Distribution System Efficiency Upgrades
How the electrical energy is delivered to the load or customer can have a significant impact on the efficiency of the system. The use of newer, more efficient transformers and more flexible power distribution systems that allow easier balancing of the village loads can increase the efficiency of delivered power 3% - 6%.
Electrical loads on the distribution system must be reasonably balanced to obtain the greatest efficiency from the generation system. Loads shift seasonally and annually as new loads and buildings are added or removed. The generation system must be monitored and the distribution system loads adjusted appropriately. Distribution systems may need upgrading if appropriate load shifting adjustments cannot be made.
The voltage of the distribution system can have a significant effect on line losses. An older system design utilizing 208, 480, and 4160 voltages becomes inefficient when the system is expanded to accommodate a growing community’s new subdivisions and projects. Newer transformers more efficiently convert between voltages. Power factor can be a significant issue in rural communities where long underground runs have small loads.
Fuel boosters have not yet been proven under the harsh, varying conditions in remote Alaskan powerhouses. The Alaska Energy Authority suggests test bed studies through the University of Alaska Center for Energy and Power and pilot testing in rural powerhouses.
Operations and Maintenance
The ability a community has and the methods it uses to maintain and operate its powerhouse have a significant impact on efficiency. Keeping diesel generation systems operational and maintained has a direct influence on the energy produced for each gallon of diesel fuel consumed. Operator training, spare parts availability, automatic system monitoring, data trending, and data analysis, along with prompt maintenance and repair are key factors in keeping efficiency and performance high.
|Inconsistent Maintenance (sporadic repairs, generators out of service for long periods).||Low Level Maintenance (timely repairs, general engine decline, system detuned).|
The previous charts document variations in diesel efficiency due to operation and maintenance practices.
Village 1 received a new powerhouse upgrade in 2000. Efficiency immediately improved from previous years. Notice the decline in the years directly after 2000. This is due to the fact that the utility was unable to consistently operate and maintain the powerhouse. In 2005, maintenance assistance was provided via the Circuit Rider program. Efficiency improved and then again declined when the proper operations and maintenance were not continued.
This chart presents powerhouse efficiency as a percentage of improvement. The new Rural Power System Upgrade project improved efficiency by >26%. Over time, the powerhouse lost nearly 10% of the improved efficiency from lack of proper routine maintenance.
Improvement to the operation of existing diesel systems is a short-term opportunity for almost every rural community. As such it should be an area of immediate focus. If Rural Power System Upgrades and Circuit Rider maintenance were fully funded across a five year period, a significant amount of fuel oil could be saved. If a portion of the funds from the Circuit Rider maintenance program savings were set aside, local communities or regional associations could continue the Circuit Rider from the reserves, and the efficiency gains could be sustained. If proper routine maintenance is performed on the 31 powerhouses that have already been upgraded, and if the 62 remaining powerhouses in communities AEA assists are upgraded and properly maintained, over 800,000 gallons of fuel per year will be saved. Another fuel-saving measure that could be effected immediately is to get existing heat recovery systems operating properly. While a number of Alaskan communities have some type of waste heat recovery system, a substantial number of those systems are not functional. Available records show that if all existing waste heat recovery systems were operational, an estimated 2,917,099 gallons of fuel could be saved annually. Assuming a $3.00 per gallon fuel cost, that translates to over $8,751,298. These numbers are impressive, reinforcing the value of supporting heat recovery systems. It would take only a fraction of this annual savings to get all of these systems back up and running effectively.
Since technologies for increasing the kWh per gallon of diesel burned are mature and commercial generator engine and powerhouse controls are in production, all utilities should consider the feasibility of using them to reduce the cost of electrical power in rural Alaska. Routine maintenance and operations can have a significant impact on efficiency.
These charts presents the information from a different perspective. Notice the projected loss in savings and efficiency if powerhouse upgrades are not continued and routine maintenance via Circuit Rider is not performed.
Since technologies for recovering heat from jacket water and exhaust gases are mature and commercial heat recovery devices are in production, all utilities should consider the feasibility of employing jacket water and exhaust heat recovery for heating applications.
Heat to Electricity
More research is needed to evaluate the suitability of organic Rankine cycle and Kalina cycle systems for use in most small Alaska utilities. These technologies may be suitable for use in Alaska’s larger power generating plants that operate on fuel oil, but they should first be demonstrated via a pilot project or the diesel testbed at the University of Alaska.
The following table provides rough preliminary construction estimates for various types of diesel efficiency upgrade projects in rural Alaska.
AEA’s Rural Power System Upgrade (RPSU) program is well suited to rapid implementation of diesel efficiency technologies in rural Alaskan communities. The RPSU program also offers technical and emergency assistance to over 130 isolated, rural villages, and has a longstanding relationship with the Alaskan rural utilities and local native organizations. The program has upgraded 32 rural village power systems over the last eight years, primarily using Denali Commission funding. This program replaces obsolete, inefficient diesel powerhouses with regulatory-compliant facilities that employ new diesel and control technology. These improvements have increased diesel fuel efficiency by 20% - 50%, saving hundreds of thousands of gallons of fuel to date.
With proper funding, RPSU has the resources in manpower, engineering support, and construction management capacity to build five new powerhouses and to upgrade an additional five powerhouses every year.