This project assessed the feasibility of solar hot water heating systems on residential units in the NANA Region of Kotzebue. The Kotzebue Community Energy Task Force (CETF) identified ten Elder's homes in need of home heating assistance. These homes served as test sites. Six solar-thermal heating systems, some using flat plate and some using evacuated tubes, were installed. This project was designed to determine whether technology could prove feasible above the Arctic Circle, and whether these systems could be installed in homes throughout the region and serve as a model for alternative methods to heat homes without the use of fossil fuels.
Solar thermal systems are not a new technology, but the technology is not widely used in Alaska. Using solar thermal power to actively supplement other methods of water and space heating has many benefits; however the deployment in northern Alaska has been nearly non-existent for several reasons, primarily economic. The benefits of solar thermal will become increasingly obvious as fossil fuel prices continue to rise. Initial modeling done in ReScreen showed payback on these systems could be less than 8 years-finance depending-but this payback must first be demonstrated in order to streamline the design of these systems using off-the-shelf technology. It is important to note that in the time between the initial grant application and the following award, the price structures of the equipment and labor increased.
The primary objective of this project was to investigate solar thermal technology as a way to mitigate the rising costs of home heating in rural Alaska. Kotzebue Electric Association (KEA) installed solar-thermal heating systems, in six different homes, to assess the feasibility of this technology above the Arctic Circle. To our knowledge, very few people or organizations have experimented with solar thermal technology at this latitude; however, Alaska Battery Systems installed one system in Nome, and the Cold Climate Housing Research Center has installed an evacuated tube space heating solar thermal system and a glazed panel water heating system in Fairbanks. Each system has its advantages and disadvantages; the purpose of this project was to determine the most efficient combination for home space and/or water heating.
KEA coordinated with the Kotzebue CETF to identify homes that were suitable for this demonstration project. KEA and CETF had over 25 applicants and 10 met the following criteria: Elder status in Kotzebue, full-time Elder's residence, and final criteria that the applicant currently be on State Energy Assistance. KEA then worked with CETF and Susitna Energy Systems (SES) designers to identify the homes with the least amount of equipment needed in order to demonstrate the most systems. After careful review, and pricing evaluations, 6 homes were selected for solar collector installation.
Planning and Design
Several of the 6 homes selected for this demonstration project utilized hydronic base board heating to heat the homes. In this type of home heating system, a glycol based fluid is heated by the same boiler that heats domestic hot water. It is therefore possible to allow a solar thermal collector to pre-heat both systems. This requires slightly more complex plumbing and more advanced, thus more expensive, storage tanks.
In order to best demonstrate the capacity of solar thermal collectors to reduce fossil fuel consumption, and therefore energy cost, KEA deemed it necessary to install both DHW (domestic hot water) systems as well as combined DHW and hydronic base board heating capacity. Again, the selection of which homes would receive DHW or combined systems was based on costs of installation and space within the home’s utility room to accommodate the necessary equipment.
Final System Selection
Additionally, this demonstration project needed to evaluate the production differences between flat plate and evacuated tube solar collectors. There are several manufacturers with respectable reputations that make both types of collectors, but only two that are well-represented with installation companies here in Alaska: Viessmann Manufacturing Company Inc., represented by Gensco Alaska and installed by Susitna Energy Systems (SES), and Heliodyne Inc, represented and installed by Alaska Battery Systems (ABS). KEA elected to split the 6 homes between the two manufacturing and installation companies as well as to purchase both flat plates and evacuated tubes from each.
Generally, evacuated tube solar thermal collectors have performed slightly better than flat plate collectors in the lower 48. However, evacuated tubes are more expensive and have the potential to be more troublesome and fragile. In the interest of installing and testing the most systems, KEA elected to install 2 evacuated tube and 4 flat plat systems as follows:
The specific angle of each solar collector was also considered. Generally, a solar collector is south-facing with an angle approximate to the latitude on site. This is the case with 4 of the collectors. The two Viessmann flat plate collectors were installed at the angle of the roof (approximately 29 degrees) for two reasons: 1) reduced wind resistance (lowering the possibility of damage to the unit), and 2) to determine if the DHW-only systems would benefit from increased production during summer months when the sun in Kotzebue stays high in the sky for 18-24 hours and the boiler systems in the homes are generally not running to produce space heating.
Solar thermal technology converts energy from the sun into thermal energy. There is a wide array of technology types and applications, but all types primarily produce heat as opposed to electricity, like PV systems.
Solar heating technology converts solar energy for heating applications such as water heating, space heating and space cooling. One main component of a solar-heating system is the solar collector, which converts the sun's radiation into heat and conducts the heat to a heat transfer fluid such as water, air or ethylene glycol. Other components include storage, heat exchangers, pumps and controls.
There are several common types of active solar collector systems, which rely on pumps or controls to circulate heat transfer fluid through a collector. A flat-plate solar collector is comprised of a flat absorbing surface that is heated by sunlight. A heat transfer fluid such as water or ethylene glycol passes through the collector in a series of tubes, and heat is transferred from the absorbing surface to the heat transfer fluid. While typically inexpensive, these types of collectors can be hindered in cold-weather applications as their performance can be strongly influenced by the ambient temperature.
Another common active solar collector system is an evacuated-tube collector. In this system, tubes of transparent, evacuated glass are attached to piping at either end, filled with a heat transfer fluid. Metal conduction material inside the tubes conducts heat to the fluid, while the vacuum reduces heat loss to radiation and convection. Although evacuated-tube systems are typically more expensive than flat-plate collectors, they have an advantage in cold-weather application as the amount of energy they absorb is not strongly dependent on the ambient temperature.
Cold Climate Housing Research Center found an interesting phenomenon: while flat panel collectors are less efficient than evacuated-tube collectors in cold weather, the heat that was released from the flat panel collectors caused snow to melt off of the panels.
The solar resource in Alaska is significant, but utilization of solar technology has been limited. Historically, major challenges to using solar energy technology in Alaska are its seasonal variability and its dependence on weather conditions. In general, the solar resource is most abundant in the summer, when it is least needed. However, there is a reasonable resource available for seven to eight months of the year for all but the most northern areas of the state. Technological advances, particularly in solar thermal technology, could bridge this gap between availability of the resource and energy needs. There is a large amount of research currently under way focusing on bridging this gap, with aspirations of elevating solar energy to a viable Alaskan renewable resource.
20% of the total heating fuel in the Northwest Arctic Borough is used to heat water. Solar thermal hot water heating could be practical for up to nine months out of the year, ultimately displacing 50% of annual hot water heating needs. There are numerous ways to design a solar hot water heating system: with flat plates or evacuated tubes, tracking mount or fixed mount, large or small storage tanks. Each installed system will have a different configuration so that a comparison can be made for each home and recommendations will be made accordingly.
A typical 2,000 square foot house, rated at R20 with an indoor design temp of 65°F, will require 768 Btu/hr-F. This comes out to an annual requirement of 289 MMBtu based on Kotzebue monthly temperature averages. If heated with #2 diesel at $6.00 per gallon, this home will cost $15,606.
Data and Analysis
The results of the Kotzebue solar thermal installations were mixed. Over all the technology proved robust and able to withstand the arctic conditions. Exceptions were during a severe Arctic storm in the Fall of 2011 when the collectors of the two flat plate heliodyne systems were damaged by wind. These collectors were installed at steep angles to take maximum advantage of low sun angles. Installing steeply angled collectors on south facing walls where possible would probably have reduced the chances of wind damage. Two of the systems produced significant amounts of energy: one Heliodyne system and one Viessmann system.
Due to instrumentation challenges, the energy production data is approximate as follows.
System one did not have expected production until about day 360 (Figure 13, top), and after that, there seems to be an abnormality with the pump operation. Some days the pump ran all day long so that heat gained during the daytime was lost during the evening. Only data after day 360 was analyzed for energy production. It was estimated that fromabout February 2012 until June 2012, the system produced 2.7 MMBtu, equivalent to about 20 gallons of diesel fuel— far below its expected potential.
System two had data logger problems, only data before approximately August 2011 are available. During that period, the system appears to have had limited operation. According to the data available, the collector only reached a maximum temperature of 99°F, and the pump never ran more than 80 minutes a day. These issues deserve further investigation. During the data period, the system appears to have produced only about 330,000 Btu.
System three generated approximately 15.5 million Btu’s of energy between March of 2011 and April of 2012. This is equivalent to about 110 gallons of heating fuel, even more when boiler inefficiencies are taken into account.
System four had limited production data are available, but overall energy production appears low. From April–September 2011 and April–June 2012, the system produced about 1.4 MMBtu according to data retrieved from the Heliodyne server. The temperature data we have suggest that temperatures at the top of the storage tank were often heated to 130°F and above. Even in the very early part of the year, the temperatures reached 90°F on occasion. There is
speculation that the low solar production was tied to low hot-water consumption by the occupants. Water meters would have been needed to confirm this.
System five data is limited. From August to October 2011 and from March through the beginning of July 2012,
the system produced about 4.3 MMBtu according to data downloaded from the Heliodyne server (Figure 18). This
production rate is equivalent to 30 gallons of diesel fuel when used at 100% efficiency.Temperature data are not available for the entire year; however, a quick review of the available data suggests that maximum daily summer temperatures at the collector outlet were sometimes above 250°F. This information is consistent with a stagnation scenario, where the pumps are not operating and glycol is not circulating in the solar loop.
System six generated 14 million Btu’s were produced, equal to about 100 gallons of fuel oil at 100% efficiency.
The positive result from systems two and six is enough to warrant further investigation of solar thermal technology in Arctic regions.1
Graph based on available data, it should be noted that the house six October and November Data suspected to be inaccurate.
Graph: Chris Pike
To access more detailed analysis, quarterly reports, the final report, and full data sets, please continue to the Resources, Links and Documents section of the page.
Funding and Partnerships
This project is a Denali Commission EETG Program project. The funding goal of the EETG program is to develop emerging energy technology that has the potential of widespread deployment in Alaska and has the long-term goal of reducing energy costs for Alaskans.
The Alaska Center for Energy and Power (ACEP), an energy research group housed under the Institute of Northern Engineering at the University of Alaska, Fairbanks, is serving as the program manager of the EETG solicitation. As the projects deal with emerging energy technology and by nature are high risk, high reward, ACEP’s technical knowledge and objective academic management of the projects, specifically for data collection, analysis, and reporting, is a vital component to the intent of the solicitation, i.e., providing lessons learned and recommendations.
Kotzebue Electric Association is a rural electric utility cooperative, based in Kotzebue, Alaska. KEA has 840 members, and generates over 18 million kilowatt hours per year.
Community Energy Task Force
The citizens of Kotzebue have created a Community Energy Task Force committee, made up of leaders of the community of Kotzebue who meet regularly to find ways to alleviate the ongoing energy crisis. In particular, the CETF has focused its efforts on helping the elders. CETF was formed and recommended by the participants of the Northwest Arctic Energy Summit that was held in June 2008 in Kotzebue.
NANA Regional Corporation
NANA Regional Corporation, Inc. (NANA) is a Regional Alaska Native corporation formed in 1971 under the Alaska Native Land Claims Settlement Act (ANCSA). The NANA region is located in northwest Alaska. It encompasses an area that is 38,000 square miles, most of which is above the Arctic Circle. There are 11 villages in the region. They are: Ambler, Buckland, Deering, Kiana, Kivalina, Kobuk, Kotzebue, Noatak, Noorvik, Selawik and Shungnak.
Since its inception in 1988, ABS Alaska, Inc. has continued a thirty-year tradition of excellence to establish itself as the premier source in Alaska for batteries, alternative energy, and remote or mobile power products. ABS has two distribution centers in Alaska: its Fairbanks headquarters and Alaska Battery Mfg. in Anchorage.
Susitna Energy Systems is Alaska's premier source for alternative energy systems and other energy saving solutions. Susitna Energy Systems has solar, wind, hydroelectric, diesel generators, batteries and more for Alaskans' energy needs.
Project Links, Resources, and Documents
KEA Site Visit, November 2010
EET Forum 2-14-11 Presentation
EET Forum 2-14-11 Q&A
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