Column: Going Green


fact, energy output from a turbine can drop without warning – and there is no proven method to precisely determine when output will improve. The case is similar in photovoltaic


(PV) solar farms. In fact, hydro-electric power is the only energy source that can be physically controlled, since water can be stored in reservoirs and released when required, thus simulating the natural generation of hydro power.


Energy volatility The volatility of renewable energy sources can also create problematic surplus situations. Let’s say wind speeds were to dramatically increase. If unprepared, the grid may not be able to handle the sudden surge in power from a wind power farm and this could cause power outages. In fact, there have been instances of operators paying customers to use excess electricity to balance this surplus. Reserve power flow, or back-feeding,


is one way of managing this excess energy. However, back-feeding isn’t exclusively for renewable sources; it occurs regularly on small-scale power grids, usually during the middle of the day when people are out of their homes. As residential energy demand during these periods is low, some of the generated electricity can be fed back to a transformer through the network. Traditionally, though, distributed


systems did require back-feeding. Most of the power output came from large- scale fossil-fuel sources located on the main network, with power flowing predictably into smaller systems. However, more renewable energy


sites, as well as microgeneration sites, means energy volatility is increasing, causing more occurrences of back- feeding, as well as a new need for energy storage.


Forecasting generation Improved forecasting could alleviate this challenge. However, it is argued that forecasts are often provided solely as a comfort to decision makers – the network operators, investors


in renewable energy and customers. Forecasts, due to their limitations, are not used in the daily operations of energy sites. Accurate forecasting requires


a complicated cross-disciplinary approach, examining mathematics, statistics, meteorology and an accumulation of historical data from the generation site. Even then, the shortcoming of a forecast is that it is simply an extrapolation of what has occurred, rather than certain knowledge about the future. By employing more accurate


forecasting, however, operators could better manage supply and demand. New technology is already beginning to improve the accuracy of predictions by using advanced computer models. However, it is clear that this is best used in combination with real-time system monitoring.


Real-time insights Real-time insights, enabled by smart- grid control software such as COPA- DATA’s Zenon for example, allow operators to actively manage grid behaviour in real time, even though this still doesn’t lessen the volatility of renewable generation. For instance, the software could immediately alert an operator when wind speeds increase. By correlating this data with information from the wider network, the software could provide a warning that a surplus of energy will occur, requiring back- feeding. Back-feeding isn’t always a feasible


option, and, in some instances, excess energy must be stored. Research by market analyst Aurora Energy Research suggests that to meet its renewable- energy targets, Britain requires an additional 13GW of energy storage in order to successfully balance the grid.


Energy storage Energy storage plays an important role in creating a flexible grid. When there is more supply than demand, excess energy needs to be stored safely to avoid wastages. Similarly, when demand is


greater than supply, energy storage allows storage facilities to discharge this stored energy back to the grid. With increasing reliance on renewables, energy storage facilities will be essential buffers for excess power. Aside from the water-storing methods


of hydro-electric plants, traditional electricity grids have almost no way to store excess power. In fact, Aurora Energy Research’s study claims that deploying energy storage on Britain’s network would require a £6bn investment. While there are many research projects dedicated to the development of energy-storage methods, including compressed air and thermal and battery storage, these technologies are still largely in their infancy. On the continent there are several


successful examples of using batteries to store excess renewable energy. This includes a BMW-commissioned battery- storage farm in Leipzig, Germany, on the grounds of its own wind energy generation site. The site uses 700 second- life electric vehicle batteries to store excess wind-generated power before it is fed back into the wider grid. Without knowledge of when, where


and how much energy is required on the grid, battery storage is redundant. Feeding this energy back to the network requires real-time data on the state of the grid. Large-scale installations, like BMW’s facility in Germany, will use intelligent software to constantly monitor and record demand for power and adjust its supply appropriately.


Transition Moving from a traditional energy network to a fully-functioning smart grid is incredibly complex. Britain’s ageing infrastructure means that maintaining and repairing these facilities are essential, but investments in new technology cannot be overlooked. Britain might be capable of generating


100% of its energy supply from clean sources, but until the nation has adopted technologies to efficiently manage, store and distribute this energy, that goal may not come to fruition.


www.electronicsworld.com July/August 2021 15


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