement over the 800-EJ threshold in some mainstream scenarios.
Compared to 2014, when fossils met 78% of global energy demand, the Ecofys model shows wind, biomass, and solar photovoltaics supplying 70% by 2050. In the course of the 36-year transition, carbon dioxide emissions total 680 gigatonnes, toward the top of the 200- to 800-Gt carbon budget available for a 1.5°C outcome.
To get there, Ecosys stresses, there’s no time to waste.
“Fast global action is needed, and the way we live, produce, consume, and dispose of products and services needs to be redesigned, especially if society wants to reduce dependence on future technologies that enable negative emissions,” the report states.
“An energy system transformation as set out here is feasible but highly disruptive. While it is based on technologies that are already available, it will have a high impact on all players in the energy system because of far-reaching electrification and the increased use of bioenergy. Existing businesses will need to be completely reoriented and new business lines developed to cope with the energy technology requirements of the future.”
The scenario assumes a global population of 9.2 billion by 2050 and a tripling of global GDP between 2014 and 2050, with most of the growth taking place in Asia and Africa. Demand for energy services rises “considerably”, with increased demand for seven energy-intensive industrial materials—from chemicals and fertilizers to cement, aluminum, and steel. Almost all transportation modes grow dramatically—aviation by 275%, private cars by 210%, rail by 201%, and trucking by 197%—and more frequent, intense heat waves drive up space cooling demand by a mind-boggling 1,307%.
To meet that demand for energy services with net zero emissions, “efficiency improvements and technology switches are required throughout the whole economy,” the study states. Industrial processes use already available tools and techniques to boost energy efficiency 4% to 50% for different production processes. Buildings reduce heating and cooling demand by 35 to 70%. Transportation energy savings span all modes, with the phaseout of internal combustion engines nearly complete by 2030, freight and bus transport shifted to hydrogen fuel cells and batteries, and rail powered by electricity of biodiesel.
“By 2040 the total demand for liquid fuels in transport is assumed to be met by biofuels to bridge the transition towards electric and hydrogen-powered transport,” the study states. “The application of biofuels before 2050 results in peak demand for biomass, which can and has to be produced sustainably.”
Ecofys draws a sharp contrast between its “disruptive approach” and the collection of more conventional low-carbon scenarios that rely on more exotic, still unproven negative emission technologies.
“The outcomes of integrated assessment models (IAM) demonstrate that least-cost pathways that reach this target would first exceed the carbon budget significantly and subsequently deploy negative emissions on a large scale in the second half of this century,” the study states.
“However, there are several reasons to challenge this proposed trajectory. First, it is questionable whether this is actually the least-cost path,” with solar, wind, and energy storage costs falling fast and development of carbon capture and storage (CCS) behind schedule. The need for rapid decarbonization is also driven by scientists’ concerns about “the effect and undesirable side effects of negative emissions,” along with “a significant risk of temperature overshoot if emissions are not reduced quickly.”
Ultimately, Ecofys writes, “the question can be raised whether it is ethical to shift the responsibility of climate change mitigation (again) to future generations. Nevertheless, utilizing negative emissions is probably unavoidable given the current annual emissions from fossil fuels and cement production of over 35 Gt CO2.”