Energy Storage 101

 

Overview:

Energy storage captures energy when it is produced and stores it for later use through a variety of technologies including, but not limited to, pumped hydro, batteries, compressed air, hydrogen storage and thermal storage. 

This ability to store energy for later use enables increased flexibility in an energy system, because energy storage can act as a generation, transmission, or distribution asset – sometimes within a single piece of infrastructure. Energy storage assets can augment any number of resources in an electricity system, including complementing the intermittent generation of renewable assets, responding to fluctuations in grid demand, helping meet peak demand, or reducing the need for generators to increase their output. 

Moreover, the ability to store low-cost energy to supply additional energy during high-cost peaks, increases the amount of energy available within the system, but also reduces costs for consumers. Energy storage can also serve as a backup if power generation is interrupted, boosting the reliability and resilience of the system, and helping to reduce the negative environmental impacts of increased energy demand through the support of renewables, a reduced need for generation, and avoiding peaking.  Slotting energy storage into an existing system can also reduce the need to build additional generation assets if existing transmission or distribution assets might be hard-pressed to meet increases or changes in demand.

 

FAQ’s

Where is energy storage operating in Canada today?

At the time of this being written, there is currently energy storage installed in four provinces in Canada: Ontario, Alberta, Saskatchewan & PEI. There are several additional projects slotted for development in these provinces in the coming years, as well as in New Brunswick & Nova Scotia. 





Can energy storage technology work with all fuel sources?

Absolutely. Energy Storage has direct synergies with intermittent, renewable resources such as solar or wind power, because it can store excess energy for later use when the sun is shining or the wind is blowing, which is why projects often incorporate both elements. Hydropower resources can be used to store energy directly with pumped hydro. 

However, energy storage technology can store energy generated by any resource as demonstrated by ATCO’s gas-storage hybrid project in Alberta (now owned by Enfinite) HERE or the Nuclear Innovation Institute’s recent publication, “Store of Value: How energy storage delivers clean power on demand.”


Is energy storage the same as carbon capture utilization & storage (CCUS)?

No, they are not the same. Energy storage stores electricity to be used later. Carbon capture utilization & storage (CCUS) is an interrelated group of technologies that captures, compresses, and transports CO2, often from emitting generation sources, to use in the production of concrete or synthetic fuels.[1]


How does energy storage decrease consumer costs?

Energy storage development helps to defer investments in existing transmission and distribution infrastructure or in building new generation assets. Energy storage is also key to optimizing generation at the grid level, minimizing the need to curtail generation. 

For further details, be sure to check out our 2020 Paper HERE.


Is energy storage clean?

If the grid is clean then energy storage is clean. Where energy storage can help make a grid clean is to reduce reliance on peaking fossil fuel generation and better optimize clean energy sources like wind, solar, nuclear and waterpower. Additionally, through electrolysis & Power to Gas, energy storage helps support green and blue hydrogen. 


Energy storage is important to creating affordable, reliable, deeply-decarbonized electricity systems

MIT Energy Initiative report supports energy storage paired with renewable energy to achieve decarbonized electricity systems



What are the different types of Grid Storage Technology?

IESO’s Pathways to Decarbonization - (Appendix B, Section 4) identifies 8 types:

  1. Storage Type: Chemical
    Grid Storage Technology: Batteries
    Description: Electrochemical energy storage systems charges and discharges electricity in the form of chemical redox reactions. An electrochemical battery is made of cells consisting of a positive and negative electrode separated by an electrolyte. Varying the materials for the electrodes and electrolyte give rise to many different variations of battery storage technologies. Established and commercialized electrochemical storage technologies include lead-acid and lithium-ion batteries while emerging technologies include sodium ion batteries and metal-air batteries.

  2. Storage Type: Mechanical
    Grid Storage Technology: Flywheels
    Description:     Stores energy in the form of rotational kinetic energy. When charging, a motor accelerates the spin of a large mass in a vacuum. When discharging the generator converts kinetic energy into electrical energy, decelerating the rotation of the mass.

  3. Storage Type: Chemical
    Grid Storage Technology: Flow
    Description:     Similar to batteries, flow batteries charges and discharges electricity in the form of chemical redox reactions. However, in flow batteries, the electroactive elements are stored externally and pumped into the cell to generate electricity. Types of flow batteries include Zinc Bromine, Polysulphide Bromine and Vanadium Redox flow batteries.

  4. Storage Type: Mechanical
    Grid Storage Technology: Gravity Energy Storage
    Description:     Involves storing energy in the form of gravitational potential energy by raising a large mass of material (solid/liquid) and recovering the stored energy by lowering the mass to power a turbine that converts kinetic energy back into electricity. This includes established storage technology such as pumped hydro storage in hydro reservoirs and emerging technologies such as Lifted Weight Storage (LWS).

  5. Storage Type: Thermo-Mechanical
    Grid Storage Technology: Compressed Air Energy Storage
    Description:     Uses a compressor to store pressurized air in a cavern. When discharging, the heat captured by the thermal energy system during the compression process is integrated back into the pressurized air and decompressed in an expansion turbine coupled with a generator.

  6. Storage Type: Chemical
    Grid Storage Technology: Hydrogen Storage
    Description:     Hydrogen gas is generated either through electrolysis, pyrolysis or steam methane reforming which can then be compressed or liquefied and stored either in tanks or underground salt caverns. When discharging, the stored hydrogen can generate electricity by combustion using a hydrogen turbine or reverse electrolysis using a fuel cell.

  7. Storage Type: Thermal
    Grid Storage Technology: Pumped Thermal Energy Storage
    Description:     Electricity is used to generate heat using a heat pump and then stored as thermal energy in a hot store. Thermal energy storage mediums could include molten salt, molten aluminum, molten silicon etc. When discharging, the temperature differential between the cold and hot stores is used to convert thermal energy back into electricity. Pumped thermal energy storage systems consist of a hot and cold store, compressors, turbines and generators.

  8. Storage Type: Thermo-Mechanical
    Grid Storage Technology: Liquid Air Energy Storage
    Description:     Electricity is used to clean, compress and cool to liquefy air/nitrogen and stores energy in the form of liquid air in a tank. When discharging, the liquid air is pumped, evaporated and the expansion of air is used to drive a turbine.

What is a Battery Energy Storage System (BESS)?

Watch “Decoding BESS: What is Battery Energy Storage Systems”


Where can I learn more about Energy Storage Tech?

Read “The Long and the Short of Energy Storage Tech” (https://www.ctvc.co/ldes-long-duration-energy-storage-tech/)


How does the Power Grid work? (see the original answer at Canary Media)

How does electric power reach our homes and workplaces? Via the grid — a vast network of electrical lines, transmission towers, transformers, and control and sensing equipment that carries electricity from power plants to where it’s used. The U.S. grid has been called the biggest machine ever built. And it has a pulse: an electric alternating current of 60 hertz (cycles per second) in the U.S.

The grid moves power around at different scales: Transmission networks carry large amounts of power over longer distances, while distribution networks carry power the final miles to our electrical outlets. Almost all electric power starts its journey from a large-scale generator like a solar array, wind farm, hydroelectric dam, nuclear reactor or coal- or gas-fired power plant.

The power then goes to substations where devices called transformers increase or ​“step up” the voltage — the force pushing electric current through the system. That boost enables the power to travel over long distances more efficiently.

Closer to where the electricity will be used, transformers then reduce or ​“step down” the voltage so power can more safely flow into the local distribution network, which includes underground cables as well as the power lines you see along neighborhood streets, bedecked in pigeons.

The changing energy mix is presenting major challenges to today’s grid. For example, the distribution system was designed to push electricity out to customers. But as more people install rooftop solar and batteries, an increasing amount of electricity is flowing in the other direction: from customers to the distribution network. This two-way system is more complicated for utilities to manage.

Customer electricity demand is also changing. As people shift to electric vehicles and switch from fossil fuels to electricity for home heating and appliances, the amount of power they can draw from the grid at any one moment increases dramatically. To keep up, the aging grid will need some serious upgrades.

More on the grid:

More on the grid from Canary Media:

What does Behind The Meter mean? (see the original answer at Canary Media)

Utilities use electricity meters to measure power going into customers’ homes and businesses. Devices that produce or store power inside those customer buildings are on the customer’s side of the meter, or from the utility’s perspective, behind the meter.

The term is most commonly used to describe things like rooftop solar arrays and home batteries. It’s also applied to smart appliances and smart thermostats, which can alter how much power a customer is using and when.

Conversely, front of the meter is used to describe technologies that are connected to the grid on the utility side of the meter, such as large-scale batteries.

More on behind-the-meter technologies from Canary Media:

What is a Distributed Energy Resource (DER)? (see the original answer at Canary Media)


The grid currently gets most of its power from central power plants. But electric power sources that are sprinkled throughout communities — such as solar panels, batteries, backup generators and, increasingly, electric vehicles — can also feed power to the grid. These distributed energy resources, or DERs, are found everywhere from households to commercial sites.

You may also hear the term DER applied to devices that don’t generate power but instead can be controlled so their electricity consumption ramps down when needed, such as water heaters and appliances. That’s because when they’re turned down or off, they free up energy on the grid. So — if you squint — they could be seen as energy resources.

Utilities and grid operators are usually unaware of exactly how much energy DERs are generating. But in some cases, they can control DERs through a combination of technologies that come together in what are called DER management systems, or DERMS.

More on DERs from Canary Media:

What is a Virtual Power Plant (VPP)? (see the original answer at Canary Media)


Like a real power plant, a virtual power plant, or VPP, provides electricity to the grid. But instead of being sited in one place, a VPP harnesses distributed energy resources, or DERs (see above!) that are spread across an entire community. Private companies or utilities ​“operate” VPPs using software and digital communication networks to conduct a symphony of DERs.

By coordinating tens to thousands of these devices, VPPs can inject power into the grid or curtail demand, potentially as quickly as central power plants — or sometimes even faster. Depending on where you live, your household might be able to sign up to participate in a VPP and maybe even get compensated in return. Because VPPs take advantage of privately owned resources (such as homeowners’ solar panels and batteries), they can save a utility money, and the utility in turn could pass those savings on to customers in the form of reduced rates.

Bonus activity: Play this game to see how long you can manage power sources on a grid to prevent a blackout. Then switch the game into VPP mode and watch it crush your record.

More on VPPs from Canary Media:


What is Demand Response? (see the original answer at Canary Media)

Say there’s a spike in electricity demand on a sweltering summer afternoon as people blast their air conditioners. Utilities could ramp up power generation to meet demand. But utilities could also pay customers to respond to the spike by voluntarily cutting back their electricity use. That’s the activity and business of demand response.

For decades, utilities have made demand-response agreements with big industrial customers to pay them to dial down their power consumption during grid emergencies. For example, a utility would call a manufacturer and ask it to temporarily shut down a factory line.

The next phase in the evolution of demand response came in the residential sector, with programs that paid customers who agreed to let the utility remotely turn off their air conditioners, electric water heaters, pool pumps or other energy hogs during demand spikes.

In the last 15 years or so, demand response has become more automated. Utilities and independent companies called demand-response providers use two-way wireless communications to link devices, like smart thermostats, to demand-response management systems (DRMS), which can more actively monitor and change the ​“shape” of a device’s electricity demand.

More on demand response:

More on demand response from Canary Media:

What does Balancing The Grid mean? (see the original answer at Canary Media)

On the grid, the supply of electric power must perfectly match demand. Think of the grid as a massive, interconnected web of energy, constantly humming at a perfectly tuned frequency. For power to flow from any node in the web to any other node, that frequency must be maintained at all times — an activity known as balancing the grid. Any imbalance between the power energizing that web and the energy being consumed at the web’s millions of endpoints can cause that frequency to go out of whack — and if it goes too far, dangerous things can happen.

When demand outstrips supply, utilities and grid operators can either allow the imbalance to overwhelm the grid, which can cause extensive damage to the electromechanical parts of the system, or they can start to force customers off the grid with rolling blackouts. If the grid goes out of balance faster than grid operators can react, the safety equipment on the grid takes over, shutting off major swaths of the network and causing massive blackouts that can take days, weeks or longer to recover from.

To balance supply and demand, utilities have traditionally relied on central power stations, and when demand peaks, they have turned to so-called peaker plants that often run on fossil gas. But renewable energy and batteries offer cleaner ways to balance the grid. Also, equipment and appliances that can adjust their energy demand, such as air conditioners and freezers, can help if a number of them are coordinated together (see distributed energy resource and virtual power plant above).

More on balancing the grid from Canary Media:


[1] https://www.nrcan.gc.ca/climate-change/canadas-green-future/carbon-capture-utilization-and-storage-strategy/23721