Hawaiian Electric, Maui Electric and Hawaii Electric Light Company are committed to reducing Hawaii's A key challenge to any major infrastructure project, including renewable energy facilities, is location. Most people say they favor renewable energy, but when it comes to building a project, they may say “Not in My Back Yard.”
Renewable resources are not shared equally among islands. Oahu has the most people and thus the greatest electricity demand but limited sites and resources for renewable energy projects. Hawaii Island has abundant geothermal energy, a resource no other island presently uses for electricity.
Each Hawaiian Island has a separate stand-alone grid and it presently is not possible to move electricity between islands. Some renewables are not always available, like sunshine, wind, even the water in small streams. Having a large percentage of variable or “as available” energy on small, remote grids such as those in Hawaii is challenging, making it harder to maintain reliability and power quality. In addition to variable renewable energy sources, the electric utilities need “firm” energy sources which are available on-demand 24 hours a day to meet its customers' energy needs.
Supporting facilities, including power lines, substations, transformers and other equipment also pose a challenge. Most renewable energy projects are built in remote areas, far from population centers. Infrastructure to bring the power from these places to the grid – and to store or “smooth” variable “as available” energy -- is expensive and adds to the cost of the electric power.
Still, Hawaiian Electric, Maui Electric and Hawaii Electric Light Company are working hard to increase renewable energy. This includes encouraging other companies to develop renewable projects, adding power lines and substations needed for renewable projects and working on ways to smooth and store “as available” power.
Firm vs Intermittent
Because electricity is constantly being used 24 hours a day, we need reliable sources of energy. Traditional generators are considered “firm” because they provide continuous power. Some renewable sources – waste-to-energy systems like H-Power on Oahu and geothermal plants like Puna Geothermal Ventures on Hawaii Island - are also considered firm sources of power.
However, many renewable energy sources are considered “intermittent” or “as-available” because they do not provide continuous power. For example, the output of a wind farm will depend on minute-to-minute, second-to-second changes in wind speed and direction. Also, wind continues to blow overnight, when the demand for electricity is lowest. Rainy days or passing clouds can reduce the output of a photovoltaic system. Output from hydroelectric systems depends on the amount of rainfall and the flow of streams.
These kinds of intermittent or as-available renewable systems usually require “firm” generators to serve as back-ups or some type of battery system to store the electricity they generate. Currently, these kinds of battery systems are still being developed and are expensive investments.
A solar water heater is able to store water heated from the sun and provide hot water even during the night. However, storing photovoltaic power requires batteries that are currently expensive. Batteries large enough to store wind power for long-enough periods at a reasonable cost are just now being developed and tested.
As energy storage devices, including new generations of batteries, become available it will make it easier to reliably add more renewable energy to the grid.