Ideas and Information from a Maui Perspective

Toyota Proposal

By Steve Rose
Wednesday, October 23, 2002

A Proposal for a Joint Venture Between Viaduct Corporation and Maui Toyota, and Toyota Corporation for the development and marketing of the Prius as an Alternate Energy Source


An Opportunity for Toyota to Capitalize on their Development of Hybrid Technology


Steve Rose

Viaduct Corporation

23 December 2000


The Prius is a logical step forward in automotive technology, enabling economy through the appropriate application of various technologies for energy conservation, recapture, and efficient application.  However, it also represents a major opportunity for Toyota to enter an unanticipated new market, which could propel Prius sales to a level unprecedented in the introduction of a new technology.  With its ability to efficiently generate electricity, and a built in high voltage self charging storage system, the Prius makes an ideal self contained energy source.  In normal times, the market for such a system would be limited to those living “off-grid” – outside the range of the normal power system.  These are not normal times.  As the headlines below demonstrate, electrical power has become unreliable and remarkably expensive, particularly in California.  These conditions will not be ameliorated for several years, as new generating capacity comes on line (or heavy industrial consumers of electricity relocate).  In other areas, a harsh winter will lead to widespread, life threatening power failures of significant duration.  This is likely to become an even more predictable winter event.


In California, Energy Deregulation Creates a Crisis and Sparks Acrimony


Power Shortage Sends Ripples Across West


After Summer of Power Woes, California Is Hurting Again


“The system operator squeaked by at the last minute, the energy executives said, paying more than $1,000 per megawatt for electricity imported from the Pacific Northwest. By contrast, the price cap for electricity bought in California is usually $250 per megawatt.”


Homeowners plug in to generators 

Some are spending plenty to keep power coming

“…That's because they were among the 15 families in Wisconsin Gas Co.'s pilot program of installing gas-fired power generators in homes, a program now available to everyone…."This last storm, six weeks ago? The power was out 17 hours straight here, from 5 p.m. Sunday on into Monday. …The 8-kilowatt system, called Power Now!, cost about $7,000, which Melby doesn't consider extravagant considering his subdivision's vulnerability.”


The high voltage system of the Prius is ideal for power conversion to 117V AC 60 cycle sine wave output.  The technology to build a compatible switching inverter is very straightforward, and there are already several manufacturers with off the shelf solutions (from the on-line UPS world).  However, it might be a project that Toyota would rather handle internally, since it is the same technology already in use in the Prius control system (it may even be that the output of the motor control system could be used directly).  There is no reason that their couldn’t be several output voltages, to accommodate various applications and regions of the world.


An ideal local power system is quiet, safe, simple to operate, and economical.  Fuel should be readily available and systems which make the fuel safe to handle should be in place.  Operation of the power system should require no technical knowledge on the part of the user – it should be a matter of plugging in the power source and pressing start.  The power system should be self contained, easily maintained with local technical support, and protected against vandalism.


The Prius meets all of these objectives:  It is quiet, safe, and economical (see below for estimates of operating costs in this context).  Its fuel is readily available with an existing safe infrastructure for distribution (“Filling Stations”).  Its operation requires no technical knowledge (the onboard computer controls starting and stopping of the engine according to the charge state of the battery, ideal for local power generation).  It is already set up for “plug and play” operation – only the plug is missing.  It is self contained, Toyota has already set up a maintenance support infrastructure that is bound to grow quickly, and the Prius can be locked securely.


The most likely application would be to power necessary services only in a residential context, although some small businesses have low enough power demands to take advantage as well.  Emergency service would be the most likely scenario, using all of the standard approaches for stationary local emergency power (including a cutover switch which prevents feeding energy back into the normal electrical distribution system).  The Prius is primarily an automobile, with emergency power a secondary consideration, making it easy to cost justify.  It is also much safer than an emergency generator for which fuel must be transported externally, since the Prius is built to transport fuel safely.


A secondary application is as a recharging station for a self contained residence.  For example, a photovotaically powered residence typically makes enough energy for normal household use (lights, refrigerator, computer, stereo, small appliances).  However, a generator is sometimes required for a boost charge or direct energy source when usage exceeds system capacity due to weather conditions, high load, or the use of high demand appliances (washer and dryer,  shop tools, auxiliary heaters).  The Prius would be ideal for this application, as the boost source or even sole charging source.  It could also serve as a heat source for winter applications, recapturing what would normally be waste heat from the engine by coupling (e.g. via a window adapter) to the Prius’s normal passenger compartment heating system.   (Year around, the waste heat could be used to augment or replace the energy normally consumed by the household hot water heater).  The need for the additional energy goes away when the residents drive off in their Prius!


What makes the Prius ideal for these application? 


Efficient energy generation:  The motor runs only as needed to recharge the batteries, totally under autonomous control, and runs at a constant speed under an appropriate load while charging the batteries regardless of the rate of usage of electrical energy.  While there may be periods when the motor must run continuously due to the applied load, there are other periods when usage drops, and charging only need occur intermittently.  Generator based stationary systems do not typically have that capability, but must run continuously regardless of applied load.


Electricity costs vary from about seven cents per KWH to a dollar or so per KWH (amortized photovoltaic system).  I would guess that the cost of electricity from the Prius falls within this range (see calculations below).


Multipurpose investment:  The cost of a Prius is justified as an automobile.  An emergency generator of remotely similar capabilities would typically cost one fifth to one half of the cost of the Prius, be significantly less fuel efficient, and only be useful in an emergency (if one occurred).  The Prius is the most elegant solution for both applications.

Peace of mind:  The Prius offers a safe, reliable solution to two problems:  transportation and emergency (or off-grid) power, with no fuel issues.  Due to its long term fuel savings, I believe the Prius can be justified for energy generation alone.


Energy cost estimate:


I have very little information to go on, and I believe that the following parameters are very conservative, yielding an estimate for cost per kilowatt hour that is significantly higher than reality.  The cost derived, which is still reasonable relative to commercial power, is based totally on the use of the Prius as an energy source – disregarding its primary value as a car!



Amortization, 8 years, $20,000, disregarding value as transporation:


20000/(8*365)= $6.85 per day


Assumptions  (derived from use as vehice based on Toyota specs, and actual usage results report on the Web, as well as some guesses):


Electrical power output:


Assume 16 HP average engine/motor power output at  30 MPH average speed

12 KW average equivalent electrical output (746 watts per HP)


Assume 50 MPG average under these conditions

Gasoline cost assumed to be $2.00 / gallon

10 gallons per refill

$20 cost per refill

16.7 running hours per refill


200 KWH per tank (16.7 hours x 12 KW)

$.10 per KWH (200 KWH / tank divided by $20 / tank)

Amortization burden at 16.7 hours per day (assuming one tank per day):  .035 per KWH ($6.85 per day divided by 200 KWH per day). 


Maintenance overhead: .02 per KWH ($4.00 per day, $120 per month – probably too high). 


Total so far:  $.10 plus $.035 plus $.02:  $.155 per KWH.


Assuming 90% conversion efficiency to 117V (switching inverter):  15.5/.9 =

17.2 cents per KWH, comparable to commercial electricity in some areas, and certainly a bargain relative to no electricity (due to shortage, weather, or off grid location).


Notice that in transferring power over the grid, utilities themselves are forced to pay as much as $1 per KWH as noted in the New York Times article quoted above, and that the normal cap is $.25 per KWH.


The Prius IS the Grid!


Viaduct Corporation (and its predecessor) have been involved in electronic design, computers, and alternate energy since 1971 on Maui.  We have been responsible for the  design of CRC Electronics (Honolulu, HI) cable automation products, the Capacity Plus computer system (the first computer to offer RamDisk, as well as self repair), embedded devices (e.g. the Capacity Plus six port multiplexer), the Pathfinder / Menu Plus user interface (bundled for 12 years worldwide with CompuPro computers (Hayward, CA)), and the unshared 40 megabit per second per subscriber data system being developed by Advent Networks (Austin, Texas).  We have also produced the initial designs and prototypes for the Texscan (Salt Lake City) Comserter line (manufactured by them for 14 years), and the Video On Demand server deployed by Video Networks, Inc. (Atlanta, GA) to all NBC News affiliates last year.  Some of this work was accomplished at our off-grid workshop, where we have focused on alternate energy.  We have been computer consultants to Maui Toyota for several years.


Maui Toyota has several people of exceptional competence due to their desire to be on (or remain on) Maui.  It is also in an ideal test market for the concepts proposed, as energy costs are high, Maui itself is “off-grid”, we have an unusually intelligent consumer population, we are near Japan, and we are isolated from other markets.



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