Solution 1: The SuperGrid

Viren Gupta
Nov 21, 2022
6 min read

Updated: Dec 29, 2022

💡 This blog is meant to assimilate all my readings and solve the crisis of articulation. Each post will address one technology, theory or idea that reduces climate change. It's important to note that all of these solutions need to work in tandem to actually solve the crisis. The blogs will be brief but should provide the opportunity to dive deeper. There may be some gaps in my writing so please validate my musings with external sources. Occasionally, we may have some actual experts and climate tech pioneers who will be writing guest blogs! Please feel free to comment below or reach out.

I wanted to stray away from titling this ”Decarbonizing the Grid” (a buzz phrase for everything clean energy) because I’ve observed a general unawareness towards the logistics and delivery of clean electricity. So, let’s bring some clarity to that piece of the puzzle!

Our Current Grid

The main premise behind the current grid system is to make power where users exist. This means power plants are fairly close to us and, on average, only need to be transported around 300 miles (483 km) from a power plant to a distribution station next to your home.

Visualization of the Grid. Source: Laughing Squid

Two types of current are used to transport electricity: direct current (DC) and alternating current (AC).

AC and DC. Source: Docscity

When Thomas Edison initiated the first power plant, it used DC. However, as the grid scaled, AC won the competition due to a few key advantages:

AC is malleable and can be transformed into higher voltages by expanding its waves (to be transmitted across long distances) or smaller voltages by contracting its waves (to be sent to homes).
When needed, it's easier and cheaper to convert AC to DC, than DC to AC. This makes a compelling case for AC powerplants to catch on and scale, thus, most modern powerplants produce AC inherently.

This grid system has stayed relatively the same since Thomas Edison, Nikola Tesla and George Westinghouse contributed to developing it around the late 1800s and early 1900s. Unfortunately, this lack of innovation has finally kicked us in the a**.

How renewables change the game?

Distance

The thumb rule of “make power where users exist” gets thrown out of the window when dealing with renewables.

Solar vs Wind Energy in the US. Source: NREL

I generated the above visualization using NREL's RE Data explorer which shows the geographical generation capacity of solar energy vs wind energy in the US. Areas stained with a darker red have more direct sunlight (or greater irradiance level) and areas stained with a darker blue have a greater mean wind speed. This articulates that we have more potential to generate solar energy from the southwestern states and wind energy from the central states.

To increase our reliability and to simply fulfill energy needs we will need to transmit this electricity from these concentrated pockets across the country. This will be way more than the average 300 miles that we transmit electricity now. For context, in the future winters when a New-Yorker will need energy, solar energy from Arizona will need to be transported more than 2100 miles or 3400 km.

Vulnerability

Tying in with the distance factor, renewables are very much at the mercy of the seasons and daily weather. Seasonal dependencies make it economically impractical for some city centers to construct wind farms if they only receive a few months of consistent high wind speed (the maintenance and upkeep costs will mitigate the benefits).

Another key factor contributing to vulnerability will be adverse weather events like floods, hurricanes, blizzards, etc. Here is graph depicting the increase in adverse weather events over the last 40 years, and it's not planning on slowing down.

Increase in extreme weather events. Source: Met Office

When these storms take place renewables will stop generating electricity for those few days. This will leave the grid with no alternative option if excellent storage capabilities are absent. On the other hand, even non-renewable power plants have not developed resistance to these weather events despite weather-proof build materials and proximity to users. Above-ground transmission lines are just too fragile.

How to Solve it?

1. High-Voltage DC (HVDC)

Yes, I know regular DC was dismissed earlier as not being appropriate for longer distances due to its low voltage capacity which resulted in Thomas Edison being a sad man and AC being the primary driver of the grid. However, DC was always on the mind of scientists due to its steady-state nature compared to AC’s oscillating nature. Therefore, there have been major technological advances from the 1950s to 1990s that have created High-Voltage Direct Current. There are some clear advantages over the regular AC system:

HVDC cables can be run underground over long distances which means intercontinental transmission lines are possible, along with being a great enabler for offshore wind technologies. Current underground HVDC projects are being built for 260 miles, compared to HVAC’s 40-mile underground limit. Additionally, underground lines are not susceptible to above-ground weather menaces.

Off-shore wind farms connected by HVDC in Germany. Source: PowerMag, Hitachi Energy

Over long distances, HVDC results in 30-50% less energy loss due to conversion technologies and fat cables. The thickness of cables also allows them to have 40% more current carrying capacity.
Since HVDC has a steady state, its flow is much easier to control which results in quicker adaptation to energy needs across the grid. It also has this pretty crazy ability to connect AC transmissions with different frequencies from neighboring countries.
Most of the renewable sources of energy generate electricity in DC which eliminates the additional step of converting to AC

One key disadvantage of HVDC is the cost. Due to its current lack of adoption, we haven’t found ways to construct HVDC systems for nearly the same upfront cost as HVAC. In the field of HVDC, Siemens Energy and Hitachi ABB are the forefront companies.

💡India has been one of the leading countries to adopt HVDC and has many projects in the pipeline with over 2000kms of HVDC already laid down.

2. Long-duration Battery Technology

To address the vulnerability of renewables, we need storage capabilities that are significantly better than the ones currently mass adopted. We need to make sure that we’re secure for the non-sunny and non-windy days. Here are some critical advances in battery technologies:

Flow batteries: these are batteries that store energy in the form of liquid electrolytes in shipping containers (yes, it's f***ing crazy!). One company, ESS, wants to make this mainstream and fill half-acre buildings with this electrolyte liquid (which is made out of iron salts dissolved in water). Having a life cycle of 20 years, this form of battery is one of our best shots to perfect long-duration storage.

Rendering of Flow Batteries. Source: Solar Power World

Iron-air Batteries: these are batteries that harness rusting as a form of energy storage. Electrodes are released when you rust iron, so when you pack a bunch of iron in a cell and effectively rust and de-rust it - you have a battery. Form energy is the major start-up developing this technology. The main argument for this battery is replacing the expensive (and controversial) lithium with cheap iron.

Pumped-storage hydropower: these are batteries that use electricity to pump water into reservoirs on top of hills, and then release the water back down the hill into turbines to regenerate that electricity. Surprisingly, this is 95% of the current long-duration storage in the US but is severely geographically limited to scale.

PSH visualization. Source: The Conversation

3. Smarter Grid

Lastly, we need to combine HVDC, batteries, and grid control technologies to transform our grind into an interconnected smart grid. Grid control technologies are technologies that make use of sensors for real-time communication and insight generation to discover faults, control current flow and re-route excess power to batteries. IBM, Camus Energy, Octopus Energy are all companies pioneering grid control technologies.

We need to make sure to resolve the misalignments of our transmission lines to make sure we have one huge grid - spanning across countries - that is disciplined by AI control technologies. Something like this -