Mention energy storage and many people will first think of batteries. While this is part of the story, electricity is just one form of energy. Growers may be more familiar with heat released through the combustion of fuel in a boiler or engine, for example. Heat too can be stored, often as hot water in accumulators or buffer tanks – think of them as heat batteries.
But what’s the point of energy storage? Well, it means surplus electricity or heat can be stored when supply exceeds demand, for later use. As an example, a solar PV array harvests the sun’s energy during a bright summer’s day, uses batteries to store the electrical energy and releases it at night when lights are turned on.
Alternatively, batteries can be used for arbitrage (i.e. trading energy): energy can be bought from the grid at night, when prices are lower, and sold back during peak hours when prices are considerably higher. The profitability of this type of operation should be carefully considered, however, as only a limited amount of energy can be stored, meaning a relatively modest daily income. Consider also the cost of the batteries; arbitrage alone is rarely a profitable option.
The most financially attractive option at present is ‘contracted grid support’, where National Grid pays the owner a fee for helping out at times of stress. This can offer returns in the region of 7-12%.
Growers are likely to be more familiar with heat storage than batteries. Suppose a boiler is running to produce and supply CO2 to a glasshouse; the heat can be stored if not immediately required. Buffer tanks and accumulators can also be used to help meet peaks in heat demand and to improve systems operating efficiently by supplying heat even when the primary heat source isn’t operating. To make the most of heat storage, growers must be considerate and efficient, such as the use of insulation on tanks or ensuring optimum setup of the heat source.
For further information on the subject of energy storage, come along to our GrowSave event on 20th September in Kenilworth. Click here to sign up... We will also be holding an event on the topic of Looking After Your Biomass Boiler in November, more details will be released on the GrowSave website soon.