The Electric Grid is THE Bottleneck to Decarbonizing Energy by 2050

Key Takeaways:

Ensuring a clean energy future for the United States requires a stronger electricity grid — one that can move more power over longer distances while also supporting new loads like electric vehicle charging and energy-intensive industrial processes, and providing reliable service through more extreme and variable weather conditions.

Decarbonization models suggest that the transmission system will need to double in capacity or more — not necessarily twice as many lines, but twice as much capability of carrying power over distance. More high-power lines would mean fewer miles added, and existing electrical lines can be upgraded to get many more times the power through the same or similar land footprint.

Our existing grid system has been built around one-way flow — from power generation to load. We need widespread deployment of sensing and control systems for managing two-way flow — where power could come from a rooftop solar power or home battery system.

The grid was designed and built over the last 140 years and is considered one of the most highly reliable engineering feats in history. The grid is highly regulated and dominated by a technology-cautious perspective. These can be great for maintaining a system but become major barriers to transforming a system. The grid is the system we most need to transform, though, and fast.

A good friend who is an expert in energy technology describes herself akin to a soothsayer: “I know what the future of the grid looks like. I just can’t tell you when it’s going to happen.”

The “grid” spans from the power generation station all the way to the residential meter. First, hundreds of thousands of miles of interconnected high voltage transmission lines (>100 kV) primarily bring power from a plant towards a population center. These transmission lines connect to millions of miles of lower voltage lines that spread that power out to homes and businesses, called the distribution system.

The future grid will have many more transmission lines sharing renewable power across long distances to account for weather variability and time of day usage differences, and a distribution system that will collect power from homes and businesses nearly as much as it delivers power to them. Our nonessential electrical appliances will at times be managed for us, and our electrical bills will reflect both the energy we used and energy we supplied to the system. That vision is a long way off, though, partly awaiting technology breakthroughs but primarily stalled by regulatory reform.

A very short primer on electricity

Electric power (P) is measured in Watts (W, MW, GW), and expended energy is measured in Watt-hours, the power used over time. For most of us at home, Watts and Watt-hours are how we experience electricity (wattage of appliances, watt-hours on our bills), because the components of power (voltage and current) are managed for us:

Power= Voltage x Current

High power can be delivered by ramping up either voltage or current, but only one of those comes with a penalty. Increasing current increases electrical losses exponentially:

Losses = Resistance x Current2

Thus, the best bet today for moving power over distances is by using high-voltage lines. This is the transmission system — most states define transmission at 100 kV or higher, and in the US transmission lines go up to 765 kV. The lines can carry hundreds of megawatts (MW) to a few gigawatts (GW). In a year, the average US home uses only 10MWh. Transmission lines bring bulk power to the distribution systems, which move the power around the smaller local lines we see around our neighborhoods.

Why move it at all?

Every decarbonization study finds that we need to dramatically expand our transmission system to reach our goal, even after accounting for local resources. It’s simple economies of scale. Rooftop and community solar, and home and EV batteries, can only go so far, especially any place other than the southwest, and those investments must be made everywhere. Electricity transmission allows a single investment to aggregate and provide power to multiple regions. In 2020, MIT looked at decarbonization pathways at various scales, and found that more regionalization led to less expensive overall systems and more system benefits.

A quick look at recent extreme weather proves out the value of being able to share resources. This summer southern California experienced an extreme heatwave. The grid operators pulled in power from neighboring regions to keep the lights on, even while asking consumers to limit their usage. During the winter storm event of 2021, Texas was unable to do the same, resulting in multi-day blackouts for many residents. California is fairly well connected to its neighbors via transmission, unlike Texas.

This is not to discount the need for investment in local solutions, especially technology solutions. Southern California imported a lot of energy, but it also asked its residents to reduce their consumption, something called “demand response.” Demand response could be so much more than simply manually reducing consumption, though. In extreme cases, where the power demands could not be met, rolling blackouts could be replaced, or at least tempered, by selective energy management — utilities turning off water heaters or adjusting thermostat settings and EVs providing power back to the grid are just the tip of the iceberg for what a democratized system could provide — with the right technology in place.

How do we get there from here?

Transforming the way the grid works, and the way we work with the grid, requires both hardware and software changes. The software challenges of the grid are the software challenges of many application areas: gathering, managing, analyzing and acting on lots of data. The hardware challenges are a bit different.

There are four ways hardware can help the transmission system today:

Advanced conductors: New kinds of transmission lines that can carry more current. The exponential power losses from increased current dissipate as heat and cause lines to sag due to the aluminum expanding. Advanced conductors use stronger cores to limit sag (a safety issue) and allow more power on the line. The next frontier of advanced conductors is superconductors, which are incredibly cold and therefore can carry much more current without much loss.

Power flow management: Electricity takes the path of least resistance, so power flow can be managed by changing the resistance. These semiconductor-based devices can change the characteristics of a line temporarily to influence where the power goes. This leads to better use of existing infrastructure for more reliable and cheaper power. With more intermittent resources coming on line as solar and wind continue to get cheaper, this kind of management is increasingly important to ensure that clean energy can get to where it’s needed.

Line sensing: Current carrying capability is determined by the weather conditions. For safety reasons, lines can carry more power on colder and windier days (as long as they aren’t too windy), and less power on hot and sunny days. For decades, line limitations have essentially been set from weather stations, which have pretty poor resolution. Sensing and communicating the microclimates of transmission lines allow for far more effective use of the existing system.

Modular transformers and converters: Electricity transformers are the building blocks of the grid; they are the components that turn low voltage into high voltage and vice versa. Converters are the components that turn AC to DC. Both of these essential components need a modular solution. Our grid is surprisingly bespoke — modular transformers and converters would enable a faster and cheaper expansion of capacity. This is the least technically ready option of the list.

Why is changing the grid so hard?

Though the grid is sometimes compared to the highway system, building it out and managing it is far more complex. A traffic jam in NYC does not cause a traffic jam in Nashville, but the interconnected grid can have such far-reaching consequences without sufficient management. And electricity must be used as it is generated — the electrons can’t show up 30 minutes late because of a detour. Adding more storage to the grid will help this last aspect of course, but the operations challenge still remains. Storage is another component that must be managed to ensure the electrons are all still accounted for.

This complexity makes most utilities risk-averse. The regulated monopoly structure does not incentivize innovation or maximization of infrastructure use. It also makes it difficult to build high power lines to move power across states. At the transmission scale, we largely have the tech but are stymied by the policy barriers. At the grid edge (i.e. the residential meter), we need hardware and software tech to be proved out and then deployed at scale to change the way we use electricity. This area has seen the most innovation lately because it is experiencing the most technology changes: smart thermostats, electrified heating, and electronic vehicles are changing how (and how much!) we think about electricity. There are still data access and integration issues that must be tackled to reach the full potential of distributed resources, though.

As my wise friend noted — someday the grid will allow us to more actively participate, but we’re not there yet.

Prime Movers Lab invests in breakthrough scientific startups founded by Prime Movers, the inventors who transform billions of lives. We invest in companies reinventing energy, transportation, infrastructure, manufacturing, human augmentation, and agriculture.

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