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HomeMy WebLinkAboutBethel Wind Power Project Feasibility Study - Mar 2015 - REF Grant 7040015AEA – 7040015 TDX Power, Inc.; Coleman Page 1 of 23 AEA Renewable Energy Fund Grant Round IV Bethel Wind Power Project Phase 1 Deliverable: Feasibility Study TDX Power March 1, 2015 This Feasibility Study summarizes the work done to date to analyze the potential for wind power production integrated into the Bethel utility system. This summary report follows on two earlier TDX reports, which covered: - Current status of the utility, its infrastructure, loads, thermal loop and operations. - Potential wind farm sites and distribution limitations - Power plant controls assessment for wind farm integration The two earlier reports in PowerPoint format are in the Appendix. This report focuses the sizing of potential wind farms and the inherent issues and limitation imposed by the site, environment and utility infrastructure. An initial task was to define a set of criteria for the development of future wind farms that were gated by the amount of impact to the utility infrastructure and operational protocols. The goal was to define the maximum feasible wind farm size that fit each level or gate. These AVEC selected criteria set the level of changes that will be required within the utility infrastructure (power plant, controls and distribution). The three defined levels proposed are: o Low – No changes o Medium – Minor changes only:  Add secondary loads  Reasonable transformer upgrades o High – Significant system wide upgrades. AEA – 7040015 TDX Power, Inc.; Coleman Page 2 of 23 Bethel Electrical Load Overview: The load on the Bethel electrical utility ranges from a low of 3 MW to a peak 7 MW, with typical Alaskan seasonal variations. In the recent past there have been minor variations due to weather, but no significant change in overall demand. There is some current and future growth anticipated for the Bethel electrical demand, but that was not predicted, nor incorporated into this study. 2014 2010 2013 AVERAGE 2014 2010 2013 AVERAGE Max Max Max MAX Min Min Min MIN Jan 6850 7025 6575 6817 3975 3950 3800 3908 Feb 6775 6475 6675 6642 4200 3800 3850 3950 Mar 6656 6525 6525 6569 4050 3990 3925 3988 Apr 6350 6090 6000 6147 3850 3600 3500 3650 May 5950 5550 5950 5817 3400 3200 3400 3333 June 5400 5225 5400 5342 2875 3125 2875 2958 July 5400 5275 5400 5358 2875 3150 3100 3042 Aug 5575 5425 5575 5525 3350 3300 3350 3333 Sept 5660 5725 5660 5682 3420 3300 3420 3380 Oct 5950 5975 5950 5958 3550 3600 3550 3567 Nov 6850 6300 6700 6617 3975 3900 3050 3642 Dec 6675 6800 6675 6717 3825 4050 3825 3900 Diesel dispatch in Bethel currently is operator controlled, from initial engine prep, to starting and warm up and then to a manual synchronization and stabilizing process. Typically the entire start sequence takes around 20 to 30 minutes and is fully ingrained into the operational protocol. The five 900 rpm EMDs are rated at 2.2 MW each and currently their minimum power output is limited at 1.2 MW (55% of rated). The minimum number of diesel engines under any situation is two and the maximum is currently four engines. The introduction of wind energy will lower the diesel fuel consumption, however a number of operational impacts need to be assessed, and at each of the three levels the issues change. These issues will be identified and addressed in the analysis of each level. An overriding issue for any wind integration into Bethel will be the capability of the EMD governors and voltage regulators. A program to address this issue is being contemplated, but has not been accomplished. Given the age of the equipment and the manual control adjustment currently required, there is sufficient evidence that this could create a limiting factor for any changes to the power plant. It is presumed that rapid ramping of the EMDs in response to changes in wind turbine output may destabilize the control system. Currently ramps rates are very minimal under normal operations so there is no firm evidence, but the concern certainly exists. TDX would propose a test plan to evaluate this situation as part of the next phase of activity. This report focused on the dispatch protocol for the engines, as it relates to the level of wind power being contemplated. This approach provides a solid high level understanding AEA – 7040015 TDX Power, Inc.; Coleman Page 3 of 23 of the basic performance parameters (fuel savings, diesel run times, wind penetration, wind curtailment and thermal energy) using basic diesel control requirements as defined by the current EMD engines and their controls. It is hoped that this evaluation of levels will guide AVEC to select a configuration (level) and rough wind farm size that fits their needs, budget and operational goals. Once this selection is made then TDX Power can begin work on the Conceptual Design. Performance Modeling Process Homer was selected as the hybrid wind system performance modeling program for this analysis. There are multiple limitations with Homer which needed to be overcome to develop a realistic model for the hybrid system operations. Wind Turbine Performance Adjustment - Turbine and Wind Farm Losses: Degrading wind energy output for real world simulations. Homer does not take into account normal wind turbine, wind farm and distribution system losses when predicting system performance. In our exercise, we used two methods to solve this problem. First, we degraded the power curve for the wind turbine to account for typical losses, which for practical purposes occur continuously. These included the following: Typical Turbine/Farm Losses Tuning 2% Dirt 2% Array 1% Transmission 5% Turbulence 1% Misc 1% Total 12% - Operational Reduced System Performance: Operationally, the wind farm output is also limited by turbine and farm availability, which tends to be longer in rural Alaska since repair time is hampered by long distances and lack of infrastructure. Likewise the utility will have needs to Curtail the turbine output during utility maintenance events or other situation which might arise. In addition, Bethel is subject to icing at a significant level in the winter. Anemometer data indicated icing sufficient to impact the anemometer system in excess of 30% for 3 months and some impact of icing for up to 8 months a year. These losses combined are 26% . AEA – 7040015 TDX Power, Inc.; Coleman Page 4 of 23 Operational Impacts Lack of Availability 10% Curtailment 3% Icing 13% Total 26% - For the EWT 900 on a 75 meter tower using the wind data collected by AEA in 2006 the wind turbine predicted outputs were adjusted for these impacts. EWT900 - 75 Meter Tower AEP Predictions MWh/yr Capacity Factor Homer uncorrected 3,095 39.3% WaSP 3,135 39.8% 12% turbine losses 2,724 34.6% 26% operational 2,016 25.6% The losses modeled appear to be quite conservative, in that, well run wind systems in the lower 48 experience significantly less over all losses but cumulatively, the total losses are in the range of AEA’s past experience for rural Alaskan community wind systems. Homer Modeling Assumptions Within the Homer model there are a number of factors that can be changed to adjust the operational decisions of the model. To better simulate the Bethel power plant, two gensets were forced on continuously, no matter what the wind output or total load was. In addition, genset dispatch decisions included having operational reserve (diesel capacity) for 10% load variation and a 20% wind variation within the time step. The modeled thermal load roughly twice the current demand, with seasonal variations based upon Bethel temperature data. One hour time steps were used for simulation. Homer Results The Homer results were calculated for the various size wind farms sizes with a focus on the amount of diesel fuel saved. The wind turbine power curves were reduced by 12% at all AEA – 7040015 TDX Power, Inc.; Coleman Page 5 of 23 wind levels to account for the typical losses, which are essentially constant. Then, the Homer performance results were then reduced by 26% for the Operational losses identified. The assumption is that 26% of the time the turbine is not operational, so the utility is essentially operating without a wind farm. The remainder of this report will include the impacts on wind farm performance due to both the turbine/farm losses of 12% and the Operational losses of 26%. - 200,000 400,000 600,000 800,000 1,000,000 1,200,000 0 2 4 6 8 10 12Gallon per YearWind Farm MW Utility Fuel Savings Uncorrected 26% Reduction AEA – 7040015 TDX Power, Inc.; Coleman Page 6 of 23 Low Level Analysis: Requirements for Wind Farm Sizing o Max amount of wind power without any changes to the power plant, controls strategy or distribution. o No Operational Protocol Changes With the current power plant and controls the maximum amount of wind energy that can enter the system under ANY condition and have no adverse effect on the power plant is 500 kW. However, this limiting condition (500 kw) exists only when total demand is between 4 and 4.5 MW and a genset dispatch decision is eminent. Specifically the condition exists when the load is around 4 MW and operators must decide to start or stop a third engine. If the wind exceeds 500 kW, then three engines will be operating below their current minimum operational limit. If two engines are running, and the load grows even moderately, and the wind turbine output suddenly drops, then the two engines may become overloaded, until a third engine can be brought on-line (minimum of 30 minutes). Short-term operation under this condition would certainly not be destructive to the system but would fall outside the current operational protocol. The following graphic highlights this concern. The wind farm is modeled at 1 MW capacity. The upper and lower stair steps are the minimum and maximum rated output for the diesel genset with 1, 2, 3 or 4 engines dispatched. Each step in the max and min output lines represents an additional operating generator. -1 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 10MW of DemandMW of Supply "w 1 MW Wind" DEMAND Maximum Minimumminimum loadArea of Concern AEA – 7040015 TDX Power, Inc.; Coleman Page 7 of 23 When looking at these curves, these 1 and 2 MW lines represent the turbines rated output which only occurs at high winds. The winds in Bethel will reach turbine rated power 10% of the year. The Bethel load currently is below 4.5 MW about 20% of the time, mostly at night, so this concern is real and it would happen almost any night of the year. Grossly this means there is a relatively small amount of time during the year when the turbine power control must be implemented and a relatively small amount of curtailed energy. Options: - Pick a wind turbine model with controllable adjustable power set point. This would allow a controller to automatically dial back the wind turbine output to avoid under loading the diesel engines. This type of control would allow for a much higher rated wind farm, whose practical limits might be the financial metrics associated with lack of revenue due to excessive curtailment of wind power. - The EWT-900 and the GE 1.7 MW turbine allow for controllable power adjustment while the turbines are operational. The following graphic shows the areas of concern (diesel dispatch) for wind farms of 1 and 2 MW capacities. With a 2 MW wind farm the area is expanded up to 7 MW. From just the dispatch analysis, summarized above, it appears that a 2 MW wind farm with only wind turbine controlled power output control is doable. It appears that this technique would be deployed across a wide range of load conditions, whenever the winds are high. Wind curtailment would occur most when the winds are high and the load is low. -2 0 2 4 6 8 10 0 2 4 6 8 10 DEMAND Maximum Minimum w/ 1 MW Wind w/ 2 MW Wind Areas of Concern AEA – 7040015 TDX Power, Inc.; Coleman Page 8 of 23 To analyze this situation will configured the Homer model with two diesel engines forced on, so that there would always be a solid diesel base load, and then look at the amount of “excess” energy that would be kicked off to the secondary load. This should provide a reasonable assessment of the amount of energy that would need to be curtailed, since both control techniques are geared to address the same problem. So in our case instead of shunting the excess energy to a secondary load, it was simply curtailed by dialing back the output of the wind turbines. The following graph summarizes the curtailed energy that would be lost as the wind farm size increases. The modeling shown is for the EWT 900 turbine where from 0 to 5 units have been deployed (0 to 4.5 MW) With wind farms 2.7 MW the total curtailment is near zero. As the wind farm grows the percentage of wind energy curtailed increases. At 4.5 MW the curtailed wind energy is close to the annual output of a single turbine. The curtailment of this significant amount of energy reduces the economic viability of this large a wind farm, if curtailment is the only control technique. The following graphs provide comparison of the curtailment activity for 2.7 MW and 3.6 MW wind farms. The amount of total curtailment (kW) and timing for curtailment as predicted by Homer are shown to illustrate the impact. These graphs provide relative information because they don’t include the 26% Operational Impacts, since those losses cannot be modeled within the current version of Homer. - 2,000 4,000 6,000 8,000 10,000 0 1 2 3 4 5MWH per YearWind Farm MW Useful vs Excess Wind Energy Useful Wind MWH Wind Heat MWh AEA – 7040015 TDX Power, Inc.; Coleman Page 9 of 23 Therefore the following graphs are valid but should be dialed back across the board by 26% to account for the wind farms non-operational periods. Homer Modeling for 2.7 and 3.6 MW Wind Farm for Curtailed Wind Energy 2.7 MW Wind Farm 3.6 MW Wind Farm The mean level of curtailment with the 2.7 MW wind farm is about 25 kW with peaks of 1.2 MW. With a 3.6 MW wind farm the mean increases to 100 kW with a peak of 2 MW. Viewing the same information as a Duration Curve, direct from Homer without the 26% Operational Losses. These graphs illustrate that active power control for the wind turbines is a viable technique without incurring excessive wind energy losses. AEA – 7040015 TDX Power, Inc.; Coleman Page 10 of 23 2.7 MW Wind Farm 3.6 MW Wind Farm The ultimate value of integrating the wind farm with the utility is the reduction if diesel fuel burned by the power plant. The predicted fuel saving in the operational scenario being considered is presented in the following graphic for a range of wind farm sizes. This graph takes into account the 12% wind turbines losses plus the 26% Operational losses. AEA – 7040015 TDX Power, Inc.; Coleman Page 11 of 23 It is interesting to note there is no difference in system wide performance between curtailing wind energy by controlling the output of each turbine and using secondary dump loads. Both control strategies perform the same basic function. Essentially the same MWh per year would be accounted for in each scheme. A third alternative would be to adjust the operational protocol for dispatching of engines based upon the wind energy available; essentially using the wind energy to avoid starting additional diesel engines. This would save more fuel but would require operators to track the wind farm performance and have some predictive information on the wind and load to make dispatch decisions. The fuel savings increases predicted from this more risky scenario at the 3 MW size make only marginal gains of 25,000 gallons/yr, which does not seem to justify the Operational Protocol changes required. Given the definition of the Low Impact scenario is appears that a wind farm up to 3.6 MW could be viable with only active controlled power output control. Distribution Limitations: A preliminary analysis of the distribution system shows that currently the transformers, not the power lines, are the limiting factor. Currently it appears that the transformer would limit the max wind farm sizes at 3 MW for the city site and 2 MW for the KYUK site. The limitation is imposed by the thermal capacity of the transformers. In actual operation of the wind farm the electricity would be flowing back from the farm, feeding the loads on the distribution before entering the powerhouse. Clearly the loads on the distribution will need to be factored into the analysis to understand what additional wind curtailment might - 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000 0 2 4 6 8 10 12Thousands of Gallons/YrMW of Wind Farm Utility Fuel Savings AEA – 7040015 TDX Power, Inc.; Coleman Page 12 of 23 occur, if during high wind power periods when the loads are low, the capacity of the transformers might be exceeded. Conclusion: The Low Level wind farm should probably be limited to 3 MW is size and be located on one distribution feeder. This is a relatively low risk, low cost option, for AVEC to pursue. AEA – 7040015 TDX Power, Inc.; Coleman Page 13 of 23 Medium Level Analysis Requirements for Wind Farm Sizing o Max amount of wind with minor changes to BEU system  Controllable wind turbine power adjustment optional o Minor Allowed Changes  Allowed System Changes  Secondary Thermal Loads  Transformer upgrades o Improved thermal handling performance  Fins, fans, pumps etc  NO  Power plant impacts  No distribution impact Approach: Install controllable Secondary Thermal Loads to limit wind power disrupting current Operational Protocols or impacting diesel dispatch strategy. The excess wind energy would not be curtailed but used with the current thermal heating loop to provide useful energy. Installation of the dispatchable thermal heaters into the thermal heating loop, after the loop has been modified to include a heat exchanger to isolate the thermal loop into town from the engine cooling water. Currently, the engines can deliver 6 to 7 MW of heat to the thermal loop with average contribution of roughly 4 to 5 MW. The current thermal loops efficiency and effectiveness was not addressed by this study, but it appears that not all the available diesel engine waste heat is currently being utilized. The actual capacity limits, customer demands and performance for the thermal loop need to be better defined, but for the purposes of this study it appears viable that wind energy could augment the waste diesel heat to provide usual thermal energy to customers in Bethel. Secondarily, if the thermal loop were isolated with a heat exchanger than installing exhaust gas heat recovery units on the existing diesel units might be another attractive approach to increasing the efficiency of the power plant. Currently, there appears to be a significant amount of excess heat being produced by the current diesel genset configuration. The addition of a significant wind farm would lower the amount of thermal engine available from the diesel engines due to their lower average output. However, the combination of thermal output from the engines and the wind farm would more than handle the current load and possibly even a doubling of the current thermal load. As the following graph illustrates, we believe the current diesel generated thermal energy is more than double for the actual thermal energy being delivered to customers. AEA – 7040015 TDX Power, Inc.; Coleman Page 14 of 23 Current use is estimated at 12,000 MWH/YR, but clearly the current configuration, with or without the wind turbines could provide 24,000 MWH/yr of heat. If the thermal load were increased by double, the combined output of the recovered diesel engine heat and wind energy would be satisfied and provide an economic benefit. There will still be periods when there is too much thermal energy for the loads (no thermal storage was envisioned in this exercise) in this graph, this is called EXCESS. There will also be times when the system cannot meet 100% of the thermal demands, on cold nights when utility loads are low and there is no wind. In this model, the Boiler is deployed to provide this heat. However, the Bethel thermal contracts are not for firm delivery of heat, but only for intermittent delivery, so there is no requirement for a boiler. If the Bethel utility were to offer a firm supply of thermal energy, which may have a higher value to the customers, than the addition of a small boiler would be advisable when the thermal load increase to roughly double the current load. 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 MWH/YR FOR HEATWIND FARM SIZE ( 0 TO 5 EWT TURBINES) THERMAL ENERGY SOURCES EXCESS Boiler WIND Diesel Heat AEA – 7040015 TDX Power, Inc.; Coleman Page 15 of 23 Distribution Limits Transformer upgrades would increase the transformer rating so that more power could be brought back into the power plant from wind farms located on the distribution lines. Currently it appears that the transformer would limit the max wind farm sizes at 3 MW for the city site and 2 MW for the KYUK site. The distribution line limitations are approximately twice this much. Increasing the capacity of the transformers could also be considered. If both sites were developed then roughly 5 MW of wind turbine could be installed. If the transformers were upgraded or replaced, then the maximum capacity would be approximately 3 to 3.5 MW on the KYUK feeder and 4 MW on the City feeder for a total of 7.5 MW. Optional Configuration: Incorporating dispatchable electrical heating equipment on the electrical distribution lines may be a viable approach and may be economically competitive to the central thermal loop. This approach would also eliminate the need to upgrade the distribution transformers as the wind energy would be absorbed along the lines prior to entering the power plant. The advantages of dispatchable electrical heating would be a) No expansion of the current thermal loop customer base or thermal loop infrastructure needed. b) New customers not exclusively in the downtown area could take advantage of wind energy for heating c) The installation cost is very reasonable d) Thermal storage can be part of the electrical heating package, Steffens heaters as an example. e) Increase utilization of the distribution grid with little or no expense. For the Medium sized wind farm case, the size of the future wind plant is dependant on the size of the thermal load and the thermal distribution system to be deployed . The upper limit is defined by the current transformer ratings on both of the likely distribution circuits. Deploying controllable power set point on the wind turbines to curtail energy production could also help manage distribution system overloads during situations of high wind and low load without needing to fully shut down the wind turbines. Conclusion: The Medium size wind farm is not a technical challenge and represents a project that would have significant impact to the Bethel. It will require design changes to the thermal loop and integration of a dispatchable secondary loads. This presumes that adequate additional AEA – 7040015 TDX Power, Inc.; Coleman Page 16 of 23 thermal customers are available and willing to pay a reasonable rate for thermal energy. Depending on site(s) availability this option could be deployed with wind farm sizes from 3 to 4 MW. With transformer upgrades and utilizing both sites a total of about 6 to 7 MW could be deployed. Clearly identification of thermal load customers and siting of the turbines become the gating issues. AEA – 7040015 TDX Power, Inc.; Coleman Page 17 of 23 High  Define Limitations in the current system  Propose Work-Around for each Limitation  Define Size Limits of Wind Farm post change  Limitation Identified  Distribution System  Power Plant o Diesel Gensets o Controls  Thermal Sales  Not Considered Viable at this time  Diesel Off Mode Operations  Large Scale Electrical Storage Limitation and Potential Solutions. 1) Distribution, Transformers, Protection, Bus Connection If the two main feeders in the distribution system were brought up to their current line capacity by changing or upgrading the thermal capacity of the transformers, and modification of the protection equipment and bus connection, then it appears that the maximum wind farm size as limited by only the conductors, at the current voltage, would be - 3.5 MW at KYUK site - 4.5 MW at City site If utilizing the maximum capacity of the feeder, active VAR support to maintain voltage within an appropriate window will most likely be required. This capability might be an internal function of the wind turbine, or a dedicated external device on the feeder itself. For larger capacity wind farms, a trade-off analysis between rewiring, changing the distribution voltage with the same wire, or building a new distribution line will need to be considered. For a very large wind farm (10 to 12 MW) a new dedicated feeder run from the wind farm to the powerhouse is probably advisable. 2) Automatically Dispatch Diesel Genset As the wind farm increases in size, and with the caveat that the system will not be run in Diesel-Off mode, there is a fundamental limitation in the speed of diesel engine dispatch, that won’t be overcome until an automated genset is deployed. The option of deploying a diesel genset with automatic dispatch, synchronization and control capability would provide for faster dispatch control that would shrink the dispatch control time frame to approximately 20 to 30 minutes. This has potential to save significant AEA – 7040015 TDX Power, Inc.; Coleman Page 18 of 23 fuel. This system would provide greater flexibility for the operators and eliminate the need for fast dispatch scenarios for the EMD engines current in the power plant. The EMD’s do not appear to be suitable for automatic dispatch due to their inherent start- up requirements, which demand operator intervention. Once started the current synchronization system is fully manual. An automatic synchronization system was tried in the past to no avail. It was abandoned and the tried and true manual system was reinstated. It is not clear that these units could not ever have automatic synchronization, but from the operator’s point of view, it didn’t work successfully. A single automatically dispatchable genset (or two units so there would be one backup unit) in the 1 to 2 MW size range is probably appropriate. A new automatic dispatchable genset coupled with dispatchable load control would be very appropriate system architecture for the HIGH case. The difference between an automatically dispatchable diesel vs. the current manual dispatch approach would be the additional fuel saving and lowering of diesel run times. The reduction in run time would be most prevalent when previously the diesels would be running at or near there minimum load level, where their fuel efficiency is lowest. 3) Thermal Sales Thermal sales by the utility represent a significant opportunity in Bethel. Historically the utility has provided building heat at a competitive price from diesel engine waste heat. Using wind energy, when the wind contribution exceeds the allowable instantaneous penetration levels, for heat is a stable configuration. The value of the wind energy as heat isn’t as high as it would be if utilized for electrical energy but it still has a significant value. Wind power used to offset diesel fuel in electrical generation is equal to roughly the price of fuel and the diesel engine conversion rate. At 14 kwh/gallon and $5/gallon the wind energy on just a fuel-offset value is worth 36 cents. (utility bulk delivered price) With resistive heating the value of wind generated electricity is about 16 cents/kwh if oil were selling for $6/gallon. (Customer delivered retail price) If heat pumps were deployed with an average Coefficient of Performance in the 2.5 range, than the wind energy would be worth close to 40 cents a kWh using diesel fuel $6/gallon. Clearly, the value of wind energy as a heating option appears to be a viable, economically attractive reason to expand the wind farm size beyond that which might be justified by the reduction in electrical generation cost alone. From the thermal consumer point of view, if one can heat their home or business for less by using wind energy than why wouldn’t they. AEA – 7040015 TDX Power, Inc.; Coleman Page 19 of 23 Value of Heat To End Customer Fuel Oil Electricity Resistive Heat Pump BTU/gallon 138,700 COP=3 BTU/kWh 3416 10248 Heating Efficiency 85% 100% 100% Cost $6 $0.10 $0.10 Gallon Kwh Kwh Value $/Therm $5.09 $2.93 $0.98 Therm=100,000 BTUs The graphic, “Value of Heat To End Customer” normalized the value of thermal energy measured in $/therm for three difference sources of heat. For market based economics, it’s clear that electricity to heat would be competitive to $6 fuel oil if the electricity were valued at 16 cents using resistive heating. Any value less would be economically attractive to the customer. The use of a heat pump, which might be practical in a number of discreet loads in Bethel, has enhanced economics due to the significant efficiency gain from that technology. Development of viable heat pump options for rural Alaskan applications needs to be undertaken to consider this option viable. It clearly has promise, but at this time, the technology is not ready for commercial deployment. TDX would recommend a development and demonstration program be undertaken by AEA to validate the use of heat pumps, especially in medium to high penetration wind farm applications. The capacity of the current thermal loop is not clearly defined, nor is the current thermal load and possible expansion of thermal load with new customers. AVEC is currently evaluating the current thermal load profile, customer base and thermal system configuration. The unknowns of the Bethel thermal energy market will need additional study to evaluate the business options, there does appear to be an attractive opportunity to exploit wind energy for serving thermal loads. 4) Alternative Uses As the wind farm size increases there will significantly more wind energy available for alternative loads such as electrical transportation. When dispatchable wind energy is available a majority of the time, than incorporating electric vehicles transportation options could be viable in Bethel. AEA – 7040015 TDX Power, Inc.; Coleman Page 20 of 23 Conceptualization of a 10 MW Wind Farm Currently there is one identified site west of the airport with sufficient land for a 10 MW wind farm. Given the location and distance from the powerhouse, a separate MV distribution feeder is a reasonable assumption. To take advantage of the wind power, a major expansion of the thermal energy delivery system will be required. It may involve both thermal loop expansion and distributed dispatchable electric heating appliances. For the purposes of this study, we will assume sufficient viable loads exist. The powerhouse can remain in it’s current configuration, using only dispatchable load controls backed up with wind turbine set point control to provide sufficiently robust and fast load matching for the wind energy. In this configuration, one 2.2 MW EMD will always be running to provide voltage and frequency reference, therefore not requiring a newer automatically dispatchable diesel engine nor electrical storage, however there is legitimate concern that the governor response on the EMD’s will remain stable. This issue clearly needs more research and investigation before contemplating this large a wind farm. A 10 MW wind farm will supply roughly 25% of the electricity needs of Bethel and can provide significant thermal energy as well. Impact of 10 MW wind farm on the Bethel utility compared to current configuration - Diesel fuel reduction ------- 738,000 gallons - Diesel run time reduction ------ 1,500 hours - Wind Energy for thermal loads -----11,470 MWH/yr From the thermal energy side, the wind energy that is not used directly for electricity is shunted off for thermal needs. This analysis assumes only resistive heating technologies are deployed, whether within the thermal loop or via distributed resistance heaters. Clearly developing appropriate heat pumps for Alaskan conditions would enhance the wind energy available for thermal heating. The wind generated thermal energy, while only available when there is excess wind, is available about 40% of the year at a pretty significant rate and available 60% of the time at some level. Essentially if the wind is blowing there is sufficient capacity in the wind farm to fulfill thermal needs. In the 10 MW wind farm case the utilization of the wind energy is roughly 50/50 between electrical and thermal. Preliminary Financial Evaluation AEA – 7040015 TDX Power, Inc.; Coleman Page 21 of 23 Preliminary financial review of the three level of wind farm integration into Bethel has begun on a macro level to provide a gross over view of the economics governing the potential projects. It will be important to revisit this analysis as more accurate and comprehensive cost analyze are available. However, for the purposes of helping determine the most appropriate first project for Bethel, this analysis provides high level guidance. The assumption used in this analysis needs to be fully reviewed, but the tool seems adequate for a first look for comparison sake. Major Economic Variables: Prices scale down as project size increases. Especially true for Alaskan sites, there is a significant cost reduction on the price per MW for larger project because many of the fixed project costs (soft project costs, project management, construction equipment deployment, logistics and transportation) are spread over a larger project. Therefore larger projects will most certainly have cost advantages over smaller projects. The electrical infrastructure modification for each level of wind farm has been estimated and needs a fully review. The value of delivered diesel fuel is well understood and can be fined tuned. Longer-term projections are valuable here since the true economics of a wind projects are only fully understood when viewed from a 20-year lifetime point of view. The simple Pay Back Period analysis provides a very simple comparative value, but under values the long term benefits of the project. Resistance heating vs. Heat pumps: the significant performance advantage that heat pumps have over simple resistive heating makes this option important for these types of systems. This is especially true when the energy for thermal loads becomes a common occurrence and utilization factors are 50% or more are possible. AEA – 7040015 TDX Power, Inc.; Coleman Page 22 of 23 Bethel Wind Project Feasibility Project Preliminary Financial Evaluation 16-Feb-15 Turbine installation Pricing 1 MW COSTS $4,500,000 Bethel Energy Values Diesel Fuel $5 per gallon Electricity for Heat $150 kWH LOW MEDIUM HIGH Wind Farm Size MW 3 6 10 10 Thermal Process None Resistive Resistive Heat Pumps COP 2.5 Relative Project Costs 100% 95% 90% 90% Turbines Installed Cost $13,500,000 $27,000,000 $45,000,000 $45,000,000 Utility Modifications $- $500,000 $2,500,000 $3,500,000 Total Project Costs $13,500,000 $27,500,000 $47,500,000 $48,500,000 Value Stream Diesel Saving: Gallons 383,200 581,200 738,000 738,000 Fuel $$ Saved $1,916,000 $2,906,000 $3,690,000 $3,690,000 Wind MWH to Heat - 4,500 11,400 28,500 Heat $$ Generated $- $675,000 $1,710,000 $4,275,000 Total Revenue $1,916,000 $3,581,000 $5,400,000 $7,965,000 Simple Pay Back Period 7.0 7.7 8.8 6.1 This simplistic financial model is only valuable for rough guidance on a macro scale. However, it illustrates one major point: Large wind farms that provide a significant amount of thermal energy could be as financially viable as smaller wind farms. This fact is driven by the lower installed cost per MW for larger project, which is especially true in rural Alaska, the high current cost for thermal energy and the use of heat pump technology. The most significant financial drivers for the Bethel project will be the project costs and the value of the diesel fuel saved and the thermal energy from the wind turbines. This chart uses our current best guess for these values. For larger sized wind farms the dominant AEA – 7040015 TDX Power, Inc.; Coleman Page 23 of 23 economic driver will be the value of thermal energy and the cost of delivering that product. For this exercise we used $150/MWH for thermal energy, which equates to $4.50/Therm. Recently the utility sold thermal energy for $3/therm or about 60% of the current price of heating oil. A thermal energy marketing study for Bethel might provide more realistic long-term thermal energy pricing estimates. Conclusions: The economic viability of the 10 MW wind farm appear attractive and certainly justifies further exploration. However, the sheer size of the project with nearly a $50 million price tag may be currently out of reach. Other hurdles include the necessity of a land deal adequate to site a 10 MW wind farm, developing a thermal market for the wind power and design and permitting for a new distribution feeder.