It’s been six years since the Clean Energy Agreement called for an undersea cable. Since then, progress has been disappointing.

We’ve been talking about the cable and the smart grid since the agreement was made. Although we’ve built capacity in renewables, we haven’t built the platform for them.

Now, six years later, it’s time. The Public Utilities Commission should determine that the cable is in the public interest and issue or order a Request for Proposals to get it done.

In the Silicon Century we live in a world of amazing devices. To use them we need better and more reliable power. But PV and wind are in curtailment contention and require a solution to store or balance the load. The cable could be a big part of that solution.

Although a bill was passed to facilitate cable development in 2012, it didn’t help; activist opposition and the change in ownership of Lanai sidetracked the Big Wind project, including the cable.

Although Hawaiian Electric had included the cable in an RFP proposed in 2011, last year the PUC separated it onto an "investigative" docket. Since then the PUC has taken submissions and held public meetings in that investigation.

(On a different docket, the PUC is reviewing Castle & Cooke’s proposal to develop a 200-megawatt wind project on Lanai that would transmit power to Oahu by cable.)

Although the cable was going to be between Oahu, Lanai and Molo­kai, it’s now a two-strand, 3-inch, 100-mile cable between Oahu and Maui. It will cost $700 million, take two years to build and have a useful life of 30 years.

The PUC will determine whether the Oahu-Maui cable is in the public interest, for example, whether the benefits to ratepayers are worth the cost.

The cable can share power between the islands, from those with more clean energy at any given moment to those with less. It can also smooth out the power spikes in nonfirm renewables.

A utility must maintain additional generating reserve when it uses nonfirm renewables. The cable, however, has voltage source converters that act like controllable generators to respond to demand and regulate voltage and frequency. This reduces the reserve otherwise required.

The equipment on the cable can direct all the smart-grid elements it controls to work together. Since it manages so much electricity through those elements, economies of scale make it much more efficient than a distributed grid.

Hawaii is in an unprecedented transformation to clean energy. When we succeed, we won’t have oil generators to fall back on. Instead, we’ll be relying on high-tech equipment for clean energy and possibly liquefied natural gas. What if that equipment fails and we don’t have a spare? Suppose it takes weeks to get a replacement?

We can’t afford not to have the security of the redundant sources the cable will provide. Reliable electricity is mission-critical, and responsible planning requires nothing less.

When one island’s grid is affected by weather (the state spans 1,500 miles) or disaster, that island could go dark even when others are still lit. Surely, such disparities are not in the public interest. We can do better with an interisland grid.

The state’s submissions calculate that the cable will give ratepayers a net saving of 6 cents per kilowatt-hour, or $423 million over 30 years, by allowing the grids of the two islands to operate more efficiently.

From these submissions it seems clear that the cable will increase grid security and reliability, lower energy costs, reduce curtailment losses, increase the use of clean energy, reduce fossil fuels, move toward uniform rates between islands and help Hawaii’s economy.

With all this in mind, the benefit of redundant interisland sources certainly seems worth $700 million over 30 years. It’s insurance, at only 10 percent of what we spend for foreign oil in one year.

But so often we are tentative in deciding on big projects, disorganized in planning them, hesitant in embarking on them and forgetful in recalling what we decided. None of that is acceptable here.

We need to move clean energy ahead on all fronts, as if our economy depended on it. We don’t have the time to lose confidence in the decisions we’ve made or go into lockup on executing them.

Nor is this a time to play to the claims of anti-progress activists. Every year we send billions away for fossil fuel. The expenses of the transformation must come before the savings. In building clean energy, and the infrastructure to carry it, time remains of the essence.

Jay Fidell, a longtime business lawyer, founded ThinkTech Hawaii, a digital media company that reports on the tech and energy sectors of Hawaii’s economy. Reach him at fidell@lava.net.