Engineered bacteria to convert carbon dioxide into liquid fuel

Introduction

Global warming is becoming a major concern for environmentalists and the general public. On the other hand, the power plants and factories need to continue their operations in order to meet the demands of the growing population. This goes to show that greenhouse gases will still be generated and emitted to the environment. Thus, pollutants such as carbon dioxide, nitrous dioxide, ozone will absorb and re-emit the infrared radiation back to the atmosphere.

However, a recent study made by a team from University of California-Los Angeles (UCLA) Henry Samueli School, Engineering and Applied Science, has produced a promising solution to the problem.

In December 2009, the research was published in an online journal Nature Biotechnology. The team applied the fundamentals of recombinant DNA technology to genetically modify a cynobaterium. The genetically modified bacterium has the ability to consume carbon dioxide and produce isobutanol. Isobutanol is a liquid fuel and can be a gas alternative to automobiles. The process will only require sunlight as the main source of energy. This is to ensure that the cynobacterium will photosynthesize the carbon dioxide.

Process

Steps taken:

1. Constructing the bacterium
2. Gas extraction
3. Chemical catalysis process


Constructing the bacterium

The cynobacterium, Synechoccus elongatus, is altered to possess carbon dioxide fixing enzyme (RuBisCO) and other genes. This step is carried out to ensure that the genetically modified bacterium has the desired characteristics. The strain has the ability to uptake carbon dioxide and sunlight to produce isobutyraldehyde gas.

Genetically modified cynobacterium + Carbon dioxide + Sunlight → Isobutyraldehyde gas

Gas extraction

The isobutyraldehyde gas can easily be extracted because it has a low boiling point and high vapor pressure.

Chemical catalysis process

After extraction, chemical catalysis process will help convert isobutyraldehyde gas to isobutanol or other petroleum-based products. This process is inexpensive and easier as compared to allowing the gas to directly produce isobutanol.

Isobutyraldehyde gas → Isobutanol + Petroleum based products

Advantages

There are several advantages of this new method. Firstly, it ensures a cleaner and greener economy in a long run. This is true because it recycles carbon dioxide. This reduces the amount of greenhouse gases produced as a result of burning fossil fuels. In other words, the method is reducing the rate and minimizing the impacts of global warming.

In addition, the energy requirement is minimal and clean. Solar energy is needed for the cynobacterium to convert carbon dioxide into liquid fuel, which can then be supplied to automobiles. Solar energy is a green form of technology and can be powered by natural sunlight.

Furthermore, it provides an alternative to biofuels(plants, algae, cellulosic biomass). The only difference between the two methods is in one of the steps towards fuel refinement. The new method allows operators to skip biomass deconstruction. It is believed that biomass deconstruction is an expensive process. Therefore, it is evident that the method is more efficient and cost effective.

Disadvantages

In any technology or process, there are advantages and disadvantages. Similarly, this new method has its flaws. On the contrary, there is still room for improvement. As the method is new, it will need further study to emphasize its capability to reduce greenhouse gases and produce liquid fuels. In depth studies will enhance rate and yield of production. The team will need to consider the following factors namely the efficiency of light distribution (photosynthesis) and cost reduction of the bioreactor.

Application

In the future, the bioreactor can be constructed next to power plants. The gases emitted from the stack can be captured before the plume disperses into the atmosphere. Furthermore, the captured gas can be recycled by converting it to liquid fuel. The production of liquid fuel will be an additional benefit to the power plant. It can be used within the premises or sold to external companies.

Evaluation

The above process is supported by the U.S Department of Energy. This implies that the government is keen in venturing into the technology. It is interesting to see that even a pollutant can be a resource with the assistance of technology. The future for this technology is bright and promising. Time will tell whether this technique will be effective in controlling the rate of greenhouse gas emissions into the atmosphere and in slowing down the rate of global warming.