A Big Future for Giant Batteries
A Big Future for Giant Batteries

Renewable energy (RE) is a key part of the future of the electricity industry – and the Battery Energy Storage System (BESS) has a critical role to play in ensuring power can be reliably delivered to users, whatever the weather and whatever the time of day or night.


Catastrophic wildfires and extreme weather worldwide in the last few months have alerted us to an urgent reality facing humankind: We must act quick to reduce carbon dioxide emissions and halt the advance of climate change.


The stark warning is echoed in an alarming new report by the United Nations Intergovernmental Panel on Climate Change, which found global surface temperatures have risen faster since 1970 than in any other 50-year period in the past 2,000 years.


RE is clearly part of the solution – but can it provide an electricity supply that is reliable enough to sustain our economic development, as well as clean enough to counter the impact of climate change?


Watching the weather

One of the most obvious and fundamental features of RE is that it is affected by the weather. Solar irradiance varies significantly depending on the cloud cover and time of day. Wind energy, meanwhile, is affected by seasonal fluctuations and the location of the wind farm.


A “duck curve” illustrates the common phenomena surrounding the difference between the level of demand for electricity and the amount of available solar energy throughout the day. 

Duck curve
Source: California ISO


The duck’s tail shows a peak in the morning as people start to use electricity. Then, solar power generation picks up as the sun rises, demonstrated by the duck’s belly.


As the sun sets and solar systems stop generating power, network demand rises to a peak at the back of the duck’s head.


If the duck’s belly drops too low, it means RE sources are producing too much electricity, which will either get wasted or damage the grid. 


At the point of the duck’s head and tail, there isn’t enough electricity coming from RE sources to meet demand, and it has to be sourced from elsewhere.


That is where a BESS comes into play.

Saving energy for rainy days

BESS can help straighten out the duck curve dilemma by storing surplus energy when electricity generation exceeds consumption, and then releasing it during times of peak demand.


The technology is mature and its efficiency is high. However, development has stalled for some time because of fire safety concerns and the high cost of lithium-ion cells.


A fire in July at the Tesla Megapack BESS in Australia, for instance, took 150 firefighters four days to extinguish, highlighting the potential risks of using batteries to store RE.


Other developments favour the expansion of BESS projects, however. For one thing, the price of a lithium-ion battery pack has fallen drastically by 89% from US$1,100/kWh in 2010 to just US$137/kWh in 2020, according to BloombergNEF


In addition, utility companies are becoming more experienced in battery technology. A utility-scale BESS can now be used as a primary power supply or as a resource to plug the gap between demand and RE supply, allowing governments and utility companies to include them in long-term energy infrastructure planning.


Harsh lessons from California 

The summer heatwave of 2020 brought harsh lessons in RE management from California, where millions of residents faced hours of power outages because of rolling blackouts that affected hundreds of thousands of homes and businesses.


RE supplies around 36% of California’s electricity, and the state aims to use RE for 60% of its energy by 2030 and to achieve a carbon-free grid by 2045.


Critics say inadequate supply-demand planning and market issues led to the blackouts, while a root cause report concluded California should be more aggressive in investing in long-term energy storage, ensuring power from resources like solar are available at peak demand times.


In an effort to avoid future blackouts, the state is investing in 1,700MW of new battery capacity by August 2021, sufficient to power 1.3 million homes. 


California will need to install an estimated 48.8GW of energy storage – five times the output of all utility-scale batteries currently operating worldwide – to meet its target of a carbon-free grid by 2045.


Lawmakers in the US Congress introduced legislation in March to create a tax credit for residential and utility-scale energy storage projects. This will help support the widescale expansion of BESS projects and RE systems across the country. 


A burgeoning battery industry

Across the Asia-Pacific region, BESS projects are taking shape as the move towards a greener future with greater use of RE gathers pace.


EnergyAustralia has brought forward the closure of Yallourn Power Station in the state of Victoria by four years and is building a new 350MW battery storage facility, the largest in the world, to help provide more RE.


For households, EnergyAustralia’s Solar Plus plan has made solar energy simple by charging selected customers zero upfront cost and a fixed low rate for the electricity they use. Harnessing virtual power plant technology, the company can manage the solar and battery systems installed at customers’ homes, improving the stability of the electricity grid.

In Hong Kong, CLP Power has developed the city's first commercial-scale standalone RE system on Town Island, combined with a BESS to support the demand for electricity at night.


As energy storage becomes more affordable and provides greater flexibility to balance demand and supply throughout grids, BESS projects will continue to flourish and will play an increasingly pivotal role in the global transition to clean energy.

Hong Kong’s standalone RE system
Hong Kong's first commercial-scale standalone RE system on Town Island has an installed capacity up to 192kW.