Would your IoT system freeze up in a storm?

In February of this year, the US state of Oregon suffered one of its most intense ice storms in living memory. Heavy rain fell into sub zero temperatures and froze immediately on contact. Trees carrying five times their own weight in ice collapsed onto the electricity grid which began to fail on a massive scale. The storm not only took out power supply to customers, it also took out the power to the communications towers the grid relied on. 

This and other major storms raise interesting questions about the resilience of 4G and 5G Smart Grid IoT systems. Specifically about the role low cost, low earth orbit (LOE) IoT satellites could play in making smart grid communications more resilient.

The storms in Oregon knocked out electricity for over 730,000 homes, they also cut power to cell towers. Those 4G and 5G towers are a critical component in providing the internet backhaul that powers Smart Grid IoT systems. Those Smart Grid systems are the eyes and ears that maintenance teams need as they work under difficult storm conditions to recover the grid.

Assuming cell towers physically survive the storm itself, they will generally have a battery or a generator back-up that kicks in when the power goes out. But this will only last a short period. As was seen in both hurricane Andrew and hurricane Katrina, in a large enough weather event, those back up systems tend to fail well before the grid is restored. This means smart grid IoT communication is lost just when it could offer the maximum value to teams in the field. 

A common complaint from communications network managers interviewed after Hurricane Katrina was that the auxiliary generators were unreliable because they were either poorly maintained or simply ran out of fuel before crews could get to them along the roads strewn with trees and debris. While many generators have now been replaced with lithium ion batteries, these batteries just become expensive paper weights, after a few days, if the grid is not restored to recharge them.

In the case of the Oregon’s ice storms, with power going out in so many areas of the state, even the fibre internet services that many IoT systems rely on became disrupted as their infrastructure lost power. At one point Comcast announced that 125,000 customers in Oregon and Southwest Washington were “still without internet service”.

These simultaneous grid and communications systems failures are inevitable when the systems exist in the same physical environment and this presents an interesting challenge for Smart Grid designers.

Optimally, grid related Smart Grid IoT systems should be designed to be as independent as possible of the grid. In a perfect world the IoT system would be capable of operating uninterrupted during grid outages of any length. If that independence could be achieved then critical sensor data would continue flow from around the grid to aid in recovery efforts. 

How do network operators evolve their IoT systems to have that improved independence and resilience during large scale weather events? One solution might be space. The storms that can wreak havoc on the grid do not affect the satellites passing over it.

While satellite connection has historically been too expensive for large scale Smart Grid projects, the new low cost IoT oriented satellites services, such as the Swarm network, make it an economically feasible option. Swarm Technologies (which reaches 1 minute latency by October 2021) offers such a low cost of IoT connectivity that grid operators can now seriously consider deploying satellite IoT right throughout their operations, without having an annual OPEX blowout.

If the IoT data backhaul path is up in space, safely out of harm’s way, there would no longer be any single points of failure in the Smart Grid IoT system. While individual grid asset sensors might be disrupted by a weather event, any grid related sensors that remain intact with a battery power supply will continue to provide helpful grid intelligence. 

Battery life, for a low energy wireless IoT device, can be impressive. As an example, ioSphere are designing our new Nexus IoT SWARM satellite gateway to include an onboard battery capable of providing a full month of IoT data transmission (for up to 150 sensors) via the SWARM stallite IoT network if mains power supply is lost. In addition we are working to provide a modular solar power pack for the SWARM satellite gateway that can completely replace the need for any mains power supply to the gateway. In this configuration the IoT gateway will provide SWARM satellite connectivity for grid sensors (over LoRaWAN) indefinitely, regardless of the state of the local grid.  

At ioSphere we’re already having some interesting conversations with grid operators around the world and learning about how the Swarm satellite network might be used to address their industrial IoT requirements. Exactly how LEO satellites like SWARM will complement other IoT data channels such as 4G and 5G cellular in grid communications remains to be seen. The General Manager of one large rural electricity grid recently told us he expects “every aspect of grid IoT communications to go to satellite eventually”.

However it plays out, LOE satellites will certainly have a role to play in bringing the most remote grid assets into the industrial IoT system. But, with events such ice storms and hurricanes revealing the genuine vulnerability of 4G and 5G cellular IoT networks to extreme weather, it seems likely that low cost IoT oriented satellites, such as SWARM, will also be used as fall back service - to maintain visibility of critical infrastructure assets inside areas that have reliable cellular service during normal conditions.