Net Zero Emergency Power

Generation or Storage

Originally published here.

Many electricity customers in all customer classes have fossil fueled emergency or standby generators which they use to power some or all of their electrical loads in the event of a grid power outage. For some commercial customers, such as hospitals, standby power systems are essential to assure the safety of patients such as those undergoing surgical procedures. For some industrial customers, such as those who operate continuous processes, standby generators are required to avoid loss of product in process or to avoid damage to equipment. For many other customers, emergency or standby generators are used to avoid the inconvenience of power outages.

The net zero energy economy would require elimination of these on-site fossil fueled generators since they are too small to justify implementation of carbon capture and storage systems to eliminate CO2 emissions. In some cases, on-site generation could be replaced by electricity storage systems, charged either by the grid or by on-site solar and/or wind generation.

State laws generally require that standby generators for hospitals must either be fueled by pipeline natural gas or supported by on-site fuel storage. The design process for these installations includes determination of the demands of essential electrical loads which are to be supported by the generator and the duration of the grid outage through which the system must be able to operate. This information is used to size the generator(s) and to determine the required on-site storage for other than pipeline-delivered fuels.

The design process would be similar for standby systems based on electric storage batteries. Battery system design would determine both the cumulative demand of the loads to be supported by the batteries and the cumulative power consumption of those loads over the expected duration of the grid outage. This design process must be conservative, since the batteries cannot be recharged during power outages. Also, these battery systems would require long-duration batteries capable of supporting the required loads during multiple day outages.

Some larger customers might negotiate with the grid operators to install grid scale storage capacity on their properties, with the understanding that the customers would have first call on the battery capacity in the event of a grid outage. However, that would require that battery capacity installed on the customer sites be long-duration and that it be first in line for recharging in the event of storage drawdown due to limited wind or solar generation output.

Some larger customers or groups of customers might choose to install small modular nuclear reactors (SMRs) on-site. However, those customers would likely choose to use the SMRs as their primary source of electricity and to use the grid as backup or to supply loads which could be safely shed in the event of a grid outage.

An “all-electric everything” renewable plus storage grid is likely to be somewhat less reliable than the current predominantly fossil plus nuclear grid, especially during the period of rapid capacity and demand growth. This might lead greater numbers of customers to install on-site electricity storage systems.