Fighting climate change in the electrical grid

Electrical power generation is a significant source of fossil fuel emissions that we must reduce using wind, solar and geo-thermal sources. But there are limits to how much wind and solar will help.

If we want to continue to get closer to a lower carbon economy, we need additional techniques to further reduce carbon emissions — not just from power generation, but from the electrical grid that brings the power to our homes. This is a part of the system that most people don’t know about, and one that shows how complex the challenge is.

How much gets to us

What really counts is not how much power is generated, but how much is actually delivered to the end user. We can make the grid more efficient and reduce those losses, so that we burn fewer fossil fuels while delivering the same amount of power to the end user.

How much energy is wasted generating power that never reaches the user? A substantial 6% of electrical power generated is lost in transmitting and distributing that power.

Part of this loss occurs in transmission, sending the power from the power plant to locations near the point of use. Part occurs in the distribution, the system that takes the high voltage transmitted power and reduces the voltage so it can be used in homes and businesses.

Two-thirds of the losses occur in distribution and take place physically in distribution transformers. The Department of Energy has long recognized the importance of the efficiency of our electrical distribution system and has implemented minimum efficiency standards for distribution transformers.

The most recent proposed standard was released last year, to be implemented in 2027.

The new standard sets a high threshold for distribution transformer efficiency, focusing specifically on one type of power loss that occurs in the transformer core.

The DOE standards would require a conversion from the industry standard core material of grain oriented electrical steels (produced at Cleveland Cliffs in Butler) to a new material called “amorphous.”

Different standards

Amorphous does, indeed, reduce the core losses at medium to low loads compared to the industry standard grain oriented electrical steel. The problem is that the new standard treats transformers as if they are all made the same.

The goal shouldn’t be just low losses in the core, but for the whole transformer. The use of amorphous requires a larger transformer core. Larger cores mean bigger copper windings around the core.

Large copper windings increase power losses due to electrical resistance to the power flowing through them.

The DOE study assumes that distribution transformers are loaded to 40% to 50% of capacity. At those loads, the losses in the core are equal to the losses in the copper windings and the amorphous material does increase efficiency.

But utilities commonly load the transformers to higher numbers because they want to avoid the expense of installing more transformers. This is especially true in urban areas where space is an issue. As the loads go over 50%, the transformers with the standard grain oriented core are actually more efficient.

A large proportion of Canadian distribution transformers are made from amorphous, because outside of a few large cities, Canada is much more sparsely populated and their load factors are typically 40% or less.

The US population is larger, and the urban areas are more numerous and larger, leading to higher load factors.

Several sizes fit all

What this means is that for true energy efficiency and reduced carbon emissions, we can’t flatten our approach into a one-size fits all solution — using amorphous alone — as the DOE suggests with the new standard. We must take into account the different efficiencies at different loads to decrease the carbon footprint of the electrical grid, and slow climate change.

As with many things in life, the correct answer is more complicated than a one-size fits all solution.