Report on Energy Audit Aitutaki Island Power Supply

Transcription

1 Report on Energy Audit Aitutaki Island Power Supply Aitutaki - Cook Islands June 2000 Technical Report No. 314 Prepared by: Tangi Tereapii, Energy Planner, Energy Division, Ministry of Works, Energy and Physical Planning (MOWEPP). Rarotonga, Cook Islands Paul Fairbairn, Energy Manager, South Pacific Applied Geoscience Commission (SOPAC) Suva, Fiji Islands

2 Report on Energy Audit - Aitutaki Island Power Supply Aitutaki - Cook Islands June 2000 In fulfilling the activities required under Task Profile CK Energy Audit Aitutaki the following energy audit activities were carried out between 16 th 17 th June The audit was implemented as an in-country training activity for Mr Tangi Tereapii, Energy Planner, Energy Division, Ministry of Works, Energy and Physical Planning (MOWEPP) by Mr Paul Fairbairn, Energy Manager, South Pacific Applied Geoscience Commission (SOPAC) Suva, Fiji. The report of the audit has been jointly prepared by Tereapii and Fairbairn. The objective of the energy audit was to identify the high-energy consumers connected to the Aitutaki Island Power Supply and to carry out preliminary energy audits to identify means of consumption and possible areas where energy savings in general could be made. The timing for the audit was opportune considering that the Aitutaki Local Council had just recently taken over the running of the Aitutaki Island Power Supply and was now operating with a revised power tariff structure. Details of the power tariff structure are provided. Ms Teauparetea Maki, Administration Officer was extremely helpful in providing assistance (as the Officer in charge of the Power Station was away on vacation) and information on the operation of the Aitutaki Island Power Supply. This general information, technical data and generation statistics were necessary to carry out the audit effectively. Other people met and talked to during the audit visits were: Steve Christian, General Manager, Aitutaki Lodge Resort Tom Harrison, Engineer, Aitutaki Lodge Resort Junior Maoate, Manager, Maina Superstore Paula Maoate, Manageress, Maina Superstore Andrew Mc Birney, Manager, Ralphies / Airport Store Harold Brown (JJ), Manager, Sunset Maina Motel Power Tariffs The Aitutaki Island Power Supply power tariff was recently reviewed (late 1999) and the following tariff rates set, effective from 1 January Domestic Consumers 34 cents /kwh plus $5.00 surcharge + VAT (12 1 / 2 %) Commercial Consumers kw 48 cents /kwh plus $5.00 surcharge + VAT kw 40 cents/kwh plus $5.00 surcharge + VAT kw 37 cents/kwh plus $5.00 surcharge + VAT Akitua - Special negotiated rate 37.5 cents kw/h Previous Tariffs (pre January 2000) Domestic Consumers 36 cents /kwh plus $5.00 surcharge + VAT Commercial Consumers 58 cents /kwh plus $5.00 surcharge + VAT

3 Power House / Generator Configuration Engine Engine Rating (max) (kw) De-rated Output (kw) No No No (not in service) No No Quality of Power Supplied Aitutaki Island Power Supply Measurements taken during the mission were as follows and separate readings are also provided in the section on Ralphies Restaurant. The measurements were taken using an ELV Energy Monitor, which was placed in line with the appliance being monitored. Besides being able to monitor the actual power consumption the meter also allows the condition of the power being supplied to be monitored. During the energy audit a number of these meters were deployed in various locations to measure the power consumption of a number of appliances and the quality of the power. Unfortunately, as the time allowed for the initial audit was relatively short, the loads that were measured in a number of cases may not have been the largest regularly experience. This is especially true with restaurants etc. Although, in most cases, where the measured power consumption was compared against that billed, the results were relatively consistent and comparable. Aitutaki Lodge Resort Engine / Generator Configuration Primary Unit 180 kva Secondary Unit 120 kva The primary unit is used to provide energy to the resort between 0900 and 1500 hours. The input is generally around 100 kw (per hour) from Monday to Saturday. This arrangement is as agreed between the Aitutaki Island Power Supply and the Aitutaki Lodge Resort (Akitua). The main loads at the Aitutaki Lodge Resort are: Clothes dryer (40 kw) Reverse osmosis plant for the resort s water supply (23 kw) Kitchen oven (10 kw) Unit air conditioners / lighting / boosters on solar hot water systems. The Aitutaki Lodge Resort has a total of 33 units with further units being constructed. Rinos Motel - Units (Measured from an electrical powerpoint) Unit Instantaneous Maximum Minimum Reading Volts (V) Frequency (Hz)

4 Ralphies Restaurant (Glass fronted drinks fridge) The glass fronted drinks refrigerator was targeted as the high-energy consumer in the restaurant. The Manager had already replaced a large deep fryer with a smaller unit and had noticed a considerable reduction in the monthly power consumption. This smaller unit was also switched on, on an as required basis as opposed to being continually consuming electricity when not in use. Power consumption readings and variations are recorded in the table below. Unit Instantaneous Maximum Minimum Reading Volts (V) Frequency (Hz) Amps (A) Watts (W) Lag 55 o 65 o Installed equipment and appliances. 2 Glass-fronted drinks refrigerators Chip cooker and general lights / ceiling fans Drink Refrigerator Make, Model and Ratings Make ORFORD (FM 30A) Model FIFR30ADG Ratings volt / 4.21 Amp Measured consumption over 20 hours 6.28 kw Sunset Maina Motel Motel configuration and installed equipment and appliances. 8 Studio Units 4 Self Contained Units (electric stove) Managers Residence and Office Each unit has 2 x 60 W incandescent lights 300 litre SHW heater serves 4 studio units 150 litre SHW heater serves 2 self contained units Other electrical loads / water supply on demand pump (560 W) and swimming pool filter pump. The Manager indicated that SHW boosters had remained on due to a fault in the thermostat causing power consumption to be high. This has been rectified and the power consumption is considered to have returned to normal, although this will require checking over the next couple of months.

5 Maina Superstore Installed equipment and appliances. Glass-fronted drink coolers 2 (6.9 Amp) door seal needs repairing / replacing Ice cream freezer glass-sliding top 1 (1.3 Amp) Freezers (Fisher and Paykel) litre 1.3 Amp (Model KH701XL) litre 1.3 Amp Lighting / fluorescent tubes mixture of 40 W & 36 W Recommendation need for replacement with all 36 W and cleaning tubes and reflectors. Ceiling fans. Fresh fruit chiller Capacity of compressor not known. Recommendation door needs repairing so as to seal properly. Maina Superstore - Warehouse Main freezer (3HP) Reefer freezer (8kW) The Manager indicated that they tried to enforce a procedure whereby the freezers were only opened once a day, so as to reduce the loss of cold air from the freezers. The main freezer was located inside a galvanised iron shed, which is likely to increase the external ambient temperature around the freezer. The Reefer Freezer sits outside and will obviously be subjected to direct sunlight and heating of the outer casing. Insulation over the main freezer will assist in reducing the ambient temperature surrounding the main freezer and a shed constructed over the reefer freezer will assist in reducing the direct sunlight. However, in constructing such a shed sufficient space must be left above the freezer unit/s to ensure that a natural flow of air can still be maintained. Similar heating will also occur to the chiller unit, which is a freezer box inside an old mobile freezer unit (icecream truck). The condition of the door seals and latches on a number of the freezers, chillers and drinks refrigerators require replacing / maintenance. This will assist in improving the efficiency of the units and reducing the electricity consumed by these units.

6 Airport Store Installed equipment and appliances. 1 Glass-fronted drinks refrigerator (3 Amp / 240 Volt) Freezer (0.7 Amp / 240 Volt) Night / security lights (2x 40/36 W fluorescent tube lights / 3 x 18W CFls) Electric Jug Recommendations General The energy audit identified a number of areas where savings could be made. Most of these are already listed above and more generally here for completeness. When purchasing or ordering electrical appliances the consumer should consider the efficiency of the appliance by checking the appliance-rating label. In most cases the cost of an appliance with a higher efficiency will be slightly more than a less-efficient model. However, in the short term this additional cost will be recovered indirectly in savings from using less electricity. The appliance rating labels provide a visual star rating for the appliance and a consumption figure for the appliance for the year, usually in kwh. An example of the STAR rating label is provided in the ANNEX 6 for information. Lighting Improving general house keeping will assist in conserving energy. Turn lights off when not required. Clean regularly the tubes / bulbs and reflectors. Flickering light tubes / bulbs should be replaced and the starter also if necessary. The style of lighting used should be appropriate for the application (fluorescent / bulbs / compact fluorescent), High-efficiency lights should be used in high occupancy and use areas. Refrigerators / Freezers Located with adequate ventilation and keep away from ovens and stoves. Keep cooling fins at the back of the refrigerator / freezer clean. Ensure that the seals are kept in good condition. Have the coolness setting at the desired level so as to take into account the seasonal ambient temperatures and variations. Reduce unnecessary opening of freezer and refrigerator doors. Chest freezers are generally more efficient than vertical freezers. Commercial Glass-Fronted Drinks Refrigerators General house keeping points as above for other refrigerators and freezers. Seals are important due to the high usage and repetitive openings. Turn the light off inside the display cabinet when not in use. Keep the storage area full as this reduces losses and improves efficiency. These units are high-energy consumers designed to promote customer sales and not energy efficiency.

7 Power Tariff Although the power tariff is relatively high compared to New Zealand, it still remains average for the Pacific region. However, the actual tariff structure itself does not encourage energy efficiency because the higher the consumption (48/40/37 NZ cents per kwh) the lower the average amount paid per kwh consumed. This is a non-incentive for consumers to conserve or to be energy efficient. Under normal service arrangements of this nature, the more consumed the higher the payment or unit rate. This is not the case on Aitutaki. If the tariff schedule were to be inverted as follows this would provide a more logical fee structure. Domestic Consumers 34 cents /kwh plus $5.00 surcharge + VAT Commercial Consumers kw 37 cents /kwh plus $5.00 surcharge + VAT kw 40 cents/kwh plus $5.00 surcharge + VAT kw 48 cents/kwh plus $5.00 surcharge + VAT An example of this incentive arrangement is shown in ANNEX 2 Revised / Inverted Tariff Rates. Also on the tariff issue, if you compare where the percentage (%) of the load comes from and when [night time or day time] - (this is a little more difficult to do and could not be done with the data that was available) it may be that the domestic rate should also be increased marginally. However, from the figures available from October 1999 to May 2000 the percentage consumption of the main consumer groups was as follows: CONSUMER GROUP PERCENTAGE Based on $ value of power consumed. ** Domestic 45 Akitua (Hotel) 28 Commercial 22 Others 5 TOTAL 100% ** To use the dollar value of power consumed does, unfortunately, not project the best picture of consumption due to the varying rates and therefore these need to be recalculated into kwh values representing the true consumption and providing a better comparison. This additional comparison has been provided below based again on the period from December 1999 to May 2000, this slightly shorter period was adopted because billing for Akitua prior to December 1999 was under a different arrangement and consumption was considerably lower. See Spreadsheet in ANNEX 2. CONSUMER GROUP PERCENTAGE Based on kwh of power consumed. ** Domestic 49.5 Akitua (Hotel) 31.5 Commercial 14 Others 5 TOTAL 100%

8 Information Available Although the Aitutaki Power Station has a computer system used for accounting, the billing process is currently still manual (which is appropriate given the number of consumers and the areas over which they are spread) and figures for seemingly only accounting purposes are entered later. There is a need to develop a record of station performance based on kwh not on dollar values. This will allow technical performance as well as financial performance to be determined and to make longer-term projections. It would be useful to have the kwh generated from the log sheets entered daily into a simple spreadsheet and where possible a history regenerated from archived records of past operation. Obviously there is also a need to record any specific events such as the change in tariffs and the addition of loads and outside supply arrangements like the Akitua (Aitutaki Hotel Resort) activities.

9 Explanatory Information on the Reports Annexes Presented in the Form of Charts, Tables and Spreadsheets The following charts, tables and spreadsheets provide data of the March and May power generation figures. Unfortunately the power utility currently does not keep a digital record of their generation, therefore it was necessary to input all the figures manually prior to being able to implement the audit. Under normal circumstances a larger sample of data would be preferable so as to allow a better picture of the generation history to be cast. For ease of interpretation a brief statement has been prepared on a separate cover sheet to the annexed documents and highlights the features of the charts, tables and spreadsheets that immediately follow. This information supports the statements made in the body of the report and provides the raw and managed generation data and information collected should anyone wish to further examine the figures. Annexes / Spreadsheets ANNEX 1 Electricity Consumption by Consumer Type (3 pages) ANNEX 2 Commercial Consumers (2pages) ANNEX 3 Aitutaki Island Power Supply March 2000 (14 pages) ANNEX 4 Aitutaki Island Power Supply May 2000 (14 pages) ANNEX 5 Airport Store Analysis / Aitutaki Lodge Resort (2 pages) ANNEX 6 Description of Appliance STAR Rating Labels (1 page)

10 ANNEX 1 Electricity Consumption Electricity Consumption Pattern for the Island of Aitutaki by Consumer Type Chart and Data (3 pages)

11 ANNEX 2 Commercial Consumers (2 pages) Brief Analysis Based on the information provided from the Aitutaki Power Station for the individual consumer groups and as provided in ANNEX 1 [Domestic 47%, Commercial 22%, Akitua 28%, Others 5%] it was agreed to focus on the commercial consumers. The rationale for this is that usually domestic consumer profiles and energy efficiency opportunities are relatively well defined in this sector and their consumption is similar in nature. Therefore from the information provided the highest commercial consumers were targeted for further investigation and auditing as appropriate. Reverse / Inverted Tariff Rates As an example of the tariff rates applied as follows for the commercial sector: Commercial Consumers kw 37 cents /kwh plus $5.00 surcharge + VAT kw 40 cents/kwh plus $5.00 surcharge + VAT kw 48 cents/kwh plus $5.00 surcharge + VAT Based on current consumption of the selected consumers an increase in income of 6% could be generated. However, this is only based on a small sample of the commercial consumers and therefore a more detailed analysis of the consumer population including the domestic consumers should be carried out before any revision is considered.

12 ANNEX 3 Aitutaki Power Station Records March Power Generation Data Daily at 30 minute intervals Data (2 pages) 2. Average Demand March / May Chart and Data (2 pages) 3. Weekly Profile of Demand 4 10 March Chart and Data (2 pages) 4. Weekly Profile of Demand March Chart and Data (2 pages). 5. Adjusted Power Generation Data Daily at 30 minute intervals Data (3 pages) 6. Adjusted Power Generation Data Chart and Data (3 pages) Brief Analysis Based on the plot of the average power consumption the profile from hours appeared reasonable. However, the decline in demand during the daytime was not consistent. After further investigation it was most some of their own electricity requirements allowing the Aitutaki Island Power Station to reduce their production. As a result there is on average a 100 kw drop in demand. Although this happens it is generally only for 6 days a week (Monday through Saturday). The time of coming on line and amount generated is not always consistent. For the data collected in the months of March and May it was necessary to make an adjustment to take into account this additional input to the system. Based on the average amount of power generated by Akitua (from their records limited) the make up was generally in the order of 100kW. Therefore a set of adjusted figures was prepared that provided for the additional Akitua contribution to the grid. The inclusion of this into the data records then gave a profile consistent with what would have been expected. The record for May was also treated in the same manner. Delineation of when the additional power of 100 kw should have been supplied is marked in yellow on the data sheets. More specifically the daily plots were looked at for the periods of 4-10 March and March and a similar profile was obtained where they were generally consistent and there was little variation between days. This trend is consistent with that expected from a domestic load especially where there are no significant commercial loads due to nighttime activities. The plot of daily averages based on the adjusted figures shows an even more consistent range of demand figure for the individual weekdays with a typical profile. The minimum demand being in the order of 210 kw and a maximum of 450 kw.

13 ANNEX 4 Aitutaki Power Station Records May Power Generation Data Daily at 30 minute intervals - Data (2 pages) 2. Average Demand March / May Chart and Data (2 pages) 3. Adjusted Power Generation Data Daily at 30 minute intervals Data (3 pages) 4. Adjusted Power Generation Data Chart and Data (3 pages) 5. Adjusted / Unadjusted Demand Chart and Data (2 pages) 6. Comparison Adjusted / Unadjusted Demand March/May Chart and Data (2 pages) Brief Analysis The analysis of the demand figures for May is basically the same as for March. The plots show the average power consumption profile from hours as being reasonable. However, the decline in demand during the daytime was not consistent. As for March the demand / generation figures from the Aitutaki Power Station were also adjusted to take into account the generation / contribution provided by the Akitua (Aitutaki Hotel Resort) between 0900 and 1500 hours. Delineation of when the additional power of 100 kw should have been supplied is marked in yellow on the data sheets. Individual weeks of daily consumption were not considered for May but the daily averages were calculated and plotted. The plot of daily averages based on the adjusted figures shows an even more consistent range of demand figures for the individual weekdays with a typical profile. This trend is consistent with that expected from a domestic load especially where there are no significant commercial loads due to nighttime activities. The minimum demand being in the order of 200 kw and a maximum of 450 kw.

14 ANNEX 5 Energy Audit Data Sheets 1. Airport Shop Aitutaki (1 page) 2. Aitutaki Lodge Resort Power Consumption (1 page) Brief Analysis Airport Shop Aitutaki A demonstration energy audit was carried out on the Airport Shop where the owner considered that comparatively the monthly bill was high. The Spreadsheet calculation provides a comparison of actual monitored and estimated consumption. When compared against actual billed amounts this was consistent and comparable. Here the largest cost or consumption is generated by the soft drinks / beer refrigerator. There are specific notes relating to these types of appliances in the body of the report. Aitutaki Lodge Resort Power Consumption Provides a summary of billing figures against the record of kwh supplied. This matches OK.

15 ANNEX 6 Appliance Label STAR Rating System Appliance labelling is a recognised method of comparing appliances with respect to their individual energy consumption under normal operating conditions. The small the number of STARs the more energy efficient the appliance. The example on Sheet ANNEX 6a provides some typical figures for refrigerators and the likely savings in purchasing an energy efficient appliance as opposed to a less energy efficient appliance, ie more STARs versus less STARs. The example on Sheet ANNEX 6b depicts an old label design and a new label design. The new label design has been introduced in an attempt to encourage industry to strive for higher levels of energy efficiency in their products.