We are three Dartmouth College alumni who have led major scientific programs and research institutions dealing in part with forests as cause and cure of climatic disruption. We have also been involved for decades in evaluating alternatives to fossil fuels in domestic and institutional settings. We have read with interest, and no little alarm, that Dartmouth intends to replace its oil-fired steam heating system with a $200 million wood-burning heating plant, nominally in the interest of reducing institutional carbon emissions.
While it is commendable to find ways to reduce the college’s dependence on fossil fuels, the important goal is to reduce Dartmouth’s net carbon dioxide emissions.
Shifting from steam to hot water will provide a modest saving in the need for primary heat. However, shifting from heating oil to wood to supply that energy will increase the college’s carbon emissions substantially, worsening global warming and climatic disruption at a time when dramatic emissions reductions are urgently needed to limit climate change.
The problems are several.
First, the Intergovernmental Panel on Climate Change and many peer-reviewed studies show that wood generates significantly more CO2 than the fuel oil it would replace, and even more than the natural gas used by Dartmouth-Hitchcock Medical Center. The carbon content of wood is about 30% higher per unit of primary energy than fuel oil and about 80% higher than natural gas. Second, the combustion efficiency of wood is less than that of modern oil and gas systems. Third, the wood supply chain requires substantial energy for harvest, transport, processing and drying prior to use, and for ash disposal.
Therefore, the first impact of switching from oil to wood will be an increase in Dartmouth’s carbon dioxide emissions, worsening climate change.
Of course, over time, the forests harvested to supply that wood may grow back, gradually removing CO2 from the atmosphere. That is the great hope underlying the use of bioenergy. However, and crucially, regrowth takes time and is not certain.
In the northern forests that would supply the proposed plant, the time required to remove the excess CO2 emitted from burning wood instead of oil is many decades at least, and possibly more than a century. This is true even under the optimistic assumptions that the harvested lands will remain forest and will not be converted to pasture, cropland or development, and that the new growth in those forests will not suffer die-off from disease and insect damage or burn in wildfire — all more likely as the world warms.
These dynamics mean that switching from oil to wood will worsen Dartmouth’s contribution to climate change for decades, even as the IPCC and scientists around the world agree that global emissions must fall dramatically by 2030, and essentially to zero by mid-century.
The college says only “waste wood” that would normally decay will be used, but it is difficult to verify that all such fuel is waste wood. And removing wood, “waste” or not, deprives forests of the nutrients needed to ensure vigorous replacement growth. Northern New Hampshire, where a number of wood-burning power plants are located, has a much-depleted forest in terms of carbon stocks compared with forests in the southern part of the state.
Burning wood generates a variety of public health harms beyond its harm to the climate. Wood smoke contains dangerous particulates. Many regions have restricted wood burning for this reason. Winter temperature inversions in the Connecticut River Valley capture fireplace and wood stove smoke now. A large wood-burning heating plant would impose an additional burden on residents.
We urge the college to avoid making a heavy investment in a mistaken assumption that a wood-fired heating plant will benefit the college or the world.
Instead, we urge a major effort in improving energy efficiency for the college’s facilities.
Efficiency is the fastest, cheapest and safest way to meet the need for warm buildings in winter and cool ones in summer. The increase in up-front capital costs of highly efficient buildings, both new construction and retrofits, is very low (from roughly zero to a few percent), while their operating costs are far lower, often generating positive net present value while imposing little burden on cash flow.
Simultaneously, we urge a careful look at potential local solutions for heating and cooling, including air- and ground-source heat pump systems, powered by renewable energy from local sources, including solar, wind and water.
George M. Woodwell, Dartmouth Class of 1950, is the president emeritus and founder of the Woods Hole Research Center in Woods Hole, Mass. William Schlesinger, Dartmouth ’72, is the James B. Duke Professor of Biogeochemistry and dean (emeritus) at Nicholas School of the Environment, Duke University. John D. Sterman, Dartmouth ’77, is the Jay W. Forrester Professor of Management at the Massachusetts Institute of Technology and director of the Sustainability Initiative at MIT’s Sloan School of Management.