Advocates of clean energy take encouragement from watching the use of fossil fuels to generate Hawaii’s electricity continue to decline.

Conversely, they point with mounting frustration at the rising consumption of those polluting energy sources for ground transportation, partly due to the resurging popularity of SUVs and other large vehicles.

That disconnect was the reason for officials representing the state’s four counties to come out last week and sign a joint proclamation. The pledge: Ground transportation vehicles powered by fossil fuels will be off Hawaii roads by 2045.

This is an aspirational goal, of course. Government regulates the public utilities, enabling officials to press for clean energy at electric plants, with enforceable commitments to reducing petroleum- based fuel sources.

But as much as electric vehicles are rightly touted as a potential environmental tool, lowering the nation’s carbon footprint, government cannot control what vehicles consumers buy.

Even so, such pledges are welcome, even necessary, to move the needle in the desired direction. An island state should align its practices with efforts to slow the climate change that threatens with rising sea levels and severe weather conditions.

The question is, how is progress to be encouraged?

Innovation is an essential ingredient, and developments on multiple fronts — hydrogen cars and biofuel-powered vehicles, as well as EVs — are needed. Hawaii can meet its ground-transportation energy goals through a technological mix, but plainly EVs have advanced the most to date and provide the best hope for progress, at least initially.

And within that category, a great deal of the responsibility for that progress rests, as it should, on the free market: manufacturers producing EVs with standards and features — and at a price point — that consumers want.

But there is room for partnerships between the public and private sectors that lay the groundwork to make EV use more practical for more people.

The pledge was signed Tuesday by Honolulu Mayor Kirk Caldwell, Maui Mayor Alan Arakawa, Kauai Mayor Bernard Carvalho Jr. and Hawaii County Managing Director Wil Okabe. Efforts were made last session by state lawmakers seeking to set a similar 2045 target to phase out fossil fuels in ground transportation.

The measure, House Bill 1580, moved through both chambers but sputtered and stalled in conference committee. So kudos go to the county leaders for stepping up and uniting behind the challenge.

The accord will bring some needed commitment from the counties to EV conversion. Caldwell, for example, said next month the city would begin transitioning to an all-electric bus fleet, a process that will take until 2035. This should save money over the long term because the vehicles operate with fewer maintenance problems.

It also makes sense to transition this gradually, replacing combustion-engine buses over time. The prices should drop in the interim, to make the most of the city investment.

What’s less clear is the path the mayors will follow to develop the infrastructure: EV charging stations and pumps to deliver hydrogen and renewable diesel.

Jeff Mikulina is CEO of Blue Planet Foundation, an environmental nonprofit focused on clean energy. The organization supported HB 1580 and was chagrined to see that measure fail, along with HB 793, which sought to strengthen the regulatory push for more charging stations.

There are various strategies that could still grow the network of charging stations. The state and counties could provide some property and other assists to a private partner who could do the buildout; a public-private sharing of revenue from drivers buying the electricity also could be arranged.

However, Mikulina said, the potential for a giant leap forward lies in encouraging their installation in complexes where people work; drawing power during the day when electricity use is low could help the stability of the grid, he said, something the power utility has an interest in supporting.

A scheme of this sort could be forthcoming when Hawaiian Electric Industries presents its “electrification of transportation” plan in the spring, as scheduled, before the Public Utilities Commission.

Hawaii is one of the few states that does not fund tax credits for EV purchases, he added, to pair with the federal subsidy. That is not necessarily a failing: Hawaii comes with its own incentives to persuade buyers to make the EV purchase. Fuel costs are high, and generally short commutes make the cars a practical choice.

There are subsidies in the form of free EV parking and other perks that are an easier sell, politically. Someday even these will need to go, but Hawaii has not reached that tipping point quite yet.

The clean-energy movement is picking up speed. If the transportation and related industries do their part to meet consumer demands, smart policies from local leadership could give the accelerator a nudge.