So, after a short break, we're back to our examination of Dell's Plant a Tree for Me program (earlier posts are here: 1, 2, 3 and 4).
In the beginning I asked whether the program is really capable of doing what it says it can, namely removing the CO2 that results from powering Dell PCs. I identified four areas of concern, and we've touched on two of them. Today's focus is on the scalability of the program, or, in other words, if it's successful, can it really keep up with the volume of CO2 that is generated.
If you recall, in an earlier post we did a spreadsheet to look at the amount of CO2 that would have to be sequestered each year. That analysis showed that, assuming no growth in Dell's business, we'd need to sequester about 50M tons of CO2 per year in order to cover all of their PCs. Furthermore, Dell is a little under 20% of the PC market, so we'd need to do around 250M tons to cover all PCs (assuming Dell's systems are a good estimate of the rest of the PC industry).
So first, lets start with the simple calculation of land required to sequester the CO2. I found lots of different estimates for CO2 per acre of forests. I'll use the high end of the EPA number of 2.6 metric tons of carbon per acre per year, or approximately 10 tons of CO2 per acre per year. This means we need 5 million more acres of forest to handle the CO2 from Dell's PCs, or about 25 million acres for all PCs (note that with no growth, we only need the new forest once - it will sequester enough per year to keep up for a long time). At 640 acres per square mile, we'd need around 10 thousand square miles of new forest, or approximately the land are of Maryland or Vermont.
According to this FAQ, all of the US today sequesters about 840M metric tons, covering roughly 15% of the total CO2 emitted each year. So we're talking about adding another 30% capability to handle this. Of course the rest of the world can help sequester as well. Putting this all together, the numbers look big, but not impossible.
However, as I researched this topic, I ran across a slightly different issue. According to the EPA, the amount of carbon that can be sequestered by a forest is greatly effected by how much money is set aside to manage that forest. Ultimately, in an undermanaged forest the carbon is re-released into the atmosphere, negating the original intent. So the question we need to be asking isn't whether CO2 sequestration in trees can scale, but whether it can scale at $6 per ton per the Dell program.
Table 4-5 of the EPA report is shown below. The role we care about is 'Afforestation', aka 'planting trees'. 
This table confirms our results above, namely that we could plant enough new trees in the US to sequester the worldwide PC energy for all vendors. However, it also says that at $6 per ton, we can only cover less than 10% of the CO2 emissions of just Dell PCs. And while this analysis is only counting sequestration opportunities in the US, the numbers are still way off, and remember that this doesn't include any growth for Dell's business or PC power.
So to summarize, I have to conclude that this program does not scale as currently designed. There appears to be the land capacity to support the program, but the program is currently not setting aside enough money in order to pay for the land management required to maintain sufficient sequestration capacity.
Posted by Elizabeth Bell on March 08, 2007 at 11:09 AM EST #
As you point out, planting trees then letting them fall down and rot in place doesn't help with total CO2 emissions in the long term. All it does is provide a delay. You have to cart the wood out of the forest and store it (e.g., in the structure of a building) to be useful (or at least further delay the release).
This is fine from the point of view of the amount of carbon in the forest but what about the other elements taken from the forest soil and not returned? As I understand it, forest soil tends to be fairly nutrient poor anyway so won't there eventually be a need to add fertilizer, with all the carbon costs of that to consider too?
Posted by Ed Davies on March 09, 2007 at 10:52 AM EST #
Since I co-own 340 acres of forest land. I am fully sequestered. I can do anything I want. In fact, given 10 tons of CO2 sequestered/acre per year, and 20 tons of CO2 produced/person per year, my family's forest land can offset the CO2 produced by 170 people. If there are 5 people in the families which own the farm, we can sell offsets to 165 people. Or each member of the families can consume 34 times the energy of a normal person. After all, we are offset. Not by future trees, but current adult trees. We are offset!
Ridiculous? Of course!
This whole thing is maddening! They mowed down tens of thousands of acres of rainforests in Brazil to plant sugar cane to produce Ethanol to use in their cars instead of oil. How carbon neutral was that?
We need to reduce consumption, not get enamored with "alternative energy" or "offsets". And oddly enough, PC trends are positive in this regard.
Has you noticed the reduction in power of the typical PC? My company issues me a laptop PC. It is very energy efficient. I wonder how much less energy it uses than a typical PC from five or ten years ago, with a big CRT monitor? Probably about 1/4th, is my rough guess.
Vendors need to keep up this trend of innovation. Instead of planting trees, customers need to upgrade to newer, more power efficient equipment, and stop excessive overprovisioning.
Posted by Mark on March 12, 2007 at 12:33 AM EDT #
Posted by David Douglas on March 12, 2007 at 12:40 PM EDT #