Carbon Capture, Storage and Utilization

A Possible Climate Change Solution for Energy Industry

Malti Goel, M. Sudhakar, R.V. Shahi, Malti Goel, M. Sudhakar, R.V. Shahi

• Publisher: CRC Press
• Year: 2019
• ISBN:
  9780429602474
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Conservation & Protection
• Index: Biological Sciences

Carbon capture and storage (CCS) is among the advanced energy technologies suggested to make the conventional fossil fuel sources environmentally sustainable. It is of particular importance to coal-based economies. This book deals at length with the various aspects of carbon dioxide capture, its utilization and takes a closer look at the earth processes in carbon dioxide storage. It discusses potential of Carbon Capture, Storage, and Utilization as innovative energy technology towards a sustainable energy future. Various techniques of carbon dioxide recovery from power plants by physical, chemical, and biological means as well as challenges and prospects in biomimetic carbon sequestration are described. Carbon fixation potential in coal mines and in saline aquifers is also discussed.

Please note: This volume is Co-published with The Energy and Resources Institute Press, New Delhi. Taylor & Francis does not sell or distribute the Hardback in India, Pakistan, Nepal, Bhutan, Bangladesh and Sri Lanka

Section III

CO₂ FIXATION AND UTILIZATION

CHAPTER 11

Prospects in Biomimetic Carbon Sequestration

Shazia Faridi and T. Satyanarayana

Department of Microbiology, University of Delhi, South Campus, New Delhi-110021

E-mail: [email protected]

INTRODUCTION

The adverse climatic changes occurring all over the world indicate that global warming has reached an alarming level due to increasing concentrations of greenhouse gases (GHGs) in the atmosphere. It has also created pressure to develop strategies to reduce these changes [1]. Carbon dioxide (CO₂) is the major contributor to greenhouse effect in terms of both emission and its climate altering potential. The atmospheric CO₂ concentration has increased from a pre-industrial level of 280 parts per million (ppm) to 390 ppm at present. Several attempts are being made to develop alternatives to fossil fuels, such as using renewable energy sources. Fossil fuels will probably continue to rule the next few decades. Thus, there is an urgent need to address the increasing level of CO₂ in the atmosphere. Towards this end, various carbon sequestration technologies are being assessed for mitigating CO₂ levels in the atmosphere [2].

Physical means of CO₂ storage (geological and ocean sequestration) are associated with high costs and risk of leakage. In this context, the use of biological sequestration (in short bio-sequestration) processes is considered viable and promising for reducing emissions of CO₂ in the atmosphere. Bio-sequestration is the capture of CO₂ from the atmosphere by the biological processes. Bio-sequestration of CO₂ may be by enhanced photosynthesis by increasing soil carbon storage, or by using heterotrophic bacteria and their enzymes [3]. This chapter is aimed at summarizing the developments in carbon bio-sequestration.

BIO-SEQUESTRATION THROUGH PHOTOSYNTHESIS

Preserving and adding to the world’s forest canopy is the cheap and easily manageable natural means for minimizing the impact of global warming. Kindermann et al. [4] reported that by avoiding deforestation in tropical regions, around 2.8 billion tonnes of CO₂ emissions could be reduced per year. Increasing the earth’s percentage of plants which have C₄ carbon fixation mechanism will also contribute to bringing down atmospheric CO₂ level. The efforts are also underway to increase the photosynthetic efficiency of RuBisCO genes to increase the catalytic and/or oxygenation activity of the enzyme [5].

Another way by which plants can act as carbon sinks is by the use of bioenergy crops, thereby minimizing GHG emissions from fossil fuels. Bioenergy crops provide a carbon neutral energy source. Today sugarcane, oil crops, and cereals, particularly maize and wheat, make the largest contribution to bioethanol. Globally appropriate forest policies could increase the amount of carbon sequestered in terrestrial biomass by up to 100 Gt or up to 2 Gt per year [6].

CARBON CAPTURE BY SOIL

Soil contains three times more carbon than the amounts stored in living forms. Long-term storage of carbon in soil can be attained when carbon from aboveground biomass enters the pool of soil organic carbon (SOC) or soil inorganic carbon (SIC).

One of the approaches to sequester carbon in soil involves development of a carbon farm which would be devoted to growing biomass for the production of phytoliths or biochar. Phytoliths are microscopic spherical particles of silicon which can store carbon for thousands of years [7], while biochar is charcoal which is created by pyrolysis of biomass. Panicum virgatum, a perennial switch grass which is valuable in biofuel production and soil conservation, has increased soil organic carbon at 0–12 inches and 0–47 inches at the rates of 0.5 and 1.3 tonnes carbon acre⁻¹ yr⁻¹ (equivalent to 1.8 and 4.7 tonnes CO₂ acre⁻¹ yr⁻¹), respectively [8].

MICROBES IN CARBON FIXATION

The ability of microbes, especially prokaryotes to recycle the essential elements that make up the cell, significantly affects the environment. The global carbon cycle is profoundly dependent on microbes. Microbes are considered to be capable of capturing CO₂.

Role of Microbes in Photosynthesis

In addition to plants, photosynthetic microbes such as algae and autotrophic bacteria (cyanobacteria and anoxyphotoautotrophs) also play an important role in the fixation of CO₂. They play an important role in carbon cycle by converting atmospheric CO₂ into organic matter. Cyanobacteria fix CO₂ and produce oxygen during photosynthesis, and they make a very large contribution to the carbon and oxygen cycles. Cyanobacteria can be developed as a microbial cell factory for converting atmospheric CO₂ into beneficial products by using solar energy.

ALGAL SEQUESTRATION OF CO₂

Microalgae are capable of carrying out photosynthesis using free CO₂ and bicarbonate ions as a source of inorganic carbon. The rapid growth rates of algae and their capacity to grow practically in any kind of environment makes them attractive for capturing CO₂ emitted by power plants and other industrial sources worldwide. Algae are known to thrive at high concentrations of CO₂ and nitrogen dioxide (NO₂). Kubler et al. [9] studied the effect of elevated CO₂ levels on the seaweed Lomentaria articulata, and found that twice the ambient CO₂ concentration had significantly affected daily net carbon gain and total wet biomass production rates; 52% and 314% greater than they were under ambient CO₂ conditions, respectively. The microalgae such as Chlorella grow much better at 100,000 ppm of CO₂ than in the ambient air [10]. It can, therefore, be concluded that a pollutant from power plants (flue gases containing CO₂) can act as a nutrient for the algae. Thus, flue gases from power plant emissions such as from coal-based power plants can be fed to algal production facilities to significantly increase productivity resulting in capture and storage of CO₂ in the biomass. For making this process cost-effective, algal biomass generated after sequestration can be used for the production of biofuel, food supplements for humans, pharmaceuticals and enzymes, animal feed, and electricity generation upon combustion directly or by anaerobically transforming the algal biomass to CH₄.

Seambiotic is the first company in the world that cultivated algae using flue gas from coal burning power station.

HETEROTROPHIC BACTERIA IN CARBON SEQUESTRATION

Wood et al. [11] proposed that CO₂ is reduced during the fermentation of glycerol by certain representative genera of heterotrophic bacteria such as propionic acid bacteria, Propionibacterium, Escherichia, and Citrobacter, and further showed that CO₂ and pyruvate combine to form oxaloacetate. This pathway of oxaloacetate formation using CO₂ and pyruvate can be exploited for carbon capturing using heterotrophic bacteria involving carbonic anhydrase (CA). The ability of CA to convert CO₂ into bicarbonate may be utilized by carboxylases such as phosphoenolpyruvate (PEP) carboxylase and pyruvate carboxylase to form oxaloacetate [12]. Such anapleurotic pathway exists in organisms to compensate the loss of oxaloacetate siphoned off for the synthesis of amino acids of the aspartate family.

Thus, heterotrophic bacteria can be used to sequester carbon and in turn produce oxaloacetate and amino acids by providing CO₂. The production of amino acids such as glutamic acid and lysine by Corynebacterium glutamicum is well known. This bacterium contains the enzymes, PEP carboxylase and pyruvate carboxylase and PEP pyruvate-oxaloacetate node [13], and, thus, fixing carbon in the form of amino acids. In elevated CO₂ conditions, increased supply of bicarbonate by the action of carbonic anhydrases, PEP carboxylase and pyruvate carboxylase activities make the conditions favourable for lysine production [14].

NON-PHOTOSYNTHETIC CO₂ FIXATION BY HETEROTROPHIC BACTERIA

Methane (CH₄) is the main component of natural gas. The biological conversion of CO₂ to organic compounds like CH₄ is an attractive method for the sequestration of CO₂. Microorganisms such as hydrogenotrophic methanogens can very efficiently convert CO₂ to CH₄ as they utilize CO₂ as a source of carbon and hydrogen as a reducing agent. A part of CO₂ reacts with hydrogen to produce CH₄, generating electrochemical gradient across a membrane, which is then used to generate adenosine triphosphate (ATP) through chemiosmosis (CO₂ + 4H₂ → CH₄ +2H₂). These methanogens inhabit anaerobic environments that contain CO₂, acetate, and low sulphate concentrations. They grow in the temperature range between 9°C and 110°C.

The bioconversion of CO₂ to CH...