The Energy ChallengeIt ’ s Maple Syrup Time , So Why the Whiff of French Fries ? Caleb Kenna for The New York TimesDan Crocker , owner of Sidelands Sugarbush in Westminster , Vt . , making repairs to tubing . More Photos > By SAM HOOPER SAMUELSPublished : April 28 , 2007 WESTMINSTER , Vt . — Ah , early spring in Vermont . As temperatures warmed and the maples yielded up their annual crop of syrup , the hills and forests of the state were dotted with the familiar sights , sounds and smells of sugaring time . The Energy ChallengeAlternative Fuel in Vermont Articles in this series are examining the ways in which the world is , and is not , moving toward a more energy efficient , environmentally benign future . Previous Articles in the Series » Special SectionThe Business of GreenCompanies seek economies of scale in alternative energy . MultimediaSlide Show Tapping Trees Enlarge This Image Caleb Kenna for The New York TimesDan Crocker and his wife , Christine , checking the quality of syrup made with the help of used vegetable oil . More Photos » But here at Sidelands Sugarbush in southeastern Vermont , the sweet aroma of maple syrup was mixed with a very different smell : the pungent odor of hot , used restaurant grease . “ Smell that ? ” asked Dan Crocker , owner of Sidelands , as he fired up his evaporator for a night of boiling on a recent April evening . “ There ’ s that French fry smell . ” To do his bit to stave off global warming , Mr . Crocker this year converted his sugar house from regular fuel oil to used vegetable oil . Such oil , sometimes pumped into the tanks of environmentally friendly “ grease cars , ” can also be used as an alternative to heating oil . While a dwindling number of small , traditional sugar makers still boil their sap over wood fires , the majority burn heating oil , a fossil fuel that contributes to global warming . Derived from living plants rather than fossil fuels , used vegetable oil adds little or no carbon dioxide to the atmosphere . Mr . Crocker buys his from a company that collects it as a waste product from restaurants , then filters and processes out the dirt and impurities . By converting from traditional oil , Mr . Crocker is taking a stand for the environment . As an industry , Vermont ’ s maple sugaring is highly vulnerable to climate change . Last year , of the 1 . 45 million gallons produced in the United States , nearly a third came from Vermont . The entire year ’ s harvest of sap is gathered during a short season , which generally begins in March and ends by early April . The sap flows only during this brief window , when the temperatures rise above freezing during the day but plunge back below freezing at night . That short season of daily freeze - thaw cycles is getting shorter . “ Right now , the season is starting about a week earlier throughout New England than it did 40 years ago , ” said Timothy Perkins , director of the Proctor Maple Research Center at the University of Vermont , who has been warning of the challenge posed by global warming for a while now . “ And it ’ s ending about 10 days earlier than it did . Over 40 years , we ’ ve lost a net of three days of the season . ” Three days may not sound like much . But because the season lasts only about a month , it represents about a 10 percent reduction in the crop . Some long - range projections are even more dire , threatening not only the shortening of the maple season , but also the disappearance of most maples from this region . “ We ’ ve projected a very large loss of sugar maples across New England ” by 2100 , said Steven McNulty , co - chairman of the Forest Service ’ s Eastern Forest Environmental Threat Assessment Center . “ Presumably these forests will move up into Canada , farther northward . ” Canada already dominates the international maple syrup market , producing more than seven million gallons a year . If Dr . McNulty ’ s projections prove accurate , within 100 years Canada will have a virtual monopoly on the maple sugar industry . For Mr . Crocker , all this makes the stakes of climate change very high . “ I ’ m a hypocrite if I ’ m going to help global warming , ” Mr . Crocker said . “ Everyone says the first thing to go will be the southern Vermont maples . ” Converting from regular oil to used vegetable oil , known as U . V . O . , was not an easy process . Like many sugar houses , Mr . Crocker ’ s is unheated , and vegetable oil congeals at low temperatures , making it too thick to flow through the burner ’ s pipes . Vehicles that run on U . V . O . solve this problem by heating the oil . To convert his sugar house , Mr . Crocker installed an electric heater to warm the oil on its way to the burners . He still keeps a regular oil tank as a backup . He frequently starts the burner on regular oil , which ignites more easily , then switches to the grease after a few seconds of burning . It was expensive , and as the first sugar maker to try it , Mr . Crocker was uncertain if it would even work . He got help in the form of an $ 8 , 900 government grant from the Agriculture Department ’ s Sustainable Agriculture Research and Education program . He learned of the grant only a few days before a deadline and stayed up all night filling out the grant application . To a sugar maker , though , all - nighters are just part of the job . At the height of the season , when the sap is flowing fast and the evaporators are running well past dark , Mr . Crocker averages about four hours of sleep a night . For Mr . Crocker , saving the environment was not the only motivation . In this business of uncertain yields and razor - thin profit margins , the survivors keep their costs low . The vegetable oil is about a dollar a gallon less expensive than regular heating oil , though it may not remain so cheap if demand increases substantially . “ When I converted to vegetable oil , it was a business decision , ” Mr . Crocker said . Sugar making is a highly energy - intensive operation . It takes Mr . Crocker about seven - tenths of a gallon of oil to produce each gallon of syrup . His yearly crop averages 5 , 500 gallons , making Sidelands the largest maple syrup producer in southern Vermont . His fuel saving should average nearly $ 4 , 000 , not an inconsiderable sum for a business with a total annual revenue of about $ 140 , 000 . While vegetable oil is his latest cost - saving measure , Mr . Crocker has built his business on efficiencies . His 300 - acre farm includes six experimental stations , where he tries out new equipment and techniques to shave pennies off the process or squeeze a few more gallons out of the season . He was among the first in the region to use reverse osmosis , a process that partially concentrates the sap before boiling it , greatly reducing the amount of fuel burned . He uses a vacuum system that sucks air from the plastic tubes carrying the sap from the trees to the sugar house . He is experimenting with a two - part spout that is part plastic and part stainless steel that retards the growth of bacteria . This year , by combining the stainless steel spouts and the right level of vacuum suction , he coaxed sap from his trees in January , more than a full month ahead of the start of the season for most producers . Although there is no such thing as a typical season in the sugaring business , 2007 has been genuinely freakish , shattering all the expected patterns . The sap started running late but then seemed never to stop . When many thought the season was over , and some hapless sugar makers had already pulled out their taps , an April cold snap started the sap flowing again . In northernmost Vermont , extreme cold froze the sap up again . Generally , the lightest syrup , the Grade A Fancy , is produced early in the season , and the darker , less - expensive grades come toward the end . This year , many producers started out producing medium , and then had a burst of Grade A Fancy at the end . “ This year , on April 14 th I was making fancy , ” Mr . Crocker said . “ Tell me something isn ’ t wrong . ” But the weird weather actually led , at least for Sidelands , to one of the longest and most productive seasons on record . Mr . Crocker ’ s total crop , produced through April 20 , was 6 , 100 gallons , just 120 gallons below his best year ever . “ You hear the yield is low , ” Mr . Crocker said . “ I ’ ve turned it into a good year with technological innovation . ”