Carbon Recycling

The Problem: Greenhouse Gas Emissions

The link between greenhouse gas emissions and global climate change is becoming better understood. It’s estimated that greenhouse gases such as carbon dioxide (CO₂) have risen to more than 380 parts per million, a 41% increase over pre-industrial values. This increase affects global weather and climate, ocean temperatures and currents, glaciers, permafrost and snowpack.

Burning fossil fuels adds about 6 gigatons of carbon into the atmosphere each year. Coal-burning plants are particularly “dirty”: A single coal-burning power plant can release more than 5 million tons of CO₂ into the atmosphere annually.

Currently, there are more than 3,000 coal-burning power plants in the U.S. alone, producing over 1 million megawatts of electricity for homes, businesses and public areas throughout the country. As U.S. consumers’ demand for electricity increases, so do the requirements for “cleaner” energy sources. In fact, government regulations for greenhouse gas emissions are responsible for as many as 72 coal-burning power plants being denied permits for construction because they were unable to demonstrate their ability to operate cleanly enough. In addition, 85% of the world’s power is generated via coal production facilities.

The most common approach to making cleaner coal-burning power plants is to sequester the CO₂ emitted. “Carbon sequestration” refers to the long-term storage of carbon so that the build-up of CO₂ concentration in the atmosphere is diminished or stopped.

Current or proposed methods of CO₂ sequestration include:

Terrestrial: Quite simply, this means planting trees – lots of trees. Reforestation projects encompass thousands of acres and require years to establish. Once established, they do have long life cycles, barring any environmental or development issues that might arise. These forests, however, can sequester only small quantities of CO₂ in comparison to the amount a coal-burning plant generates – hundreds of tons sequestered vs. millions of tons created. These plantings are also located, in most cases, several hundred or thousands of miles from the emission-emitting facility. In one recent example, the facility indicated that the “sequestration” would have a life of 70 years. What happens after that?

Geological: Gas emissions are pumped into old salt mines, empty oil reservoirs and other similar caverns beneath the earth’s surface. This is by far the most prevalent method in use today to remove greenhouse gases from the atmosphere. Unanswered are many serious questions, starting with, where does the gas go from here?

Oceanic: This method is still under consideration and has not proven itself to be truly viable, but it has a number of proponents. The idea is that the CO₂ would be liquefied and pumped to deep ocean areas where the cold ocean water would (presumably) store the liquid. Little data is available to the general public concerning this method. Currently, this practice is being conducted in an ongoing operation in the North Sea above the Netherlands. If this approach does not work as hoped, the potential for catastrophic die-offs in the ocean is enormous.

Filters: Most coal-burning power plants use complex filtering systems to clean the CO₂ and separate it from other toxins. The filtered CO₂ is sold to the consumer market for use in various applications. Unfortunately, there is more CO₂ generated than used in this marketplace. The conversation around the use and disposal of the filters is not one that is held up to public review and therefore might be a larger issue than is known.

Chemical: The use of very cold ammonia to clean and separate the gases is being tested and researched. This process still leaves the CO₂ to be dealt with in later-stage applications.

Another approach gaining momentum is the use of algae, a plant that uses photosynthesis to absorb CO₂ and expel oxygen, as a means for recycling CO₂ emissions. As an added bonus, the algae “fed” by the CO₂ can be harvested and sold to supply manufacturers of algae-based products, such as biofuels, animal feed and nutraceuticals. As a result, this approach is more accurately described as CO₂recycling, as opposed to sequestration.

While extremely effective for this use, current algae recycling projects suffer from some serious drawbacks, including:

•   Lack of scalability. The algae typically are grown in ponds or raceways. The only way to increase capacity is to add acreage.
•   Lack of control. Algae growth can be compromised by pollution, heavy rains, too much or too little sunshine, freezing weather, infestation by rogue algae species and other environmental influences.
•   Reliance on specific algae strains. Providers of algae sequestration typically work for years to hybridize a “perfect” strain of algae to meet a particular need, often for biodiesel production.

Ternion Bio Industries starts with all the inherent advantages of algae to mitigate CO₂ build-up, with the added advantage of an innovative, closed-loop system called the Photo BioReactor.