Introduction to Diesel Integration
Rural Alaska relies heavily on diesel engine technology as the main energy source for producing electricity. According to the Alaska Energy Authority (AEA), 94% of electrical generation in rural Alaska comes from diesel generators and this reliance is not likely to change significantly in the immediate future. Hybrid and standby diesel generation is still required to augment almost all rural renewable electrical energy sources. In addition, the development of renewable and alternative energy sources for the production of electricity is typically a multi-year project, while diesel efficiency can usually be implemented in a much shorter time. For this reason, diesel efficiency is one of the most cost-effective strategies with the shortest payback. Diesel efficiency can almost immediately reduce the energy cost burden on rural, grid-isolated, Alaskan communities while renewable and alternative energy resources are developed.
Recent advances in diesel engine efficiency, automated generator controls, heat recovery, and continuous operations and maintenance techniques have made possible diesel fuel efficiency improvements of more than 50% in old, sometimes obsolete, rural powerhouses.
Over the last six years, deployment of modern diesel technology in rural community diesel powerhouses has been documented to increase the usable electrical energy generated from a gallon of diesel fuel by 20% - 30%. Installation of monitored heat recovery systems from both traditional water jacket systems and new exhaust stack heat recovery
systems can increase the fuel conversion efficiency of diesel powerhouses by another 20% - 35%. The deployment of automatic, load sensing switchgear with data acquisition and remote monitoring capabilities has lowered the maintenance and operational costs in powerhouses recently constructed by the Alaska Energy Authority (AEA) in rural villages.
The Alaska Village Electric Cooperative (AVEC), with 53 member villages, has also reported similar increases in fuel efficiency as documented by communities that have taken advantage of AEA’s Energy Cost Reduction grant program. The following charts illustrate general estimates of the typical distribution of the fuel energy used in diesel electric power generation.
|Old Technology||New Technology|
|80% Wasted, 20% Utilized||63% Utilized, 37% Wasted|
Challenges with Diesel in Alaska
Because of the high cost of petroleum, diesel engines generate electricity at a high cost. Besides the cost of fuel, the cost of transporting diesel to remote villages is an additional burden. One limitation to installing newer, more efficient diesel generators is that new units and the associated controls require more time and expertise in order to operate in the most efficient manner.
Diesel Power in Alaska
Diesel Working group
In June 2008 a Diesel Efficiency Workgroup formed to focus on reducing diesel fuel consumption in rural communities through generation and distribution efficiency measures. The group also reviewed the sustainability of available technology for use in rural Alaska, and verified the capital costs and debt service assumptions, along with long term operation and maintenance costs. The structure and output of the task group is represented in the following graphic.
The next steps include:
- Identify and correlate funding sources for stable multi-year budget for the program
- Ramp up the current RPSU Program for five plus new powerhouses and five plus upgrades per year
- Evaluate new technologies and support field testing of promising techniques that will increase fuel efficiency
- Add fuel efficiency parameter to evaluation process for new powerhouses
- Reevaluate powerhouses replaced over the last eight years for new technology efficiency upgrades
Overview of Generator Fuel Efficiency and Heat Recovery##
|TECHNOLOGY SNAPSHOT: DIESEL EFFICIENCY|
|Resource Distribution||Most rural Alaskan communities generate the major portion of their power with fuel oil|
|Number of communities impacted||Nearly 180, consuming more than 2,500 MWh of electrical energy annually|
|Environmental Impact||Reduction of fuel use and related emissions|
|Economic Status||Typical payback of 3 to 5 years depending on technology used and specific application per community|
|Case Study||Ouzinkie, TCC's Organic Rankine Cycle Heat Recovery System|
|Diesel Working Group||Recommendations|
Improvements in diesel engine and powerhouse control technologies have reduced air pollution, noise, increased fuel efficiency over a wide range of load conditions.
Increases in diesel generation efficiency can generally be found in three broad areas.
1. Increasing the amount of electricity (kW) produced per gallon of diesel consumed by the generator engine
2. Recovering heat from the engine water jacket cooling system and, if applicable, from the engine exhaust stack
3. Minimizing losses in the electrical distribution system
A more detailed breakdown with categories, related technologies, and potential gains is shown in the graphic on the right.
Diesel Engine Controls
Tighter control over the fuel systems provided by electronic fuel injection, electronic speed governors, and electronic engine controllers has boosted the usable kWh per gallon of diesel. Efficiency improvements of 10% - 15% over the older mechanically governed engines have been achieved in over 25 rural powerhouses upgraded by AEA.
Powerhouse Switchgear Controls
Advances in powerhouse switchgear control for the automatic dispatch of the most efficient generator or combination of generators to closely match changes in the village load demand throughout the day have allowed efficiency increases of an additional 10% - 20%.
These next two graphics are computer screen captures of the Supervisory Control And Data Acquisition (SCADA) interface utilized in modern powerhouses. Notice that this one is a diesel-hydro hybrid. Programmable switchgear controls facilitate more efficient coordination with renewable and alternative energy sources of electrical power like diesel/hydro and diesel/wind hybrid power systems.
Screen images of diesel engine controls.
Additional benefits of new switchgear
- Automatic recovery from power outages
- Automatic dispatch of available alternative energy sources
- Data acquisition, historical data downloads for utility planning, energy engineering and research
- Remote monitoring for faster, more efficient troubleshooting
Heat Recovery Technologies
There have been significant improvements in recovering the otherwise wasted heat that is given off by diesel engines. This excess heat can be used for space heating of community buildings or augmented electrical power generation. To learn more about these technologies, go to the heat recovery technologies page.
Links, Resources, and Documents
- Nick Szymoniak, Ginny Fay, and Alejandra Villalobos-Melendez. Components of Alaska Fuel Costs: An Analysis of the Market Factors and Characteristics that Influence Rural Fuel Prices. Institute of Social and Economic Research, University of Alaska Anchorage. Feb. 17, 2010. From the executive summary: "The Alaska State Senate Finance Committee asked economists at the University of Alaska Anchorage, Institute of Social and Economic Research (ISER) to investigate rural Alaska fuel markets and identify policy options that could be considered for legislative action to reduce fuel prices. This study is both an update and an evolution of previous ISER Components of Fuel Costs studies. It does not include road-accessible communities."
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