Sap from sugar maples is 2 percent sugar. By law, Vermont maple syrup is between 66.9 to 68.9 percent sugar, which is a higher standard than most other US states and Canada. It takes a lot of energy to remove that much water from the sap.
Fortunately, reverse osmosis equipment, used in water purification, can remove pure H2O from sap without changing the flavor of the syrup. By concentrating sap from 2 percent sugar to 4, that cuts the boil time and fuel in half. By concentrating to 8 percent, we use 1/4 of the wood that we otherwise would have needed. That is not just time saved in the sugarhouse, but in the woods cutting, hauling, splitting, and stacking.
We could use reverse osmosis to concentrate the sap higher and make maple syrup faster. Honestly, we like hanging out in the sugarhouse with family and friends. This is a comfortable pace, not a race.
We have a 4 kW array of solar panels, which power the RO and our house. Even if we did not have solar panels, over 90 percent of Vermont's electricity is from renewable sources, not fossil fuels or nuclear.