We still have a long way to go to reach Hawaii’s goal of 100% renewable energy generation by 2045 — a mere 23 years from now.

The state has made significant advances in developing renewable energy, primarily solar and wind, the most efficient and cost-effective renewables available today. However, the sun doesn’t always shine and the wind doesn’t always blow.

The reliability and stability of our electrical grid still depends on fossil fuels, which are always available and provides energy 24/7, 365 days a year. Most of Hawaiian Electric’s electricity — roughly 68% — comes from fossil fuels.

But fossil fuels are dirty, contributing to greenhouse gas emissions. It’s also getting more expensive, due to world events beyond our control. Last week, Hawaiian Electric warned residential customers of price increases, fallout from Russia’s invasion of Ukraine.

It is imperative that the state expands its own sources of firm energy generation from renewables, at a reasonable cost to consumers.

We do have H-POWER, which generates an estimated 10% of Oahu’s electricity by burning garbage. And Hawaiian Electric has begun the process for seeking proposals to develop new firm renewable generation projects on Oahu.

“It would be difficult, if not impossible, to replace all fossil fuel generation capacity with wind, solar, and storage, particularly on Oahu,” because of the large quantities of electricity required, the impact of prolonged poor weather and land use and infrastructure requirements, Hawaiian Electric said in describing its plans to the state Public Utilities Commission (PUC).

How many more firm sources will be needed — and what they will look like — is anyone’s guess.

Nonetheless, last week state lawmakers made a pretty specific guess. The Senate sent to the House Senate Bill 2510, which would, among other things, require each island to have a minimum of 55% firm renewable energy generation. It also would limit the percentage of any one type of renewable energy source to 45% of all generation for each island.

Fossil fuel generation would be prohibited after Dec. 31, 2045, except under emergency conditions.

Those renewable energy percentages, as well as the fossil-fuel deadline, could be altered by a concurrent resolution of the Legislature.

Laying down aspirational benchmarks is one thing, and a good thing; predicting the future is something else. SB 2510 simply goes too far at this time.

A 100%-renewable energy portfolio will require different kinds of electricity generation; the correct proportion depends on certain unknowables, among them the evolution of technology and the market. We can’t know whether 55% is a reasonable number; it might be, or it might be wildly off the mark. SB 2510 could lead to the adoption of technology that is inefficient, overpriced or just not ready for prime time.

It also makes little sense for the Legislature to micromanage this complex and evolving industry; utilities, power producers and state regulators depend on reliable and predictable processes to develop projects that can cost many millions of dollars. It’s no place for transitory politics.

Of course, the future for firm renewables isn’t entirely opaque. Besides H-POWER, hydroelectric power (on Kauai), geothermal and biofuels already are in limited use in the islands. Last year, 6% of Hawaiian Electric’s electricity was generated by firm renewables. And waiting in the regulatory wings is Hu Honua Bioenergy LLC, aka Honua Ola, which hopes to open its eucalyptus and albizia tree-burning facility in Pepeekeo, Hawaii island, as soon as possible.

Hu Honua’s plant is at the right scale: It would generate up to 21.5 megawatts, enough to power 14% of Hawaii island’s electrical needs. But opponents of the plant, now 99% complete, say it will generate as much carbon dioxide as fossil fuels, contravening the state’s goal of reducing greenhouse gas emissions. The plant’s owners dispute this claim, and the PUC is now considering whether to allow the plant to open.

Hawaii’s renewable energy future is bright. But meeting the three most important goals — clean energy, reliable energy and affordable energy — will require careful planning and maximum flexibility.

The state’s guidance should allow for both.