Page 343 - ISES SWC50

12.2 What are Some Pathways to 100% Renewables?

There are numerous studies, including by organizations with which ISES has a strong partnership, that outline
the bright future for renewables and the pathways to achieving 100% renewables. Mitigating climate change
is certainly a key motivator, although other significant societal issues, such as improved local air quality, access
to secure energy supplies free from foreign influences, and the recognition of a dwindling finite supply of
economically accessible fossil fuel reserves are among the other key motivators for these studies. The points
that support the practicality of these studies, such as the steep declines in the costs of renewable technologies
and their deployments, are indisputable.

12.2.1 The Selected Studies

Three specific studies are chosen here to evaluate options for achieving a completely carbon-free and 100%
renewable energy supply well before the end of this century:IRENA’s Sustainability and Climate Change
Analysis (formerly known as ReMAP), published most recently in their 2020 Global Renewables Outlook [1];
the recent Springer book by the University of Technology Sydney (UTS) titled “Achieving the Paris Climate
Agreement Goals” [2]; and the study by the Finnish Lappeenranta University of Technology (LUT) and Energy
Watch Group titled “Global Energy System based on 100% Renewable Energy – Power, Heat, Transport and
Desalination Sectors” [3].Clearly there are many other studies that have been undertaken in recent years, such
as those by Greenpeace International, the International Energy Agency (IEA), the Intergovernmental Panel
on Climate Change (IPCC), Shell Renewables, and others that the reader is encouraged to explore.The three
studies summarized here have been chosen mainly to establish the foundational principles that must be met
to achieve 100% renewables.

12.2.2 The Clmate Argument for 100% Renewables

Each of these studies referenced below are motivated by the Paris Climate Agreement, negotiated at the
Conference of the Parties (COP) 21 in Paris in December 2015 and ultimately by signed by all 196 nations.
The Agreement calls for steps to be taken by all nations to urgently reduce greenhouse gas emissions to levels
that will limit global warming to no more than 2ºC above preindustrial levels and ideally to 1.5ºC by the end
of this century. The 2018 IPCC report [4] estimates that global warming has already reached approximately
1.0ºC. The 1.5ºC target has become an even more crucial to achieve given the potential catastrophic impacts of
climate change, including severe droughts and flooding, sea-level rise, dramatic shifts in agricultural patterns,
increases in airborne disease vectors, and a resulting displacement of hundreds of millions, if not billions, of
climate “refugees”, as reported in [4].

However, when the Paris Climate Agreement was signed, limiting global warming to 2ºC was still considered
to be a meaningful target given the state of science at the time. This target had been set in an earlier IPCC
study [5]), and also reflected the willingness of countries to establish GHG emission-reduction measures that
could realistically be achieved given the current political and economic conditions. The 1.5ºC target was added
into the Paris Agreement as an aspirational target to which the UNFCCC and the signatory countries should
strive. Even a 2ºC target would mean that all global GHG emissions would need to be eliminated entirely by
2075.Given that roughly ¾ of global anthropogenic GHG emissions are related to energy production and
consumption, the energy sector would already need to take aggressive action to achieve the 2ºC target.
But with the more recent findings of the IPCC in [4] which calls for limiting global warming to no more than
1.5ºC, the need to decarbonize our energy systems is even more urgent and must be done even more rapidly
than what was thought at the time of the Paris Agreement. Between the two IPCC reports (from 2007 to
2018) global GHG emissions increased by roughly 30%. Therefore, the new 1.5ºC target requires all countries
to find the means to eliminate GHG emissions a full generation earlier, or by 2050. Despite this ambitious
target, however, the Nationally Determined Contributions (NDCs) submitted by all signatory countries at the
time of the signing of the Paris Agreement would still result in global warming to increase to 3.6⁰C.
Rapid expansion of renewable energy technologies to the point where they provide all of our end-use energy
needs, combined with aggressive energy efficiency measures that dramatically reduce energy intensity per
capita is seen as the most cost-effective way to achieve the Paris Climate goals while maintaining social
justice and economic prosperity. A number of studies such as those cited below have been undertaken to
identify pathways to achieve the Paris targets, especially without resorting to any expansion of nuclear energy
or to implementing costly and risky technologies such as large-scale carbon capture and storage.

ISES SWC50 - The Century of Solar-Stories and Visions | 325