IEEE Power & Energy Magazine - November/December 2021 - 65

The macrogrid concepts presented in this article for the United States
and Europe cannot be planned, designed, or implemented without
an entity that is responsible for executing transmission at that level.
centers. Transmitting electricity to the hydrogen production
facilities was more cost-effective than producing hydrogen
near electricity generation facilities and transporting the
hydrogen to the utilization centers.
Does the Use of Local Resources
or DERs Obviate the Need for
Transmission?
Distributed solar, storage, and responsive demand will be critical
to reach clean energy goals. However, land scarcity and the high
correlation of weather-driven generation within concentrated
urban areas will limit the ability of these resources to meet
all energy demands. Transmission enhances the use of DERs:
ZeroByFifty built 50% more DERs with the HVdc network.
Distributed PVs and storage injected energy and balancing services
into load centers. But during times of excess or insufficient
generation, additional transmission infrastructure was needed to
balance the system over all hours of the day.
Most of the capacity expansion studies model distributed
PVs either by endogenously setting targets or by examining the
economic tradeoff of utility-scale PVs plus transmission versus
distributed PVs. To our knowledge, only Vibrant Clean Energy
has co-optimized generation, transmission, and the distribution
interface. In " Why Local Solar for All Costs Less: A New
Roadmap for the Lowest Cost Grid, " they found that costs of
upgrading distribution feeder infrastructure increase with the
electrification of buildings, transportation, and industry. They
found that by including these distribution infrastructure costs in
the capacity expansion model, some storage and PV investments
shifted from large utility-scale projects to distribution-level
installations. This analysis found that the increased capacity
of DERs did not reduce the need for bulk system transmission.
Rather, the co-optimized clean energy scenarios built substantially
more distributed solar and storage and required 10 million
MW-mi more of transmission than the scenario, which did not
co-optimize distribution. Because 100% clean electricity may
be a step on the road to 100% clean energy, and because electrification
has significant impacts on the distribution system, modelers
will need to increasingly include the distribution interface
when they study optimal decarbonization pathways.
A Path Forward for Transmission
The following steps may provide a path forward to support
100% clean electricity.
✔ Establish a national or international transmission
planning authority: The macrogrid concepts presented
in this article for the United States and Europe
november/december 2021
cannot be planned, designed, or implemented without
an entity that is responsible for executing transmission
at that level. This wide-scale geographical perspective
on transmission planning requires at least a nationallevel
perspective on current and long-term future resource
locations, demand requirements, system optimization,
and planning. A national transmission planning
organization would work with regional planners and
others to coordinate top-down and bottom-up needs
and optimize solutions. ENTSO-E offers an example
of an international solution.
✔ Conduct a national or international transmission planning
process: Long-term, ongoing transmission planning
processes are superior to " one-off " planning exercises,
which can quickly become outdated. A successful
decarbonization strategy will require the accelerated
construction of clean energy resources and transmission
as well as rapid technological innovation. All of these
would be reflected in recurring, comprehensive planning
cycles to capture the full range of the transmission's
benefits and evolving grid needs and opportunities. This
approach must include reliability analyses, such as resource
adequacy, capacity expansion, system balancing,
steady-state stability, and dynamic stability. This effort
will look like an integrated resource and transmission
planning effort. Even though resource deployment is
often left to developers, regulators, and utilities to plan
and build, transmission availability determines where
and how much generation is built. Local and regional
transmission planning needs to integrate into and coordinate
with a national plan. European law requests twoyear
cycles of joint scenario development from both the
gas and electric ENTSOs. It also requests pan-European
infrastructure plans for electricity and gas for a 10- to
20-year time horizon and annual adequacy assessments
for a 10-year time horizon.
✔ Renewable energy zones and proactive transmission
development: The best wind and solar resources are
typically located in regions that are distant from large
load centers. The interconnection of resources with individual
generator tie lines can be inefficient, slow,
and costly. A planned approach that identifies preferred
renewable energy zones and proactively builds
properly sized transmission to these zones will enable
an expeditious, efficient growth of clean resources.
As in the CREZ process, this can be combined with
a fair and reasonable cost allocation (recognizing that
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IEEE Power & Energy Magazine - November/December 2021

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