How innovation can fuel the fight against climate change

When it comes to climate change, cities are both the problem and the solution.

They’re the source of 70 percent of global carbon dioxide emissions. But cities are also where the boldest climate leadership is coming from, and where innovative ideas to slash carbon from daily life show the greatest promise to scale up and make a real difference.

With Earth Day coming next week, Bloomberg Cities checked in with sustainability officers from some of the 25 cities that recently won the American Cities Climate Challenge. We asked them the same question: What’s the most exciting way cities can innovate in the fight against climate change?

Here’s what they had to say.

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Make renewable affordable

In the city of Austin, we own our own power utility, Austin Energy — the city council is the board of directors for that utility. Our residents want renewable energy, and Austin Energy has delivered it. We have major programs for solar on peoples’ homes, for utility-scale solar, for utility-scale wind. Now, we’re up to 40 percent renewable energy that is delivered to all our residents. And that’s while Austin Energy is keeping rates in the lowest 50 percent of electricity providers in the state of Texas. That’s the trend for us in Austin: We have leadership to make the right environmental choice, but at the same time we have pressures for affordability and our city council and our city management has driven us to do things that are also economical and work for all residents, money-wise.

Move with urgency

One of the ideas in Boston is that we just want to get out there and do it — to try things. We have 86,000 buildings in Boston that need deep energy retrofits in the next 30 years. But first we’ve got to retrofit one building and learn from that process and then do the next two, three, and 10,000. In Boston, we see climate change as not just a challenge but an opportunity — an opportunity to create a healthier and more thriving city with a stronger future. There’s a lot of opportunity to come out of this. And if we’re going to make the most of it, we’ve got to get out there and start working with our residents and businesses — more often and more quickly.

Turn sustainability into a perk

Orlando is trying to position itself as a truly experimental prototype community of tomorrow, like Disney’s EPCOT. If 90 million visitors are coming to our city every year, how can Orlando showcase the next generation of technologies and solutions to create smart and sustainable cities? We’re working with our rental car agency and the airport to offer electric cars to rent — and for those vehicles to double as a VIP pass to the city. You get free parking at theme parks, you get free charging at any of the stations around the city, and you get valet parking at your hotel. We want to make this a perk, for people to come to Orlando and have the experience of test-driving an all-electric vehicle while they’re here.

[Read: Building city hall capacity to fight climate change: 6 takeaways from U.S. cities]

Another thing we’re working on is floating solar, what we call “floatovoltaics.” In Orlando, and throughout the state of Florida, we manage storm water by building these man-made retention pond systems. They’re just cesspools for sediment and runoff, and don’t have a lot of value. We’ve now started to test floating solar panels on top of these water bodies.

Follow Chris Castro on Twitter @CastroIdeas.

Make carbon-free fun

One of the most exciting things about climate action at the local level is that the innovations are often the types of solutions that make our cities better places to live. We’ve been investing in expanding transportation options in D.C., so we have a great bikeshare system, and now we have lots of dockless scooters and bicycles. They’re fun and they make it easy to get around, but they also reduce our carbon emissions.

Follow Kate Johnson on Twitter @Katej07.

Focus on solar energy

We are in Ohio, which can be considered coal country, but we have our eyes set on large-scale solar. We’re doing everything we can to take city government 100 percent solar, and now have solar on 27 of our city facilities. We’re also delivering solar energy to the businesses and residents of the city through what’s called energy aggregation, where we purchase 100 percent green electricity and deliver it to almost 90,000 homes and businesses.

Follow Ollie Kroner on Twitter @OllieKroner.

Take a collaborative approach

There are a lot of ways that cities can innovate to combat climate change — everything from electric vehicles, to renewables, to how do we use the methane from our wastewater treatment plants to fuel our vehicles. It requires looking across multiple silos. Tackling this huge challenge will require multiple departments and community partners. Innovation needs to spill over into the collaborative approach that we need to achieve our goals.

Follow Rob Phocas on Twitter @NCgronk.

[Read: 5 women mayors to watch for climate leadership]

Prioritize equity in the energy transition

We need to not only mitigate our climate emissions but also make all of our communities thrive — to invest in solutions that benefit people. That’s something that in the past, climate action has missed in the communications of what we could do. It’s not just about the environment, it’s about how we empower communities, all communities, to thrive.

One of the most exciting things for me and for our community is our 100% clean energy plan, which was actually unanimously passed and adopted this year. And what is so exciting about it is that it’s not just about the clean energy transition, but it also prioritizes a 100 percent equitable clean energy transition. So the focus is on affordability for homes, on reducing energy burdens, on making our grid more resilient. Hopefully we can be a model for others not just to have that transition, but one that helps all communities thrive and have those positive benefits.

Follow John Seydel on Twitter @JohnRSeydel.

Inspire behavioral change

Our Smart Columbus initiative is tailored to get more folks interested in adopting electric vehicles, and also to get folks out of their single-occupancy vehicles and into other forms of transportation. For us in Columbus, that is generally on our bus line, so we’ve added a lot of rapid-transit options to be able to do that. Behavioral change is the most difficult thing for a city to try to do. So it takes a lot of creative ideas, marketing campaigns, things that appeal to folks’ behaviors.