The world is moving toward a distributed energy future. For that future to be realized solar power must be available when the sun is not shining. The missing piece of this puzzle is energy storage.
Caleb Stratton | PlanSustainable
The world is moving toward a distributed energy future. For that future to be realized solar power must be available when the sun is not shining. The missing piece of this puzzle is energy storage.
Drake Landing Solar Community has proven that this critical key can be addressed successfully. Drake approaches alternative energy and sustainable development in a way that challenges traditional thinking. If communities begin to embrace renewable energy systems, where can the associated cost savings be deployed? Can renewable energy become the vehicle that bridges the gap in funding for jobs, education, infrastructure, healthcare, and cultural enrichment? Can renewable systems also decrease our environmental impact; improve social equity, economy and the environment for current and future generations? Amory Lovins thinks so, as he’s provided a roadmap in his most recent publication “Reinventing Fire”. Although I highly recommend his work, the following article will not discuss his blueprint, but rather profile a resilient community that is married to the process of reinventing fire.
Drake Landing Solar Community is a group of 52 master planned homes in the Town of Okotoks, Alberta, Canada. Built to Canada’s R-2000 building standards the units are designed to have 80% of their residential heating load be met by solar thermal energy. Each unit is equipped with two solar thermal collectors to provide roughly half of the needs for water heating. Placed atop garages throughout the community are an additional 800 solar collector units that capture thermal energy and send it to the innovative borehole thermal energy storage (BTES) system. Enclosed by insulation, clay and a vapor barrier, the system stores thermal energy when in low demand (summer) and releases it when in high demand (winter).
Source: Drake Landing Solar Community www.dlsc.ca
The process of capturing thermal energy is accomplished by heating a glycol (anti-freeze) solution within the array of collectors, piping it through the collector loop and then conveying it underground to the community’s energy center. The energy center transfers thermal energy from the glycol solution to water stored in a short-term storage tank, then returns the glycol to the solar collector system to receive more energy. The water from the short-term energy tank is then pumped through a series of pipes located within the BTES unit to transfer heat to the surrounding soil. This effectively creates a giant thermal battery that stores energy during periods of inactivity such as night time and cloudy days, and then releases energy when system users call for it.
Source: Drake Landing Solar Community www.dlsc.ca
The borehole system will reach up to 176° F in the summer time in order to store sufficient heat for the entire community during heating season. When space-heating season arrives the system works in reverse. Thermal energy is drawn from the borehole seasonal storage unit to the energy center, transferred to the short-term storage tank and then circulated to the homes through the district-heating loop. Each home has a specially designed heat exchanger, coupled with a low-temperature air handler unit that blows air across the warm fan coil, therefore transferring the thermal energy from water to air, and enabling the distribution of heat through the house’s ductwork. Redundant systems exist as well as emergency systems in the event that electric power is lost. PV emergency power eliminates the need for standby generators, and has sufficient capacity to keep critical systems running for an indefinite period of time. This array also makes a contribution during non-emergencies by generating power for energy center pumps and controls.
The homes themselves have been designed to reduce load and increase efficiency within the collector system. Highlights include: 30% increase in systems efficiency over conventionally built homes, upgraded insulation and vapor barrier systems, sustainably forested lumber, recycled materials, locally sourced materials, upgraded windows, upgraded roofing materials, water conservation measures, and low impact landscaping.
The borehole system was designed to reach full charge after a period of three years, and measured data has surpassed modeled projections in the 4th year. The following figure is important because it depicts a system that is:
- Proven that the missing piece of distributed energy’s future (Storage) is possible.
- Performing better than projections
- Proven in a large residential development setting
Four key areas measured annually by Drake Landing include collector efficiency, BTES efficiency, energy provided to load demand, and solar fraction. The following table depicts measurable efficiencies of the system. Collector efficiency is measured by how much sun the collectors can receive, versus how much sunlight actually hits the collector. This may seem low, but is actually hovering around industry best efficiency. The BTES measures how much energy is captured and how much energy is stored. Energy to load measures the output from the borehole system to the homeowners. Solar Fraction measures the amount of energy provided by solar energy versus demand load.
Source: Drake Landing Solar Community www.dlsc.ca
By capturing solar energy for water and space heating, Drake Landing residents can potentially reduce their natural gas use by 110 GJ/year/house. This equates to a 90% reduction of space heating bills, and 50% reduction of water heating bills. In addition to financial savings each household can a reduce carbon dioxide emissions by up to 5 tons or 260 tons per year for the community.
Source: Drake Landing Solar Community www.dlsc.ca
The cost savings and reduction of carbon emissions do not necessarily represent the greatest benefits of this project. What is truly remarkable is the creation of a storage medium that is quite literally as cheap as dirt. The BTES does not introduce toxic materials underground, and uses water and earth to store solar energy. In fact, the borehole center acts as a park for Drake Landing, demarcating an area for recreation and community. More remarkably, the system allows solar energy to be stored, and then released to meet demand. This development is monumental as up to 80% of residential sector energy use in colder climates comes from space and water heating. Widespread adoption of solar energy has been plagued by the intermittent natural of collection, and the practicality of storage for future distribution demonstrated by Drake Landing offers a glimpse of future energy systems.
Source: Drake Landing Solar Community www.dlsc.ca
By successfully storing thermal energy Drake Landing provides a piece of the puzzle in decentralizing energy infrastructure. Situated at 51˚N latitude, Drake Landing’s location translates to international applicability for community based BTES. The work undertaken at Drake Landing has not gone unrecognized, although the general public is not aware of this project and its significance. In November of 2011 Doug McClenahan received the Energy Globe World Award on behalf of Drake Landing and Alberta Canada in Wels, Austria. 40 nations gathered to celebrate energy efficiency in categories of earth, fire, water and air. Drake Landing won an addition award under the category of fire, based upon their ingenious heating system. Energy Globe founder, Wolfgang Neumann is convinced that greater quality of life can be achieved at the same time as economic viability. “This great pioneering spirit of innovation will ensure our planet will remain a worthwhile home for our children as well.” His Energy Globe project attracts thousands of individual projects from hundreds of countries that demonstrate how energy can be used efficiently anywhere in the world. Drake Landing is clearly at the forefront of this energy conversation, and provides a valuable resource to those looking to change the dynamic of community development through renewable energy systems.
Images from this article and more information on how Drake Landing is reinventing fire can be found at www.dlsc.ca. A scientific paper detailing the measured and simulated performance of the high solar fraction district heating systems with seasonal storage at Drake Landing can be found at: http://www.dlsc.ca/reports/ISES_SWC_2011_final.pdf
Caleb Stratton is a development consultant at PlanSustainable undertaking his Master of Science in Sustainability. His professional work revolves around green project development. This article stems from a series of studies undertaken through the lens of Industrial Ecology, which ask: How can we close human systems loops and mimic natural cycles of production, consumption and decomposition? He can be reached via e-mail at: cstratton.peak@gmail.com
The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag
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