Sept 2011 – North American Clean Energy

Capturing Wasted Energy from Natural Gas

by: Chris Cote
Sept 2011
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There is enough energy currently being wasted in the United State at gas pressure reduction stations to power about 10 million homes—and for mere pennies. So, why aren’t we using it?

Much natural gas is found in remote or distant regions (like Canada), and needs to travel thousands of miles from the wellhead to more populated areas (like Southern California) where gas consumers live. An elaborate 272,000+-mile natural gas pipeline grid pushes gas downstream using compressor stations every 40 to 100 miles or so. Compression stations are used to increase the pressure, often to a linepack of 1,000 psi to 1,750 psi. Energy in the form of enthalpy is contained in this highly pressurized gas.

As the gas nears populated areas, however, this tremendous pressure needs to be reduced to acceptable levels, and eventually to as low as 1/4 psi for residential use. That’s where letdown stations come into play (also known as citygates, gate stations, farm taps, or reducing stations, etc.). Though a necessary part of the process, it’s the series of letdown stations in the distribution system where all the potential energy from pressure is wasted due to the use of reduction-throttling valves.

The Challenges

This wasted energy isn’t a new discovery. Many attempts have been made to capture wasted energy with turboexpanders, a complex centrifugal or axial flow turbine. Turboexpanders were originally designed for other applications and have been used for over a century but, in the 1980s, axial flow turbines were placed in natural gas pipelines between the high-pressure and low-pressure pipes. As the gas flows from the high-pressure pipe into the turboexpander, it spins the turbine, which in turn spins a generator to produce electricity. By replacing a conventional control valve or regulator with a turboexpander, the energy in the pressure of the high-pressure gas (or the enthalpy) that would otherwise be lost, can be converted to electricity. Simultaneously, the turboexpander reduces the pressure of the gas for the local gas network.

The challenges associated with utilizing turboexpanders in the natural gas pipeline letdown stations are primarily cost related. For one, the equipment must be custom-engineered for each specific application. Turboexpanders are complex machines that generally operate efficiently in a specific band of flow-rate volume. Efficient sizing of the turboexpander requires an analysis of seasonal flow-rate fluctuations. Maintaining a turboexpander is also relatively expensive as the delicate, rapidly spinning blades can be damaged by moisture or foreign elements. Perhaps, most significantly, the capital cost doesn’t increase proportionally with the expected output. The larger the output, the lower the cost on a per-kilowatt basis. Therefore, an acceptable payback can only be obtained at the higher pressure stations—those which are furthest from the cities. Yet, a huge part of the unharnessed energy is found closer to the cities at smaller letdown stations.

In 1983, San Diego Gas and Electric attempted to recover this energy with a turboexpander, as did other companies in later attempts in other states. Even many European companies, including the owner of most of the UK’s gas pipeline network (the National Grid), have or have considered installing turbine generating systems, but couldn’t justify the cost to capture this wasted energy without being subsidized. More complicated systems with fuel cells have been tried in Canada but, once again, the cost was just too great.

The Benefits
Giving up is one option, however, the benefits of utilizing the wasted energy at gas reduction stations are compelling and numerous—particularly from an environmental stance. Not only is the energy readily available and cheap (assuming there’s a cost-effective way to capture it), but it’s a form of baseload power that’s available 24/7, rain or shine. It’s the epitome of distributed energy: located where the need is the greatest, both close to and in cities. Moreover, no fuel is used to generate this energy; it’s simply the pressure from the gas. So, there are no emissions and no CO2.

Another potential by-product of using such wasted energy to generate electricity is the creation of extreme cooling—which can be a challenge at gas letdown stations, but would be a huge benefit to end users of gas further down the distribution line (such as manufacturers who can use the cooling to eliminate air conditioners).

The Solution
The good news is that when there’s a need, often and eventually there is a way. Thanks to dedicated innovators and engineers, equipment has recently been commercialized that solves the challenges of the turboexpander. One solution is an extremely robust expander with very low RPMs (1/5th the speed of turboexpanders) that is highly efficient, simple, flexible & easy to install. This equipment allows gases, dry or wet steam, hot water, impurities & contaminates directly into the machine without hurting the machine. It allows changes in flow rates and pressure so it is flexible enough to allow one design to handle multiple applications. The initial cost of under $2,000/kW is lower than the cost of turbo systems and the operating cost of less than 25 cents/kW is substantially lower than the cost of operating a turbo system. It’s also flexible enough to use either a synchronous or an induction generator. And, as a direct-expansion device, the generator isn’t limited to gas, and may be designed for various applications, including natural gas letdown, wet or dry steam, geothermal liquid/vapor, as well as hot air and hot exhaust gas streams.

Simply search online for “gas letdown generators,” to find viable solutions other than turboexpanders available to capture wasted energy. Some are even worth the cost. Langson Energy has a prototype running in its R&D shop in Carson City, NV. With new, economical technology available, wasted energy no longer has to be wasted when it comes to gas pressure reduction systems—or other systems.

Sept 2011 – Pipelines International

The natural gas industry in Argentina: development and perspectives

by: Jorge Epelbaum
Marketing Manager, Morken Group
September 2011

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The natural gas industry in Argentina has gone through many changes and faced many challenges over the years, including the privitisation of companies and tough economic times. This article will describe the situation of the natural gas industry in Argentina from its origins and the development of the natural gas pipelines network, to the present day situation of the sector.

The gas transportation industry, from its origins, has been a key factor in the development of energy and industry in Argentina.

Since 1945, the Argentinean Government took control of the ‘Compañía Primitiva de Gas’ a private company that was in charge of coke gas distribucion since 1910, and in 1946, created the NOC Gas del Estado. Argentina became one of the international leaders in the development of natural gas, together with the USA and the Soviet Union.

In the late 1940s, the first main pipeline in Argentina was built, the Lavallol – Comodoro Rivadavia Pipeline, and in 1960 construction began on the North Pipeline, bringing gas from Campo Durán in the north to Buenos Aires.

The North Pipeline was installed following the technological guidelines developed at the time, with pipe of high resistance X52 carbon steel, asphalt coatings applied onsite and Compression Stations based on reciprocating engines.

Later, in the 1980s, with the development of Loma de la Lata, a large natural gas basin, new networks of gas pipelines were built.

Pipelines from Loma de la Lata to General Cerri (where a liquid extraction plant was installed) and Loma de la Lata to San Jerónimo were built.

These new gas pipelines brought significant technological change with the installation of turbo compressors in the compression plants, and new coatings of plastic tapes applied in manufacturer’s factories and in the field resulting in the improvement in the protection of the pipelines.

The development of the gas market in such magnitude has generated an enormous dependence of gas in the energy consumption matrix of Argentina. Natural gas consumption has grown from approximately 30 per cent in 1979, to more than 50 per cent in 2010 (see Figure 1).

Privatisation and deregulation of the system
In the early 1990s, the government began a process to privatise the state-owned utilities companies in Argentina. Some of the public services companies had not been very well managed, creating public support for the privatisation process. However, this was not the case for the technical areas of Gas del Estado, which employed outstanding professionals and with experience.

Gas del Estado was privatised at the end of 1992. From there, Argentina began a process of deregulation, trying to imitate the evolution of the market in countries like England (Transco experience), USA and Canada.

In addition, international operators began to enter into Argentina’s gas pipeline industry, with Nova and Enron purchasing interests in the TGN and TGS gas transmission systems and taking responsibility of pipeline operation.

The availability of gas, the relative geographic advantages, and the growing requirement of energy in nearby countries (mainly Chile, Uruguay and Brazil) guided the development of cross-border pipelines. As a clear signal of this process, from 1994 to 1999 seven cross-border gas pipelines were developed crossing the Andes between Argentina and Chile:

Gas Andes taking Loma’s gas to Santiago de Chile;
Gasoducto Norandino and Gasoducto Atacama in the north; and,
Gasoducto del Pacífico in the south.

Argentina became an important exporter of energy, with a natural gas production rate that seemed to allow Argentina to expect a stable horizon of expansion.

2001: the crisis of the model
The collapse of the economic model that was installed in Argentina, produced a deep crisis in December 2001, with the default of Argentine debt and a marked devaluation of the Peso, which decreased rapidly from equal value of the US dollar, to a third of the former value.

To mitigate the impact to the public, tariffs of public services were frozen, and a paralysis in economic activity occurred.

The activity of the natural gas industry suffered. Tariffs, which were fixed from 2001, were a major limitation cited by pipeline companies as a reason for limited or no pipeline expansion. Currently, the GNEA is under construction, and the first stage (Gasoducto Juana Azurduy) has been completed.

The low price of gas in the domestic market generated a double effect, reducing the companies’ investments in exploration and production as well as infrastructure, while low relative prices increased the demand in a non-sustainable way.

Gas production became rapidly insufficient for exporting, and the pipelines that crossed the frontier with Chile proceeded to transport only minimal quantities far below their initial designs.

The Argentine Government embarked on a programme of investment in pipeline and compression station infrastructure in both the TGN and TGS pipeline systems, as part of a capacity upgrade. While this eliminated bottlenecks in gas transportation, it highlighted the issue of natural gas supply shortage.

The demand was not covered by traditional sources and there was an important effort for develop LNG import terminals.

A first reception terminal for regasification vessels was installed in the south of Buenos Aires in Bahía Blanca, and a second unit at Escobar, located north of Buenos Aires on the Parana River, has recently started operation.

Three more units are being planned. One in Cuatreros, near Bahia Blanca; one in Golfo de San Matias probably financed with Qatar investment; and one in Montevideo, with Uruguay. A pipeline between Buenos Aires and Colonia is going to revert its flux, from Argentina to Uruguay.

Argentina has also increased its capacity for importing natural gas from Bolivia via the recent inauguration of the Juana Azurduy Pipeline.

Impact of the present day situation on the technical aspects of the industry
While private company investment in the development of Argentinean pipeline networks was restricted due to the financial situation of the country, the trend to maintain the levels of excellence in pipeline integrity of the installations has not been abandoned.

The standards that applied to pipeline integrity changed in line with international regulations (Appendix O NAG 100) and these have given renewed impetus to the activities of pipeline control and maintenance.

The utilisation of modern in-line inspection (ILI) tools has improved and companies have used combined technologies (MFL and TFI) and EMAT tools.

The techniques of direct assessment, particularly for unpiggable pipelines and risk analysis, have continually evolved, and pipeline owners and operators are now using these in conjunction with traditional CIS/DCVG techniques to evaluate the status of the lines.

The older asphaltic coated pipelines are rehabilitated by means of a detailed inspection and re-coating using mainly epoxy coatings, or in some cases plastic tape. Repairs with composite materials are also used.

New gas pipelines and pipeline loops are now being built with materials of higher resistance, since X70 grade steel was used for the construction of the GasPacífico Pipeline in 1998. This requires the development of stricter procedures and techniques of welding to avoid cracks and other defects in the welds.

In addition, coatings are being improved, with new pipelines coated with 3LPE. Fusion-bonded epoxy is not widely used, although it is the best international solution found for isolation in special related to stress corrosion cracking (SCC) problems.

SCC has been one of the most challenging issues for the pipeline integrity industry in Argentina, both in TGN and TGS. These kind of defects were leading to pipelines ruptures around 1998–99, necessitation efforts to understand the problem and to implement solutions. With assistance from major specialists from Canada like CC Technologies and local experts, methods of control, monitoring and re-mediation were applied with excellent results.

Although there are no effective tools for the direct detection of SCC cracks, the introduction of the EMAT tool has greatly increased the precision in diagnosing the problem.

Information systems have also been introduced in different areas of pipeline industry activity. They add to the basic information of transportation (including SCADA and HMI) systems that collects and analyse information for integrity area, risk analysis tools and GIS.

These systems are mandatory due to changes in integrity regulations, and have been introduced to transportation companies and distributors with different approaches and degrees of success.

Companies are examining advanced optical fibre systems for the detection of intrusions or leaks along the right-of-way, and control of operating parameters and strength analysis for controlling geotechnical risks.

Future expectations
Currently, the main pipeline project under development is the Gasoducto del Nordeste Argentino (GNEA). The pipeline is complementary to the development of Bolivian exports to Argentina (Juana Azurduy) and will contribute to the industrial development of the northeastern provinces of Argentina that do not currently receive natural gas supply.

The development of this pipeline has seen the industry consider the introduction of new technological advances with regard to construction, As the gas demand in this area is so high, the schedule for construction is critical, and methodologies to increase construction speed must be found.

An important gas distribution project is under development to service the province of Córdoba.

The increasing need for gas supply also demonstrates the importance of LNG. Many neighboring countries, such as Uruguay and Chile, have LNG projects implemented and on execution phase, which would allow transporting gas to Argentina, even reversing gas export pipelines such as the Norandino and Gasandes pipelines.

The government has set an important long-term contract for LNG with Qatar, and has plans to install new regasification plants in the future the most important of which will be settled in Golfo de San Matias. These proposed plants will require significant investment for installation and the development of associated pipeline infrastructure.

Exploration and production perspectives
In recent times YPF has indicated the existence of a large shale gas reserve at Neuquén’s zone.

It is pertinent to bear in mind that the degree of development of this gas will be correlated to the conditions of the market and the economical incentives and that this development will not be implemented immediately.

A very recent document from the US Energy Information Administration, DOE World Shale Gas Resources: An Initial Assessment of 14 Regions Outside the United States placed Argentina as the third country in the world gas prospective resources, with expected 774 Tcf.

A number of big companies like Exxon and Shell, and smaller ones like Madalena, Arpetrol, Quintana, as well as the two main Chinese companies (Sinopec and CNOOC) came to invest in Argentina buying becoming shareholders in local companies.

On the other hand, there is currently a gap to fill between gas demand and supply. Although it is planned that this will be filled by means of gas imports, including LNG and gas supply from Bolivia.

It is impossible to sustain an important economic growth without the availability of energy, so it is critical to find the right incentives to allow the country to keep on growing in a sustainable way having a large increase in Exploration and Production activities.

The author would like to thank Instituto Argentino del Petroleo y del Gas (IAPG) for the statistical data provided in this article, as well as acknowledge Eduardo Barreiro, Energy Consultant from Argentina for his important help and comments.