Powering the Future with Microbes

How to generate energy using microbes

Science in the Public Eye

It’s a bright new day in America, filled with challenges and opportunities for the future. A key challenge we face as a species is generating enough energy to sustain and enhance our lives—and doing so in a way that can be relied on indefinitely. Currently, 77.6 percent of the energy produced in the U.S. comes from non-renewable fossil fuels, mostly natural gas, coal, and crude oil. Nuclear plants generate 10.6 percent of our energy, and the remaining 11.8 percent comes from renewable sources. Since global stores of non-renewable resources deplete over time, until we find a way to send organic matter back in time a few million years, we need to plan for a future in which they exist in far fewer quantities. This much is obvious before we even consider the impacts of harvesting and using non-renewables.

Still, renewable energy sources cannot presently meet global demand for energy. I often hear one of two diametrically opposed responses to this information: that fossil fuels are the only effective solution at present and that investment in renewable resources is wasteful, or that fossil fuels are destroying the planet and we should transition entirely to renewable energy immediately.

I would offer a compromise between the two: We should recognize that fossil fuels will compose a significant portion of our energy production in the near-term while at the same time investing considerable resources into making renewable energy abundant, efficient, and safe. While wind, solar, and nuclear energy get considerable attention, another promising solution to the Herculean task of global energy production lies in the hands of our smallest relatives, the humble microbes.

Microbes are an incredible tool from an engineering perspective, as they are programmable, self-repairing, ubiquitous, exist in limitless variety, and require little upkeep. While traditional biomass needs to be grown, taking up arable land that could house food production or forests, microbes can be grown anywhere with a light source and a supply of nutrients. Traditional solar panels can break down and degrade over time, but a microbial system can maintain population equilibrium ad infinitum.

There are two major methods through which microbes can be used to generate energy. The simplest method is to use microbes to generate simple organic compounds, which can be consumed just as any other biogas, bioethanol, or biodiesel. Another promising method employs microbial fuel cells, which harness electricity directly from the energetic activity of microbes.

Sweden recently made headlines by announcing a plan to import 800,000 metric tons of waste from other countries for energy production. The country generates 20 percent of its heat and a decent portion of its electricity by incinerating waste, which is used to power generators. While their incinerators have advanced measures to reduce emissions by collecting ash, flue gas, heavy metals, acids, and other byproducts, combustion of complex waste components is still a relatively inefficient and non-transportable mode of energy production. Were they to digest the organic compounds in their trash using microbes, they could produce hydrogen, natural gas, butanol, or ethanol as byproducts, which can be consumed both efficiently and portably, with a much cleaner end product. As a rough estimate, 100 pounds of plastic can be converted biologically into 70 pounds of oil, 16 pounds of natural gas, 6 pounds of ash, and 8 pounds of water.

Microbial fuel cells are less developed than microbe-assisted fuel production, but they show great promise for the future because direct production of electricity is far more efficient than combustion. Researcher Hong Liu’s lab at Oregon State University made headlines this summer by demonstrating that microbial fuel cells can not only generate electricity from wastewater, but that they could also sterilize and treat the water. Other researchers have created microbial desalination cells that use similar processes to generate electricity with a byproduct of desalinated seawater. Given that finding abundant sources of both water and energy will be major challenges to tackle in the coming decades, both of these technologies show incredible promise in providing abundant, clean energy and fresh, sterile water. It will be some time before these technologies can be employed on a global scale, but they are certainly a promising area for future research.

Providing abundant, cheap, renewable, and easily transportable energy will be one of the greatest challenges of the 21st century. Research that maximizes any of these variables for both renewable and non-renewable resources is laudable. Research into microbial energy sources, both through production of fuels and direct production of electricity, shows particularly great promise and could be a major stepping-stone on the path to a bright future.

Jack M. Cackler is a Ph.D. candidate in biostatistics. His column appears on alternate Wednesdays.

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