My calculations might be wrong, but it looks like these Rdot displays use significantly less energy than Memory LCDs.

Using numbers from Sharp[0], Memory LCDs use ~226µJ/cm2 each second when static. I'm assuming they are 60Hz displays & therefore require a refresh 60 times each second but even if they only refresh once a second, that's ~3.8µJ/cm2 a second or 13,680 times the power consumption of the Rdot displays.

The article claims these Rdot screens use 0.25mJ/cm2 every 15 minutes when static.

Again, these are my "back-of a napkin" calculations so take with some salt.

[0]https://www.sharpsma.com/products?sharpCategory=Memory%20LCD