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Transporting Natural Gas by Sea

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Transporting Natural Gas by Sea 7.3 Transporting natural gas by sea 7.3.1 The geographical distribution is particularly notable in the United States, where, after of gas and commercial nuclear and hydroelectric power, gas is the energy activities source most widely used to meet the growing demand for electricity. The increase in consumption in the In terms of its contribution to energy production, at countries of the Asia-Pacific area is significant (about present natural gas occupies the third place worldwide, 5%); these countries previously tended towards the after oil and coal, and with little difference in relation exploitation of other energy sources. The same is true of to the latter. At the beginning of the twenty-first the ex-Soviet countries, where the increase in demand is century, gas meets just under a fourth of the world’s due to economic recovery after the late 1990s, when the energy needs. difficulties resulting from radical political and Gas is the object of intense commercial activities, economic change slowed production. Lower, but still due mainly to the unequal geographical distribution of significant, is the increase in gas use in the African this resource. This is evident from a consideration of the (3.3%) and Middle Eastern (2.5%) macroregions. six geopolitical and economic macroregions into which The abundance of reserves and versatility of use the planet Earth is now conventionally divided (Europe- make natural gas an energy source of primary Former Soviet Asia, North America, Central and South importance, almost certainly the most interesting of America, the Middle East, Asia-Pacific, Africa). In the the twenty-first century. It is generally recognized that early years of the twenty-first century, verified gas natural gas will represent the main substitute for coal, reserves see the Middle East and Europe-Former Soviet as is already happening, and at least in part for oil (gas Asia in an absolutely dominant position, with 41% and is expected to overtake oil about half way through the 36% of the total respectively, with the other four decade 2020-2030). These trends are dictated mainly macroregions falling far behind. However, even within by environmental concerns, in other words the need to individual macroregions, considerable inequalities are limit the threat of climate change by reducing evident if individual states are compared: three emissions of carbon dioxide and other greenhouse countries alone, the Russian Federation, Iran and Qatar, gases. The only energy source which can be counted possess more than 55% of the world’s reserves. on in the medium term to achieve this reduction is The demand for gas is also distributed fairly natural gas; if used in two-cycle plants gas produces irregularly, being concentrated particularly in the very low carbon dioxide emissions, with no sulphur Europe-Former Soviet Asia macroregion (42%) and in dioxide emissions whatsoever. It should be the North American macroregion (29%). However, the remembered that renewable resources (such as solar ratio of production to consumption in these and wind power) certainly have high potential, but in macroregions differs considerably, being basically the long term. Many years will pass before they can balanced in the former and showing a heavy shortfall in play a decisive role in replacing current fuel sources. the latter. There is a shortfall in the Asia-Pacific The forecast increase in demand for natural gas will macroregion, too, whereas the ratio is positive in the necessarily entail a significant expansion of the gas remaining three macroregions, and especially in Africa. trade, leading to a genuine process of globalization. The Overall, world consumption is growing rapidly need for this expansion can already be seen in the (increasing by 2.8% in 2002, for example). The increase reduction of reserves in the two most industrialized VOLUME I / EXPLORATION, PRODUCTION AND TRANSPORT 855 HYDROCARBON TRANSPORT AND GAS STORAGE macroregions (North America, Europe-Former Soviet increase in supplying countries and the growth of Asia). Here some heavy consumers (the United States currently developing markets (China, India, etc.) is and some western European countries) are no longer leading towards market globalization. This in turn gives self-sufficient, and are beginning to experience rise to the commercial development of numerous difficulties even in obtaining supplies from large transport technologies which have hitherto remained neighbouring producers (Canada and Russia relegated to the experimental or design phase. respectively). The expansion of the gas market will necessarily involve a drastic change in forms of The properties of natural gas transport: an activity prevalently based on local supply In order to contextualize natural gas transport (around 80%) and which in any case involves short technologies, it is useful to give a brief description of distances and neighbouring countries (and thus overland the properties of gas, and the forms in which it is transport through gas pipelines) will give way to a found. Natural gas is always present in hydrocarbon predominance of long-distance transport by sea. This reservoirs, either as gas associated with oils, or as will mean the need for a widespread use of gas non-associated gas. It is customary to distinguish liquefaction processes. The shift towards LNG between lighter fractions of gas consisting of methane (Liquefied Natural Gas) has already begun, and a rapid and ethane (commercial natural gas), and intermediate increase in supply is forecast; in around 2020 it could fractions consisting of propane and butane; these are reach 15-20% of the world gas trade. A further commercially known as LPG (Liquefied Petroleum contribution to long-distance transport is made by Gas), since they can be liquefied at ambient growing demand in a third macroregion, the Asia- temperature with modest pressure. LPG, together with Pacific region. Here reserves are wholly insufficient, heavier fractions, forms natural gas liquids or supply zones are distant, and demand, already high in a condensates, also known as gasolines; this is found in fully industrialized country like Japan, is rapidly the liquid state at ambient temperature and a pressure growing in two fast expanding economies: India and of around 15 bar. especially China. An increase in demand of over 60% is predicted for the countries in this macroregion. All of Transport costs this has led to growing interest in the transport of LNG In the production chain, costs vary depending on and other transmission technologies which allow the capacity of treatment plants, whether the field is significant distances to be covered; these will have to onshore or offshore, the distance from the coast, and ensure interconnections between regional markets geographical location. Calculating the impact of (examples can already be seen in western Europe, transport on the entire production process is extremely where regasification terminals are widely distributed important in determining the feasibility of the along the coast), eventually leading to the development transport project itself. of a global market. Projects to build the necessary Take as a reference point a unit cost for natural gas at infrastructure require huge financial and technological the wellhead of 1 dollar per million BTU (British resources, and high levels of co-operation between Thermal Unit; 106 BTUϭ0.252·106 kcalϭ1.055·106 kJ). experts in this sector. It is predicted that in the Atlantic By adding transport costs within the exporting basin alone the development of LNG transport, two- country to the costs associated with transport thirds of which will be destined for the United States, technologies, the border cost is obtained, allowing will require investments of 80 billion dollars over the transport alternatives to be evaluated. For example, in next ten years. the case of a field located about 300 km from the coast and gas transport over a distance of 2,000 km, the border cost if a subsea pipeline is used can be 7.3.2 Transport technologies calculated as 3.16 dollars per million BTU; for LNG the cost is 3.26 dollars per million BTU. If distribution Transport technologies form part of the natural gas costs are added to the mean wholesale price, a mean chain; they are fundamental for the use of this energy distribution price of about 6 dollars per million BTU resource, and form a reference point for the economic is obtained. The impact of distribution costs, about viability of field development. It is always the transport 50% of the final total, highlights the importance of the technology, in the broad sense, which determines the availability of low cost technologies with a high unit sales price for gas. market impact. As mentioned earlier, forecasts of future world energy consumption indicate constant growth for The gas pipeline natural gas, with oil and coal showing a simultaneous The technology employed for the transport of decrease. The expansion of the gas market, linked to the natural gas is the pipeline. This technology is now 856 ENCYCLOPAEDIA OF HYDROCARBONS TRANSPORTING NATURAL GAS BY SEA broadly consolidated, and investment costs, depending The technologies which convert the energy content on the diameter of the pipeline, range from 0.66 to of gas into other forms of energy, however, can be 1.44 dollars per million BTU. To these we must add divided into two groups: technologies for conversion the operating costs, accounting for between 1 and 3% into liquid compounds such as methanol and/or of investments. synthetic hydrocarbons (such as gasoil and diesel The potential for expanding the transport of natural based on the Fischer-Tropsch synthesis), known as gas by pipeline must be sought in innovative offshore Gas-To-Liquid (GTL) technologies, and technologies engineering technologies; today the latter make it for the conversion of gas into electrical energy, then possible to develop subsea pipelines even at great transmitted via cable, known as Gas-To-Wire (GTW).
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