Sewage waste energy

The concept of turning sewage waste from humans into energy is a new one. For years, sewage has been turned into fertilizer, but it is only recently that leaders in the field have made progress in creating energy. The benefits of turning sewage waste into energy are monetary as well as environmental. The use of these biofuels cuts the number of greenhouse gases polluting the air.

History

A town in Spain, Chiclana de la Frontera, contains the world’s first plant that converts sewage into energy. The wastewater plant produces algae-based biofuel. The ability of microbes to produce electricity has been known for decades now, but only recent technological advances have made their commercial production possible. Some places, like the European Union, have recently passed a Renewable Energy Directive to encourage an increase in transport biofuels from 2.4% to 10% by 2020.

Conventional waste disposal

Converting wastewater into energy is typically accomplished through anaerobic digesters, which collect methane, or biogas, and produce energy through a combustion reaction. These anaerobic digesters are high-energy intensive and therefore produce less energy than the new technologies that have started to emerge. The conventional methods of waste disposal create 7 million tons of dry biosolid per year, which is usually dumped into landfills or turned into mulch. The wastewater that is able to be purified often still contains pharmaceutical drugs because they are water-soluble and difficult to extract.

Sewage-to-energy

Recent technological advances have so far proved that sewage can be turned into electrical power and transportation fuel. The extent of this power, however, is yet undetermined. In order to understand how sewage can be used as an energy source, one must understand the chemical process involved. Bacteria is a big part of this process. Bacteria use sewage to drive chemical reactions that produce an electrical current and thus, energy. Bacteria naturally generate electrons as they break down organic materials, such as sewage. These electrons can then be used by microbial cells to create an electrical current. Sewage that is treated in this way can produce large amounts of electricity and can also purify the wastewater that is used in the process. Another process for creating energy from the waste is to run electrical current through the sewage. This creates vapor which, once captured and condensed, is a No. 2 diesel fuel. This fuel can be burned like other fuels to create energy. One great advantage to this method of energy harvesting is that there are no toxic byproducts.

Emerging technology

An important technological development that has arisen with the advancements made in sewage waste energy is the tri-generation system. This three-part system uses sewage to produce heat, electricity, and hydrogen. The tri-generation system is currently in use by a leading company in the sewage waste energy field, FuelCell Energy Inc. located in California. This company also uses another important technology that has recently emerged called microbial fuel cells. Fuel cells in general produce electricity through chemical reactions involving hydrogen ions. Microbial fuel cells make energy in a process similar to that of hydrogen fuel cells, except for the fact that it runs of wastewater.

Companies focused on sewage waste energy

Economics

Treatment of wastewater could be a great energy producer, not energy cost. Some benefits include saving money, better water treatment, and promoting energy sustainability. Construction costs of this new technology could even be less expensive than the activated sludge systems that are currently in use.

Challenges

Most of this technology, such as microbial fuel cells, is still in early development stages. Other challenges include how to generate enough energy to offset the costs of running a sewage treatment plant as well as how to create bigger, more effective microbial fuel cells that can generate more energy for large-scale commercial use. The storage of waste in homes before its collection may also lead to problems.

References

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