Better Integration: Pairing renewable energy systems with energy storage

Pairing renewable energy systems with energy storage

Rajiv Menon, Country Manager and Managing Director, India, Black & Veatch

Ambitious emission reduction programmes are driving unprecedented amounts of renewable energy into the grid as the world strives to em­brace a zero-carbon energy future. Inte­grating re­n­ewable energy resources while also im­pro­ving the reliability of India’s electric grid is a significant challenge and will require the use of energy storage systems and other modernised grid enhan­ce­ments to accelerate a successful energy transition.

In 2021, India, an economy traditionally de­pendent on fossil fuels, pledged at the COP26 conference in Glasgow to inc­re­ase its non-fossil energy capacity to 500 GW and meet 50 per cent of its energy requirements from renewable energy by 2030, and achieve net zero emissions by 2070. The pledge recognises the deep in­te­gration of fossil fuel resources in India’s energy mix and the recurring climate challenges that are stressing the grid assets. These two factors will requi­re significant investment in new generation, transmission and distribution resources.

Wind power is viewed as an increasingly significant element of India’s new energy future. In June 2022, the country an­no­un­ced that it will auction 4 GW of offshore wind per year for a period of three years starting 2022-23 for development off the coast of Tamil Na­du and Gujarat. Solar PV generation at sc­ale will also play an im­portant role in shifting India’s economy from its historic reliance on coal power.

Over the years, India has committed to de­veloping close to 500 renewable energy pro­jects, with a value of about $196 billi­on, including wind and solar resources.

Enter energy storage

Supportive government policies such as the offshore wind plan and the production-linked incentive (PLI) scheme for high efficiency solar PV modules are en­co­uraging India’s private and public po­wer sectors to aggressively pursue the implementation of large-scale renewable energy generation projects.

While wind and solar power help resolve the climate crisis by replacing fossil fuel energy with zero-emission electricity, their variability creates challenges for power sy­s­tem operators seeking to increase ac­cess to reliable power across the country.

Hybrid renewable energy projects pair renewable energy from solar and wind fa­c­i­lities with energy storage systems, in­cluding battery energy storage systems (BESSs) and eventually green hydrogen sto­rage. Such combinations improve grid operators’ ability to meet customers’ rou­nd-the-clock (RTC) power supply re­quire­ment. These systems reduce the risk of curtailment by effectively smooth­ening electricity prices through arbitrage, management of evening energy ramps and backup power.

So far, several large hybrid projects utilising solar and wind technologies paired with storage solutions have been awarded in India. More public tenders for hybrid projects are expected, mirroring state-ow­ned utility Gujarat Urja Vikas Nigam Limi­ted’s (GUVNL) plans to enter into power purch­ase agreements for up to 500 MW of rene­wable energy projects along with en­ergy storage systems for the rural electrification of off-grid villages in Gujarat.

Different energy storage technologies will be required to balance the demands of a population seeking to boost electrification across the residential, commercial and industrial sectors.

How much storage do we need?

Lithium-ion (Li-ion) batteries, which can support up to eight hours of storage, are currently among the most mature and economical BESS technologies available. Li-ion batteries are the lightest in weight and smallest in size of any commercially available battery chemistry, which makes them a suitable option available today.

Lithium-iron phosphate is also the least prone to thermal runaway, in which a battery’s short circuits heat up and catch fire. Unlike other Li-ion batteries, when lithium-iron phosphate is forced to short-circuit, it remains cool and composed.

BESS is favoured for its flexibility and capability to perform multiple functions in a single facility. For example, in a freq­u­en­cy regulation role, BESS can help ba­lance electri­city supply and demand, making the grid st­a­ble and reliable. In an arbitrage role, BESS can assist in saving electricity when it is not needed to be us­ed later when it is n­e­eded. That said, Li-ion batteries may fa­ce potential future supply chain challe­n­ges as they are extremely mineral-intensive.

Other storage options include thermal storage, in which heat is stored in the form of steam, molten salts or other mediums for use at a later date; and emerging battery technologies such as flow batteries or alternative chemistry batteries.

India also has the opportunity to deploy pumped storage hydropower (PSH). PSH plants are storage systems based on hy­­­dropower operations between two or more reservoirs (upper and lower) with an ele­vation difference. PSH plants are geo­graphy and weather dependent, have long gestation periods and lack modula­rity. However, PSH plants are a highly effective and viable form of storage when conditions permit.

Hydrogen energy storage

In addition to short-duration energy storage, Asia requires cost-effective, utility-sc­ale, long-duration energy storage to un­lock the full potential of renewable energy to cut carbon emissions. One such emer­ging longer-duration technology is hydrogen.

Hydrogen, as a form of chemical energy storage, is ideal to both complement and serve as a reliable alternative to batteries, particularly when hydrogen prices will be­come more competitive going forward. Gr­een hydrogen, produced through the electrolysis of water powered by renewable energy, offers a carbon-free solution.

To be economical, traditional batteries need to be charged and discharged on a daily basis. Hydrogen, on the other hand, can be produced continuously and sto­r­ed, providing seasonal storage that can be used for backup power, limited only by storage volume capacity. As an example, excess solar power captured during summer could be stored as hydrogen for use as an energy source in months when solar power generation is more constrained.

Along with batteries, hydrogen can be procured from generation facilities and de­ployed when it is needed with fast ramp-up times, much like the natural gas or diesel backups in use today. This flexibility and its feature as a carbon-free, mineral-free electricity generator provides premium benefits that offset the conversion losses as hydrogen is extracted from water, stored, then used in backup turbines or engines that are the conventional power equipment so­­urces that produce electricity.

Diversifying revenues

Another capability hydrogen offers that is unique to other storage technologies is its potential for direct use. For example, as a feedstock in the hard-to-carbon-abate ce­ment, steel, chemical and petrochemical industries; as a zero-carbon fuel in fuel-cell vehicles; for creation of synthetic fuels ran­ging from methanol to gasoline to sustainable aviation fuel; and as “green am­m­o­n­ia”, an energy storage medium whi­ch can be more readily transported compared to li­­q­uid hydrogen. Multiple re­venue stre­a­ms make hydrogen even more valuable. As cost remains an issue for hydrogen today, it is critical for developers to consider its full potential as an energy source.

To advance hydrogen energy storage technologies, these projects will first need to be demonstrated and scaled up so as to lower cost. Further, regulation changes and government incentives will be re­qu­ired to speed up the transition.

In 2021, India launched its National Hydrogen Mission to aid the government in meeting its climate targets and making the country a green hydrogen hub. The eff­orts of the mission have led to the de­ve­lopment of the Green Hydrogen Policy. The policy aims to scale up green hydrogen production and its utilisation in India by identifying manufacturing zones for green hydrogen, and providing concessions to developers to set up renewable energy-based green hydrogen and green ammonia projects.

Where to start?

In India, a combination of electrochemical storage and hydrogen will ultimately be required to meet the country’s RTC power requirements. This journey is far from strai­ghtforward. Factors such as the evolving geopolitical landscape, technology ma­turity and costs, contingent infrastructure modifications, time-to-deploy, developme­nt of ancillary markets to monetise storage deployments as well as global su­pply chain issues will all impact the optimal mix of these systems and challenge the timeline for cost effectively integrating storage with variable renewable energy resour­ces and creating stable and reliable decarbo­ni­sed electric grids in India.

What is critical is that both the public and private sectors remain focused on their co­mmitments and vision for a decarbo­ni­sed future and work together to ac­hieve their targets while maintaining reliable energy systems that continue to support the country’s growth and prosperity.