How many living cells on Earth?

A NY Times article "Exactly How Much Life is on Earth?" (research article here, behind a paywall) says that there are about 10³⁰ cells currently on earth and the total numbers of cells that will be on earth through its future lifespan is about 10⁴¹ cells.

That is:

more living cells on Earth — a million trillion trillion, or 10^30 in math notation, a 1 followed by 30 zeros — than there are stars in the universe or grains of sand on our planet

But for now, Dr. Crockford and his colleagues wrote in their paper, “the extension of today’s relatively high rates of primary productivity will likely squeeze more life into less time.”

It was implied in the article that overall planetary productivity is limited by the energy sources available to the life forms. This is an ecological argument.
This amounts to how much energy (sunlight or chemical) is available for life forms to use at different geological times. The earliest life forms may only have had geochemical energy from H₂ and CO₂ in special locations to use for their purposes. Eventually other chemical sources were made available for use as well as sunlight. These greater energy resources allowed more cells to be made and supported with energy sources.

There was an article a few years ago on changes in biological energy usage through evolution:
The Energy Expansions of Evolution by Olivia Judson(also paywalled).

Truly remarkable! One may scoff until you consider the number of microbes in the deepest seas, highest atmosphere, and deep crust.