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Thinking smaller on LNG

Liquefied natural gas is increasingly being shipped to locations where relatively small quantities are needed. Wärtsilä provides solutions for key stages of such supply chains, from production and transportation to storage and regasification, as well as gas-fuelled power plants that can be integrated with coastal LNG terminals.

Text: FRAN WEAVER Photo: WÄRTSILÄ AND MICK RYAN PHOTOGRAPHY, SHUTTERSTOCK

The International Energy Agency predicts that the world may be entering “a golden age for gas”. New natural gas fields are being discovered and utilised, and it is clear that gas has considerable advantages over energy sources like oil, which is becoming increasingly costly.

Gas has traditionally been used to generate energy on a large scale, supplied in pipelines or huge LNG tankers. But in many parts of the world there is now demand for smaller-scale supplies of gas.

“This is particularly true for islands and in other disconnected regions such as the Caribbean and Indonesia,” says Reidar Strande, LNG Director at Wärtsilä Oil & Gas Systems. “LNG is a clean and efficient alternative to imported oil as a power source for a country like Indonesia, for instance, which has its own gas supplies, and a large population spread around many islands.”

SOLUTIONS ALL ALONG THE CHAIN

This new demand means that the market for smaller-scale LNG transportation, storage and regasification solutions is growing fast.

LNG export terminals will need loading facilities for smaller vessels as well as huge tankers. Import terminals equipped with regasification plants will also be needed in suitable coastal locations. In the Caribbean a network of relatively small terminals could viably receive LNG from export terminals around the Gulf of Mexico and in Colombia, for instance.

“Terminals can flexibly meet different needs: feeding local pipelines, fuelling local industry, and also providing fuel for power plants built in connection with the terminals,” says Strande. “Wärtsilä can provide entire solutions for integrated complexes encompassing storage and regasification facilities as well as power plants that will use the gas.”

He emphasises that Wärtsilä has technologies for all of the key stages of the small-scale LNG supply chain, including initial gas liquefaction and shipping. “Wärtsilä Oil and Gas supply effective technical solutions for gas liquefaction plants with small and medium capacities. Such plants are already in use in Finland and Norway.”

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GAS HAS TRADITIONALLY BEEN USED IN LARGE AMOUNTS BUT THERE IS NOW DEMAND FOR SMALLER-SCALE SUPPLIES.

One Wärtsilä liquefaction plant that recently began operating in Norway liquefies organic biogas to provide green waste-to-energy liquid biogas (LBG) for buses in the city of Oslo.

LNG AT SEA

“LNG is increasingly being used as a shipping fuel, due to environmental considerations, so networks of coastal supply points have to be expanded,” says Strande.

The transportation of smaller quantities of LNG by sea has been pioneered in Norway, whose unique geography of mountains and fjords makes shipping preferable to road transportation.

“Norway even ships quantities as small as 1000 cubic metres, though when we think about small-scale LNG transportation we usually mean vessels of about 7500-14,000 m3.”

Vessels transporting LNG can use their own cargo for their propulsion. “Most new-build LNG vessels today are fitted with Wärtsilä Ship Power’s unique dual fuel engines, which can run on natural gas as well as conventional maritime fuel oils,” explains Strande. “In fact Wärtsilä can design entire small LNG vessels including their propulsion and cargo handling systems.”

FROM LIQUID BACK TO GAS

The next step in the supply chain is to convert the LNG back to gas. “This requires a lot of heat, since LNG is typically transported and stored at a temperature of about minus 160 degrees Celsius.

“Wärtsilä’s regasification plants typically use seawater and propane loops to safely warm the LNG. Seawater is freely available at most locations for warming purposes, but propane loops are used to avoid freezing in heat exchange systems.”

Floating storage and regasification units (FSRU) can be located on jetties or floating facilities, such as converted LNG vessels or robust barges. “Retrofitting an FSRU onto an old LNG carrier is a fast and low-cost way to provide an efficient facility,” says Strande. “Larger facilities of this kind can supply as much as 500 tonnes of gas an hour, capable of producing about 2500 MW of energy – as much as a large nuclear power plant.”

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Palau Islands in the Pacific Ocean.

A FIRST FOR ASIA

Indonesia’s first LNG receiving terminal, which started operating at Jakarta in May 2012, contains Asia’s first floating LNG storage and regasification unit, designed and engineered by Wärtsilä. “The vessel, named Nusantara Regas Satu, was converted from an old 125,000-cubic-metre tanker at Jurong shipyard in Singapore,” says Business Development Manager Per Helge Madsen from Wärtsilä Oil & Gas Systems.

The unit can supply well over 400 tonnes of gas an hour to generate electricity for the local grid.

“This successful installation demonstrates that we have a quick, reliable and efficient way to execute such projects. We do it by supplying complete storage and regasification modules that can be easily hooked up to ships,” says Madsen. “Floating units can typically be completed within just 15-18 months.”

Madsen reckons that many regions of the world with increasing energy demand will be interested in such units. “Asian markets like China, Indonesia, Malaysia, India and Pakistan are very promising, and there are also good prospects in South America, Africa and Europe.”
Storage and regasification facilities can also be located on shore or on specially constructed jetties. “We recently supplied a jetty regasification unit for an LNG receiving terminal run by Petronas at Malacca, Malaysia, which started operating  this June,” says Senior Project Manager Atle Liknes of Wärtsilä Oil & Gas Systems.

This jetty-mounted unit has three gasification loops and weighs 945 tonnes. “It can gasify more than 400 tonnes of LNG per hour to feed the onshore grid system via a subsea pipeline,” explains Liknes “This project was challenging technically, as we had to find ways to handle unusually large amounts of vapourised boil-off gas within the incoming LNG.”

IDEAL LOCATIONS FOR POWER PLANTS

Wärtsilä has recently supplied retrofit floating regasification units to Petrobras in Brazil and Shell in Dubai. More new-build floating storage and regasification units will soon be delivered to Höegh LNG for recipient terminals in Indonesia, Chile and Lithuania.

New LNG terminals typically feed local pipeline networks, but they are also ideal locations for gas-fuelled power plants. “In most locations where LNG is imported into a country or region as a new fuel, there will be opportunities for Wärtsilä’s flexible gas power plants or fuel conversion at Wärtsilä’s existing power plants,” saysTord Johnsson, Area Business Development Manager, Oil and Gas Business, Power Plants.

Wärtsilä provides a wide range of power plant engine units capable of running on gas, including dual fuel options. “The reliability of the LNG supply is an important factor. If gas is available all year around the best choice is a plant running on gas only, using our spark ignited SG engines.

“Where the gas supply may be intermittent, or where a power plant is built ahead of the LNG terminal, the obvious choice is a multi-fuel power plant with our dual-fuel DF engines, which can run on either liquid or gaseous fuels.”

Johnsson adds that it makes good logistic sense to locate power plants right alongside LNG terminals – on barges or on solid ground. Gas can then be piped short distances to plants which can economically supply process heat for the LNG terminal itself, as well as electricity for the local grid.

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Hermit crab in the Indian Ocean.

ONE STOP SHOP

“Customers who use Wärtsilä as the single partner responsible for supplying the terminal, regasification facility and power plant, can get added value and quality by optimising the performance of the whole system instead of subsystems,” says Johnsson.

In each location, power plants and terminal facilities must be carefully scaled considering supply and demand factors. “This can be a tricky process. Parameters to consider include the source and price of LNG, the availability of ships, and the volumes of gas demanded by customers over the year.”
Wärtsilä is in a favourable position as a single company able to offer integrated engineering, production and construction packages for LNG terminals and power plants.

The improving LNG supply chain can help rapidly developing, energy-hungry regions around the world with an energy source that has many advantages over other fossil fuels. Wärtsilä has complementary and integrable solutions all the way along this supply chain.

LNG pluses

Liquefied natural gas (LNG) is made of natural gas (either fossil gas from underground sources, or biogas from decayed organic matter), which is condensed to liquid form by cooling it to a temperature of about -160°C for storage under pressure. It consists mainly of methane, with small quantities of ethane, propane and butane.

LNG is becoming an increasingly attractive fuel around the world for many reasons:

- In most regions LNG prices are much lower than oil prices per unit of energy.

- Liquefying natural gas reduces its volume to about one six-hundredth of its volume in gaseous state. This concentrates large quantities of energy into volumes that are easily transportable in specially designed ships, containers or trailers.

- This makes LNG the best option in locations where gas pipelines are not viable due to the distance to gas sources or the limited volumes needed.

- Emissions from burning natural gas are much cleaner than those from oil and coal, particularly in terms of concentrations of sulphur, nitrogen compounds and polluting particles.

- Carbon dioxide emissions per unit of power generated by burning gas also are clearly lower than those emitted when burning coal or oil.

 
 

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