- Category: ARTICLES
- Published on Friday, 22 July 2011 15:25
- Written by Godwin J. Igwe, Ph.D., PE
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INTRODUCTION: Natural gas as a raw material is produced in abundance in oil and gas wells throughout Nigeria. However, according to a U.S Geological study, Nigeria may now be considered more a gas producing country, as opposed to an oil producing country. This conclusion is drawn from recent estimates indicating that the country's gas reserves could be as high as 600 trillion cubic feet, which is three times more than the current conventional estimate of 187 trillion cubic feet.
Nigerian gas is concentrated in the Niger Delta which covers an area of about 41,000 sq. miles (106,189.50 km2). Of the total Nigeria’s proven reserves, 70% is located on land while 30% can be found off-shore. About 60% are located east of the River Niger while the rest are to the West of the River Niger. Experts estimate that the reserves locked in the Nigerian soil is enough to last as long as 500 years, fuelling our industries, homes, and international export.
Although produced in such large quantities, the lack of infrastructure and effective transmission and distribution systems result in a significant percentage of this energy being flared off, thereby resulting in wastage of valuable and scarce foreign exchange for the country.
In 1983 alone, 78.65% of the total gas produced was flared, amounting to approximately 106.36 T kcal/year (1.241 GSCF/D). In an attempt to curtail this colossal wastage of energy and valuable raw material, the Federal Government of Nigeria passed a law on gas flaring, and imposed a fine of thirty kobo (30 kobo per m3 in 1979 was equivalent to about 45 cents/m3) per cubic meter of gas flared. This yielded little or no result, since the oil producing companies found it more convenient and economical to flare the produced gases. The question, however, is how does this impact or affect the level of poverty prevalent in a nation so richly endowed with natural resources in the affected areas where the gas is being explored and exploited?
It is well known that the gas sector is attracting new players, which will increase competition and stimulate more gas supply and utilization system in Nigeria. This includes establishment of gas plants such as Liquefied Petroleum Gas (LPG or cooking gas), Liquefied Natural Gas (LNG), Gas to Liquid (GTL), and Compressed Natural Gas (CNG) businesses to boost the revenue base of the country. As stated above, creditable estimates have been produced regarding Nigeria’s gas reserves: It has “proven” gas reserves of about 184 tcf (trillon cubic feet) broken into 95 tcf associated gas and 89 tcf non-associated gas, and is estimated 7th largest in the world.
The estimated “proved” plus “proven reserve” is estimated at 185 tcf, and the combined total of “proved”, “probable” and “possible” reserves is 300 tcf.
Gas flares declined between 1999-2005 because of the growth of Liquefied Natural Gas (LNG) and new export projects in Gas-to-Liquid plants, best illustrated by the Nigerian Liquefied Natural Gas project in Bonny, the US$3.5 billion Brass LNG, and the US$7 billion OKLNG (Olokola Liquefied Natural Gas) project.
Other reports rank Nigeria as having the 7th largest gas deposit in the world, with current reserves at over 185 TCF, and undiscovered reserves put at 400 TCF. Estimates have gas reserves potentially growing to as much as 600 TCF, making it the world’s 4th largest after Qatar.
A study, financed by the World Bank and Government of the Netherlands through the Bank-Netherlands Partnership Program (BNPP), conservatively estimates our gas reserves at more than 150 trillion cubic feet.
At a lecture delivered on May 2, 2006, at the Baker Institute Energy Forum within Rice University, located in Houston, USA, the former Group Managing Director of the Nigerian National Petroleum Corporation (NNPC) said our reserves have grown steadily to over 35 billion barrels, of which over 7 billion barrels of oil and 19 tcf of gas have been discovered from the deepwater since 1996. Despite these impressive statistics, five key barriers have delayed the pace of Nigeria’s growth and economic impact to date. These barriers are: pricing, fiscal terms, institutional and infrastructural arrangements, legal and regulatory framework, and financing.
Put in its simplest terms, Nigerian leadership lacks innovative drive, and the fortitude to transform nascent innovation into concrete reality. No grand vision or idea for anything like Dubai, which owes its growth and outstanding success to visionary leadership, strategic planning, innovative projects, and meticulous execution. No ideas like the fast bullet train in Japan and China, or the magnificent airport of Hong Kong, has been proposed by Nigerian leaders.
The problem with Nigeria is not lack of technical expertise. It can be characterized by decades of non-implementation of any ideas, recycling and revolving unsound leaders, and primitive unpatriotic accumulation of personal wealth. Less qualified foreign experts are rather preferred, often for kickbacks. No country on planet earth has ever developed without making things independently for itself.
Let me quote, for our leaders, some memorable passages from the words of President Roosevelt at his Inaugural Address:
“More important, a host of unemployed citizens face the grim problem of existence, and an equally great number toil with little return. Only a foolish optimist can deny the dark realities of the moment. Happiness lies not in the mere possession of money; it lies in the joy of achievement, in the thrill of creative effort. Recognition of the falsity of material wealth as the standard of success goes hand in hand with the abandonment of the false belief that public office and high political position are to be valued only by the standards of pride of place and personal profit”.
He goes on to say:
“Our greatest primary task is to put people to work. This is no unsolvable problem if we face it wisely and courageously. It can be accomplished in part by direct recruiting by the Government itself, treating the task as we would treat the emergency of a war, but at the same time, through this employment, accomplishing greatly needed projects to stimulate and reorganize the use of our natural resources.”
TECHNICAL SPECIFICATIONS AND DESIGN OF PROPOSED SOLUTION
Back in 1988, my colleagues and I suggested a solution of developing a pipeline network for natural gas distribution for Port Harcourt (SPE Paper 17732: Igwe, Wami, Ewili: SPE Gas Technology Symposium, 13-15 June 1988, Dallas, Texas). One of the main objectives in the design of pipeline systems is the optimal selection of the diameter of the pipelines, location of the compressors, and its capacities such that the overall cost of transportation is minimized. Essentially, optimization of gas distribution or transmission network and capacity expansions of natural gas can be divided into four overlapping parts, namely, optimal layout of the network, static design, determination of the steady state flow and pressure characteristics, and the dynamic design which optimally expands the network over time to meet a given time variant demand/supply for gas.
Our solution consisted of static design model, and the optimization of the network was carried out on the main pipeline diameter such that no pressure or technological specification was violated. The distribution network was designed to have a capacity of 522 Mscf/D (14.62 Mm3/D) based on an estimated gas supply/demand for thirty years in Port Harcourt city. The distribution pattern to the residential areas was based on population density of the city. The total length of the network was 16.6 miles (26.72 km). The maximum and minimum pressure specified at any point in the main pipeline were 300 (2067 kPa) and 100 psi (689 kPa) respectively. The design was also carried out within the compression ratio range of 1 to 1.6, and diameter of 40.64 to 96.52 cm (16 to 38 in.) of the main pipeline. The design was performed for inlet pressures ranging from 150 to 200 psi (1033.5 to 1378 kPa).
DISTRIBUTION AND PRICING
Natural gas may generally be distributed using three broad methods: by tankers, bottling, and by pipelines. Distribution by tankers has the disadvantage that at the receiving terminals the liquefied gas must be reconverted into a useable gaseous state by some form of degasifying plant. This adds to the carriage cost and thus increases the price per unit volume.
Distribution by bottling covers a wider area than the tankers, but for large scale gas distribution, it is not economically viable. There are no standardized gas cylinders, and there is the added inconveniences incurred by users in transporting cylinders to and from the filling stations, and this adds to costs.
Pipeline distribution systems is less expensive, consumes less energy, produces less traffic and also minimizes resultant pollution due to spillage. It is therefore of fundamental importance economically for a natural gas producing country such as Nigeria. The only problem is that it involves huge capital outlay.
In our study, only one case of static design was considered, which deals with a proposed new transmission network whose layout and compressor stations are fixed or known. We further considered the analysis and optimization of the network that contained the fewest number of pipelines that can deliver gas from the source to the demand supply points (also known as tree shaped networking).
Based on our work, significant progress can be made towards solving the problem of design of natural gas transmission network in Nigeria, thereby conserving the huge energy wastage due to flaring. Though this study was carried out using Port Harcourt, it can also be applied to other cities in Nigeria by either adding more branches or decreasing the branches, or simply modernizing the network to suit the particular city. In addition, since natural gas has a higher calorific heating value (per unit mass) than liquefied petroleum gas (LPG), Government should standardize the gas burners in order to make room for the use of natural gases at home. Finally, the Government should formulate an energy policy that will encourage both industrial and residential users of natural gas.
Godwin Igwe is a Fellow of The American Institute of Chemical Engineers. He is also a World Bank Robert McNamara, and Alexander-von-Humboldt Fellow.