Public Power - November 2008 - (Page 53)

DEED SMUD Introduces New Tree Benefits Estimator Tool By Laurel Lundstrom At a time when an ability to reduce carbon emissions may play a role in determining the future of the utility industry, many utilities are scrambling to increase investments in new clean coal technologies and renewable sources of energy. Meanwhile, the Sacramento Municipal Utility District has developed a tool to showcase the benefits of investing in one of the world’s oldest and timetested resources: trees. Using the Tree Benefits Estimator, an Internet-based tool first created by SMUD in 2004, utilities can quantify and track the benefits of planting shade trees. The calculator can be used to estimate the energy savings, in kilowatt-hours, and capacity savings, in kilowatts, of planting new trees next to residential homes. Utilities can also determine the carbon sequestration values of different tree-planting scenarios. However, with the original estimator, all energy and capacity savings estimates were based on climate data for Sacramento, Calif. The tool worked well with SMUD’s dedication to treeplanting programs, which started in 1990. Since then, SMUD has planted approximately 450,000 shade trees in Sacramento County, according to Misha Sarkovich, Ph.D., the utility’s shade tree program manager. SMUD became the first utility in the United States to conduct a formal impact evaluation of shade trees on energy and capacity savings in 1996. Over the nearly two decades www.APPAnet.org that SMUD has operated its tree-planting program, the utility has discovered that fully grown and properly placed trees can reduce home cooling costs by as much as 40 percent. By sharing the free Internet tool, SMUD hoped to promote and encourage other public power utilities to establish comparable shade tree programs, said Sarkovich. Jan Schori, SMUD’s former general manager, believed utilities would be more likely to invest in urban tree-planting programs if they could quickly and easily quantify the energysavings benefits of such programs, he said. But Sarkovich realized that although the estimator was wellreceived by other public power utilities, it often generated imprecise results for utilities in other climate zones. Many found you could not “blindly accept the energy savings estimates because summer energy consumption is directly related to the ambient temperature,” he said. Thus, SMUD decided to upgrade the estimator to make it a better tool for other climate zones. The utility was awarded a grant from the American Public Power Association’s DEED Demonstration of Energy-Efficient Developments program to undertake the upgrade. SMUD worked with the U.S. Department of Agriculture’s Forest Service and the Center for Urban Forest Research at the University of California at Davis to expand the tool to incorpo- rate climate data from across the United States, as well as other tree-planting externalities. With the updated tool, a residential consumer anywhere in the United States can obtain a more precise estimate of the annual dollar savings of planting a specific tree. The expanded estimator uses information from standardized climate zones across the country and then models that impact of climate on summer cooling load and winter heating requirements. In addition, the tool now allows users to determine the effects of evapotranspiration, or the impact of trees emitting water vapor, as well as the heating penalty engendered by direct shade in the winter To use the expanded tool, a user must know: the average cost of electricity in summer and winter months; the tree species; the age of the tree from the tree-planting date or the tree diameter at the breast height; the number of trees planted; the tree planting location; the orientation or direction the tree faces; and, the distance between the tree and the building that is being shaded. In addition to specific climate considerations, the new tool takes into account tree growth, and tree mortality and survival statistics. These factors enhance the accuracy of estimates of energy and capacity savings and carbon sequestration rates. As regulatory agencies propose to mandate the reduction of greenhouse gas emissions, measuring and recording the results of urban tree-planting programs could become a part of reporting requirements, according to the DEED project report on the estimator. “The tool would provide a standardized and transparent method of measurement and reporting that could be used by any publicly owned utility,” said the report. Regardless of whether a utility has any summer cooling load or winter heating requirements, carbon sequestration values can still be estimated for specified tree species. The new tool includes a long list of trees common to many areas of the country. SMUD designed the estimator to be used by individuals with no formal training in urban forestry or demand-side management utility practices. A person with little expertise can determine a tree’s evapotranspiration effect, as well as the shade tree heating penalty in winter months. The new Tree Benefit Estimator Tool is posted on SMUD’s Web site: https://usage.smud.org/treebenefit/. ❚ Laurel Lundstrom is a former production editor of Public Power magazine who now works as a freelance writer. NOVEMBER-DECEMBER 2008 53 https://usage.smud.org/treebenefit/ https://usage.smud.org/treebenefit/ http://www.APPAnet.org

Table of Contents Feed for the Digital Edition of Public Power - November 2008

Public Power - November 2008 Contents Perspective 10 Questions Capturing Knowledge Before It Retires Jackson’s GIS Search Keeping a Job Journal Japan Tackles the Kyoto Protocol Getting to 20 by 10 Damless Hydro Power Earthquake: The Hidden Disaster For Engineers Safety For Governing Boards DEED Hometown Connections Parting Shot

Public Power - November 2008

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