The heft and feel of a well-worn handle,
The sight of shavings that curl from a blade;
The logs in the wood pile, the sentiment of huge beams in an old-fashioned house;
The smell of fresh cut timber and the pungent fragrance of burning leaves;
The crackle of kindling and the hiss of burning logs.
Abundant to all the needs of man, how poor the world would be
Without wood.

Everard Hinrichs, quoted by Eric Sloane in A Reverence for Wood


Tuesday, June 14, 2011

Biomass Power - Sometimes the Right Call, Sometimes Not

My email inbox was stuffed with biomass energy goodies this morning, of various and sundry topics. The overall tone of the various topics was positive for biomass...such as the April 1 announcement (slow email?) from Virginia that their governor Bob McDonnell announced that three coal-fired power plants will be converted to biomass power plants, each of 50 MW capacity, joining the 83 MW Pittsylvania, VA, biomass power plant in generating green energy for the citizens of that great state.

Governor McDonnell and David Christian, the CEO of Dominion Generation, did a nice job of elucidating the positive aspects of biomass energy, in general...

"Dominion Generation CEO David Christian said, "Our proposal to convert these units from coal to biomass provides customers with economical electricity, delivers environmental benefits and takes advantage of a renewable, low-cost fuel source." Virginia Gov. Bob McDonnell said, "Conversion of these units to biomass creates jobs and generates tax revenues in a manner that will have a positive impact on the environment. The majority of the biomass product being used – wood slash – is typically left on the ground after timber or logging operations are complete.   So, the state is now better utilizing a product that would normally go to waste.   The projects are reflective of the 'all of the above' approach we need to take when it comes to energy production in the Commonwealth.  They are essential to expanding our alternative energy portfolio and closing our import gap, not to mention creating good jobs here in the Commonwealth." "
Good points, well stated. We must be careful, however, before extrapolating this particular decision on one energy company's part to a broader endorsement of large biomass power. There are several points that make  Dominion's decision unique to their situation.

The first, of course, is that they have the three power plants in place. Therefore, the investment necessary to generate new green energy, in this case, is only one of the conversion costs from the coal-firing equipment to biomass-firing equipment. I assume the power turbines and distribution lines will remain from the existing plants. Thus, the pay-back on this particular decision is much better than a greenfield project would likely deliver.

The second is the location of the plants...all in southern Virginia. They are well-positioned to take advantage of the large southern pine industry in that region, extending from there down through North Carolina and points south and west. Biomass from southern pine plantations is harvested more economically than from mixed hardwood forests farther north, and growth rates there allow for faster sustainable conversion. I recall one OSB plant in northern West Virginia I visited a couple of years ago that was bringing all their wood feedstock from Virginia and North Carolina, despite being surrounded by hundreds of thousands of acres of unharvested WV and PA timber...all too expensive to harvest on that large of a scale.

The third is the fact that Virginia heating demand is not quite what we have here in the Northeast. If it were, the energy customers could logically question the projects on an energy-efficiency basis. Li Ma, a Ph.D. student working here in my lab on biomass energy utilization, put together a simplified table for us to compare different uses of the 1.2 million tons of wood these three power plants will consume.

Source: Penn State Wood Operations Laboratory
The table demonstrates that the three plant conversions will convert 1.2 million tons of wood into 4.2 trillion BTU's (or 1231 gigawatt-hours), whereas if that same wood was converted to energy in either a) 6, 20-MW capacity combined heat and power (CHP) plants, or b) 12, 10 MM BTU/hr district heating facilities, it could generate over 10 trillion BTU's (2930 gigawatt-hours) of energy. And in fact, if the same amount of wood were converted into cellulosic ethanol, the resulting 96 million gallons of fuel would have an value of over 7.3 trillion BTU's of transportation energy.

So, if Dominion Generation did not already have an investment in place that Virginia had an interest in keeping running, the state might opt to utilize that available woody biomass in more energy-efficient conversion technologies. This is why the energy efficiency-conscious European countries have opted for the smaller plants on such a broad scale...they want and need to stretch their forest resource to its maximum capability, in order to reduce fossil fuel consumption as much as possible.

It's also why all such potential projects should be evaluated on a case-by-case basis, and "one size fits all" policies are to be avoided. The economics and total benefit package, in this case, might make sense for the citizens of Virginia, primarily because of the investment in place...but three new 50 MW biomass plants, or even three converted coal plants, often will not make sense in the Northeast, due to the various reasons we've previously discussed on Go Wood.

I commonly urge biomass proponents to resist the temptation to rubber-stamp all proposed biomass projects just for the sole reason that they are biomass...just as I recommend to proponents of any of the alternative energy technologies. Let's evaluate all ideas for individual circumstances, and make best use of the resources, both natural and economic.