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All about ESS from Definition to Key Technologies

Among many different forms of energy, electricity is the one that isn’t very easy to store. In order to match its demand, the supply of this power has been tweaked according to its consumption load as hydro-electric plants can use a pump storage method to control this and manage their supply and demand issues.

ESS can be categorized into two different systems as physical storage systems (CASE, flywheel) and chemical storage systems (lithium batteries, NAS batteries, lead-acid, etc.). The battery related technologies have significantly advanced since 2000s as they have become the key resources of storing energy from power generation terminals to power transmission/distribution and finally to power consumption.

This type of ESS utilizing batteries is specifically called BESS (Battery Energy Storage System). Today let’s take a look at BESS based energy storage system, which is one of chemical storage systems for LG CNS ESS business.

Global ESS Market

[Figure 1] Global ESS market (Source: Navigant Research, July 2014)

[Figure 1] Global ESS market (Source: Navigant Research, July 2014)

As you can see in Figure 1, the global ESS market is expected to hit $880 million by 2020. The growth rate is also as high as 63.3% based on the CAGR.

As the market is still in its beginning phase, the price for lithium battery and legal/institutional systems haven’t been settled, yet. Then, how can this ESS with a great potential for growth be utilized?

Why Do We Need ESS?

The utilization of ESS is briefly introduced in [Table 1] below.

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[Table 1] Utilization of ESS, Sandia report (DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA, 2013)

Some of you may find these terms in the table quite complicated. According to the data analyzed by the United States Department of Energy, ESS can be used for 16 different purposes. Based on the current businesses we are witnessing, the use of ESS can be summarized into three big categories below.

  1. Peak management (peak shifting and peak cut)
  2. Renewable power source: renewable integration
  3. Ancillary Service

–  Frequency Regulation

–  Voltage Management

–  Reserved Service

–  Black Start

Let’s find out how ESS is used one by one.

Peak Management (Peak Shifting / Peak Cut)

ESS always starts with peak management.

Peak management basically means storing extra energy on ESS during the light load (when electricity is cheaper) for later use during peak times (when electricity is more expensive).

This is to keep a balance between demand and supply by storing energy when the demand is low and using it when the demand is high. The mechanism can be graphed like in [Figure 2] below.

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Peak cut stands for lowering the load during the peak time each year by using ESS in order to reduce the electricity rate. By saving on the energy consumption during the peak months of July and August, the electricity rate for the entire year can be lowered.

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[Figure 3] Peak Shifting

As in [Figure 3], peak shifting refers to when power is saved during the part of the day when electricity is cheapest and then used when it’s most expensive to save money.

ESS projects established by LG CNS at Shilla University, LG Chem Iksan factory and Ochang factory can be seen as examples of peak management.

Renewable Power Source: Renewable Integration(RI)

ESS, which started with peak management, has become more classified into various forms on electricity grids since 2012. The area where ESS is expected to be most actively used is RI.

The most popular renewable power sources are solar and wind power. Wind power is growing especially fast, as it shows a high establishment utilization rate and requires only small areas of land to produce.

Wind power, however, has one critical problem which is intermittent energy production. Because wind does not blow constantly, power generation relying on wind is also destined to be irregular. This can result negative effects in connecting with the existing wattmeter.

ESS can become quite useful for such an unbalance in wind power generation.

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[Figure 4] ESS simulation for RI to control intermittent wind power generation (Source: LG CNS SGS Lab)

In [Figure 4], the pink line means wind power generation and it shows that the amount of power generated each hour differs greatly. The yellow line is the power discharge from ESS to cover this gap, and the blue line is for the total power generation integrating wind power generation and ESS power discharge.

You can also see on the bottom of [Figure 4] that the pink line bounces up and down noticeably when it only depends on wind power. This means the power generated by wind is highly irregular.

With the help of ESS, however, this irregular line becomes much more consistent as you see from the blue line. Like this, ESS assists power grids by combining new and saved renewable power sources making power generation more stable.

Ancillary Service

Ancillary service is the service which deals with quality issues that may occur when the power supply and demand are unbalanced.

In order to run a power system, consumption and generation have to figure out the perfect match. So far, the generation terminal has adjusted the supply based on consumption. Although it is theoretically correct, it would not be easy in reality.

When power generation and consumption are not in balance, quality issues involving frequency and voltage will occur. This may cause partial power failures and even black outs. The service that takes care of these kinds of problems is the power system ancillary service.

The ancillary service consists of four different types: Frequency regulation, voltage management, reserved service, and black starts. In this article, I’ll cover frequency regulation only.

Currently power transmissions mostly use alternating currents (AC), though there are rare cases of direct current transmission. AC has a frequency of 60 cycles per second. The problem is that this frequency goes down when the consumption is higher than the supply, and goes up in the opposite case.

As we see from [Figure 5], frequency becomes irregular as time passes. In order to keep the frequency at 60Hz, ESS rapidly (200ms) goes back and forth between charging and discharging.

Through this process, where ESS heightens or lowers the frequency within 200ms, and it is called frequency regulation.

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[Figure 5] Frequency regulation (Source: LG CNS SGS R&D center)

In 2014, LG CNS has achieved the contract for the frequency regulation project from Korea’s one and only electric power supplier, Korean Electric Power Corporation and it is currently test running.

Although the ESS market is in its early phase, its potential is endless. ESS is expected to be used in a wide range of areas as the optimal alternative in order to overcome unstable power supplies.

LG CNS is endeavoring to obtain the necessary references and skill sets for ESS, based on its anticipation and predictions for the electricity market. As we announced recently, we’re raising the level of ESS technology up to the highest global standard by establishing an environment-friendly micro-grid for Ulleung Island.

Written by Myoung Jin Bae, Business Development Senior at LG CNS Smart Grid Business Team

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  • Raj Nath

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