The Minuteman of the half hour

Posted on Apr 25, 2019
The Minuteman of the half hour

The Concord Minuteman – “Minutemen were civilian colonists during the American Revolutionary War. They were known for being ready at a minute’s notice, hence the name. They provided a highly mobile, rapidly deployed force that allowed the colonies to respond immediately to war threats.”

The burgeoning popularity of electric vehicles and the increase in renewable micro-generation are undoubtedly good things. But the system for balancing the UK’s electricity networks was conceived for a time when electricity came from a few predictable and controllable power stations and when the biggest consumer of electricity in the average property was an electric kettle.

Mismatches of energy generation and consumption in a local area can cause physical damage to network infrastructure, as energy rushes into or out of the local network through the ‘pinch-points’ that are the connections to the national grid. Network operators, therefore, expend vast amounts of money and effort on ensuring that their local area remains balanced. Although network operators build in a lot of redundancy at great expense, they must sometimes still cut off a large consumer, such as a factory, or a generator such as a solar farm, to prevent damage, thus impacting productivity and wasting much-needed renewable energy.

A Local Energy Market allows consumers to buy energy generated within their local area. Because locally produced energy can be sold locally for more than a supplier will pay through a Feed-in Tariff, but is still cheaper to the consumer than energy bought from a traditional supplier, everyone in a Local Energy Market has an incentive to keep energy local, by generating it when someone locally wants to buy it or by consuming it when someone locally is generating it, and therefore to invest in the energy storage infrastructure which makes this possible.

This automatically balances the local network area, helping to reduce the amount of money that needs to be spent on network management and infrastructure, and, ultimately, helping to encourage local renewable generation. Everyone’s a winner!

To pull off this balancing act energy needs to be traded on time scales shorter than the half-hour settlement periods traditionally used in the electricity industry. Whilst, within a half hour period, a generator and consumer might match in terms of total energy generated and consumed, they might nonetheless fail to match in terms of power at any point within that half hour. It only takes minutes of the network being unbalanced to cause some very expensive damage, so matching based on half-hour averages just won’t do.

The graph below, of current generated by a solar panel over a day, shows just how much real-time generation power can vary from the half hour average. Because of this, charging a battery to absorb excess solar generation, for example, if done on the basis of half hourly average power, will at best have a minimal effect on network balancing, when the solar panel’s real-time generation power is higher than half hour average, and at worst might actually make the balancing situation worse by pulling energy from the grid when the solar panel’s real-time generation power falls below the half hour average.

Swanbarton’s Real-Time Trading Platform can detect and respond to local energy imbalances within a minute, providing the price signal necessary to make it economically viable for a battery charge or discharge, or turn off an unnecessary load, thus balancing the system in close to real time.

This reduces the need for traditional balancing services, which are largely procured in advance by network operators based on extremely conservative long-term energy generation and consumption forecasts, necessitating huge amounts of redundancy in the system due to the inaccuracy of such long-term forecasts.

The Real-Time Trading Platform is currently being tested on the Isle of Iona in Scotland, and Swanbarton has just secured funding to develop fully operational versions of the platform in Rwanda and Nepal, with our partners Scene Connect. We’ll update you with progress on these projects as it happens.