Enlarge / Natural gas plants like these may find themselves burning hydrogen over the next 20 years. (credit: Ron and Patty Thomas )

Today, the Biden administration formally announced its planned rules for limiting carbon emissions from the electrical grid. The rules will largely take effect in the 2030s and apply to gas- and coal-fired generating plants. Should the new plan go into effect, the operators of those plants will either need to capture carbon or replace a large fraction of their fuel with hydrogen. The rules will likely hasten coal's disappearance from the US grid and start pushing natural gas turbines to a supplemental source of power.

Whether they go into effect will largely depend on legal maneuvering and the results of future elections. But first, the rules themselves.

Clearing the air

Back in 2007, the US Supreme Court ruled that the Clean Air Act applied to greenhouse gas emissions . This allows the EPA to set state-level standards to limit the release of greenhouse gasses, with the states given some leeway on how they reach those standards. Since then, the court has clarified that these standards must be met on a per-plant basis rather than at the grid level; the EPA can't set rules that assume that the grid has more generation from solar and less from coal plants.

Enlarge / Aerial view/solar panel floating in the dam. (credit: SONGPHOL THESAKIT )

The cost of solar power has dropped dramatically over the past decade, making it the cheapest source of electricity in much of the world. Clearly, that can mean cheaper power. But it also means that we can potentially install panels in places that would otherwise be too expensive and still produce power profitably.

One of the more intriguing options is to place the panels above artificial bodies of water, either floating or suspended on cables. While more expensive than land-based installs, this creates a win-win : the panels limit the evaporation of water, and the water cools the panels, allowing them to operate more efficiently in warm climates.

While the potential of floating solar has been examined in a number of places, a group of researchers has now done a global analysis and find that it's huge. Even if we limit installs to a fraction of the surface of existing reservoirs, floating panels could generate nearly 10,000 TeraWatt-hours per year, while keeping over 100 cubic kilometers of water from evaporating.

Enlarge / The Northern Isles , a 12-rack / 864-server underwater data center pod, is winched off the seafloor in this picture after its two-year trial deployment. (credit: Microsoft )

Microsoft retrieved a 40-foot-long, 12-rack, self-contained underwater data center from its seafloor home offshore from the Orkney Islands earlier this summer.

The retrieval of the Northern Isles began the final phase of Microsoft's Project Natick research initiative, exploring the concept of deploying sealed server pods just offshore major population centers as a replacement for traditional onshore data centers.

Why put servers underwater?

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  On the day of its 2018 deployment, the Northern Isles sported a gleaming white paint job with colorful Microsoft logo. Two years underwater isn't kind to that sort of thing, though... [credit: Scott Eklund ]

Project Natick has been underway for several years; we covered the two-month trial deployment of Leona Philpot , the company's first underwater server pod, in 2016, and the deployment of the newly retrieved Orkney Isles pod in 2018.

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