Skip navigation

Category Archives: waste heat utilization

There is so much discussion about Hydrogen as a source of clean energy because, it is the choice of Nature. Nature has provided us with fossil fuels which are Hydrocarbons, chemically represented by CxHy, Carbon and Hydrogen atoms. In the absence of Hydrogen in a Hydrocarbon, it is nothing but Carbon, which is an inert material. The Hydrocarbon gets its heating value only from the presence Hydrogen atom. The natural gas, now considered as the cleanest form of Hydrocarbon is represented by the chemical formula CH4, containing 25% Hydrogen by weight basis. It represents the largest Carbon to Hydrogen ratio at 1:4.This is the highest in any organic chemicals. In aromatic organic compounds such as Benzene, represented by C6H6, the Hydrogen content is only 7.69%.Even in Sugar which is an organic compound from Nature, represented chemically as C12H22O11 has only 8.27% Hydrogen. But Bioethanol, derived from sugar represented by C2H5OH has almost 13% Hydrogen.  Ethyl Alcohol known as ‘Bioethanol’ derived from sugar is blended with Gasoline (Hydrocarbon), for using as a fuel in cars in countries like Brazil. Brazil is the only country that does not depend on imported Gasoline for their cars. The same Bioethanol can also be derived from Corn starch. But the starch should first be converted into sugar before alcohol is derived; that is why it is more expensive to produce Bioethanol from starch than from cane sugar molasses. The climatic conditions of Brazil are more favorable for growing Cane sugar than corn.  Brazil is in a more advantageous position than North America, when it comes to Bioethanol. US is one of the largest consumer of Gasoline.US has imported 11.5 million barrels/day of oil in 2010.It has used 138.5 billion gallons of Gasoline (3.30billion barrels) in 2010) according to EIA. (US Energy Information Administration) It is estimated that Brazil’s sugar based Alcohol is 30% cheaper than US’s corn-based Alcohol. Brazil has successfully substituted Gasoline with locally produced alcohol .They also introduced ‘flexible fuel vehicles’ that can use various blends of Alcohol-Gasoline. Most of the Gasoline used in US has 10% Ethanol blend called E10 and E15, representing the percentage of Alcohol content in Gasoline. Brazil is the largest producers of Bioethanol in the world. Both Brazil and US account for 87.8% of Bioethanol production in the world in 2010 and 87.1% in 2011.Brazil is using Bioethanol blends of various proportions such as E20/E25/E100 (anhydrous alcohol) (Ref: Wikipedia). Almost all cars in Brazil use Bioethanol blended Gasoline and even 100% anhydrous Bioethanol are used for cars. Brazil has set an example as a ‘sustainable economy introducing alternative fuel’ to the rest of the world. The ‘bagasse’ from cane sugar is also used as a fuel as well in the production of ‘Biogas’, which helps Brazil to meet sustainability on renewable energy and greenhouse gas mitigation. The above example is a clear demonstration of sustainability because natural organic material such as sugar is the basic building block by which we can build our Sustainable clean energy of the future. The same Bioethnanol can easily be reformed for the production of Hydrogen gas to generate power and run Fuel cell cars. Many companies are trying to use chemicals such as metal Hydrides as a source of Hydrogen. For example, one company successfully demonstrated using Sodium Borohydride for Hydrogen production. Many companies are trying to find alternative sources of Hydrogen generation from water, including Photo-electrolysis using direct solar light and special photo catalyst materials. We know Nature produces sugar by using sun’s light, water and carbon dioxide from air by photosynthetic process. Can man duplicate this natural process and generate Hydrogen at the fraction of the cost by simply using water and sun’s light? The race is already on and only time can tell whether our pursuit for cheap and clean Hydrogen can become a commercial reality or just stay as an elusive dream.

Distributed  generation system, is a system that generates power at the point of usage; unlike the centralized electricity generation, where power is generated at a remote place and then distributed to various locations using Power transmission  grids. The centralized systems became popular, due to its convenience, to transmit large power over long distances, under high voltage. However, there are several disadvantages, in centralized power generation and distribution. Most of these power generation plants are using fossil fuels, like coal, oil and gas, whose efficiency is only about 40%; which means, only about 40% of the heat value of the fuel used is converted into electricity, and the balance is a waste heat, discharged in the form of greenhouse gases, into the atmosphere. That is why; power station are the largest emitters of greenhouse gases, in the world. These plants are  not only the biggest emitters of greenhouse gases, but also a very inefficient, because bulk of the fuel is simply combusted and discharged into the atmosphere. With ever-increasing cost of oil and gas, these power plants are ‘white elephants’ that drain the oil and gas resources in the world and turn them into greenhouse gases. Such inefficiencies drive the cost of power high, and also increase the pollution levels. This unabated emission of greenhouse gas has to be curtailed.

At this juncture of global warming, and increasing energy cost, Governments and companies, should encourage distributed energy systems. The advantage with distributed energy systems is, when we generate energy  on site using a fuel, we can use the waste heat  in a productive way, thus increasing the power efficiencies from 40% up to 80-85%.This increase in efficiency, will result, is the reduction in the cost of energy. The power savings from distributed energy system varies  from 10% up to 80%. Industries and business who use continuous processes (24×7) and whose energy bill is substantial, are the ideal candidates for distributed energy systems. It is easier to adapt distributed energy system, with gaseous fuels, like natural gas and Hydrogen, than with liquid fuels such as diesel or solid fuel such as coal.

Distributed energy system can even be installed, using ‘Biogas’, where large quantity of  organic waste or waste water is available throughout the year, like dairy plants, breweries, municipal sewage systems etc.The power generated in DES system, is invariably a direct current (DC), which is usually converted into alternating  using rectifier,   before usage. But, part of this DC load, can be used directly in the form of Dc current, wherever necessary. For example, many consumers are using Light-emitting diode bulbs for lighting, to save energy. In distributed energy system, it is possible to use direct current for these applications because you can save a certain amount of energy in the process of converting DC to AC, and then again AC to DC.In fact, we can connect number of appliances directly  to  direct current.

In addition to the above advantages, we can utilize the waste heat  to generate steam, hot water, chilled water or space airconditioning.For example, if a distributed energy system generates  500 kw Electric power using natural gas, with an efficiency of 30%, the gas consumption will be about 1666 Kws.The remaining waste heat available is about 1166 Kws, which is equal to about 300 TR chilling capacity. This chiller can be used to air-condition an office space. The total efficiency of such system can be as much as 80%.We can reduce the cost of energy as much as 60% or more, in some cases.

Distributed energy system, is the best and cost-effective system to cut energy bills as well as to reduce Greenhouse gas Otherwise the power for air-conditioning has to come from the grid. It is a win situation, for everybody involved. Such system can also be used, with Hydrogen. In fact, the heat value of Hydrogen is much higher than any other fuel, such as coal, oil or gas. Hydrogen is the energy of the future that is not only clean but also sustainable.

%d bloggers like this: