More efficient renewables could address building electrification inefficiencies

A collaborative research study has drawn attention to the need to use more efficient renewable energy in building electrification to minimize stress on the US electric grid during peak winter energy consumption.

The direct consumption of fossil fuels by buildings, burned in water heaters, furnaces and other heating sources, accounts for nearly 10% of greenhouse gas emissions in the United States. Building electrification or building decarbonization, which involves switching to an electric system that powers heating from renewable energy sources, rather than coal, oil and natural gas, is a critical step towards achieving net zero global climate goals.

However, most building decarbonization models have not taken into account seasonal fluctuations in energy demand for heating or cooling, making it difficult to predict what a possible move to all-electric heating will clean in buildings could mean for the national power grid, especially during energy peaks. use.

Researchers from Boston University School of Public Health (BUSPH), Harvard TH Chan School of Public Health (Harvard Chan School), Oregon State University (OSU), and the nonprofit Home Energy Efficiency team Team (HEET) examined these seasonal changes in energy demand, and found that monthly energy consumption was highest during the winter months.

Published in Scientific Reports, a journal of the Nature portfolio, the study presented new modeling of several building electrification scenarios and revealed that this seasonal increase in winter energy demand will be difficult to meet from current renewable sources, if buildings switch to low-efficiency systems. electrified heating.

“Our research reveals the degree of fluctuation in building energy demand and the benefits of using highly efficient heating technologies when electrifying buildings,” says study leader and corresponding author Jonathan Buonocore, Professor environmental health assistant at BUSPH. “Historically, this fluctuation in building energy demand has been largely managed by gas, oil and wood, all of which can be stored throughout the year and used during the winter. Electrified buildings, and the electrical system that supports them, will need to provide this same reliable heating service in the winter. More efficient electric heating technologies will reduce the electrical load put on the grid and improve the ability to meet this heating demand with non-combustion renewable energy.

Analysis of building energy data from March 2010 through February 2020 revealed that the total monthly average of energy use in the United States – based on current fossil fuel use, as well as future energy use. electricity in winter – varied by a factor of 1.6x, with the lowest demand in May and the highest demand in January.

The researchers modeled these seasonal fluctuations in what they call the “hawk curve,” because a graph of changing monthly energy consumption represents the shape of a hawk. The data revealed that energy consumption was highest in December and January due to winter heating demand, followed by a secondary peak in July and August for cooling, with the lowest levels seen in April, May, September and October.

By calculating the amount of additional wind and solar power expected to be generated in January, the researchers determined that the buildings would need a 28x increase in wind power or a 303x increase in solar power. just to cope with winter heating peaks.

However, switching to more efficient renewables such as air source heat pumps (ASHP) or ground source heat pumps (GSHP) would mean that buildings would only require 4.5 times more wind power generation or 36 times more solar energy, which would “flatten” the Falcon curve. because less new energy demand is placed on the power grid.

“This work really shows that technologies, both on the demand side and on the supply side, have an important role to play in decarbonization,” says study co-author Parichehr Salimifard, an assistant professor at the Faculty of Science. engineering from Oregon State University. Examples of these technologies on the energy supply side are geothermal building heating and renewable energy technologies that can supply energy around the clock, such as renewables coupled with long-term storage, distributed energy resources (DER) at all scales and geothermal electricity generation where possible. .

“These can be combined with technologies on the demand side, i.e. in buildings, such as passive and active building energy efficiency measures, peak shaving and energy storage. energy in buildings. These building-level technologies can both reduce overall building energy demand by reducing both base and peak energy demand, as well as smooth fluctuations in building energy demand and therefore flatten the Falcon curve. .

“The Falcon Curve draws our attention to a key relationship between the choice of building electrification technology and the impact of building electrification on our power grid,” says study co-author Zeyneb Magavi, Co-Executive Director of HEET, a non-profit climate organization. solution incubator.

“Using a strategic combination of heat pump technologies (air, geothermal and grid), along with long-term energy storage, will help us electrify buildings more efficiently, economically and equitably. The Falcon Curve shows us a faster path to a clean and healthy energy future,” Magavi added.

“Our research clearly shows that, when taking into account the seasonal fluctuations in energy consumption apparent in the Falcon curve, the desire to electrify our buildings must be coupled with a commitment to energy-efficient technologies to ensure that building decarbonization efforts maximize climate and health benefits,” says the study’s lead author, Joseph G. Allen, associate professor of exposure assessment science and director of the Healthy Program. Buildings at Harvard Chan School.

“Our work here shows a pathway for building electrification that avoids reliance on fossil fuels and avoids renewable combustion fuels, which can still produce air pollution and potentially perpetuate disparities in air pollution exposure, although they are climate neutral,” says Buonocore. “Avoiding issues like this is why it’s important that public health experts be involved in shaping energy and climate policy.”

Source: Boston University

Abdul J. Gaspar