Biogas

The fossil fuels where formed over millions of years from plant biomass. Rapid use of the fossil fuels is releasing carbon from these fuels in the form of carbon dioxide. Hence, there is a increase in the carbon dioxide concentration in the earths atmosphere. With the growing energy demands and the depleting fossil fuel reserves, we are in need of alternative renewable sources of energy.

A large-scale transition to renewable energy is not possible in the short term due to the current technology for harnessing the alternative sources not being cost effective. Use of biomass for meeting the needs of the energy has been explored with significant success. Gaseous forms of fuel products from biomass such as biohydrogen and biomethane are considered as good sources due to their portability and efficiency.

Hydrogen can be produced by the electrolysis or from fossil fuels in either a small or a large scale.Large scale production from fossil fuels has the advantage of being able to capture the carbon dioxide to be utilized for stimulating plant growth or for storage in chemical form such as carbonates or in underground reservoirs.

Methane production through anaerobic process of digestion of wastewater and residues involves hydrogen as an intermediate product which is rapidly taken up and converted to methane by methane producing micro-organisms. The degradation of organic matter to methane and carbon dioxide in the absence of oxygen by microorganisms is called as Anaerobic microbial digestion. This digestion occurs in several phases involving many microbes. The complex organic compounds are first degraded to simple molecules. In the second phase the molecules are degraded into organic acids and hydrogen. The last step involves organic acids and hydrogen being converted into methane.

Biophotolysis involves many microalgae and cyanobacteria which are able to split water into hydrogen and oxygen with the aid of absorbed light energy. However, this process is limited by the efficiency of the enzyme involved in the conversion process. The enzyme is inhibited by the oxygen produced in the process of splitting water. Several variants of this process are being developed to separate the hydrogen and oxygen production steps.

Organic compounds like acetic acid are converted into hydrogen and carbon dioxide with sunlight by bacteria in what is known as photofermentations. However, this process is difficult to scale up as it requires a large surface area to capture the light needed for the driving the process.

Photosynthesis, CO2, Biomass from Plants & Algae, Biohydrogen

The changing energy need dynamics is going to affect not only the way energy is produced but also how its going to be used. The winning entry for the city of the future competition of History channel predicts a future for San Francisco that has hydrogen fueled hover car networks. The city will have specific structures to collect, store and distribute water and power from various sources. Harvesting the solar energy would be a very effective contributor. Currently energy is produced by processing the biomass into ethanol and biodiesel. However, energy is lost in producing all the other complex compounds that form the part of the complex biomass. Photosynthetic organisms that produce biofuels directly will be more energy efficient than processing the biomass thats produced by plants. This concept of producing a fermentation product called photanol with the input of carbon dioxide, water and solar energy into a synthetically designed organism.

Being able to produce hydrogen for use as a fuel by splitting water using solar energy is a long term goal to overcome the energy crisis. Various options are being explored to perform the task of splitting. However, using cyano bacteria for photo biological production of hydrogen has been found to be a very promising option. Many micro-organisms can produce hydrogen using enzymes called hydrogenases. This hydrogen production will produce the Biohydrogen which can be used a fuel for various purposes due to its portability.

Two different approaches are being pursued to produce biohydrogen. The first approach is the nitrogenase based approach and it involves knocking out the uptake hydrogenase. The second approach is to introduce a foreign hydrogenase. Both the approaches are being tried out by various companies. Different growth conditions and mechanisms are being observed to get the optimal system.

Interesting developments in using LED technologies as an additional, low-energy artificial supply of light with optimal properties for photosynthesis is being explored. Growing understanding of genetic engineering, regulation of transcription and translation will improve the design of the organism used to produce the fuel. Other areas such as mass culturing of the microorganism can also lead to significant cost reduction and stability.

Due to the complex nature of the biological systems, various problems such as auto inhibition of growth in the model organism while producing the new compound. The resistance mechanisms to such inhibition has to be studied and expressed in the organism to get a higher yield.

Energy forests, Salix program & breeding

The increasing demand for energy and decreasing oil production has made it imperative to find and exploit new forms of energy. Various forms of energy such as hydro power, nuclear power, wind and biomass are being used as alternative sources of energy. Biomass has emerged as a very important form of alternative energy due to its renewable nature, low impact on the environment and cost benefits. Growing energy in the form of forest trees has been found to be a sustainable model for the production of energy. However, strict regulatory policies on the felling and growth rates are required to ensure the balance in the forest cover.

Deciduous trees of the genus salix are found to grow mostly in moist soils in cold and temperate regions of the Northern hemisphere. Being a perennial crop with a life span of 20 to 25 years, its ideally suited for cultivation with the aim of harvesting for biomass. It requires low input of fertilizers and pesticides for its growth making it easy to cultivate.

The advantage of growing these energy forests can be further increased by using these tree for phytoremediation. The short rotation crops such as willows offer the double advantage of high biomass yields and removal of hazardous compounds through frequent harvests.The cleaning of polluted sites which contain heavy metals such as cadmium can be helpful in cleaning up various wastes.

Breeding programs to improve the biomass production, drought and heat tolerance and resistance towards pests are underway. With the aim of growing the plants in southern Europe which has higher temperatures, the heat tolerant strains are being sought. Leaf beetles are the major pests of willows and reduce the biomass by up to 40%. Leaf rust caused by fungi also cause loss of biomass in excess of 40%. As a result of the breeding programs, new strains which increase the biomass production by 60% have been selected for use.

Genomics based approaches which use the sequences genomes of the trees have been used to find genes associated with specific traits. Molecular markers identified by crossing have been associated with the concerned genes.It has been predicted that successful use of knowledge from genome sequencing projects will require the successful identification of polymorphisms associated with traits of interest, the frequency of superior alleles in the base breeding population and their phenotypic effect. Hence, just the sequencing of the genomes without proper understanding of the mechanisms involved in the various traits will not be of much use. Efforts to sequence EST's and studies of the expression patterns associated with different environmental conditions are being undertaken to bridge this gap.

Artificial photosynthesis and Synthetic biology

Future global energy needs cannot be met by any single source of energy known to us today. Contributions from different energy sources might make it possible to meet the energy needs. Solar energy is converted into biomass which can be used as energy source. However, the production of biomass is a inefficient process. Hence, different approaches to mimic the efficient parts of the system is being attempted.

Hydrogenase enzyme which catalyzes the formation of hydrogen is coupled to photosystem II to use water for utilizing the solar energy more effectively. Among the different steps involved in photosynthesis, the following are considered to be worth mimicking.

1.Absorb light and funnel energy
2.Convert energy to charge separated state
3.Couple charge separation to catalysis
4.Higher level of organization

Different molecules and molecular complexes are being perfected for each of the steps in the hope of increasing the efficiency.

Synthetic biology is the design and construction of new biological parts, devices and systems for useful purposes. The purpose of making parts and devices is to be able to have standardized components which could be used to build devices. The registry of standard parts is one such collection of parts such as promoters, ribosome binding sites, protein domains, protein coding sequences, translational units, terminators etc.

The standardized parts known as bricks are characterized and ready to use for that specific function. Computer aided design and simulations will play a significant role in this process. Simulating the model of the system can give results which can be used for designing the system. Unpredictable results may occur while using these design principles due to cross talk between the different components. These have to be taken care of and modularized.

Application areas for synthetic biology are widespread. It could help in fields such as bioenergy, drugs and chemicals, biomaterials, medicine etc. Coordinating the bacteria or yeast involved in fermentation by engineering the microbes could eliminate the need for monitoring the culture as it will be self regulated. With an increased knowledge of the various cellular processes, it should be possible to engineer entire new cellular systems as per requirement. Such a use of synthetic biology to design a cell from ground up might be made possible by integrative synthetic biology.

Biodiesel and Photobioreactors

Biodiesel is a fuel similar to diesel that is obtained from oil rich plants such as reapeseed, soy, palm oil, sunflower or used cooking oils or phototrophic microorganisms. It has the advantage of producing lesser amounts of green house gases than fossil fuels. The main reason for the success of biodiesel is because it can be used without modification to engines and distribution systems.

Biodiesel has some of the same problems as bioethanol. It can start a competition for land with other agricultural crops, causing decrease in food supply or increase in food prices. Hence, the focus is on microalgae and cyanobacteria to produce biodiesel. Since, the microbes can grow in saline environments, they are not as much a threat to food crop cultivation. These methods for production of biodiesel from microbes are still experimental and slow. Developments in bioreactor design and genetic modification of the microbes may make these methods more viable in the future.

Growing the microbes required for biodiesel production requires photobioreactors as the microbes get their energy by photosynthesis. The photobioreactors can be mainly classified into open and closed systems. Open systems are lakes and natural ponds which can be used to grow the microorganisms. Closed systems are tubular or flat panel shaped bioreactors. The tubular bioreactors can be horizontal or vertical. Closed bioreactors have the advantage of not being contaminated and can be easily controlled. Open bioreactors have cost benefits.

The design of the bioreactor is driven by various factors such as light considerations, gas exchange, nutrient availability, product recovery and contamination. Proper mixing is required to ensure time for both dark and light reactions to occur. Cooling is required to remove the heat due to high irradiation. Too much light is observed by the cells at the surface of the culture and lost as heat, this is known as the shading problem. Genetic engineering changes to the cells to have smaller photosynthetic antenna seems to reduce this problem considerably.

Idea: The shading problem can be overcome by having cells of two different types in the reactor. The first type of cells do the light reaction and are positioned at the surface of the culture. Second type of cells do the dark reaction below the surface. The two cell types interact and exchange the products of their respective reactions through the medium.

Bioethanol - fuel of the future?

Most of the alternative energy sources such as solar, wind, nuclear energy have a major drawback of not being useful as automobile fuels. Automobiles are one of the major consumers of the crude fuels today. This makes it necessary to have alternative energy source that can be used with the automobile engines being used today with little or no modifications. Bioethanol is one such alternative which has shown significant potential.

Ethanol is produced by fungi such as Saccharomyces cerevisiae and bacteria such as Zymomonas mobilis. The raw material for this production of ethanol is sugar plants, cereals or ligno cellulose. The use of food crops for ethanol production has the disadvantage of having a negative impact on food production. Hence, the use of ligno cellulose is a very attractive alternative.

Ethanol production is dependent on having effective production and storage of raw materials, pretreatment, fermentation, the production step itself and transport and use of the final product. Each of these steps has many problems which have to be overcome. Cost benefits and impact on other agricultural products are the main concerns with respect to bio ethanol.

Production of raw materials for ethanol production have to consider the impact on the environment due to increased usage of fertilizers and pesticides. There has also been significant concern regarding the reduction in the rain forest to meet the energy needs. However, sugar cane is not grown on rain forest land and is not actually having any impact on the rain forests.

Storage of raw materials has to provide the optimal conditions to maintain the correct water content for later use in fermentation. The raw material should also be protected from contamination and degradation during storage. Improvements in the fermentation and refinement of ethanol are also required to get better yields. Ethanol production has the advantage of being produced locally in most of the regions. However, concerns include over-utilization of land and destruction of rain forests. Integration of the different steps in the production of ethanol will increase efficiency.

Bioethanol is more sustainable than fossil fuels, but it may not be able to solely fulfill the growing need for energy.

Solar Energy and Solar cells

With the growing need for energy, alternative energy sources are being developed and refined. Solar energy is an attractive alternative as it is a relatively clean, renewable source of energy. Solar energy has been utilized in various ways such as for direct heating, electricity production and biomass production.

The energy needs by the year 2050 have been projected to be 28 TW in comparison to the currently used 11 TW. Although solar energy could probably provide a significant share of the required energy, it needs to be made available at a reasonable cost. The price of a 100 W silicon panel for converting solar to electric energy is 350 to 400 US dollars. However, this is too expensive to be practical. The exponential growth of about 40% per year has been mostly driven by huge subsidies from the government.

A solar cell is a device that converts solar energy directly into electricity[1]. The first generation solar cells transform light energy by using crystalline or amorphous silicon as inorganic solid-state material. The first generation cells are very expensive due to the cost involved in purification and production of the solar cells. The second generation solar cells make use of thin film as the core of the solar cell. The 3rd generation of solar cells is inspired by photosynthesis and has shown the potential to be more cost effective.

Dye- sensitized solar cells have been used to generate a potential gradient to generate electricity. These solar cells have shown good performance in diffuse light and have low investment cost to initiate production. The dye stability has been improved upto 15 years in sunlight by continued research. Titanium dioxide has emerged as the semiconductor of choice due to its abundance, non-toxicity, cost and compatibility.

Solar cells are facing the problem of scalability as the third generation cells are not being cost effective at large scale. Further developments in the field would be focused on better conversion efficiency and cost of production and maintenance.

My idea:

A biological model such as living organism capable of generating the potential gradient could be a idea worth exploring as the cost of production could be reduced. Many organisms are known to be capable of maintaining potential gradients. The challenge would probably be to combined the potential gradients of individual cells to get a net higher potential.

Hydrogen from solar energy and water?

Industrialization has been largely driven by the continued discovery of oil reserves. However, the number of oil findings is decreasing. A future with no oil left to use is a reality we have to face. Apart from the obvious problem of scarcity the fuels such as oil, coal and gas have been known to contribute to the problem of global warming. The situation is further complicated by the growing need for energy from users who are yet to start using the energy resources.

Many alternative strategies such as solar energy, wind, nuclear, tidal, geothermal etc have been proposed to solve these problems. Although these alternative sources might be able to provide energy, it might not be possible to use them effectively as fuels for transportation systems. Transportation systems being the major consumer of fuels today may need a different approach. Loss of energy during the conversion process has made it necessary to have a direct product which can be used as a fuel.

Use of solar energy to produce fuels such as hydrogen has gained importance in this context. Hydrogen could be directly used as a fuel and lack of carbon in the fuel source makes it a rather clean source of energy. The problem of scarcity and global warming can be tackled with this interesting approach. Two main approaches are being pursued to achieve this goal of using water to produce hydrogen using solar energy. The first approach is the photo biological method which aims to create or alter a biological system to convert solar energy into hydrogen using water as raw material. The second approach is the chemical method, which uses photo systems or molecules that imitate photo systems coupled to other molecules to drive reaction that convert water into hydrogen.

Photosystem II uses solar energy to oxidize water releasing electrons. This reaction is rather efficient although the other steps happening in the biological systems are not as efficient. Hence, the aim is to mimic just this step of the process from nature. The chemical approach has used molecules such as ruthenium linked to the photo systems to act as electron acceptor from Manganese. This is used to drive the reaction to produce hydrogen from water. The enzyme hydrogenase which can catalyse the reaction to produce hydrogen is used in this second step of the reaction.

Biological systems such as Nostoc produce hydrogen in special cells from nitrogenase. Currently large and small scale reactors are being developed to produce hydrogen from such biological systems and make them as effective as possible.

The direct methods of producing fuels have been found to be much more effective than the indirect methods which require the energy to be converted to electricity which is then used to split the water molecules by electrolysis.