درباره جایگزینی منابع انرژی : آینده نگری سهم بازار گاز طبیعی در حمل و نقل شهری برزیل و بخش های مسکونی

The substitution process resultant of the competition between two opponents fighting for the same resource or market is pointed out through a dynamic model derived from biomathematics. A brief description of the origin of the method based on coupled non-linear differential equations (NLDE) is presented. Numerical adherence of the proposed model to explain several substitution phenomena which have occurred in the past is examined. The proposed method is particularly suitable for prospective analysis and scenarios assessment. In this sense, two applications of the model to prospect the dynamic substitution process in the Brazilian case are done: firstly, the development of the urban gas pipeline system in substituting for the bottled LPG in the dwelling sector and, secondly, the substitution of the urban Diesel transportation fleet by compressed natural gas (CNG) buses.

The presence of natural gas (NG) in the Brazilian energy balance has grown up rapidly over the last decade. According to BEN (2004), the market share of NG in the total energy gross domestic supply was 3.1% in 1990 and has increased its percentage to 7.7% in the year 2003, equivalent to 15.5×106 tOE. This fact was due, basically, to the construction of Brazil–Bolivia pipeline and discovery of new resources in Campos and Santos basin, whose consequences was a higher NG supply than the final user sectors could consume. Great efforts have been taken to increase the use of NG in finding a substitution for traditional energy sources. However, the natural barriers to a new product in an established market are well known. Even in the case in which the new product represents an appropriate and advantageous consumption alternative the acceptance decision of a new product is not straight and the obstacles to acquiring even a small market share are not trivial. As it is well known from the marketing specialists, the transition rate intensities between the “old” and “new” products are associated with behavioural, socio-economic and financial market variables: lifestyle, conservative practices, environmental cares, earnings level, tax incentives, class stratification, innovative technological level and the most important, trust and competitive prices of the new alternative. This fact is particularly true in the substitution process between energy-conversion techniques in which a respectable amount of investment is involved. Then the recovery time of the investment becomes the key variable, even when environmental healthiness and supply independence aspects are associated to the new alternative. In order to deal with the above complex system problem, this paper presents an approach derived from biomathematics. It is well known how hard it is to deal with complex dynamic system, in which so many variables are interacting in time. In order to analyse such problems, a method similar to the models developed in the biomathematics is proposed: a set of coupled non-linear differential equations (NLDE) are established to represent two “species” fed by the same “resource”. According to this reducionist approach, all the interacting variables associated with the substitution transition rate are represented by one single parameter. Using this method and through numerical approach, the aim of this article is • to examine the adherence of the proposed model to explain several substitution phenomena that occurred in the past; • apply the model to examine prospectively two dynamic substitution process in the Brazilian case: firstly, the development of the urban gas pipeline system in substituting for bottled LPG in the dwelling sector and, secondly, substitution of the urban diesel transportation fleet by CNG buses.

The aim of this paper is to present a numerical model for competition analysis, derived from biomathematics, for prospective scenario assessment. It is restricted to two competitors, in which one of them has an undoubtful competitive advantage, in order that the substitution process, if really feasible, will take place sooner or later. The proposed set of NLDE is able to explain several substitution phenomena that have occurred in the past satisfactorily. The prospective results obtained in the urban bus transportation and thermal uses in the dwelling sector give a first qualitative insight about the substitution process occurring in these sectors. However, this method has big limitations, as pointed by the Referee’s comments: ‘‘The model discussed has limitations when used to forecast the future since there is no correlation between real market conditions (price, marketing, availability, facility of the use, exchange rate, etc.) and the mathematic parameters used on the equations. It is easy to simulate futuremarket penetration changing the parameters, but it is not to show how changes in the market reflected in these parameters’’