Fresh Air Matters... with Capt. Yaw
Following on from last weeks initial foray into understanding the oil, gas and power industry, I must first respond to those who have asked me 'What does this have to do with aviation?'.
Visit any major airport. Electricity abounds in modern aviation. Airport lighting, radio transmissions, radar, etc. - and without a stable and reliable power supply on the ground, you would not want to be in the air. Ghana is looking to the oil and gas industry to power over half of its total power consumption as we move forwards - that is just the starting point of why oil and gas is important to aviation (and the nation as a whole)... Next, look at the variety of ground handling vehicles - from passenger buses to the fuel tankers - they are all consumers of hydrocarbons! Then, the plastics, oils, tarmac surfaces - and the list goes on - that are essential parts of a modern airport - all are reliant on the products of the oil industry - and that is why we must understand them. No, I have not forgotten the aircraft themselves - which are massive consumers of petrochemical production. ATK or Jet A1 (basically Aviation Kerosene for Turbine/Jet engines) is needed in vast quantities to feed the power-plants of modern aircraft. Almost every flying machine is consuming one grade or another of fossil fuel! One of the challenges of suitable aviation hydrocarbon supply is quality, anti-freeze additives (temperatures drop below -50°C at cruise altitude for an airliner) followed by appropriate storage, delivery systems and large supply quantities per aircraft, that make topping up your car at the local petrol station look like a drop in the ocean! With the big airliners taking around two hundred thousand litres - and the A380 over three hundred thousand litres - to top off their tanks - you don't want to think about the bill! You can't just fill up some jerry cans, a drum and a trailer and then drive around the airport to fill up an airliner! You can't even go just driving anywhere or anyhow with fuel at an airport! Appropriate storage, transport, filtration and careful monitoring of the amounts loaded make the aviation fuel industry almost surgical in status.
So, please understand that this sortie into oil, gas and power is about safety and sustainability more than anything else - whether just for aviation, or to fuel the nations needs as a whole. We must understand more in order to have more rational discussions and better decisions in relation to our oil, gas and power industries - and all associated with them.
Let us now take a look at gas...
Natural gas is a collection of the lighter hydrocarbons. It may be found in pockets of 'just gas' (non-associated gas) or alongside - even dissolved in - crude oil (associated gas). Ghana has both types of resources. The gas itself may be used to extract oil from a reservoir by re-injection, or may be extracted, cleaned and sold - preferably processed into other products along the way, adding value.
Natural gas is a mixture of different hydrocarbons in a gaseous state at room temperature - mainly methane (CH4) plus ethane (C2H6), propane (C3H8), butane (C4H10) and pentane (C5H12). It also contains other gases, such as carbon dioxide (CO2) and nitrogen (N2). The sulphur compounds found in the gas, such as Hydrogen Sulphide (H2S) make the gas corrosive and 'smelly'. There may be other gases, including Helium (He) which is a valuable by-product of natural gas extraction. This gas cocktail can be easily burnt - and, in theory, the carbon atoms join with oxygen to form carbon dioxide (CO2), as the hydrogen atoms join with oxygen to form water (H2O) - this combustion releases energy - which can be used to turn an electric generator (creating electricity). Of course, there are other molecules around that result in other products from combustion too.
If you 'sort' the molecules of your natural gas, you can separate out LPG (Liquid Propane or Liquid Petroleum Gas), which is mainly Propane and Butane molecules, for cooking and certain piston engines, which adds value to the whole process. Natural gas is a really amazing stuff - and we have lots of it in Ghana! In fact, we have already discovered enough to mainstay our power production for the next 25 years - and if we continue our oil and gas exploration, we must surely have enough for the next 50 to 100 years! Which makes me wonder why we aren't making more of our own natural gas supplies already!
Natural gas occurs in a pocket or reservoir underground - either under thousands of tonnes of sea water (offshore), or in land accessible areas ('onshore'). When you first discover a pocket of gas (which costs millions of dollars to 'just try to see if there is any gas there'), piercing it with the massive drill, the gas wants to escape, so you have to 'cap the well' - that is also expensive. The gas you have found will be 'wet and dirty' - it will need treating - which is also expensive. It has been down there for millions of years - and is mixed up with sand, dirt, water, oil and other molecules that requires the gas to be 'cleaned'. Generally, the raw natural gas is treated close to its source, and that requires a multi-million dollar processing plant.
In Ghana our gas is 'offshore'. We have an FPSO (Floating Production Storage and Offloading) vessel which is responsible for receiving the crude oil and raw gas from under the sea-bed, and then carrying out some basic treatments. The crude oil is stored and then, when there is sufficient, loaded on to oil tankers, by ship-to-ship transfer, for transport to market. Gas is sent via a pipeline to an onshore processing plant for the removal of water, non-combustibles, 'condensate', etc., leaving a clean natural gas that can be pumped to the power stations. The gas processing plant may also separate LPG from the raw gas, which is cost-effective. The pipelines, FPSO and gas processing plant cost many millions of dollars... so it is easy to understand why this gas story is not some 'put a hose in the ground and we have gas for free' solution! No, it costs many millions of dollars to set up, operate and most importantly for safety and sustainability, maintain. From a cost and climate perspective, it is clear that natural gas is currently the preferred fossil fuel for power generation.
So, what if you do not have sufficient market for your gas at the point of processing? It is possible to cool your natural gas into Liquid Natural Gas (LNG). To create LNG the natural gas has to be stripped of the heavier hydrocarbons (which is great for production of LPG), and once it is refined to a very high methane mix (about 90%) it is cooled to, and stored at, around minus one hundred and sixty Celsius, to keep it liquid. Although more expensive than natural gas straight from the gas fields, it is more cost effective, giving more thermal output per dollar, than burning Light Crude Oil. The transport of this very cold gas can be quite complicated, since if the liquid gets warm, the expansion from liquid to gas results in a six hundred fold increase in volume! A re-gasification plant (which can be at sea or on land) is necessary to convert the LNG to useable gas. The LNG industry is still relatively young - but growing rapidly, with lots of new uses being explored - it is even being considered for use as a fuel for future airliners!
So, natural gas is here to stay, and I would not be surprised at gas being used in more and more applications in the coming years. Thankfully, Ghana appears to have an abundance of this natural resource, let us hope that we use it wisely!
Capt. Yaw is Chief Flying Instructor and Chief Engineer at WAASPS, and Pilot/Engineer with Medicine on the Move, Humanitarian Aviation Logistics (www.waasps.com www.medicineonthemove.org e-mail firstname.lastname@example.org)