Trees Are Not the Solution to Our Electricity Needs

- by Mar­vin Rober­son, April 27, 2014. Source: Detroit Free Press

There is a lot of con­cern in Michi­gan, espe­cial­ly the Upper Penin­su­la, about meet­ing future elec­tri­cal needs. Many aging, pol­lut­ing coal plants are soon to go offline, as they should. New coal plants are unlike­ly to replace them, and would be a poor choice even if feasible.

There is, and should be, sig­nif­i­cant focus on ener­gy effi­cien­cy and renew­able sources of elec­tric­i­ty. A por­tion of our future needs is like­ly to be met through bio­mass elec­tric­i­ty gen­er­a­tion. Bio­mass elec­tric­i­ty is gen­er­at­ed by burn­ing plants.

Bio­mass can come from a vari­ety of sources. Switch grass, waste wood, corn stalk residues and the like all may be burned to gen­er­ate elec­tric­i­ty. Stand­ing tim­ber (live trees cut down for the pur­pose of burn­ing them) can also be used — and in our state, that’s the pri­ma­ry form of bio­mass avail­able. In Michi­gan, with its vast forests, many peo­ple nat­u­ral­ly think of this resource as an oppor­tu­ni­ty to gen­er­ate green, renew­able power.

This is a mis­take. Pow­er derived from cut­ting and burn­ing stand­ing tim­ber can­not be any sig­nif­i­cant part of the solu­tion to elec­tri­cal needs because there sim­ply aren’t enough trees in Michi­gan. To replace even a mod­est-size elec­tric plant would require clear-cut­ting about 5 square miles of for­est each year.

Some pro­po­nents sug­gest burn­ing wood on the grounds that it is “car­bon neu­tral,” caus­ing no net increase of car­bon diox­ide into the atmos­phere, and thus does not con­tribute to glob­al warm­ing. This is false. Every oth­er use of wood (paper, fur­ni­ture, even let­ting it fall over and rot) keeps more car­bon out of the atmos­phere than burn­ing it. But that doesn’t matter.

Some claim that it will pro­vide eco­nom­ic activ­i­ty and bad­ly need­ed jobs in rur­al areas. But the real­i­ty is every oth­er use of har­vest­ed tim­ber cre­ates more jobs than burn­ing it does. Trees are sim­ply too expen­sive to use as fuel. But that doesn’t mat­ter, either.

Some claim that using trees for pow­er gen­er­a­tion will help the for­est by pro­vid­ing incen­tives for sus­tain­able for­est man­age­ment. It won’t. Sup­ply­ing bio­mass elec­tric­i­ty plants with stand­ing tim­ber will only leave ever younger forests in Michi­gan, even though our cur­rent forests are wild­ly younger than nat­u­ral­ly bal­anced forests. But that also doesn’t matter.

Why don’t these things mat­ter, and what does?

It’s sim­ple: Even with 20 mil­lion acres of forest,there is not enough wood grow­ing in our state to pro­vide a sig­nif­i­cant por­tion of our elec­tric­i­ty gen­er­a­tion. Peri­od. Noth­ing else in the debate over bio­mass elec­tric­i­ty gen­er­a­tion is relevant.

If we used all the for­est growth from all of Michigan’s forests for bio­mass, includ­ing state parks, all pri­vate, pro­tect­ed and pub­lic lands, and closed down all cur­rent con­sumers of tim­ber (lum­ber, paper, etc.), we would gen­er­ate less than 7% of Michigan’s elec­tri­cal needs.

It’s sim­ple math. It takes about 13,000 tons of live wood to gen­er­ate 1 megawatt of elec­tric­i­ty, which can pow­er 240–400 house­holds a year.

A gen­er­ous esti­mate is that Michi­gan aver­ages for­est growth of about 1.3 tons of wood on each forest­ed acre each year. This means that we need the “annu­al growth” (the amount of new wood grown each year) from 10,000 acres to gen­er­ate a sin­gle megawatt of elec­tric­i­ty. Or, to put it anoth­er way, if we grow wood and cut it on a 40-year cycle, we need to clear-cut, chip, haul away and use every bit of wood from 250 acres a year to gen­er­ate 1 megawatt.

A few years ago, Tra­verse City was con­sid­er­ing build­ing a 10-megawatt bio­mass plant. If sourced from green tim­ber, as planned, this would have required using the entire annu­al growth from 100,000 acres, or clear-cut­ting 2,500 acres (4 square miles) each year.

How about in the UP, where we sure­ly have lots of wood? The Presque Isle coal plant in Mar­quette needs replace­ment. It gen­er­ates 450 megawatts annu­al­ly. Replac­ing that coal with stand­ing tim­ber would require the annu­al growth of 4.5 mil­lion acres of for­est land, or clear-cut­ting 112,500 acres (180 square miles) a year.

So, while small, local bio­mass elec­tric gen­er­a­tion — using mill wastes and oth­er for­est byprod­ucts — may be a use­ful and prac­ti­cal part of meet­ing our pow­er needs, large-scale replace­ment of coal-fired plants with tim­ber-based bio­mass gen­er­a­tion is sim­ply not possible.

Mar­vin Rober­son is a for­est ecol­o­gist for the Michi­gan Sier­ra Club.