HomeMy WebLinkAboutChevak Wind Energy Recovery Study - Aug 2011 - REF Grant 7050875
CHEVAK, ALASKA
ANTHC EXCESS WIND
ENERGY USE STUDY
PREPARED FOR:
ALASKA NATIVE TRIBAL HEALTH CONSORTIUM
PREPARED BY:
William Thomson PE
Alaska Village Electric Cooperative, Inc.
4831 Eagle Street
Anchorage, AK 99503
(907) 565 5342
August 20, 2011
ANTHC-Chevak Excess Wind Energy Use Analysis August 20, 2011
Alaska Village Electric Cooperative, Inc.
EXECUTIVE SUMMARY
The four Chevak wind turbines (Northern Power Systems 100B models) will generate in excess
of community requirements when there is moderate to heavy wind and when the community
load is light. Currently much of this excess is inefficiently utilized since there is no economic
way to store the energy yet. If electric heating is installed in the Chevak water plant and
controlled by the availability of excess energy, 8,603 gallons of fuel per year currently used by
the ANTHC water treatment plant could be eliminated. The design of the proposed equipment
plant. The estimated cost for the heat recovery project is $252,905. The simple payback based
on a fuel cost of $6.00/gallon and fuel saved is 4.9 years. If the cost of the interruptible
electricity is subtracted, the simple payback increases to 6.5 years.
INTRODUCTION
Alaska Village Electric Cooperative (AVEC) and Alaska Native Tribal Health Consortium
(ANTHC) have been discussing ways in which operational coordination can achieve increased
village efficiency. One clear potential is the use of excess wind energy at the water treatment
plant (WTP). The problem with excess wind is its random, unpredictable nature, but the water
storage capacity at the water treatment plant provides a method for smoothing out this
inconsistency heating water only when this is possible, and waiting out periods of light wind.
Unlike traditional heat recovery from engines, excess wind energy is transmitted via the existing
electrical distribution system. The power plant, wind turbines and water treatment plant can be
located at a distance from each other anywhere on the village electrical system and do not
require interconnecting piping.
The components of the required system break down into the following areas:
Design, purchase and installation of a 120 kW Water Heater;
Design and installation of system control and communications;
Installing new electrical service to the WTP.
be directly applied to this application and will require no additional research and minimal
development. A CCI model VWB-10 boiler can be used as a 120 kW water heater, and can be
modified when delivered to Anchorage with a suitable control system. The boiler can be piped
directly into the existing boiler system using a recirculation pump. Piping and pumping capacity
will be required with a minimum of 50 GPM.
AVEC is currently controlling the wind turbines using network radio links, and there is a high
degree of confidence that a similar low-powered line-of-sight installation over 3/4 mile will
provide sufficient coordination between the AVEC powerhouse and the WTP. The AVEC
Chevak power plant has a network dispatcher capable of controlling the four wind turbines as
well as diverting excess energy into currently existing water and air heaters at the power plant.
The AVEC-designed system dispatcher can be modified to give the ANTHC WTP load priority
access to the surplus. Note that when the WTP cannot use the energy available, energy will
automatically shift from the WTP back to the AVEC power plant.
The 120 kW water heater load will require a new utility service, including a transformer bank and
a new 200 amp 480 volt service entrance. A separate revenue meter will be part of this service
and will be billed at a nominal rate to split the savings between AVEC and ANTHC. The agreed
price for energy sales is $0.05 per kW-hr. An important advantage of this approach over heat
recovery is the ease of metering standard utility metering will keep track of the savings with a
high degree of accuracy. Monthly and other readings will be collected and billed using the
AVEC automated meter reading (AMR) system. A special system to monitor energy transfers is
not required.
Chevak has significant potable water storage and most of the fuel currently burned is used to
heat the water delivery system. No additional water storage is required.
There are no anticipated land use issues with this proposal.
There are no anticipated regulatory issues with this proposal.
There are no anticipated environmental issues with this proposal.
There is no current technology ready for implementation in Alaska Villages that would provide a
mechanism for time shifting generated energy from a time of abundant wind to a time of no
wind. While such a technology may be obtainable in the future, this proposal should still be
deemed economic as it will fully pay back the investment before any future technology could be
reasonably implemented.
THE BENEFIT ANALYSIS
The analysis of available surplus wind energy for use at the Chevak WTP was calculated with
Homer software for a typical year. In addition, these results were similar to actual wind data
collected during January through July 2011. As a requirement for system stability, the diesel
engines are not allowed to fall below 50 kW of load. This minimum requirement was included in
the Homer analysis. Energy in excess of village needs was estimated on an hourly basis and
exported from Homer.
Once the hourly data was available from Homer, a spreadsheet was used to determine the
effect of changing the size of the water heater. Based on this sensitivity check, a water heater
size of 120 kW was determined to be a reasonable compromise.
Monthly estimated kW-hrs were converted to gallons of diesel by using 132,000 BTUs / gallon
and 75% boiler efficiency.
Month
Potential Energy
available
(Gallons)
Current Usage
at the Chevak
WTP
Actual
Estimated
Savings
(Gallons)
January 861 2100 861
February 838 2120 838
March 697 1400 697
April 812 1200 812
May 311 1240 311
June 576 700 576
July 1127 700 700
August 555 700 555
September 642 760 642
October 857 900 857
November 839 1000 839
December 915 1660 915
TOTAL 9,030 14,480 8,603
CONCLUSIONS AND RECOMMENDATIONS
The estimated project cost for is $252,905. Estimated fuel savings are 8,603 gallons per year.
Using an average fuel price of $6.00/gallon results in estimated savings of $ 51,618 per year for
a simple payback of 4.9 years on the oil savings. If the cost of the interruptible electricity is
subtracted, the simple payback increases to 6.5 years. The village will see an annual savings of
$39,141 and AVEC will see an additional $12,477 of revenue from the sale of the surplus
power.
Chevak Excess Wind Energy Recovery Design ITEM HRS, All UNIT Labor Travel Materials Total Cost Disiplines COST Project Work Plan 15 120 $1,800 $1,800 Project Scoping 30 120 $3,600 $4,000 $7,600 Preliminary Design 40 120 $4,800 $4,800 65% Design 120 120 $14,400 $400 $14,800 Permit Applications 8 120 $960 $960 Negotiated Interruptible Power Sale Agreement 8 120 $960 $960 95% Design 55 120 $6,600 $6,600 Engineers Cost Estimate 24 120 $2,880 $2,880 Final System Design 40 120 $4,800 $1,200 $400 $6,400 Subtotal $46,800 Contingency 15% $7,020 Subtotal Design 340 $40,800 $5,200 $800 $53,820
Chevak Excess Wind Energy Recovery Construction and Total Project MATERIALS AND EXPENSESLABORFREIGHTTOTALITEM QUAN UNIT UNIT MAT Journey LAB Journey LAB General LAB General LAB LABOR TOTAL UNIT FREIGHT TOTAL COST COST HRS RATE HRS RATE COST WT(#) COST COST COSTAVEC Power Plant Dispatcher Software Changes 1 ea. $2,000 $2,000 80 $100 $8,000 $10,000 Radio Link Purchase and installation 1 ea. $1,000 $1,000 15 $100 $1,500 20 $1.50 $30 $2,530 WATER PLANT Pipe/Valves/Ftgs/ Gauges/Pump 1 lump $15,000 $15,000 80 $130 80 $50 $14,400 1000 $1.50 $1,500 $30,900 Radio Link Purchase and installation 1 ea. $1,000 $1,000 15 $130 15 $50 $2,700 5 $1.50 $8 $3,708 120 kW Water Heater 1 Ea. $15,000 $15,000 50 $130 50 $50 $9,000 800 $1.50 $1,200 $25,200 Water Heater Modifications 1 ea $1,000 $1,000 20 $130 20 $50 $3,600 $4,600 New 200A 480V Service 1 lump $30,000 $30,000 0 $0 400 $1.50 $600 $30,600 Control Panel 1 lump $8,000 $8,000 16 $130 8 $50 $2,480 50 $1.50 $10,480 Misc Electrical 1 lump $2,000 $2,000 20 $130 20 $50 $3,600 100 $1.50 $150 $5,750 Commission System & Training 40 $120 40 $50 $6,800 0 $6,800 Misc Hardware 1 lump $1,000 $1,000 0 500 $1.50 $750 $1,750 Misc Tools & Safety Gear 1 lump $1,000 $1,000 0 400 $1.50 $600 $1,600 Consumables, Gases, Etc. 1 lump $1,000 $1,000 0 200 $1.50 $300 $1,300 DIVISION 1 EXPENSES Construction Management 120 100 $12,000 $12,000 Construction Admin/Engrg. 80 120 $9,600 $9,600 Superintendent Off-Site 40 $130 $5,200 $5,200 Crew Travel Time 20 $100 $2,000 $2,000 Crew Airfares 4 trips $1,000 $4,000 $4,000 Crew Per Diem 20 mn.dy. $80 $1,600 $1,600 Housing Rent 1 mo. $1,500 $1,500 $1,500 Utilities 2 mo. $1,000 $2,000 $2,000 CONST SUBTOTAL $87,100 $80,880 $5,138 $173,118 CONST CONTIN 15% $25,968 DESIGN SUBTOTAL $53,820 TOTAL PROJECT $252,905