Rethinking energy storage

Energy providers face increasing demand for power to sustain the daily activities of growing global populations

By Antoinette Price

Consumers need access to a continuous, flexible and adequate electricity supply wherever they are. In addition to ensuring the provision of quality, stable electricity, energy suppliers must also consider regulations to make production cleaner, which they can achieve by using more renewable energies and moving away from depleting fossil fuels. Concern for the environment and global consumer habits are helping to drive innovation and develop improved energy storage solutions.

Jenax flexible battery Flexible battery (Photo:Jenax)

Cleaner, more efficient power supplies

Electrical energy storage (EES) is a key technology needed for intermittent renewable energy (RE) integration and expansion of the Smart Grid. When there is no sun or wind, stored power can be used for efficient and reliable on- and off-grid electricity supplies.

IEC International Standards will be central to achieving these goals. They exist for certain EES systems through the work of a number of IEC Technical Committees (TCs). For example, Standards for pumped hydro are developed by IEC TC 4: Hydraulic turbines, and those for rechargeable batteries of various types are prepared by IEC TC 21: Secondary cells and batteries. IEC TC 120: Electrical Energy Storage (EES) Systems, was established to oversee the development of International Standards for all types of EES technologies, employing a systems-based approach rather than focusing on individual energy storage devices.

A report by the International Renewable Energy Agency (IRENA), entitled Renewable Power Generation Costs in 2014, says that renewable energy technologies are priced below the cost of fossil fuels in many parts of the world. It concludes that biomass, hydropower, geothermal and onshore wind are all competitive with, or cheaper than, coal, oil and gas-fired power stations, even without financial support and despite falling oil prices. Solar photovoltaic (PV) is leading the cost decline. Since the end of 2009, solar PV module costs have fallen by 75%, while the cost of electricity from utility-scale solar PV has fallen by 50% since 2010.

The era of ingenious battery storage

EES systems can be categorized into mechanical (pumped hydro), electrochemical (comprising secondary and flow batteries), chemical, electrical and thermal types.

In the case of batteries, the falling price of renewables and groundbreaking battery storage solutions are transforming how we power everything from a patch thermometer to power stations. As battery prices also continue to drop and solar PV is expected to become even more cost competitive, it is an innovative time for the energy storage industry. It is racing ahead to develop a chameleon-like storage technology, capable of adapting itself for use in wearables, smart phones, tablets, electric vehicles, homes and electricity grids.

Energy reservoirs for the grid

Improved technology is modernizing electricity grids so that they are more efficient, cleaner and have increased capacity as they evolve into Smart Grids. Currently, pumped hydro dominates grid-scale storage. This type of storage has many advantages, but it requires two reservoirs with a substantial gap in vertical height.

Over the past decade, several companies have been developing gridbanks. Resembling containers on the outside but mini-power stations within, these energy reservoirs store excess power generated by power plants and could help greatly the transition to Smart Grids using renewable energy.

A Swiss-based company focused on grid-scale storage systems expects to produce a breakthrough battery which can be charged more than 40 000 times, cutting the lifetime cost of utility-grade batteries. It aims to bring an inorganic lithium battery to the market which is safe, non-flammable, highly durable and, the company claims, is currently the only fully dischargeable lithium one.

The benefits include:

  • Storing and delivering electricity when required
  • Keeping voltage and frequency constant to avoid costly fluctuations
  • Reducing greenhouse gases so that fossil fuel power-plants operate more efficiently
  • Integrating renewables smoothly to reduce energy waste and save money
  • Guaranteeing reserve capacity
  • Allowing existing generators to operate at higher efficiency during lower demand times by storing energy produced for use during subsequent peak times
  • Providing up or down ramping support with immediate power supply and no wear and tear to the infrastructure

Keeping the home fires burning

So much of what we do every day runs on electricity. A power cut at home means no TV, fridge, washing machine, stove, power to recharge phones and tablets and no lights. A top-end US automotive company has recently unveiled a battery-based storage system which aims to sustain an entire home. It charges using electricity generated from solar panels, or when utility rates are low, and powers the home during the evening or peak times, when electricity is most expensive.

Together with the solar panels, the batteries, ranging from USD 3 000 to 3 500 for 7 or 10 kWh respectively, are cheaper than the diesel generators used for emergency power.

They would also act as a backup supply to safeguard homes from power cuts and give independence from the grid. Excess energy stored and not used in the day could be kept for peak time use rather than selling it back to the grid only to repurchase it later.

This would not only lower private electricity bills but also reduce costs for utilities as there would be fewer power plants idling during peak times, which in turn would lower carbon emissions.

Storing electricity in cars

Electric vehicles (EVs) were first developed in the mid 19th century. Ever since, their cost, driving range and the recharging infrastructure required to run them have hindered their wide-scale adoption. Vehicles running on electricity are part of the answer to reducing carbon dioxide emissions and moving away from fossil fuels.

Though uncertainties remain on the costs of li-ion batteries for EVs, the technology continues to evolve as manufacturers find new ways to make more compact, durable and safe battery packs. For example, a well-known US car manufacturer has developed a charging technology with a cheaper, faster charging battery. The flattened, compact cylindrical cells are about the size of AA batteries and help address issues of space and safety while reducing costs. Battery power can be scaled up by wiring thousands of these cells together. An innovative cooling system that runs between the cells helps remove excess heat.

Utilities dream about storing excess grid energy in the batteries of electric cars. While feasible, the final hurdle is the car owner, who, mostly because of range anxiety, doesn’t want to leave the car battery half empty. If there is no space in the battery, storage is physically impossible. This might change with new battery technologies that will increase range substantially while offering near limitless and ultra-fast recharging.

With an increasing demand for power storage and portable power, batteries are becoming cheaper. A recent peer-reviewed study concluded that, industry-wide, the cost for li-ion battery packs declined by approximately 14% annually between 2007 and 2014, from above USD 1 000 per kWh to around USD 410 per kWh. The cost of battery packs by market-leading EV battery manufacturers is even lower, at USD 300 per kWh, and has declined by 8% annually. Soon battery-powered vehicles could be affordable for most people.

Looking ahead

The world of energy storage doesn’t stand still. Researchers are looking constantly to optimize storage systems for a wide variety of applications, reducing environmental impact and increasing power output. IEC TC 21 prepares International Standards for all secondary cells and batteries, including safety installation principles, performance, battery system aspects, dimensions and labelling. It also keeps abreast of latest developments and covers new technologies such as flow batteries, ensuring that Standards are fully in tune with this fast-moving market.

Jenax flexible battery Flexible battery (Photo:Jenax)
Renault EV range Electric vehicles (Photo: Renault)
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