Where is Coal Found?

It has been estimated that there are over 847 billion tonnes of proven coal reserves worldwide. This means that there is enough coal to last us over 130 years at current rates of production. In contrast, proven oil and gas reserves are equivalent to around 42 and 60 years at current production levels.
Coal reserves are available in almost every country worldwide, with recoverable reserves in around 70 countries. The biggest reserves are in the USA, Russia, China and India. After centuries of mineral exploration, the location, size and characteristics of most countries' coal resources are quite well known. What tends to vary much more than the assessed level of the resource - i.e. the potentially accessible coal in the ground - is the level classified as proved recoverable reserves. Proved recoverable reserves is the tonnage of coal that has been proved by drilling etc. and is economically and technically extractable.
Definitions

Resource
The amount of coal that may be present in a deposit or coalfield. This does not take into account the feasibility of mining the coal economically. Not all resources are recoverable using current technology.
Reserves
Reserves can be defined in terms of proved (or measured) reserves and probable (or indicated) reserves. Probable results have been estimated with a lower degree of confidence than proved reserves.
Proved Reserves
Reserves that are not only considered to be recoverable but can also be recovered economically. This means they take into account what current mining technology can achieve and the economics of recovery. Proved reserves will therefore change according to the price of coal; if the price of coal is low proved reserves will decrease.

Over recent years there has been a fall in the reserves to production (RP) ratio, which has prompted questions over whether we have reached 'peak coal'. Peak coal is the point in time at which the maximum global coal production rate is reached after which the rate of production will enter irreversible decline. However, recent falls in the RP ratio can be attributed to the lack of incentives to prove up reserves, rather than a lack of coal resources. Exploration activity is typically carried out by mining companies with short planning horizons rather than state-funded geological surveys. There is no economic need for companies to prove long-term reserves.
All fossil fuels will eventually run out and it is essential that we use them as efficiently as possible. Coal reserves could be extended further through a number of developments including:

• the discovery of new reserves through ongoing and improved exploration activities;
• advances in mining techniques, which will allow previously inaccessible reserves to be reached.

Additionally, significant improvements continue to be made in how efficiently coal is used so that more energy can be generated from each tonne of coal produced.

Coal Exploration

Coal reserves are discovered through exploration activities. The process usually involves creating a geological map of the area, then carrying out geochemical and geophysical surveys, followed by exploration drilling. This allows an accurate picture of the area to be developed. The area will only ever become a mine if it is large enough and of sufficient quality that the coal can be economically recovered. Once this has been confirmed, mining operations begin.

worldcoal.org