Power prices in Alberta seem high - how can electrifying heat make economic sense?

The key is the difference between the average power price, and the price during the lowest cost 6-8 hours per day. ETES technology is dispatchable, i.e. the heat battery can be charged whenever power prices are low, even in small increments. In the Alberta electricity market we are seeing a record number of zero-dollar electricity price hours, see our Q3 2024 Market Update for example. The market change is structural, due to the continuing growth of renewable generation on top of inflexible Cogen power plants, see our Alberta Power: A New Paradigm article. And we still run economics on conservative assumptions.

How about transmission costs?

Here the answer is a bit more complicated, “it depends”. Often-times, charging solutions can be set up “behind the fence”, e.g. with on-site Cogen units or nearby renewable assets. Also, in July 2024 the Alberta Utility Commission (AUC) approved a new “DOS dispatchable” tariff for intermittent loads that can provide cost effective transmission services. We perform a site-specific feasibility review (free of charge) to assess this and other key aspects for prospective clients.

Why store the heat in bricks and not for example in molten salt?

Bricks are cheap, robust, safe and highly effective. Molten salt has been widely used for thermal storage mainly in solar thermal plants. It works, but it brings a lot of operational and maintenance challenges mainly due to the corrosive nature of molten salt. Most major molten salt facilities had tank failure. We therefore decided to stay away from molten salt and concentrate on the simplest, most robust technology - bricks and resistance heaters used in the steel industry for decades.

Is the steam generator “novel” technology?

No, our solutions use an industry-standard Heat Recovery Steam Generator (HRSG). A blower blows air through channels in the hot bricks. The air picks up heat, and the air stream is blended to match the output of a standard gas burner. One can thus use a standard HRSG to generate steam. No innovation needed.

The 95% thermal efficiency seems too high - doesn’t this violate thermodynamics?

No, because we go from electricity to heat, i.e. we want the heat, thus we don’t have “waste heat”. Once we go from heat back to electricity via a heat engine the second law of thermodynamics indeed applies, and we see much lower efficiencies, likely in the low 30% range for a steam cycle gas turbine driven by an ETES unit for example. That is why we focus on applications that use heat or steam directly.

How maintenance intensive is the ETES unit?

Similar to a standard gas-fired HRSG, a few days each year.

What temperature and pressure profiles do you address?

We currently focus on industrial heat and steam between 200-600 degrees C. Since we use standard HRSG designs typically used with gas burners, we can address all standard steam pressure requirements.

Can charging be interrupted if power prices spike? Does charging have to be continuous?

Yes, charging can be interrupted almost instantly, and no, charging does not need to be continuous as long as the total amount of charging per day reaches 6-8 hours, or steam output is turned down accordingly.