Infrastructure is key in reducing flaring, from pipelines, to compression stations, to transport. We have already examined how gas pipeline infrastructure can reduce flaring. However, what are the processes involved in sending flare gas to market when pipeline infrastructure is limited? This blog will discuss three products that utilise and monetise gas that would have been flared by converting it into a liquid. These products are: natural gas liquids (NGL), liquid natural gas (LNG), liquid petroleum gas (LPG), and the process of gas to liquids (GTL).
Liquid Natural Gas
LNG is possibly the most commercial process for monetising natural gas outside of transporting it via pipelines. LNG is the result of liquifying natural gas and is done to simplify the transportation process when pipelines aren’t available.
To make LNG, natural gas is processed in LNG trains at liquified natural gas plants. Here, the gas is cooled to -260˚F, turning it into a liquid and removing CO2 and hydrogen sulphide. LNG is much denser than natural gas and takes up 1/600th of the space. This allows for transportation via tanker or truck rather than pipes. However, for LNG to remain liquid, any transportation vehicle must be properly equipped to maintain the low temperature. For example, specialised tankers are used with double-walled hulls to ensure insulation and capabilities to manage boil-off gas, a product of transporting LNG.
When received, the LNG is stored in insulated storage tanks until needed. The LNG must then be heated back up in order to return to its gaseous form before it can be sold and used, this process is called regassification. LNG, as a product of natural gas, is regarded as a cleaner source of energy than coal as it releases almost half the amount of CO2 per unit of energy produced.
However, the processes involved in creating LNG are energy intensive, and the efficiency of the process is crucial in the value of LNG. Natural gas transported as LNG is currently used in millions of homes for energy and heating and despite the processing involved, demand and production are increasing. In 2017, global LNG trade reached 293.1 million tonnes. This is a 12% increase from 2016. Bloomberg New Energy Finance predicts this demand will continue to grow and reach 450 million tonnes per year by 2030.
Gas to Liquids and Synthetic Fuel
In a bid to avoid the challenges faced when creating LNG, there is an alternative process, gas to liquids (GTL). The main product of the GTL process are synthetic liquid hydrocarbons, or liquid synthetic fuel, which can replace diesel.
GTL, like the LNG process, involves turning natural gas, or other gasses, into a liquid state. However, unlike LNG, instead of cooling the gas, this is done by changing the shorter-chain hydrocarbons into longer ones. Due to this, GTLs do not need specialised insulated transportation, and can therefore utilise existing infrastructure. Another benefit over LNG, is that GTLs have a higher energy concentration than LNG.
GTL also has advantages on the market. Unlike LNG, GTL products do not require long term sales agreements and can be sold on the open market. Looking at GTL diesel, although it is more environmentally friendly than crude oil diesel, prices are around $3-$5 more per barrel. Due to cost, GTL isn’t currently as popular as LNG and in 2017, GTL made up only 0.2% of global liquid production. However, companies are investing in GTL technology. Many plants will produce GTL alongside LNG, to ensure they aren’t solely relying on LNG to monetise their natural gas. GTL is expected to witness a boost as two major GTL projects are completed in the next 5 years. These facilities are based in Uzbekistan and South Africa.
Natural Gas Liquids
Natural gas liquids (NGL) are a way of using the components of natural gas and are extracted from it in liquid form. These extracted products include ethane, propane, butanes, isobutanes and pentanes. Once separated, these are then sold for a variety of uses, including cooking, heating, plastics and fuel. Ethane is arguably the most utilised of the liquids extracted as it is used to create ethylene, which is a key element in the production of plastics. As well as generating marketable products, recovered propane and isobutanes are entered back into the system and used as refinery and petrochemical feedstock.
Challenges with NGLs include the costs of handling, storage and transportation. Like LNG, NGLs require specialist transportation to ensure high pressure and low temperature is maintained. Despite this, as fracking has increased in the U.S., so has production, with an average of 4.3 million barrels per day (Bbl/d) being produced in 2018. This is up from the 2.5 million Bbl/d in 2012.
Liquified Petroleum Gas
The propane, butane and isobutane mentioned above, can be classed as NGLs and Liquid petroleum gas (LPG). These can be produced from both the natural gas processing and crude oil refining process.
LPG is a widely regarded as a clean fuel and can even be used in cars that have been converted to accept it. Fluctuating crude oil and natural gas prices are the main challenge for the global LPG market. However, LPG production and demand is expected to grow, with the U.S. leading this growth.
Monetise and Meter Your Flare Gas
The liquification of natural gas and all its parts is just one method to reduce and monetise flare gas while creating cleaner energy alternatives. Demand for all these by-products is growing, and as flaring increases, so does production. However, there is still much to be done regarding creating sustainable infrastructure to increase production of these and reduce flaring even further.
In order to measure how much gas is being flared vs how much is being converted and sent to market, accurate flare gas measurement is vital. Our FGM 160 meter uses ultrasonic technology, the most accurate way to measure flare gas, and can measure with an accuracy of +/-1%. Typically, the accuracy demanded in most countries is +/-5%.
As well as ensuring you meet your countries’ flaring regulations, metering your flare gas can help ensure efficiency. Measuring the gas that’s being sent to the flare stack can help you make informed decisions regarding how much is being flared, and if instead that gas could be monetised.