Catching Carbon Dioxide

Excess carbon dioxide and methane in the atmosphere, heat absorbed more readily than it is released and a world that is starting to sweat from under this ever-thickening blanket — whether it’s humanity’s fault or the sun’s fault, the climate is certainly changing.

From carbon dioxide factory emissions to methane cow farts, greenhouse gases are in too high supply to match the demand. A good deal of the anti-global warming hype has focused on decreasing the supply of greenhouse gases with cleaner factories, electric cars and, most notably, alternative power sources. Solar, wind, hydro and geothermal power aim to generate electricity without emitting harmful gases into the atmosphere. However, even all these technologies together are not yet ready to take on the task of powering human civilization. We simply can’t harvest enough clean energy to accommodate our needs.

For example, although Georgetown University has begun negotiating a massive off-site solar purchase that is the first of its kind, renewable energy is projected to account for less than half of the university’s energy needs for the next decade. Even relying on solar power for half of our electricity is too risky. The sun often stops shining in the District, and there doesn’t exist enough battery power to get us by for even a full day without sunshine.

With other alternative energy sources even less stable and developed than solar energy, we need to find other ways to reduce carbon dioxide emissions and concentrations in the atmosphere. Glaciers are melting, polar bears are losing their homes and Disney World will soon be “under the sea” in a real-life “Little Mermaid” exhibit. Since it is difficult to reduce the supply of greenhouse gases, there is always another way to reduce excess: increase the demand for them.

Trees are one of the largest slices of carbon dioxide’s customer base. Plants use carbon dioxide for photosynthesis, keeping it out of the air and releasing oxygen as waste. Among other reasons, we worry about deforestation in American cities and the Amazon because trees necessarily remove carbon dioxide from the air. However, if trees were to carpet the entire globe, our leafy friends would not be able to stave off further global warming.

Humans have a tendency to upgrade when we run into big problems. When we were fed up with spending months to cross an ocean by sailboat, we created steamships. When we finally realized that horses were too smelly, we replaced them with automobiles. So, when trees can’t keep up with our carbon emissions, we will make better trees.

First, we observe the X-Men approach. Trees, like corn, cows and humans, can be genetically modified to enhance particular characteristics. Methods of genetic modification to increase the carbon stored in the leaves and roots of plants are well within the reach of modern bioengineering capabilities. For example, annual plants could be enhanced with larger root systems from a perennial plant’s genetic library. Annual plants, which must regenerate every year, spend a lot of energy producing leaves and seeds for reproduction. On the other hand, perennials spend energy on maintaining a much larger root system, which allows them to “hibernate” through the winter until they can regrow above ground in the springtime. More roots will mean more carbon flowing into the ground, and carbon in the soil will stay out of the air for longer than carbon stored in leaves and seeds.

Of course, tampering with genes has its risks. Until researchers study the effects of such genetic modification more clearly, genetically modified carbon-eating trees are riskier than solar power.

Second, we observe the iRobot approach. Instead of leaving it to trees, we can create machines that join them in the bountiful carbon dioxide feast. Arizona State University’s Center for Negative Carbon Emissions has developed a synthetic membrane that catches 10 percent to 40 percent of the carbon dioxide in the air that passes through it. However, researchers have not come as far on figuring out where to store all the carbon dioxide they catch. Furthermore, the prototype only works in warm and dry conditions.

More recently, researchers at University of California at Berkeley developed a nano-sized ecosystem that works just like a photosynthetic leaf by populating a miniature field of titanium and silicon nanowires with two species of bacteria. The wires, acting like solar cells, catch energy from the sun, providing the bacteria with the electrons they need to turn carbon dioxide and water into acetic acid, which can be used to create drugs and fuels.

In reality, alternative energy is much further along than alternative photosynthesis. Targeting carbon dioxide from the demand end is no more of a global warming cure-all than is hydroelectricity. Greenhouse gas concentrations in the atmosphere simply cannot fall as much as we would like them to in the immediate future, but, with continued investment in carbon-eating technology, I am confident we will be able to catch up when we are finally able to create cost-efficient, effective systems.



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