Hawai`i Energy Self-Reliance
By Henry Curtis (August 1, 2007)

Introduction

There are two approaches to energy self-reliance: (1) Incrementally moving forward, picking low hanging fruit, increasing the use of efficiencies and renewables a little at a time; and (2) Assuming that we are 100% self-reliant in 2020, and looking back to see how we did it.

Looking backwards forces us to look at each option available. It forces us to look at what could happen. Once we have a portfolio we can began changing the percentage of each component, but not the total. We are 100 percent renewable. These are the portfolios and the paths that could get us there.


Photovoltaic (Solar) Systems

Take solar. PowerLight built a 0.3 MW photovoltaic system on the roof of a naval structure on Ford Island. Completed in 2005, it occupies 3/4 of an acre. Since there are 640 acres in a square mile, we can assume that a square mile of Hawaii would produce 250 MW of photovoltaic. This estimate can be compared to other installations worldwide. Reviewing photovoltaic sites throughout Hawai`i and California reveal that one square mile of sunlight will produce 200 - 300 MW of power.

O`ahu's Peak Energy is around 1400 MW, Maui and the Big Island around 200 MW each, and Kauai around 100 MW. Thus the state has a peak electrical demand of under 2000 MW, which could be produced using less than 8 square miles of solar panels.



                                                  

Another type of solar energy collection is to use a parabolic mirror to capture the rays of the sun, and to focus it on a pipe, heating its liquid contents into a gas to fire a gas turbine. This technology is based on steel and glass, rather than silicon which is in short supply.

The limitation for solar is either the sun must be shinning, or their must be batteries. The night-time light at the end of the road at Volcanoes National Park lets hikers know how to get back to the road. This light, according to the placard, is provided by a HELCO photovoltaic unit.


Wave Energy Systems

The Electric Power Research Institute (EPRI) is a national utility think tank. Its members represent over 90% of the electricity generated in the United States. In 2004 EPRI examined wave power, and more specifically, looked in detail at Hawai`i's potential wave power. EPRI found that wave energy off Molokai could produce 200 times Molokai's needs, whereas waves off O`ahu could produce just 100% of O`ahu's  total electrical demand. Each island could meet its electricity needs through wave energy. Wave energy is more predictable than wind energy. Small waves (6 inches) can be captured an converted to electricity.



            

The Blow-Hole (Oscillating Water Column) Wave Energy System consists of a compartment with water at the bottom and air on top. When a wave arrives, the water level rises and air is forced out of the blowhole. When the wave recedes, the air is sucked back into the blowhole. A two-way air turbine spins in the same direction as the air goes in and out, generating electricity. There is only one moving part and it is above water. The height of the system above water is about 30 feet.The units can be shorebased or in the ocean. They can operate with very small waves. Each unit is rated from 0.5 to 2.0 MW. The system was developed by  Oceanlinx (formerly Energetech) and WAS a Top 10 Finalist for Scientific Innovations of 2006 by the International Academy of Sciences.



Wind Energy Systems

There are three kinds of wind power: land-based, ocean-based, and micro-rooftop systems. Looking just at land-based systems, each Island except O`ahu could meet a third of its energy by wind.

                  

Rooftop Micro-Wind


          

Small wind turbines on the roof of an office in London renewable devices
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 A micro turbine installed on a rooftop in Scotland. windsave
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 Rooftop wind turbines on a new building in Bosnia veneko / bergey windpower
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The limitation for wind energy penetration is determined by the electric grid, and not by  the wind. The limitation is that a the systems generally do not exist in low wind and calm periods. Moloka`i and Lana`i could produce excess power for the O`ahu grid. That is, they could each produce 100 MW.

Sea Water Air Conditioning

Sea Water Air Conditioning involves two pipes, a U-shaped ocean-water pipe and a circular fresh-water pipe, which meet at a heat exchanger. The water in each pipe does not cross into the other pipe, rather the heat moves from the fresh-water to the ocean-water. The ocean water pipe pulls cold water from the lower depths and discharges warmer water to a warmer layer of the ocean. The fresh-water pipe brings cool water into buildings, where heat exchangers pull heat out of internal pipes within individual buildings. This alleviates the need for expensive chillers to be located within each buildings. Forty percent of the commercial load is for cooling.

Cornell University studied this approach in a multi-year environmental review, examined in depth by environmentalists and university researchers. They found that the total yearly heat added, via pipe, to a lake located six miles from campus was equivalent to one hour of summer sunshine upon the lake surface. That is, over the course of the year, the sun accounted for 99.9% of the heat entering the lake. Cornell University's and Toronto's systems were installed by  a Hawai`i company.




A. Cornell University's Lake Source Cooling Project would bring in water from the deepest part of the lake which is at an almost constant 39 degrees, ship it 4 miles to a heat exchanger at Cornell University, and then return the water to Lake Cayuga's shallow, warm south end.  The temperature of the piped lake water would rise 10 to 15 degrees at most as it absorbs the heat removed by the campus cooling system.

 
The Institute for Science in Society notes:  ''Many great cities around the world are located near ocean shores or deep lakes. The cities of Toronto, Stockholm and Honolulu, and the Cornell University campus are showing the world what can be done using cold deep water to power the cooling of large buildings, providing a large saving in energy and cutting down on carbon emissions and pollution from energy generating plants. ...

Ocean Thermal Energy Conversion

A closed-cycle Ocean Thermal Energy Conversion (OTEC) is similar to Sea Water Air Conditioning  in that it uses two ocean pipes.  OTEC systems use warm surface water, via a heat exchanger, to boil a liquid fuel, such as ammonia (NH3).  The vapor goes through a turbine/generator to produce electricity. Cold deep ocean water is then used to condense the working fluid, and then the cycle is repeated. The fuel stays within the circular piping system which can be located on a barge a few miles off the coast. Economically, the economies of scale favor a 50 - 100 MW system. Since the layers of the ocean always exist (seasonally, daily), the power can be produced continually (24/7). As global temperatures rise, the temperature difference between ocean layers increase, making the OTEC system more efficient. OTEC could provide all of the power needs of Maui, the Big Island, Kauai, half of the needs of O`ahu and maybe none of the needs of Lana`i and Moloka`i unless they were connected by transmission line to the Maui grid.


 
Open Cycle OTEC
 Closed Cycle OTEC


Thermocline energy is based on the temperature differences between surface water, which is heated by the sun, and deep water, which stays very cold. Thermal energy conversion plants use the surface water to make steam and then pass the steam through a turbine generator to make electricity.  Ocean thermal makes use of temperature gradients in a thermal (Rankine) cycle process. It requires the use large plants because of the low thermal efficiency, and hence, a large capital investment is needed for such plants.

Based on 35°F temperature difference, the Carnot cycle (best possible) efficiency is low, i.e., approximately 6%. The actual efficiency is 2-3% since the water must be pumped and there are thermal losses.  To compensate for its low thermal efficiency, OTEC has to move a lot of water. That means OTEC-generated electricity has a glut of work to do at the plant before any of it can be made available to the community power grid. In smaller plants, some 20 to 40 percent of the power goes to pump the water through intake pipes in and around an OTEC system.

OTEC plants must be located where a difference of about 40° Fahrenheit (F) occurs year round. Ocean depths must be available fairly close to shore-based facilities for economic operation. Floating plant ships could provide more flexibility. In the US, ocean thermal energy conversion is limited to tropical regions, such as Hawaii, and to a portion of the Atlantic coast.

There are three potential types of OTEC power plants, open-cycle, closed-cycle and hybrid systems. Open-cycle OTEC systems, illustrated in Figure 2a, exploit the fact that water boils at temperatures below its normal boiling point when it is under lower than normal pressures. Open-cycle systems convert warm surface waters into steam in a partial vacuum, and then use this steam to drive a turbine connected to an electrical generator. Cold water piped up from deep below the ocean's surface condenses the steam. Unlike the initial ocean water, the condensed steam desalinated (free of salt) and may be used for drinking or irrigation.

Closed-cycle OTEC systems use warm surface waters passed through a heat exchanger to boil a working fluid, such as ammonia  which has a low boiling point. The vapour given off is passed through a turbine/generator producing electricity. Cold deep ocean water is then used to condense the working fluid and it is returned to the heat exchanger to repeat the cycle.

Energy Efficiency

A Statewide Energy Efficiency Utility under PUC regulation will be established in Hawai`i in January 2009. Load Management will be kept with the utility. Aggressive energy efficiency and load management techniques can reduce electric loads by 25%. Energy Efficiency and Load Management are also called Demand Side Management (DSM)

Compact Fluorescent Lights (CFL) and Light Emitting Diode (LED) bulbs have revolutionized energy-efficient lighting

      

Daylighting is the controlled admission of natural light into a space through windows and skylights to reduce or eliminate electric lighting. Daylighting decreases air conditioning, since electric lights produce mostly heat. Daylighting also creates a visually stimulating and productive environment for building occupants.

Smart meters identify consumption in more detail method than a conventional meter; and are able to communicate that information to owners and to the utility via phone lines or wireless telecommunications.


Innovative Rate Structures

Green Time-of-Use Rates. For customers with self-generation, and the willingness to forgo grid energy during peak periods (weekdays 8 am to 10 pm), the customer would receive discounted renewable energy during off-peak (weekends and nights: 10 pm - 8 am) similar to cell phone discounting. Electric vehilces would be powered  at night and couls supply back-up power to the building during the day. The building-vehicle energy system would provide energy for heating, cooling, electricity and ground transportation.

Interruptible Load Rate Structure.  In the past dumb meters read electricity consumption and had hard-to-read displays. Modern meters can provide for both internet displayed data and wireless control. In exchange for utility discounts, the utility has the ability to curtail service to a customer during energy spikes.

Time Of Use Rates. Hawaiian Electric was an early implementer of Time Of Use Rates, however their practice was to reward customers who had flat loads (that is, customers who had the same energy demand 24/7. Modern Time Of Use Rates rewards customers who use power off-peak. In its simplest application, there would be three rates: off-peak, shoulder, and peak. The spread varies by utilities, from 1 to 100 percent. The higher the discount for off-peak use, the more customers will switch.


The Portfolio

We must include a greater portion of technology which can supply power whenever it is needed (OTEC) or can displace power whenever it is needed (SWAC). Wave, Wind, and Photovoltaic all provide intermittent power and therefore must have some form of battery. However there peaks do not coincide and therefore having north and south shore wave systems, and multiple wind and solar systems, can provide for greater security. It also requires smarter systems (computer, telecommunication, management).

State of Hawai`i 2020 Scenarios

Island
 PV (%)
   
Wind (%)   
OTEC
   
SWAC
   
Wave
   
Hydro
   
DSM
   
Batteries*
Hawai`i
100
30
100
0
100
2
25
0
Maui
 100
30
100
0
100
1
25
0
Moloka`i
 100
5000
0
0
20,000
0
25
0
Lana`i
 100
5000
0
0
100
0
25
0
O'ahu
 100
5
50
5
100
0
25
0
Kaua`i
 100
30
100
0
100
0
25
0
State
 100
15
75
5
100
0
25
0

* Batteries provide no power of their own, but can store energy and thus increase the availability of intermittent resources

O`ahu   2020 Scenarios

2020
 PV (%)
   
Wind (%)   
OTEC
   
SWAC
   
Wave
   
Hydro
   
DSM

O'ahu 5
5
50
5
30
0
5

O'ahu 40
0
0
2
40
0
18

O'ahu 25
0
35
5
10
0
25

O'ahu 40
30**
0
5
5
0
20

O'ahu 30
30**
40
0
0
0
0


** with a Direct Current Transmission Line from Moloka`i and/or Lanai

Implementation

Life of the Land is an environmental and community action organization founded in early 1970, before the first Earth Day. The organization is the only environmental group that intervenes before the Hawai`i Public Utilities Commission (PUC).  Life of the Land has won an electric rate case before the Hawai`i Supreme Court, a Transmission Line contested case hearing before the Land Board, and presented expert testimony on ocean power systems, climate change and biofuels before the PUC, which the utility chose not to cross-examine. Life of the Land  is involved in dockets on generation, transmission, renewable energy, distributed generation,  energy efficiency and inegrated resource planning. Life of the Land is formulating 2020 scenarios for O`ahu as part of the Hawaiian Electric Integrated Resource Plamming docket based on 100 percent renewable energy .



What follows is one possible implementation of one option: PV (5%); Wind (20%) with a Direct Current Transmission Line from Moloka`i and/or Lanai; OTEC (30%): SWAC (5%); Wave (25%); Batteries.

Imagine a power strip that is connected at both ends to the electrical outlet and has a number of plugs in the middle. In electricity this is known as a microgrid. Each transmission line would be installed using directional drilling to get the line beneath the shoreline and beneath the reefs, to avoid burials and sensitive ecosystems. Building three microgrids off the coast allows for multiple systems to be added and subtracted without disturbing the coast. These microgrids can allow for a variety of projects (pilot projects, small projects and large projects). They would be located off Kahe Point, Honolulu and Kaneohe.


Storage (Batteries)
 (http://www.axeonpower.com/alternatives.htm)
Capacitors - The Electrostatic Battery
The use of capacitors for storing electrical energy predates the invention of the battery.
Heat - The Thermal Battery
There are two types of thermal batteries, one based on the thermo-electric effect which produces electricity directly from heat, outlined here, and the other based on chemical or galvanic reactions
Springs - The Clockwork Battery
Energy is stored in spring which is wound up by a clockwork mechanism. When released, the spring is used to drive a dynamo which provides the electrical power.
Flywheels - The Kinetic Battery
Energy storage in a flywheel is as old as the potters wheel.
Compressed air - The Pneumatic Battery
Compressed Air Energy Storage (CAES) uses pressurized air as the energy storage medium.
Pumped storage - The Hydraulic Battery
At times of low electrical demand, excess electrical capacity is used to pump water into an elevated reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine, generating electricity .
Superconducting Magnetic Energy Storage (SMES) - The Magnetic Battery
Superconducting magnetic energy storage systems store energy in the field of a large magnetic coil with direct current flowing. It can be converted back to AC electric current as needed.