The 1.1 MW/2.15 MWh Tesla Powerpack battery system installed at the University of Queensland saved almost $ 74,000 in energy costs in just three months, and not just by storing cheap solar energy.

The UQ Energy and Sustainability Team has released a report for the Q1 2020 of its battery system. The results show that a battery system that pays for itself by saving from the university’s existing solar systems received $ 73,938 in the first quarter of 2020. And it did this not just by storing energy when grid prices were low and discharging when they were high, but also – in fact, mostly – by helping to balance the grid, including jumping to attention when major coal plants failed.

The UQ battery has been developed to deliver revenue and value from the combination of four distinct services:

Arbitrage
A custom developed control system (the ‘Demand Response Engine’ or DRE) aims to charge the battery when prices are low and discharge when prices are high - maximising the spread between prices to help offset energy costs while respecting the fact that the battery only has a finite storage capacity (roughly two hours at full power).

Peak Demand Lopping
It is intended that the battery will help UQ to reduce its monthly peak demand charges by lopping the top off the highest demand intervals of each month. The control strategy that enables this functionality was not completed in time for Q1 2020.

Contingency FCAS
Through a partnership with Enel X, the battery is paid to remain on standby to respond to sudden disturbances to grid frequency from events such as power plants tripping offline. Revenue is earnt by bidding this response capability into the NEM’s three contingency Frequency Control Ancillary Services (FCAS) markets.

Virtual Cap Contract
As a spot price exposed customer, UQ is required to put hedging strategies in place to prudently manage risk. One option available is the use of cap contracts which limit financial exposure to extreme prices (typically >$300/MWh). These hedging products can be considered as a form of insurance. The battery is able to provide this insurance ‘virtually’ in place of buying a cap contract by responding quickly to high price events and minimising UQ’s exposure. Whilst not an exact replacement for a traditional financial cap, this service has substantial value to UQ nonetheless.

62% of the value generated by the UQ battery system over the quarter was generated through participation in what’s known as frequency control ancillary services, or FCAS. Another 26% came from the battery’s virtual cap contract, while arbitrage raised 12%.

Source: The UQ Energy and Sustainability Team report

FCAS is used by the Australian Energy Market Operator to maintain the frequency on the electrical system and, as a behind-the-meter asset of less than 5MW, the UQ battery currently participates in three (of eight) contingency FCAS markets. These markets require capacity to be available to respond to a drop in system frequency below the dead band threshold of 49.85hz within stated timeframes, and for this response to be sustained until frequency is restored to the normal operating range (usually within 10 minutes). As the report explains, FCAS providers are paid for every interval in which they are available to respond to a frequency event.

“One of the reasons UQ has committed to publishing the battery’s full performance data (is) so industry and researchers can learn from the University’s experiences,” said UQ energy and sustainability manager Andrew Wilson.

“The new battery and the solar assets make UQ a significant renewable energy leader, as the whole world looks to chart the path to the new ways we will supply electricity,” said Professor Peta Ashworth, who leads UQ’s Master of Sustainable Energy program.

Featured image: The University of Queensland / UQ's Engineering Precinct Battery system