Firming or firm generation is how the electricity system stays reliable when demand is high, when generation from intermittent sources of generation such as wind and solar is low.
Wind and solar generation aren’t always available at the exact moment electricity is needed, so firming provides backup during those periods.
Firming generation can be fuelled from different sources. Coal is one option, but it comes at a financial cost and produces carbon emissions. Domestically produced gas is another but is in decline. Stored LNG is another potential option if the upfront and ongoing costs stack up. It will also increase emissions. Geothermal steam and fluid is another option. Geothermal has much lower emissions than coal or gas but is not emissions free.
Water stored in hydro lakes is another option. Think of it like a giant battery - it can be saved and used when it is needed most, such as during winter peaks or when wind and sun aren’t available. At present, New Zealand can only store around 16 weeks of electricity in its hydro lakes. In periods of low rain and inflows to the hydro lakes, when hydro generation is operating at lower levels than usual, other sources of firming generation such as thermal are required.
What Meridian is doing
Meridian is focused on firming the system in ways that are practical and lower costs. By maximising renewable generation and looking at ways to enable more stored water, we help keep the system reliable. Over time, this will create lower prices, more resilience and a system that performs better under pressure.