Stephan Dolezalek, managing director of Resourcient Capital Partners, and Nancy Pfund, managing partner at DBL Partners, both commented on the balance between the moonshots and surer bets while at Fortune’s Brainstorm E conference on Tuesday.

Their comments were in response to the recent decision by Microsoft co-founder Bill Gates and a group of fellow billionaires to create the Breakthrough Energy Coalition to spend billions on cleantech research and development. The goal is to help spur the technological breakthroughs that they say are needed to reduce the world’s dependence on carbon-based fuels.

Some critics argue that Gates’ money would be better spent on funding and scaling existing renewable technologies, such as solar and wind power. Less, they say, is needed to fund the risky moonshots.

“The reality is that we need both,” said Dolezalek, who also has a role helping advise Gates about which breakthrough technologies to invest in.

Pfund agrees, but says that there is already so much progress with current companies like Tesla, that there needs to be funding of the next Teslas too.

“As a V.C., I love a miracle. I rely on them,” she explained. “And the fact that clean energy companies are doing as well as they are is a miracle. We are building iconic companies that are replacing existing companies.”

The reasoning for funding both, she added, is because unlike other industries, energy doesn’t have time to waste. “We are in the emergency room,” Pfund says. “We have to use the technologies we have and fund the new ones.”

And not all of these breakthroughs or miracles are long term. Dolezalek explained that there are some moonshots that might have a shorter time frame of being developed and scaled. And not every miracle will completely reinvent how energy is made, he said.

It’s also important to realize that the miracles of today might become the go-to technology that we use soon. “At one time, solar was a moonshot. We used the same terms to describe it as we talk about nuclear today,” said Dolezalek.