Tony Fadell, who spent most of his career trying to turn emerging technologies into mainstream products as an executive at Apple and founder of Nest, said that even as the world faced the risks of climate change, money was flooding into less urgent developments in cryptocurrency, the so-called metaverse and the digital art collections sold as NFTs. Last year, venture capitalists invested $11.9 billion in renewable energy globally, compared with $30.1 billion in cryptocurrency and blockchain, according to PitchBook.

Of the $106 billion invested by venture capitalists in European start-ups last year, just 4 percent went into energy investments, according to PitchBook.

“We need to get real,” said Mr. Fadell, who now lives in Paris and has proposed ideas on energy policy to the French government. “Too many people are investing in the things that are not going to fix our existential problems. They are just investing in fast money.”

It has not helped that the industry has been burned before by a green tech boom. About 15 years ago, environmentally conscious start-ups were seen as the next big thing in Silicon Valley. One of the premier venture capital firms, Kleiner Perkins Caufield & Byers, made former Vice President Al Gore a partner and pledged that clean energy would eventually make up at least a third of its total investments.Instead, Kleiner became a cautionary tale about the risks of investing in energy-related companies as the firm missed out on early backing of social media companies like Facebook and Twitter.

There is evidence that these old fears are receding. Two years ago 360 Capital, a venture capital firm based in Paris and Milan dealing in early-stage investment, introduced a dedicated fund investing in clean energy and sustainability companies. The firm is now planning to open up the fund to more investors, expanding it to €150 million from a €30 million fund.

There are a growing number of dedicated funds for energy investments. But even then there is a tendency for the companies in them to be software developers, deemed less risky than builders of larger-scale energy projects. Four of the seven companies backed by 360 Capital’s new fund are artificial intelligence companies and software providers.

Still, the situation has changed completely since the company’s first major green-energy investment in 2008, Fausto Boni, the firm’s founder, said. “We see potentially lots of money coming into the sector, and so many of the issues we had 15 years ago are on their way to being overcome,” he said. But the availability of bigger investments needed to help companies expand in Europe still lags behind, he added.

The funding gap

Breakthrough Energy Catalyst, which is backed by Bill Gates, is trying to fill the gap. It was formed in late 2021 to help move promising technology from development to commercial use. In Europe, it is a $1 billion initiative with the European Commission and European Investment Bank to support four types of technologies — long-duration energy storage, clean hydrogen, sustainable aviation fuels and direct air capture of carbon dioxide — that it believes need to scale quickly.

In Europe, there are “significant difficulties with the scaling-up phase,” said Ann Mettler, the vice president for Europe at Breakthrough Energy and a former director general at the European Commission. There is money for start-ups, but when companies become reasonably successful and a bit larger, they are often acquired by American or Chinese companies, she said. This leaves fewer independent companies in Europe focused on the energy problems they set out to solve.

Companies that build complex — and often expensive — hardware, like Mr. Bitner’s batteries for long-duration energy storage, have an especially hard time finding investors willing to stomach the risks. After a few investment rounds, the companies are too big for early-stage investors but too small to appeal to institutional investors looking for safer places to park large amounts of cash.

“If you look at typical climate technologies, such as wind and solar and even the lithium-ion batteries, they took well over four decades to go from the early R&D to the large-scale commercialization and cost competitiveness,” Ms. Mettler said, referring to research and development. “Four decades — which obviously we don’t have.”

What investors want

There are some signs of improvement, including more funds focused on clean energy or sustainability and more companies securing larger investment rounds. But there is a sense of frustration as investors, companies and European governments agree that innovation and adoption of new technology need to happen much more quickly to reduce carbon emissions sharply by 2030.

“You won’t find a place in the world that is more attuned to what is needed than Europe,” Ms. Mettler said. “It’s not for lack of ambition or vision — it’s difficult.”

But investors say government policy can help them more. Despite climate pledges, the regulations and laws in place haven’t created strong enough incentives for investments in new technologies.

Industries like steel and concrete have to be forced to adopt greener methods of production, Mr. Boni, the 360 Capital founder, said.

For energy storage, hydrogen, nuclear power and other large-scale projects, the government should expedite permitting, cut taxes and provide matching funds, said Mr. Fadell, who has put his personal fortune into Future Shape, which backs start-ups addressing societal challenges.

“There are few investors willing to go all in to put up $200 million or $300 million,” Mr. Fadell said. “We need to know the government is on our side.”