The rapidly diminishing global oil supply presents not only a broad danger to our economy but also many specific problems relating to our daily existence. Hawai'i's overwhelming reliance on oil for electricity certainly ranks high among them. Those who experienced the 2006 earthquake-related power outage on O'ahu have a vivid picture of life without electricity: Essentially, it stops. How can we ensure that a Hawai'i without oil has electricity?

There is a variety of partial solutions under consideration, and some look better than others, but most likely we will be living with far less electricity than we are used to for many years. Oil will grow ever more scarce and expensive, and it's unlikely that alternatives will develop quickly enough to replace fossil fuels on the scale we use them now.

What are HECO's plans for electricity in Hawai'i, particularly on O'ahu where demand is greatest and the siting of any new energy facility the most problematic? Biofuels are a big part of its current vision, and the appeal is understandable. They can be burned in turbines similar to those used now for oil and provide 24/7 capacity. In the short run or in small quantities this may be a good solution, but it might not be workable on a large scale. By HECO's own estimate, a very large percentage of local arable land would be required to meet barely 25 percent of its biofuel demand.

The impending oil shortage is going to cause all liquid hydrocarbons, including biofuels, to be in extremely short supply for even their traditional applications such as transportation fuel. Plans to integrate increasing amounts of wind power from O'ahu and the Neighbor Islands are much more sustainable.

There are other good long-term electricity solutions for our state, although unfortunately none without significant present-day problems. Hawai'i's solar resource is immense, and can be tapped on a large scale in two very different ways — capture via photovoltaic (PV) panels or thermal-electric installations on shore, and harvesting off shore via ocean thermal energy conversion (OTEC).

The cost of solar PV, although still high, continues to drop and PV now has a quite good energy return ratio. It has been estimated that 100 square miles of PV panels operating at a currently achievable 22 percent conversion rate could supply all of the state's energy needs. While the idea of a single installation of that size is daunting, it's possible the total rooftop area within the state approaches that dimension. Escalating oil prices clearly make residential PV competitive with oil-fired electricity; it's conceivable that continuing tax credits in combination with home equity loans could make PV widely available. Utility-operated solar installations are probably better able to utilize thermal-electric technology, which is cheaper but involves tracking and focusing mechanisms unsuitable for homeowner maintenance.

The problem with on-shore solar power is its intermittent nature. There is currently no good way to store electricity made on sunny days on a large utility-sized scale for usage at other times. A growing number of PV installations could, however, contribute substantially to our daytime needs and conserve much oil.

Fortunately, OTEC does not suffer from intermittency. It operates 24/7 using the stored heat resident in tropical ocean surface waters and is thus capable of generating the same important baseload power as HECO's oil turbines. Designers believe the construction of 50 megawatt plants is achievable, meaning that several such facilities could meet a significant portion of O'ahu's needs.

OTEC's problem is the complete lack of a production track record at any useful size. It has been tested in small prototypes but no one has yet built a plant of significant capacity. It is difficult to estimate how much a plant would cost, how long it would last in a tough marine environment and whether or not there are unacceptable ecological consequences to the pumping of the large amounts of water required. Nevertheless, it seems much too promising to ignore in our current state of energy desperation, and Hawai'i is the best location in the U.S. for its deployment.

Perhaps the easiest investment HECO can make today is to prepare the grid for the coming times of oil scarcity and renewable intermittency. Our current grid is so fragile that minor hardware failures triggered its collapse during the 2006 earthquake. HECO must develop the capability to manage the rolling brownouts that are likely in the coming years due to the oil shortage. It must be able to reliably power critical services such as police, hospitals, water supply and food storage; shed and restore other customers as solar or wind sources go off- and on-line; and ration usage on a per-home basis.

Finally, the public must understand that shrinking oil supplies will surely lead to diminished service if we fail to quickly establish adequate renewable sources. Homeowners and businesses who can afford to install PV should do so immediately, and we must abandon resistance to wind turbines and other energy facilities for aesthetic reasons — the luxuries of delay and NIMBYism are no longer ours to spend.

Roger Davis is a software engineer in the School of Ocean and Earth Science at the University of Hawai'i-Manoa. Torben Nielsen is on the faculty in the Hawai'i Institute for Geosciences and Planetology at the University of Hawai'i. The views presented here are their own. They wrote this commentary for The Advertiser.