Getting to Zero

Princeton aims to achieve net zero greenhouse-gas emissions by 2046 as part of a new sustainability plan announced on Earth Day, April 22. 

Campus CO₂ emissions totaled 116,000 metric tons in 2008, according to the plan. Princeton aims to be 37 percent below that level by 2026 and to reach net zero by 2046. Net zero means that any greenhouse gases emitted from fossil-fuel-based energy production would be balanced out through strategies that include no- and low-emissions energy production, such as renewable energy, or technology that draws greenhouse gases from the air.

To reach its emission targets, Princeton will expand solar-power generation on campus, convert from a natural-gas-fueled steam system to geothermal heating and cooling, and improve the energy efficiency of campus buildings. Geothermal systems are in place in several new or recently renovated buildings, including the Lakeside and Lawrence apartments. Plans call for older buildings to get the new system over a 20-year period as they are renovated. 

The University will seek to purchase “green” electricity — generated by sources such as wind or solar power — by investing in renewable power infrastructure that would not be developed without Princeton’s support. 

The plan sets a number of targets for 2026 and for 2046 — Princeton’s 300th anniversary.

The University has not purchased market offsets, said Shana Weber, the University’s sustainability director. But she said that after Princeton has taken all possible steps, there may be a need to consider them to reach net zero emissions. As an example, she said, emissions might be produced by backup generators that run on biofuels to keep critical functions operating. 

The plan sets a number of targets for 2026 and for 2046 — Princeton’s 300th anniversary. They include reduced water usage; expanded stormwater management; more transportation options to reduce the number of single-occupancy vehicles coming to campus; less waste and expanded sustainable purchasing; responsible design and development; and cultivation of healthy habitats. No cost figure was available for the initiatives.

The new plan builds on one issued in 2008, which sought to cut campus carbon emissions to 1990 levels by 2020 — an 18 percent reduction. With that goal about to be reached — and with others, involving buying local and using alternative modes of transportation, also in sight — the University is ramping up its efforts, Weber said. “We have to seek innovations, and we also have to think about how humans behave and how we can make sustainable behaviors easier.”

The report laid out achievements in sustainability over the last several years. Forty-four percent of food purchased by Campus Dining now comes from local sources, up from 27 percent in 2008. A lighting upgrade program replaced 110,000 lamps and fixtures with LED lighting.

A campaign to encourage employees to use bikes, buses, trains, and carpools to get to work has increased the number of those commuters from 16 to 23 percent; the University hopes to double that figure by 2046. The report shows President Eisgruber ’83 doing his part, with a photo of him astride his bicycle. “I try to bike to my office and back home every day, even when the weather is pretty bad,” he said in the report. Paper purchases are down 50 percent, pesticide use has dropped 39 percent, and landfill waste has been reduced by 8 percent. 

But water use has risen 15 percent across the campus, to 222 million gallons last year; the targets are to reduce that by 23 percent in 2026 and by another 16 percent in 2046. The recycling rate for consumer items declined from 30 to 23 percent, largely due to food scraps being mixed in with recycled materials and to less tolerance for contaminants in global recycling markets. The targets call for sharp increases: to 75 percent by 2026 and 90 percent by 2036.