Responding to global disparity between energy supply and demand, a team of University of Waterloo engineering students created a distributed smart energy storage system that will extend the life of electric vehicle batteries, reduce electricity costs and help eliminate carbon dioxide (CO2) emissions.
The Wall-E green energy wall is designed to efficiently store energy and reduce electric vehicle battery waste. The project was created by Andrew Andrade, Alen Daniel, Julia Kavuma, Marwan Saadeldin and Wajeeh Syed as their fourth-year Capstone Design project, with faculty mentoring provided by advisors Mike Fowler, Roydon Fraser, William Melek and course instructor Oscar Nespoli.
Inspired by the work of Waterloo professors on the sustainable management of lithium-ion batteries, the Wall-E team set out to find a way to repurpose electric vehicle (EV) batteries no longer strong enough to power a car, using batteries recovered from a Toyota Prius. The project sees the batteries repurposed for energy storage, rather than simply being sent for material recycling.
“Believe it or not, there is only a 20 per cent capacity fade when the batteries are disposed of, meaning they are still able to hold up to 80 per cent of charge,” says Kavuma, a systems design engineering student. “Why are they disposed of?”
The solution developed by the team provides a viable alternative.
After the used batteries are determined to be safe, healthy and useful, they are built into a control system that can safely charge and discharge the batteries for a stationary application. The system, which can be installed at a household, includes sensors to measure temperature, current and voltage of the batteries, as well as electrical switches and an inverter for power conversion.
In addition to transforming the batteries into energy storage devices, Wall-E’s integrated system collects data that can ultimately save consumers money on their electricity bill and reduce reliance on fossil fuels. In one winter month in Ontario, the technology has the potential to replace up to 788 MWh of demand supplied by natural gas, eliminating 143 tonnes of CO2 emissions. It could save households up to $50 per month on electricity costs.
“In Canada and other developed countries, sometimes energy supply exceeds energy demand. This surplus in energy goes to waste if it is not stored or sold in the market,” says Andrade, a mechatronics engineering student. “In developing countries when energy demand exceeds the supply, there is a blackout and people go without power. In both cases, utility companies are forced to burn fossil fuels to meet peak energy demand, which leads to global warming.”
The high level of control integrated into the Wall-E battery system intergrates with an ‘internet of things’ system, says Kavuma, and provides utility companies with information that allows them to manage the generation and distribution of energy while still having the ability to meet a variable demand.
With this ability to store energy when the demand is low and discharge energy when the demand is high, the system enables peak shaving, which reduces the congestion on distribution lines and the need for development of increased power generation capacity.
“A great example of this is the variation of pricing of electricity in Ontario during the day,” explains Kavuma. “Utilities charge more money for electricity during peak demand which creates an opportunity for peak shaving by changing consumer behaviour.”
Unlike utility companies who navigate the uncertainty of energy demand through pricing structures, the optimized Wall-E system integrates energy storage capabilities with energy production, price and demand to create a smart, sustainable solution.
“Through the process of building an energy storage system, we have demonstrated a commercially viable smart energy data intelligence platform,” said Andrade. “We were able to use state of the art forecasting techniques to better energy consumption at a residential and provincial level.”
The technology concept garnered significant interest from both utilities, automotive manufactures, and recycling companies.
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