An heuristic approach for optimal location of gas supply units in transportation system

The best places to locate the Gas Supply Units (GSUs) on a natural gas systems and their optimal allocation to loads are the key factors to organize an efficient upstream gas infrastructure. The number of GSUs and their optimal location in a gas network is a decision problem that can be formulated as a linear programming problem. Our emphasis is on the formulation and use of a suitable location model, reflecting real-world operations and constraints of a natural gas system. This paper presents a heuristic model, based on lagrangean approach, developed for finding the optimal GSUs location on a natural gas network, minimizing expenses and maximizing throughput and security of supply.The location model is applied to the Iberian high pressure natural gas network, a system modelised with 65 demand nodes. These nodes are linked by physical and virtual pipelines – road trucks with gas in liquefied form. The location model result shows the best places to locate, with the optimal demand allocation and the most economical gas transport mode: by pipeline or by road truck.

Natural Gas location design and operation

A major determinant of the level of effective natural gas supply is the ease to feed customers, minimizing system total costs. The aim of this work is the study of the right number of Gas Supply Units – GSUs - and their optimal location in a gas network. This paper suggests a GSU location heuristic, based on Lagrangean relaxation techniques. The heuristic is tested on the Iberian natural gas network, a system modelized with 65 demand nodes, linked by physical and virtual pipelines. Lagrangean heuristic results along with the allocation of loads to gas sources are presented, using a 2015 forecast gas demand scenario.

Optimization model for medium term natural gas commitment

In this paper we study the optimal natural gas commitment for a known demand scenario. This study implies the best location of GSUs to supply all demands and the optimal allocation from sources to gas loads, through an appropriate transportation mode, in order to minimize total system costs. Our emphasis is on the formulation and use of a suitable optimization model, reflecting real-world operations and the constraints of natural gas systems. The mathematical model is based on a Lagrangean heuristic, using the Lagrangean relaxation, an efficient approach to solve the problem. Computational results are presented for Iberian and American natural gas systems, geographically organized in 65 and 88 load nodes, respectively. The location model results, supported by the computational application GasView, show the optimal location and allocation solution, system total costs and suggest a suitable gas transportation mode, presented in both numerical and graphic supports.

Natural gas system operation: lagrangean optimization techniques

To comply with natural gas demand growth patterns and Europe´s import dependency, the gas industry needs to organize an efficient upstream infrastructure. The best location of Gas Supply Units – GSUs and the alternative transportation mode – by phisical or virtual pipelines, are the key of a successful industry. In this work we study the optimal location of GSUs, as well as determining the most efficient allocation from gas loads to sources, selecting the best transportation mode, observing specific technical restrictions and minimizing system total costs. For the location of GSUs on system we use the P-median problem, for assigning gas demands nodes to source facilities we use the classical transportation problem. The developed model is an optimisation-based approach, based on a Lagrangean heuristic, using Lagrangean relaxation for P-median problems – Simple Lagrangean Heuristic. The solution of this heuristic can be improved by adding a local search procedure - the Lagrangean Reallocation Heuristic. These two heuristics, Simple Lagrangean and Lagrangean Reallocation, were tested on a realistic network - the primary Iberian natural gas network, organized with 65 nodes, connected by physical and virtual pipelines. Computational results are presented for both approaches, showing the location gas sources and allocation loads arrangement, system total costs and gas transportation mode.

Households WTP for the Reliability of Gas Supply

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The Iasi-Ungheni pipeline: a means of achieving energy independence from Russia? Moldova's attempts at gas supply diversification. OSW Commentary No. 118, 2013-10-08

Since taking power in 2009, the Alliance for European Integration (AIE) has been trying to end Moldova’s dependence on Russian gas. Currently, natural gas accounts for about 50% of the country’s energy balance (excluding Transnistria), and Gazprom has a monopoly on the supply of gas to the republic. The key element of Chișinău’s diversification project is the construction of the Iasi-Ungheni pipeline, which is designed to link the Moldovan and Romanian gas transmission networks, and consequently make it possible for Moldova to purchase gas from countries other than Russia. Despite significant delays, construction work on the interconnector began in August 2013. The Moldovan government sees ensuring energy independence from Russia as its top priority. The significance and urgency of the project reflect Chișinău’s frustration at Moscow’s continued attempts to use its monopoly of Moldova’s energy sector to exert political pressure on the republic. Nonetheless, despite numerous declarations by Moldovan and Romanian politicians, the Iasi- -Ungheni pipeline will not end Moldova’s dependence on Russian gas before the end of the current decade. This timeframe is unrealistic for two reasons: first, because an additional gas pipeline from Ungheni to Chisinau and a compression station must be constructed, which will take at least five years and will require significant investment; and second, because of the unrelenting opposition to the project coming from Gazprom, which currently controls Moldova’s pipelines and will likely try to torpedo any energy diversification attempts. Independence from Russian gas will only be possible after the the Gazprom-controlled Moldova-GAZ, the operator of the Moldovan transmission network and the country’s importer of natural gas, is divided. The division of the company has in fact been envisaged in the EU’s Third Energy Package, which is meant to be implemented by Moldova in 2020.

Rethinking the security of the European Union’s gas supply. Bruegel Policy Contribution, Issue 2016/01 January 2016

Highlights: • The security of the European Union’s gas supplies is crucial to ensuring that supplies to households are not disrupted in freezing winters, that industry can flourish and that the EU cannot be blackmailed in vital foreign policy questions. • Gas supply security should be addressed at EU level because a joint solution would be cheaper, national approaches could undermine the internal energy market and have adverse effects on other countries, and the EU Treaty explicitly calls for energy solidarity. • The current focus on supply diversification and reduction of dependence on imported gas is expensive and does not constitute a systemic response. • Instead of doing everything to reduce gas supplies from key suppliers, gas supply security could more effectively be safeguarded by ensuring that unused alternatives are maintained so that they can be tapped into for an indefinite period in case of supply disruption from a key supplier.This Policy Contribution outlines a market approach that could safeguard gas supply security at very low cost.

National gas supply and demand, 1971-1990

Bibliography: p. 151-166

A realistic view of U.S. natural gas supply : staff report /

Mode of access: Internet.

Outer continental shelf (OCS) oil and gas supply model /

"DOE/EIA-0372/1-3."

Gas demand for power generation peaked as early as 2010. CEPS Commentary, 12 February 2016

The outlook for natural gas demand is often considered bright, especially for gas used to generate electricity. This is because gas is the cleanest of all fossil fuels. The carbon intensity of modern gas-fired power stations is less than 50% that of modern coal plants. Moreover, gas-fired units are well-suited to follow rapid swings in supply and demand due to their flexibility. In the future, these balancing tasks will become more and more important given the intermittent character of the supply of wind and solar power. Gas seems to hold out the promise of being a key pillar of the energy transition and the perfect partner of renewables. Given the EU’s long-term climate policy goals, however, there is strong evidence that demand for gas for purposes of power generation peaked as early as 2010.

A multi vector energy analysis for interconnected power and gas systems

This paper presents the first multi vector energy analysis for the interconnected energy systems of Great Britain (GB) and Ireland. Both systems share a common high penetration of wind power, but significantly different security of supply outlooks. Ireland is heavily dependent on gas imports from GB, giving significance to the interconnected aspect of the methodology in addition to the gas and power interactions analysed. A fully realistic unit commitment and economic dispatch model coupled to an energy flow model of the gas supply network is developed. Extreme weather events driving increased domestic gas demand and low wind power output were utilised to increase gas supply network stress. Decreased wind profiles had a larger impact on system security than high domestic gas demand. However, the GB energy system was resilient during high demand periods but gas network stress limited the ramping capability of localised generating units. Additionally, gas system entry node congestion in the Irish system was shown to deliver a 40% increase in short run costs for generators. Gas storage was shown to reduce the impact of high demand driven congestion delivering a reduction in total generation costs of 14% in the period studied and reducing electricity imports from GB, significantly contributing to security of supply.

The effect of alternate supply of shielding gases in austenite stainless steel GTA welding

Welding system has now been concentrated on the development of new process to achieve cost savings, higher productivity and better quality in manufacturing industry. Discrete alternate supply of shielding gas is a new technology that alternately supplies the different kinds of shielding gases in weld zone. As the newdevelopedmethods compared to the previous generalwelding with a mixing supply of shielding gas, it cannot only increase thewelding quality, but also reduce the energy by 20% and the emission rate of fume. As a result, under thesamewelding conditions,comparedwith thewelding by supplying pure argon, argon + 67% helium mixture by conventional method and thewelding by supplying alternately pure argon and pure helium by alternate method showed the increased welding speed. Also, the alternate method showed the same welding speed with argon + 67% helium mixture without largely deteriorating of weld penetration. The alternate method with argon and helium compared with the conventional methods of pure argon and argon + 67% helium mixture produced the lowest degree of welding distortion.