Ethernet offers advantages in coal mining applications

Increasing demand for electricity, combined with concerns over reserves of oil and gas, has prompted a reappraisal of coal. And with the latest clean coal technologies dramatically reducing carbon emissions and cutting out other harmful pollutants, coal is proving to be both clean and reliable.

This is good news for the UK's coal mining industry, which, against all the odds, is bucking the trend of the last two decades and is on the up. After years of coal mine closures, some are reopening, creating hundreds of new jobs and driving an investment in modern technology. At the same time, the mines offer the potential to boost Britain's competitiveness.

Coal-fired power stations account for more than 80 per cent of total coal use in Britain, producing over one-third of the UK's electricity. But Britain's coal producers currently meet only one-third of UK demand, with the rest imported from Russia, South Africa, Australia, Indonesia, Columbia and elsewhere. Some 44million tonnes of coal were imported in 2005, and imports rose by 14 per cent in 2006, with demand expected to carry on increasing through 2007.

UK coal output

At the end of 2006, the UK had seven large deep mines, producing 10million tonnes of coal annually. But the Unity mine in the Vale of Neath, in South Wales, was recently reopened and was fully operational by March 2007, with the capacity to produce one million tonnes of high-quality coal per year. Surveyors at Unity believe they have 89million tonnes to mine, and a business plan has been produced to keep the mine operating for the next 25 years and beyond.

The company behind Unity has indicated that it could open four more mines in South Wales, while a second company has reopened a mine not far from Unity in Aberpergwm. Furthermore, there are plans to reopen the Hatfield colliery in South Yorkshire, which closed in 2004, and experts reckon that Yorkshire as a whole may have several hundred years' worth of coal left.

This revitalised activity will have caught many by surprise, particularly with so much emphasis on renewable energy sources. Yet the government's own findings suggest fossil fuels will continue to be our predominant source of energy for decades to come. The UK Energy White Paper, published by the DTI in May 2007, concluded that even by 2020 - and despite an emphasis on renewable energy sources - fossil fuels will still be supplying the great majority of UK energy needs.

At the same time, the UK Energy White Paper noted that the UK's reserves of oil and gas are declining, and that we are therefore bound to become more reliant on imports of these particular fossil fuels. However, the Government is also keen to remove the risk of relying too heavily on fossil fuels from overseas sources, which are growing fewer and steadily further away, and which are frequently regions of political instability. This surely brings the role of domestically produced coal to the fore.

Coal Forum

The Government's commitment to coal recovery saw it establish the Coal Forum in the autumn of 2006, bringing together key players from the coal industry and the power sector to develop strategies to maximise economic production of coal. The Coal Forum will make a detailed report later in 2007, but its emerging findings suggest that continuing access to supplies of UK-produced coal benefits both the generating industry and other industrial coal users.

Although coal has historically been the dirtiest of fuels, new technologies hold out the prospect of dramatically reducing coal emissions. Collectively these are known as clean coal technology (CCT). One of the key technologies within CTT is carbon capture and storage (CSS), which involves capturing the carbon dioxide – preventing the greenhouse gas entering the atmosphere – and storing it deep underground. This could reduce emissions from coal-fired power stations by as much as 90 per cent.

In his Budget speech in April 2007, the Chancellor announced that the Government would launch a competition to demonstrate commercial-scale CSS on power generation in the UK. The Government intends to launch the competition in November 2007, with the aim of having the demonstration operating early in the next decade. When operational, this will make the UK a world leader in this globally important technology. Successful demonstration of CSS would be a major contribution by the UK to global efforts to tackle climate change.

However, for the UK's re-emerging coal mining industry to be successful, that coal has to recovered both economically and safely.

Safe and economic extraction

To meet the need for increased safety and efficiency, mining operations are being equipped with sophisticated industrial controls and sensors. In many mining operations, live video data is joining with information from sensors and industrial controls. Of course, this dramatically increases the bandwidth requirements for the network, and quickly exceeds the performance limits of serial technology. But industrial Ethernet is emerging as a rugged and reliable networking technology for the mining industry, delivering a combination of high performance, interoperability, flexibility and cost-effectiveness.

GarrettCom has recently demonstrated the value of an Ethernet-based network in the upgrade of an environmental control system for a mine. The environmental control system operates seven days a week, around the clock, and is critical to keep the mines safe and also for management of the control systems. Using the environmental control system, the mine's operators can evaluate air quality and determine whether it is safe for workers to enter the mine. Carbon monoxide (CO) sensors and methane sensors are used underground to monitor the air quality.

The mine extended for 18 miles and had previously used serial communications technology. In designing a systems upgrade, the mine operators had run into limitations, both in the distance into the mine and in the number of serial end devices that could be supported. Furthermore, they wanted to add the capability for live video data to monitor the equipment in the mine, instead of sending manned vehicles to the equipment location to get operations status data.

All of the mine equipment and environmental information needed to be available without interruption in order to support operating decisions and to avoid compromising safety.

Ethernet advantages

Ethernet technology offers the ability to have an industry-standard common network for all of the real-time information that is crucial for safe operation of a mine. There are no problems relating to bandwidth or the number of end-devices, and fibre-optic media is future-proof for speed, and single-mode fibre easily handles the long distances. For high availability in this instance, the mine operators implemented a single-mode fibre loop in the mine shaft to establish a ring structure that can provide self-healing fault recovery.

The company chose GarrettCom's managed Ethernet switches and S-ring redundancy management software to meet its application requirements. It chose GarrettCom because of the cost-effective range of managed Ethernet products, fibre port configurability, industrial rating, AC and DC power options, and proven track record in industrial networks.

The mine's control network of SCADA systems and VLANs keeps track of PLCs, environmental conditions, longwall mining machines, beltline conveyors and pump stations. In addition, the company is in the process of adding many IP phones and video cameras. All these networks are connected via the GarrettCom switches. 6K25 managed fibre switches are used in the main office to interconnect with other switch brands. In addition, 6K16V switches are used in the underground control stations and are attached to end device. GarrettCom mP62 switches with environmentally-protected enclosures are employed in the mining area.

Safety monitoring

The use of Ethernet products in the coal mine has provided the operator with safe mining operations. The S-Ring redundancy manager software and the Ethernet switches have effectively eliminated network downtime inside the mine, keeping information flowing at all times and indicating to the company when the conditions are safe for workers to enter the mine.

The sealed enclosure of the mP62 switches is suitable for the mining environment, providing protection for the switch's internal electronics from dust and dirt. Also, the per-port configurability of the GarrettCom 6K product line provides the mine operator with flexibility and cost-effectiveness should future expansion be required.

So the future is looking good for the UK's coal industry. With the publication of the Energy White Paper, the UK Government has finally acknowledged the vital role of our domestic coal mining industry in meeting the UK's energy requirements for decades to come, while clean coal technologies mean we can continue to rely on coal-fired power stations and still meet our commitments to a cleaner energy supply.