April 14th, 2014

Fresh Air Matters... with Capt. Yaw

This week I had a visit from some international visitors who asked 'What fuel do you use at Kpong Airfield?' My reply was simple 'We rely on fossil fuels.' I went on, 'We use 95octane automotive petrol (super/gasoline) for the Rotax powered aircraft and small mowers; diesel for the genset for our electric power generation, since we are off-grid; diesel for our car, truck and tractor; and LPG for cooking.' The ensuing conversation demonstrated their lack of understanding of the fuel/power availability - and quality - challenges that we experience in Ghana. We may not have the same mains power, piped natural gas or wide range of automotive and aviation fuels available, as in other countries, but we do have what we need to solve our problems!

Later, I realised that it is not just some foreigners that fail to understand our local conditions - but it appears that many West Africans also lack the understanding of the meaning of 'fossil fuels', where they come from, their classification and their uses. I have found few people who understand how we can produce electricity from natural gas, which is found in abundance in Ghana, right now.

Therefore, I will take this opportunity to begin a series on 'Understanding Oil, Gas and Power' - since we all are touched by it - whether we fly, drive or simply switch on any electric device. We will take it term-by-term, over several weeks - and if you want a term further explained - or have question, just drop me an e-mail!

Fossil Fuels: Fossil fuels are basically hydrocarbons (chemical chains of carbon and hydrogen) that have been formed from anaerobic decay of organic matter from many millions of years ago, compressed and converted into several forms of fossil fuels. Put another way, fossil fuels are the result of massive pre-historic plant and animal deposits which have decayed in the absence of oxygen (covered in silt or other deposits) and have been compressed and 'cooked' by heat coming from the planet's core, for millions of years. It is not dissimilar to how we make charcoal, but over longer times, and in much greater quantities, to become carbon rich deposits stored in pockets/reservoirs, surrounded by rock layers, under the sea bed or simply underground. Depending on the type of originating organic matter, location, relative pressures, temperatures and time passed, the resultant product may be found as solids, liquids or in a gaseous state. Fossil fuels are generally readily combustible - and can be used to create many products with many different uses. Despite the rumours that fossil fuels are 'non-renewable sources', fossil fuels are being created all the time, even today - but it will take many millions of years before they are 'cooked and ready to use', and we are using those that are already available many thousands of times faster than they can be replaced. Let us look at some of these fossil fuels, and how they may be used in the energy cycle in Ghana.

Coal: A solid fossil fuel, generally formed from decaying matter in swampy areas at the time it was laid down. There are many different grades of coal, ranging in colour from shiny black to dark brown. Due to its formation process, and its extraction process, coal is found 'on land' and mined either by pit mining or open cast mining. There are coal deposits in Africa, but none have been found in Ghana. Coal could be brought in by ship and burnt in specially built power stations, in order to boil water, to create steam, which would then power turbines to generate electric power. Coal is also used as a cooking fuel (hence the term coal pot) and for heating homes in many countries. VRA has discussed the possibility of a coal fired power station, but it would appear to be unattractive, and more expensive, than using the ready supply of other fossil fuels available within the Territory of the Republic of Ghana.

Crude Oil: A general term for a fossil fuel of naturally occurring hydrocarbons - of varying densities - that can be pumped out from an underground reservoir, after it has been punctured by the oil rig to create an 'oil well' (in a similar way to drilling a borehole to obtain water). Normally, it is extracted in liquid form - which may require treatment of the oil deposits in order to pump them out. Crude oil comes in different consistencies, from very runny to nearly solid, at room temperature, depending on the type. Generally black or blackish-brown in colour. Crude oil is composed of different lengths of hydrocarbons and has other chemicals components in it - such as sulphur compounds. Depending on the density, consistency and content it has different values, uses and names. Each Crude oil discovery is rated using API Gravity standards.

API Gravity: This is the standard set up by the American Petroleum Institute (API) to classify crude oils. It is given as a number in 'degrees' that indicates the weight or density of an oil, in relation to water at a given standard condition of temperature and pressure. If the API is greater than 10°API, the oil will float on water. If the API is less than 10°API then it will sink. This helps to establish which oil will float on, or sink in, another oil. It also provides an indication for ease of extraction and quality for processing. Knowing the API is essential to convert between barrels of oil (a volume) to tonnes (a mass or weight) - which is really important for shipping purposes.

Light Crude Oil: This runs freely at room temperature, floats on water, and has an API gravity of 31.1°API or higher (some definitions vary, depending on the market). Often abbreviated to LCO, it may be used to fuel power stations - such as some of Ghana's current thermal power plants (many of which are dual fuel, and can also use natural gas, because LCO is much more expensive than natural gas) - or preferably processed to create a range of products. LCO is generally favoured for production of the higher value petro-chemical products - such as what we call super, which is also known as petrol or gasoline. Ghana's oil finds in the Jubilee field are reported to be 37.6°API, making it Light Crude. 

Heavy Crude Oil: Floats on water, does not flow easily, generally with an API gravity from 10°API to 22.3°API. Extraction requires special extraction techniques, such as the injection of steam into the oil reserves to make it flow sufficiently for extraction. Some deposits are so thick that the equivalent of 'open cast mining' techniques can be used. 

Between the light and the heavy exists Medium Crude Oil which would float on water, with an API gravity between 22.3°API and 31.1°API (depending on the market classification). It offers a greater challenge for extraction than light, but would be easier to extract than the heavy stuff!

Extra Heavy Crude Oil: Basically, this is bitumen or bitumen like oil deposits. It does not flow at room temperature and sinks in water. Extra heavy is defined as having an API gravity below 10°API. 

Sweet Crude Oil: Called sweet because it is low in sulphur compounds, smells pleasant and, should you put a little on your tongue, as the early oil workers would when testing, it actually has a sweetish taste. Sweet light crude oil is the most sought after type of crude oil since it is ideal (least costly/higher yields) for processing into gasoline/petrol, kerosene (including aviation kerosene or JET A1) and good quality diesel. 

Sour Crude Oil: Being higher in sulphur compounds, sour crude smells like bad eggs. It is more corrosive and expensive to process than the 'sweet crude'. Sour crude is generally too expensive to process into the higher quality petrochemical products.

Refineries around the world tend to purchase a variety of crude oil types and mix or blend them according to their capabilities and production demands.

I hope that helps you to better understand some of the terms being thrown around in our 'oil producing state'. Next week we will look more closely at terms related to one of Ghana's most valuable assets, natural gas.

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 capt.yaw@waasps.com)