County Road 29,
Mississippi Mills, ON, K0A 1A0

Almonte Battery energy storage System

Almonte BESS is a proposed 4.999 Mega-Watt (“MW”) stand-alone lithium-ion Battery Energy Storage System (“BESS”) that will be located at County Road 29, Mississippi Mills, ON, K0A 1A0. The Project will be submitted to the Independent Electricity System Operator’s (“IESO”) Request for Proposals under the Expedited Long-Term 1 procurement. 

It is important to us that Almonte BESS be successfully integrated into the Municipality of Mississippi Mills and we are seeking to incorporate feedback through Public Community Meetings and this Project Website into the development of this Project.

Provincial Needs

Ontario is entering a period of emerging electricity system needs driven by increasing residential and commercial demand due to the electrification of the automotive sector, growth of the agriculture sector, the retirement of the Pickering nuclear plant and refurbishment of other nuclear-generating plants, and expiring contracts for existing facilities. The IESO’s 2022 Annual Acquisition Report outlines the forthcoming supply gap.

In response, the IESO is conducting procurements, including the Expedited Long-Term Request for Proposals (“E-LT1 RFP”), to secure more than 4,000 MW of capacity in Ontario. Facilities that successfully demonstrate their capabilities will be contracted by the end of 2023, with operations starting as early as May 1, 2025.

The Almonte BESS Project, among other electricity storage sites, will help address emerging global and regional electricity needs for the coming decades.

Electricity Storage Explained


When Ontario’s electricity grid needs more power (like on the hottest days of the year), the IESO turns to on-demand resources, like energy storage, to support Provincial electricity needs. Decentralized energy storage infrastructure can prevent emergency grid events such as rolling blackouts, and help defer more capital-intensive system upgrades that directly impact rate-payers. Ideally, BESS sites are located near electricity substations or 3-phase power lines to improve overall efficiencies.


Although energy storage comes in different shapes and sizes, the lithium-ion Battery Energy Storage System (“BESS”) is the fastest emerging technology in North America and is planned to be deployed in the Municipality of Mississippi Mills with the Almonte BESS Project. 

Project History and Description

Almonte BESS is a proposed 4.999 Mega-Watt (“MW”) stand-alone lithium-ion battery storage Project located at County Road 29, Mississippi Mills, ON, K0A 1A0, under development by Walker BESS 4 Limited Partnership. This infrastructure project will bring significant investment and local benefits including employment, lease payments and capital spending in the local economy.

Almonte BESS Project is being developed by Wahgoshig Solar FIT5 Limited Partnership, approved by the IESO among the 55 Qualified Applicants with the experience and capabilities to successfully develop, construct, and operate facilities acquired through these procurements.


The Almonte BESS Project will consist of lithium-ion battery cells connected in stacks and installed inside an enclosed area, like a shipping container or a small enclosure. The enclosed area will also house the balance-of-plant equipment such as an inverter, a battery management system and a dedicated HVAC unit for proper ventilation. The battery packs feed inverters that connect to a transformer tied to the power grid. The Project will also have a 20-foot wide private access road connecting the site with County Road 29.


The Almonte BESS Project will comply with all regulatory bodies permitting requirements including the Electrical Safety Authority, the Municipality of Mississippi Mills, and the Ministry of Environment, Conservation and Parks. 



The Almonte BESS Project will use dedicated HVAC systems to remain well-ventilated to keep the batteries at the optimal operating temperature. Additionally, as part of the Project’s proposed Community Engagement activities, Walker BESS 4 Limited Partnership will sponsor certified fire safety training for fire department personnel at the Mississippi Mills Fire Department.


The Almonte BESS Project will have restricted access to prevent any health and safety incidents and be monitored 24×7 through a secure remote-monitoring facility.

More information about the IESO’s Long Term Capacity Procurement and the list of Qualified Applicants:


The Greater Ottawa region has been identified as an area that can benefit from new electricity capacity based on IESO’s guidance.

Almonte BESS Scaled Site Map

Almonte Bess Scaled Site Map

Benefits to the Community

There are various economic and non-economic Community Benefits associated with Almonte BESS, a proposed key energy infrastructure project located in the Municipality of Mississippi Mills. The Almonte BESS Project will provide power to meet growing regional demand in the Greater Ottawa area, lease revenues for local landowners, additional property taxes for the Municipality of Mississippi Mills and economic activity within the Municipality of Mississippi Mills.

Creation of high-skilled jobs in construction – civil works, mechanical installation, electrical connection, landscaping.

Property tax benefits, diversified income stream for landowners, especially on under-utilized land.

The development of Almonte BESS in the Municipality of Mississippi Mills will serve the larger electrical resiliency requirements of the Greater Ottawa area.

The Municipality of Mississippi Mills have published plans that are in line with the development of a lithium-ion BESS in your municipality. The Plans emphasize a need to reduce green house gas (GHG) emissions through alternative energy. Lithium-ion batteries minimize the need for natural gas peaker plants and compliment the ongoing development of alternative energy systems. The associated plans are:

  • Mississippi Mills Strategic Plan 2020-2023
  • Municipality of Mississippi Mills Community Official Plan

Battery Electricity Storage Systems support the integration of local clean energy generation and provide intelligent resilience to the regional electricity grid. Almonte BESS will further support the electrification of transport and the environmental sustainability goals laid out by the plans from the Municipality of Mississippi Mills.

Anticipated Project Timelines

Land Lease
  • Technical Assessments
  • Permitting Review
2022 → 2023
IESO Procurement
  • Consultation with municipality and neighbours
2023 → 2024
Engineering, Design & Approvals
  • IESO contract award
  • Design and construction is planned
2025 → 2026
Commercial Operation
  • Storage system is installed
  • Local electrical grid connection occurs along existing lines and connection points
  • Remote monitoring
  • Annual maintenance
  • Equipment is removed
  • Land fully remediated

Project Updates

Notice Of Public Community Meeting

Public Community Meeting Date and Time

Date: December 15, 2022
Time: 6:00 PM – 7:30 PM
Meeting Location:
Almonte Civitan Club – Main Hall

500 Almonte St, Almonte, ON K0A 1A0

Public Community Meeting Minutes

Community Meeting Presentation

Notice of Proponent Change

Community and Indigenous Engagement Plan

Walker BESS 4 Limited Partnership has developed a Community and Indigenous Engagement Plan that identifies a strategy for establishing and sustaining a transparent and productive engagement with Community stakeholders and Indigenous Communities. We encourage interested stakeholders to review this document to understand the Almonte BESS Project’s community engagement process.

Company Background

Wahgoshig Solar FIT5 LP

Wahgoshig Solar FIT 5 LP (“Wahgoshig Solar”), is a partnership formed between Wahgoshig First Nation and Compass Renewable Energy Consulting Inc. Wahgoshig Solar developed, constructed, and operates four 500 kWac/600 kWdc (2.4 MWdc total) ground mount Feed-in Tariff (“FIT”) projects under the former FIT program in Ontario. Wahgoshig Solar engaged Compass to manage the development, permitting and construction of these facilities. 

Compass Renewable Energy Consulting Inc. (“Compass”) has been consulting and developing renewable and clean energy projects in Ontario for over 10 years. We have experience across the development lifecycle from pre-screening, contracting, construction, commissioning and operations. We have developed over 100 renewable energy projects in Ontario representing over 100 megawatts (MW) in the last 6 years and supported the development of over 2,000 MWs for our clients.

Frequently Asked Questions

Energy storage fundamentally improves the way we generate, deliver, and consume electricity. Energy storage helps during emergencies like power outages from storms, equipment failures and, accidents. But the game-changing nature of energy storage is its ability to balance power supply and demand instantaneously – within milliseconds – which makes power networks more resilient, efficient, and cleaner than ever before.

BESS systems are considerably smaller footprint compared to other clean technologies such as solar or wind farms. On average, a 25MW BESS system occupies 1 acre of land.

BESS have to apply with municipal, provincial and national permitting and codes and standards. The following is a non-exhaustive list of industry standards our Project will comply with:

  • UL 9540 Standard for Energy Storage Systems and Equipment
  • UL 9540A (Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems)
  • National & Provincial Building Code
  • National Fire Code Canada
  • Underwriters Laboratories of Canada
  • NECB 2017 National Energy Code of Canada for Buildings
  • ULC (Underwriters Laboratories of Canada)
  • UL 1741 Standard for Inverters, Converters, Controllers, and Interconnections
  • UL 1973 Standard for Batteries for Use in Stationary, Vehicle Auxiliary Power and Light Electric Rail (LER)

BESS are certified to UL9540 and UL9540A standards to prevent fire spread and suppression at the cell and the BESS system level. BESS enclosures have built-in fire suppression system (FSS) solutions. The FSS system is composed of smoke detectors, gas detectors and aerosols, whose main function is to prevent fire spread in time when any open flame signal or gas signal appears in the battery system and send out an emergency fire alert signal to the EMS system.

These BESS do not use lead acid batteries, and therefore do not leak.

Mechanical failures include physical damage that could create heat or a fire. Hazards associated with lithium-ion battery energy storage systems are centred on the flammable organic electrolyte and its highly reactive electrodes. However, if the batteries are punctured, there is a risk of electrolytes being exposed to air, which will result in a chemical reaction, leading to thermal runaway and combustion.

Other potentially hazardous wastes would include fire residue, debris, and fire extinguishing agents leading to contamination of soil and underground water via leaching, burying, dissolution, infiltration and runoff. The management of these risks starts at the cell level, with the selection of battery chemistry, and compliance with local AHJs and global certifications. This is where UL9540A certification becomes critical to BESS projects. Any other hazardous leaks will be contained in the enclosure.

BESS systems are subject to third-party certification to ensure they comply with all of the required codes and standards.

BESS facilities have an expected lifespan of 22 years, or more, with equipment replacement and repowering. At the time of decommissioning, the installed components will be removed and reused/recycled, where possible, and the site restored. All removal of equipment will be done per the applicable regulations and manufacturer recommendations. The below summarizes the decommissioning procedure that would be enacted at the end of project life for each component. 

BESS – Disconnect all above-ground wirings. Remove all BESS enclosures and support structures.

Medium Voltage (MV) Stations, Substation – Disconnect and remove all electrical equipment. Remove the inverter and associated equipment. Remove high-voltage substation transformer. Remove concrete foundations for MV Stations and substation components. 

Access roads and other components – Consult with the property owner to determine if access roads should be left in place for their continued use. If roads are to be removed, the aggregate materials will be excavated by a backhoe/front-end loader, along with any underlying geotextile fabric. Compacted areas restored.

Underground cables – Underground electrical lines running between the inverters and the substation will be removed. All foundation materials will be removed.

Contact Us

It is important to us that Almonte BESS be successfully integrated into the Municipality of Mississippi Mills and we are seeking to incorporate feedback through Public Community Meetings and this Project Website into the development of this Project.

To submit feedback or send us any questions about the project, please contact us:


By mail: 
192 Spadina Ave, Suite 215
Toronto, ON M5T 2C2