LNG cold energy utilization: Prospects and challenges

Natural gas is one of the cleanest forms of fossil fuels and its usage is rising since the importance of environment-friendly conversion systems has been seen Liquefied natural gas (LNG) and pipeline technologies are two present methods for the natural gas transportation between the exporter and importer This review presents the LNG cold utilization systems which are discussed on the applications such as separation processes, cold food storage, cryogenic carbon dioxide (CO 2 ) capture, power generation, etc The minimum power consumption and flow rate are detected as 045 kWh/kg and 8 ton/hour, respectively for the air separation processes Exergetic and energetic efficiencies are increased by nearly 40% of those of the conventional separation processes In the desalination system, it is inferred that the LNG cold utilization has provided nearly 50% energy saving while 2 kg ice melt water is produced by 1 kg equivalent LNG cold energy in the freeze seawater desalination For the cold storage systems, payback periods are found less than 5 years by using the LNG cold energy Energetic and exergetic efficiency are increased significantly by using the LNG cryogenic exergy Moreover, it is used in the cryogenic CO 2 capture systems, and there is no dramatic decrement in the overall efficiency values while the other CO 2 methods decrease the overall efficiency The LNG cold utilized power generation systems are discussed in detail with different alternatives including the gas, steam, combined and Stirling systems The minimum thermal efficiencies are found nearly 40% and 20% for the gas and steam cycles The selection of working fluids in the cycles is also discussed Lastly, the importance of economic and environmental aspects of LNG cold utilization systems is discussed Basic modeling equations are presented for the designed LNG cold utilization cycle with respect to the thermoeconomic and exergoenvironmental methods

Cold utilization systems of LNG: A review

Exergy efficiency analysis of ORC (Organic Rankine Cycle) and ORC-based combined cycles driven by low-temperature waste heat

Thermo-economic analysis of combined different ORCs geothermal power plants and LNG cold energy

A review on regulations, current status, effects and reduction strategies of emissions for marine diesel engines

Vessel ozone depleting emission regulations are regulated in Annex VI of the MARPOL Convention, wherein the maximum levels of NOx, SOx and suspended particles are established These increasingly strict regulations, together with the increase in natural gas consumption and its price, have conditioned propulsion systems implemented on board vessels

This article reviews the different propulsion systems used on board vessels for the transport of Liquefied Natural Gas (LNG) The study describes the main characteristics of the propulsion systems, and the advantages and drawbacks that come along with these, from its very beginnings up to the systems installed to date The described propulsion systems include both gas and steam turbines, combined cycles, 2 and 4 stroke internal combustion engines, as well as reliquefaction plants, while encompassing mechanical, electric and Dual Fuel (DF) technology systems

The propulsion systems implemented have undergone continual alteration in order to adjust to market needs, which were always governed by both efficiency and the possibility of consuming boil-off gas (BOG), always in compliance with the strict antipollution regulations in force

The current direction of LNG vessel propulsion systems is the installation of 2-stroke DF low pressure engines due to their high efficiency and their possibility of installing a BOG reliquefaction plant Another great advantage of this propulsion system is its compliance with the IMO TIER III emission regulations, without the need to install any supplementary gas treatment system

Review of propulsion systems on LNG carriers

Thermodynamic analysis of a Brayton cycle and Rankine cycle arranged in series exploiting the cold exergy of LNG (liquefied natural gas)

Power plant based on three series Rankine cycles combined with a direct expander using LNG cold as heat sink

Combined cascaded Rankine and direct expander based power units using LNG (liquefied natural gas) cold as heat sink in LNG regasification

Thermodynamic analysis of a novel power plant with LNG (liquefied natural gas) cold exergy exploitation and CO2 capture

Manuel Romero Gómez

Papers

Review of propulsion systems on LNG carriers

Thermodynamic analysis of a Brayton cycle and Rankine cycle arranged in series exploiting the cold exergy of LNG (liquefied natural gas)

Power plant based on three series Rankine cycles combined with a direct expander using LNG cold as heat sink

Combined cascaded Rankine and direct expander based power units using LNG (liquefied natural gas) cold as heat sink in LNG regasification

Thermodynamic analysis of a novel power plant with LNG (liquefied natural gas) cold exergy exploitation and CO2 capture