The optimism usually radiating from billionaire Bill Gates when it comes to climate change is starting to fade on one of his biggest technology bets: nuclear power.

Driving the news: The Microsoft co-founder has focused much of his time lately on climate and innovation. In an exclusive interview with Axios, Gates said that setbacks he is facing with TerraPower, a nuclear technology firm he co-founded in 2006, has got him questioning the future of that entire energy source.

The big picture: At 10% of global power supply, nuclear power is the second-largest electricity source (after hydropower) that emits no carbon dioxide.

It’s declining in most places around the world due to aging reactors, cheaper energy alternatives and public unease about radioactive risk — despite its climate benefits.

• The industry’s future is riding on largely unproven technologies like that of TerraPower because they’re smaller and deemed safer than today’s huge reactors.

“Without this next generation of nuclear, nuclear will go to zero,” Gates said.

Germany is shutting 22 nuclear plants, France — a leader in nuclear power — has plans to shut down some of its reactors, and a similar trend is underway in the U.S. due to economic conditions, said Gates, before adding with a sigh: “So yes, it is daunting.”

Flashback: Gates announced in December that TerraPower was scrapping plans to build a demonstration reactor in China, largely due to the Trump administration deciding that fall to crack down on technological agreements with China.

“There are times like when TerraPower gets told not to work in China, you’re thinking, ‘Boy, is this thing going to come together or not?’” Gates said in his first public comments on the matter since it happened. “That was a real blow.”

Where it stands: Gates is now trying to build TerraPower’s demonstration reactor in the U.S., calling on the Energy Department and Congress to more aggressively support advanced nuclear power through more funding and new legislation. Such a plant could cost anywhere between $3 billion–$6 billion.

“If at the end of the day we don’t find a country that wants to build an advanced nuclear power plant, then TerraPower will fail. I’m going to keep funding it for a period of years. And working with the U.S. is our strategy right now.”

The pace of new patenting for several categories of climate-friendly technologies has seen a "notable drop-off" since 2012, according to a July 11 analysis from the IEA and OECD.

Why it matters: While far wider deployment of existing tech can do a great deal to stem carbon emissions, the steep cuts needed to meet the Paris Agreement temperature goals will likely require substantial innovation.

What they did: The analysts explored the pace of patenting in several groupings of emissions-cutting tech (see chart above). They noted that several other fields — including health and IT — have not seen this drop-off.

• "Some of this decline could be explained by the increasing 'maturity' of climate change mitigation technologies, and thus lower propensity to patent."

But, but, but: It's not all gloom and doom. Some areas have bucked the trend, such as "enabling" tech for integrating storage into power systems, and cleaner shipping.

The bottom line: The core finding is concerning despite some bright spots, the IEA and OECD analysts say, noting for instance that today's competitive costs for wind and solar are the fruit of R&D in past decades.

"The precipitous decline in patented innovation since 2011–2012 is a stark warning since there can be a long lag between innovation and cost reductions."

Late Friday, President Trump declined to impose limits on uranium imports, rejecting 2 companies that asked for a 25% floor on domestic sourcing of the element used to make reactor fuel.

Why it matters: As Amy noted Friday when she learned of the then-unreleased decision, it's a win for U.S. power companies who argued a domestic production quota would raise costs.

• It's also a victory for countries that export a lot of uranium to the U.S., including Canada and Australia. The U.S. imports roughly 93% of uranium used in power plants.
• But it’s a loss for the uranium mining companies with operations in the West — Ur-Energy and Energy Fuels — that petitioned for the quotas.

The intrigue: The decision is a departure from Trump's protectionist trade measures on foreign steel, solar panels and more, Amy notes.

Where it stands: Trump's announcement broke with a Commerce Department finding that the heavy import reliance is a national security threat.

Trump said that while he agrees the Commerce findings "raise significant concerns," he believes a "fuller analysis of national security considerations with respect to the entire nuclear fuel supply chain" is needed.

What's next: The White House is creating a multiagency "working group" to craft ideas for "reviving and expanding domestic nuclear fuel production."

Oil prices are up just slightly this morning even though Tropical Storm Barry forced a hiatus in lots of Gulf of Mexico production.

The latest: Per Oilprice.com, WTI is trading up 20 cents to $60.41 per barrel, while the global benchmark Brent crude is up 31 cents to $67.03 as we sent this newsletter.

Where it stands: China, the world's largest oil importer, on Monday reported that its second-quarter economic growth was the smallest in nearly 3 decades.

In the U.S., nearly 73% of Gulf production was shut-in as of yesterday, per Interior Department data, but Bloomberg reports that Exxon, Chevron and others are restarting output.

The intrigue: Per Reuters, traders are trying to make sense of conflicting signs from China.

Reuters notes that oil's slight uptick comes as "Chinese industrial output and retail data topped expectations but gains were capped by overall figures showing the country’s slowest quarterly economic growth in decades."

The New Republic will no longer co-host a climate forum for Democratic presidential hopefuls following criticism over a now-retracted article attacking Pete Buttigieg.

Driving the news: Gizmodo said Saturday that TNR is withdrawing from the Sept. 23 event the 2 outlets co-planned, but that the forum will still happen and they're "seeking additional media partners."

• "This incident was entirely inconsistent with our values as journalists and with the inclusive atmosphere we intend to foster at the event," Maddie Stone, managing editor of Gizmodo's Earther site, wrote in a statement.
• Several environmental groups also pulled sponsorship for the event after the TNR story. It's unclear if any groups will reconsider now that TNR is out.

Catch up fast: The TNR article by openly gay literary critic Dale Peck described Buttigieg as "the gay equivalent of Uncle Tom" and referred to the South Bend, Indiana, mayor as "Mary Pete" throughout, per NBC News.

It attracted intense backlash Friday, and TNR yanked it Saturday and apologized.

The big picture: It's a stumble for efforts to deepen the election-cycle discussion of global warming.

This is 1 of at least 2 climate forums — events where hopefuls appear sequentially but aren't onstage together — organized thus far.

• A Georgetown University politics institute and the news service Our Daily Planet are hosting a forum Sept. 17–18.
• The Democratic National Committee has rebuffed calls to schedule or sanction a formal primary debate on climate.

Go deeper: Climate forum for 2020 Democrats set for September