An Application of Energy and Exergy Analysis in Industrial Sector of India

An Application of Energy and Exergy Analysis in Industrial Sector of India

Dr. Soupayan Mitra1

Associate Professor: Dept. of Mechanical Engineering, Jalpaiguri Govt. Engineering College,

WBUT, West Bengal, India.

Devashish Gautam2

Post Graduate Scholar: Dept. of Mechanical Engineering, Jalpaiguri Govt. Engineering College,

WBUT, West Bengal, India.

Abstract The present article is dedicated for evaluating the industrial sector in terms of energetic and exergetic aspects. In this regard, energy and exergy utilization efficiencies during the period 2005-2011 are assessed based on real data obtained from Energy statistics of India. Sectoral energy and exergy analyses are conducted to study the variations of energy and exergy efficiencies, overall energy and exergy efficiencies for the entire sub-sector are found to be in the range of 67.23% to 77.83%. When compared with other neighbouring countries, such as Saudi Arabia, Malaysia and Turkey, the Indian industrial sector is the more efficient. Such difference is inevitable due to the proper use of fossil-fuel resources. It is concluded that the present technique and associated analysis is beneficial for analyzing sectoral energy and exergy utilization in India and provides the information on how efficiently energy is used. It is also helpful to establish standards to facilitate application in industry and in other processes for a successful energy planning towards sustainable development.

KeywordsEnergy; Exergy; Efficiency; Sectoral energy use; Industrial sector of India.

1. INTRODUCTION

   The Indian industrial sector accounts for 26% of GDP and employs 22% of the total workforce. India is 11th in the world in terms of nominal factory output according to data compiled through CIA World Fact book figures. The Indian industrial sector underwent significant changes as a result of the economic liberalization started from the New Economic Policy of 1991, which removed import restrictions, brought in foreign competition, led to the privatization of certain public sector industries, liberalized the FDI regime, improved infrastructure and led to an expansion in the production of fast moving consumer goods.[1]

   This work represents a brief critical and analytical account of the development of the concept of exergy and of its applications to the society. It is based on a careful and in detail consultation of a very large number of published references taken from archival journals, conference proceedings, technical reports and lecture series., considered first of its kind in India since there is no such study on energy and exergy utilizations for the sub-sector.

   Furthermore, comparison of obtained results of energy and exergy efficiencies with other countries around the world is carried out.

2. THEORITICAL AND MATHEMATICAL FORMULATION OF EXERGY ANALYSIS

   1. The concept of exergy

      Exergy can be defined as a measure of maximum capacity of an energy system to perform useful work as it proceeds from an initial state to specified final state in equilibrium within the surroundings which is called the dead state. Thus evaluation of exergy is always made with respect to a reference surrounding environment. The reference environment is in stable equilibrium, acts as an infinite system, a sink or surface for heat and materials, and experiences only internal reversible processes in which its intensive properties remains constant. In simple words, we can describe exergy as the maximum ability to produce work or, maximum usefulness of the energy content of a system or, an energy resource and it may be noted that not all energy content of a system can be converted into useful work.

      Exergy analysis permits to overcome many of the shortcomings of energy analysis. Exergy analysis is based on the second law of thermodynamics, and is useful in identifying the causes, locations and magnitudes of process inefficiencies which cannot be identified by the first law of thermodynamics or, simple energy efficiency alone. The exergy associated with an energy quantity is a quantitative assessment of its usefulness or quality. Exergy analysis is basically a qualitative analysis of the energy used to perform a job say, usage of exergy in industrial sector of a country. The exergy analysis acknowledges that, although energy cannot be created or destroyed, it can be degraded in quality, eventually reaching a state in which it is in complete equilibrium with the surroundings and hence of no further use for performing tasks.

   2. Energy and exergy values for commodities in macrosystem

      The exergy of an energy resource can for simplicity often be expressed as the product of its energy content and a quality factor (the exergy-to-energy ratio) for the energy resource. This value relates to the price of the material or resource, which is also partly defined by the environment through, for instance, demand. In assessments of regions and nations, the most common material flows often are hydrocarbon fuels at near ambient conditions. The physical exergy for such material flows is approximately zero, and the specific exergy reduces to the fuel specific chemical exergy exf, which can be written as:

      exf = f Hf (1)

      where f denotes the exergy grade function for the fuel, defined as the ratio of fuel chemical exergy to fuel higher heating value Hf . [2, 3]

      Table-1 lists typical values of Hf , exf and f for fuels typically encountered in regional and national assessments. The specific chemical exergy of a fuel at T0 and P0 is usually approximately equal to its higher heating value Hf.

      Table-1: Properties of selected fuels.*

      = (Exergy in products) / (Total exergy input)

      (3)

      Exergy efficiencies can often be written as a function of the corresponding energy efficiencies by assuming the energy grade function f to be unity, which is commonly valid for typically encountered fuels (kerosene, gasoline, diesel and natural gas).

      Heating

      Electric and fossil fuel heating processes are taken to generate product heat Qp at a constant temperature Tp, either from electrical energy We or fuel mass mf . The efficiencies for electrical heating are:

      h,e = Qp/We (4)

      and

      x x 0 p p e

      h,e = E Qp/E We = (1 T /T )Q /W Combining these expressions yields

      h,e = (1 T0/Tp)h,e (5)

      For fuel heating, these efficiencies are h,f = Qp/mf Hf

      * For a reference-environment temperature of 25C, pressure of 1 atm and chemical composition as

      and

      Fuel	Hf (kJ/kg)	Chemical exergy (kJ/kg)	f
      Gasoline	47.849	47.394	0.99
      Natural gas	55,448	51,702	0.93
      Fuel oil	47,405	47,101	0.99
      Diesel	39,500	42,265	1.07
      Kerosene	46,117	45,897	0.99

      h,f = ExQp/mf exf or

      h,f = (1 T0/Tp)Qp / (mffHf ) (1 T0/Tp)h,f

      (6)

      (7)

      defined in the text. Source: Reistad (1975). [4]

   3. The reference environment for macrosystems

      The reference environment used in many assessments of macrosystems i based on the model of Gaggioli and Petit [5] which has a temperature T0=25C, pressure P0=1 atm and a chemical composition consisting of air saturated with water vapor, and the following condensed phases at 25C and 1 atm: water (H2O), gypsum (CaSO4·2H2O) and limestone (CaCO3). This reference-environment model is used in this chapter, but with a temperature of 10C.

   4. Efficiencies for devices in macrosystems

      Energy and exergy efficiencies for the principal processes in macrosystems are usually based on standard definitions:

      = (Energy in products) / (Total energy input)

      (2)

      where double subscripts indicate processes in which the quantity represented by the first subscript is produced by the quantity represented by the second, e.g., the double subscript h,e means heating with electricity.

      Cooling

      The efficiencies for electric cooling are c,e = Qp / We

      (8)

      c,e = ExQp / ExWe = (1 T0 / Tp) Qp / We

      (9)

      or

      c,e = (1 T0 / Tp) c,e

      (10)

      Work production

      Electric and fossil fuel work production processes produce shaft work W. The efficiencies for shaft work production from electricity are

      m,e = W / We

      industrial sector is shown in Fig-1 and the main fuels that are being used are:

      1. High speed diesel oil (HSDO)

      2. Light diesel oil (LDO)

      3. Furnace oil (FO)

      4. Raw coal

      5. Lignite

   m,e = ExW / ExWe = W / We = m,e

   For fuel-based work production, these efficiencies are m,f = W / mf Hf

   (11)

   (12)

   (13)

   m,f = ExW / mf exf = W/mf f Hf m,f (14)

   which produce a change in kinetic energy ke in a stream of matter ms, are as follows:

   Electricity generation

   The efficiencies for electricity generation from fuel are e,f = We / mfHf

   (15)

   e,f = ExWe /mf exf = We/mf f Hf e,f

   (16)

   Kinetic energy production

   The efficiencies for the fossil fuel-driven kinetic energy production processes, which occur in some devices in the transportation sector (e.g., turbojet engines and rockets) and which produce a change in kinetic energy ke in a stream of matter ms, are as follows:

   ke,f = ms kes / mfHf

   Fig.1. Hierarchy Tree for the industrial sector of India [1]

   B. Energy efficiencies for the industrial sector

   Table-2 provides energy efficiencies for the various types of fuels used in the industries. These values are based on average U.S devices. They seem to represent the general nature of the devices and are assumed to represent the Indian devices in absence of any other more accurate data. Since, machines generally are not operated at full load; a distinction is made between rated load (full load) efficiencies and estimated operating load (part load) efficiencies. [4]

   Table – 2: Efficiencies for the Industrial Sector (Process and operating data). [2]

   ke,f = ms kes / mf exf = ms kes / mf f Hf ke,f

   (17)

   Fuel/Petroleum product	Rated Load/Efficiency (%)	Estimated Operating Load/Efficiency (%)
   High speed diesel oil	28	22
   Light diesel oil	28	22
   Fuel oil	–	15
   Raw Coal	80	70
   Lignite	46	40

   (18)

3. METHODOLOGY AND DATA SOURCES

   A. Analysis of the Industrial Sector

   Energy and exergy utilization in the industrial sector is evaluated and analyzed. The industrial sector of India is composed of many industries. Few of the industries are oil and gas, chemical and petro-chemical, iron and steel, cement, power plants, etc. The hierarchical diagram for the Indian

   1. Data sources

      Amount of fuel consumption by different machineries used in the industrial activities are collected from Energy statistics of India 2013 [1] and presented in Table-3.

      Table- 3: Energy consumption data for Industrial Sector in India for 2005-2011. [1]

      2010	LDO	127
      	FO	2774
      	Raw Coal	523470
      	Lignite	37690
      2011	HSDO	1649
      	LDO	102
      	FO	2409
      	Raw Coal	535730
      	Lignite	41880

   2. Steps and procedures taken for energy and exergy analysis

   Energy and exergy efficiencies were determined using (2) and (3) considering grade function as unity. The overall energy efficiency can be easily found by dividing total energy produced by total input energy. [3] The overall weighted mean was obtained for the energy and exergy efficiencies for the fossil fuel processes as well. Weighing factors are the ratio of energy input of each of the fuels to the total input energy of this sector. The device exergy efficiencies are evaluated using data for the years 2005 2011. Energy and exergy efficiencies were then used to calculate the overall energy and exergy efficiencies of this sector.

   Year	Fuel & Petroleum Products	Consumption (000 tonnes)
   2005	HSDO	964
   	LDO	325
   	FO	1828
   	Raw Coal	395590
   	Lignite	30340
   2006	HSDO	1234
   	LDO	244
   	FO	1830
   	Raw Coal	419800
   	Lignite	30800
   2007	HSDO	1241
   	LDO	200
   	FO	1634
   	Raw Coal	453570
   	Lignite	34660
   2008	HSDO	1310
   	LDO	155
   	FO	2843
   	Raw Coal	489170
   	Lignite	31790
   2009	HSDO	1502
   	LDO	143
   	FO	3134
   	Raw Coal	513790
   	Lignite	34430
   	HSDO	1440

   Table- 4: Energy consumption data for Industrial Sector in India for 2005-2011 [1, 2]

   Year	Fuel & Petroleum Products	Consumptions (000 tonnes)	Energy Consumption		Energy Efficiency
   			PJ	%	Rated Load (%)	EstimatedOperating Load (%)
   2005	HSDO	964	40.36	0.58	28	22
   	LDO	325	13.60	0.19	28	22
   	FO	1828	76.54	1.1	–	15
   	Raw Coal	395590	6341.3	91.13	80	70
   	Lignite	30340	486.35	7.0	46	40
   2006	HSDO	1234	51.67	0.7	28	22
   	LDO	244	10.21	0.13	28	22
   	FO	1830	76.62	1.03	–	15
   	Raw Coal	419800	6775.57	91.42	80	70
   	Lignite	30800	497.11	6.72	46	40
   2007	HSDO	1241	51.96	0.65	28	22
   	LDO	200	8.37	0.10	28	22
   	FO	1634	68.42	0.85	–	15
   	Raw Coal	453570	7320.62	91.4	80	70
   	Lignite	34660	559.41	7.0	46	40
   2008	HSDO	1310	54.85	0.64	28	22
   	LDO	155	6.49	0.07	28	22
   	FO	2843	119.04	1.38	–	15
   	Raw Coal	489170	7895.2	91.92	80	70
   	Lignite	31790	513.09	6.00	46	40
   2009	HSDO	1502	62.89	0.69	28	22
   	LDO	143	6.00	0.06	28	22
   	FO	3134	131.22	1.45	–	15
   	Raw Coal	513790	8292.57	91.65	80	70
   	Lignite	34430	555.7	6.15	46	40
   2010	HSDO	1440	60.29	0.65	28	22
   	LDO	127	5.32	0.05	28	22
   	FO	2774	116.15	1.25	–	15
   	Raw Coal	523470	8448.8	91.44	80	70

   	Lignite	37690	608.32	6.61	46	40
   2011	HSDO	1649	69.04	0.72	28	22
   	LDO	102	4.27	0.04	28	22
   	FO	2409	100.86	1.06	–	15
   	Raw Coal	535730	8646.68	91.04	80	70
   	Lignite	41880	675.94	7.14	46	40

4. DATA ANALYSIS, RESULT AND DISCUSSION

   1. Mean and overall energy efficiencies

      Generally, the overall or mean weighted energy efficiency is determined by dividing the total energy produced by the total energy output. In this problem, all the fuels have the same part loads. Using the part load efficiency, weighted mean energy efficiency of every fuel can be found. Based on the data listed in Table-4, the weighted mean energy efficiency for the industrial sector in the year 2010, e.g., is calculated using equation:

      0 = HSDO + LDO+ FO + Raw Coal + Lignite.

      o = (0.0065×28) + (0.005×28) + (0.0125×100) + (0.944×80) + (0.0661×46) = 77.40%

   2. Mean and overall exergy efficiencies

      Based on the process and operating data listed in Table- 2 and the estimated energy efficiencies, the overall exergy efficiency for industrial sector in the year 2010 is calculated using the equation:

      0 = HSDO + LDO+ FO + Raw Coal + Lignite.

      0 = (0.0065×22) + 0.005×22) + (0.0125×15) + (0.944×70)

      + (0.0661×40) = 66.993% 67%

      Fig. 2. Overall mean energy and exergy efficiencies for the industrial sector for 2005-2011

   3. Comparison with other countries

   Sector and overall energy and exergy efficiencies for India, Saudi Arabia, Malaysia and Turkey are compared and the comparison is shown in Fig.3. The comparison is based on previous studies, and the data used is for the year 1993 for Saudi Arabia and Turkey and 2005 for India and Malaysia. The efficiencies differ slightly, but the main trends

   described earlier in this section regarding the differences between energy and exergy efficiencies are exhibited by each country. The Indian industrial sector (including Power sector) is more efficient and such difference is inevitable due to dissimilar structure of the industries in these countries. From the above results it can be said that compared to some other Asian countries like Saudi Arabia, Malaysia and Turkey, the way energy is used in Indian industrial sector is better. Still there is a lot of scope for improvement and thereby reduction in the quantity of energy usage. Since this type of exergy analysis in industrial sector is first of this kind for India, it is expected that that the results of this study will be helpful in developing highly applicable and productive planning for future energy policies. In fact, similar analyses may be extended to cover Residential, Agricultural, Public and private and Utility sectors.

   Fig. 3. Comparison of overall energy and exergy efficiencies for the industrial sector of India, Saudi Arabia, Malaysia and Turkey. [1, 2]

5. CONCLUSION

In summary, it can be said that the potential usefulness of exergy analysis in sectoral energy utilization is substantial and that the role of exergy in energy policy making activities is crucial. The results of exergy analyses of processes and systems have direct implications on application decisions and on research and development (R&D) directions. Further, exergy analyses more than energy analyses provide insights into the best directions for R&D effort. The overall mean energy efficienc and the overall mean exergy efficiency in the Indian industrial sector for the period 2005-2011 is 77.8% and 67.23%. This study also shows that domestic industrial contribution should be increased to improve the overall energy and exergy efficiencies of the Indian industrial sector.

ACKNOWLEDGEMENT

The authors wish to acknowledge the support provided by Jalpaiguri Government Engineering College, Jalpaiguri, West Bengal-735101 and West Bengal University of Technology (WBUT).

REFERENCES

1. Energy Statistics. 2013, Central Statistics Office, National Statistical Organization, (Ministry of Statistics and Programme Implementation, Government of India, 2013).

2. Ibrahim Dincer and Marc A. Rosen. June 2007. Exergy, energy, environment and sustainable development.

   (Elsevier, 2007).

3. Dincer, I., Hussain, M.M., Al-Zaharnah, I., 2004. Energy and exergy utilization in transportation sector of Saudi Arabia. Applied Thermal Engineering 24, pp. 525538.

4. Reistad GM. 1975. Available energy conversion and utilization in the United States. J.Eng. Power 97, pp. 429434.

5. Gaggioli R.A., Petit PJ. 1977. Use the second law first. Chemtech7, pp. 496506.

6. Rosen MA. 1992. Evaluation of energy utilization efficiency in Canada using energy and exergy analyses. Energy-The International Journal 17:pp.339350.

7. Gaggioli, R.A., 1998. Available energy and exergy. International Journal of Applied Thermodynamics 1, pp. 18.

8. Rosen MA. 1992b. Appropriate thermodynamic performance measures for closed systems for thermal energy storage. ASME Journal of Solar Energy Engineering 114:pp.100105.

9. Wall G. 1990. Exergy conversion in the Japanese society. Energy- The International Journal 15: pp. 435444.

10. Wall G. 1991. Exergy conversions in the Finnish, Japanese and Swedish societies. OPUSCULA Exergy Papers, pp. 111.

11. van Gool W. 1997. Energy policy: fairly tales and factualities.

    Innovation and Technology-Strategies and Policies, pp. 93 105.

12. Wall G. 1993. Exergy, ecology and democracy-concepts of a vital society. ENSEC93: International Conference on Energy Systems and Ecology, July 59, Cracow, Poland, pp.111121.

13. Rosen MA, Le MN. 1995. Efficiency measures for processes integrating combined heat and power and district cooling. Thermodynamics and the Design, Analysis and Improvement of Energy Systems, AES-Vol. 35, American Society of Mechanical Engineers: New York, pp.423434.