LED lamps – a bright idea!
Published: 01 April, 2014
When it comes to specifying lighting for use in hazardous offshore oil and gas environments, users should consider the technical and cost advantages of installing the latest LED lamps over the more traditional fluorescent alternatives, says Willi Steckel, product line manager, lighting at Cooper Crouse-Hinds.
Today, lighting accounts for approximately 19% of all electricity consumed in the world. Around 67% of all lighting currently installed is based on traditional, less energy efficient technology that was most probably developed before 1970. However, with increasing energy costs putting more pressure on companies to reduce their energy usage and to seek out more efficient alternatives, many are now considering or have already switched from traditional forms of lighting to the latest LED technology, which is already bringing significant savings, not only in energy costs, but also in terms of the total cost of ownership of lighting installations.
Reducing the total cost of ownership of lighting is critical for an offshore oil and gas platform, which may have hundreds or even thousands of different light fittings installed. Inevitably, the platform will have a variety of different fixed and portable lighting installed in Zone 0, Zone 1 and Zone 2 hazardous gas areas: floodlights , fluorescent light fittings, pendant and bulkhead light fittings; hand lamps, safety torches and chargers; safety and escape sign luminaires; signal and vessel lights.
So, for many offshore oil and gas installations, replacing traditional HID or fluorescent light fittings with LED alternatives has to be top of the agenda. In order to properly assess whether traditional light fittings should be replaced with LED lighting, there are some important factors that need to be considered first, including light fitting performance, system efficiency, reliability, availability of replacements or spare parts, mounting and installation options – which all affect the total cost of ownership.
The benefits of LED lighting
While the initial cost of an LED light fitting is higher than an HID or fluorescent equivalent, there are plenty of advantages that offset this.
An LED is a solid-state semiconductor device that converts directly electrical energy into visible light. On average, LED lamps consume 50% less energy than comparable luminaires and 85% less energy than incandescent luminaires. LED lamps also provide higher lumens per watt compared to many traditional lighting technologies (compact fluorescent, HID, incandescent, etc.). LED lighting can also reduce the high maintenance costs associated with traditional lamps due to the frequent bulb changes and servicing. Imagine the time and cost of having to change bulbs or service thousands of different light fittings on an offshore oil platform. This means that over the long term, LED lighting reduces the overall cost of ownership.
Unlike incandescent lamps or gas discharge lamps (HPS, MH or fluorescent), LED light fittings have no filaments or electrodes. This means they are more robust, durable, vibration-proof and impact proof. It also means that an LED equivalent lamp is likely to have smaller size and shape constraints.
Efficiency & operating life
The expected lumen maintenance L70 of an LED lamp is 50,000-60,000 hours, which is a significant improvement compared to traditional light sources such as HID and fluorescent lamps, whose expected operating life varies between 15,000 and 20,000 hours. With LED light fittings, there are also no negative influences on the life of the lamp due to switching cycles.
The overall efficiency of an LED lighting system is determined by the efficiency of the LED package, i.e. the driver, heat sink, secondary optics and controls.
LED drivers are more efficient than HID ballasts, resulting in higher overall system efficiency. Whereas traditional light fittings use transformers or power converters, LED drivers regulate the energy passing through LEDs to produce consistent (constant or PWM current) output. Most drivers are 85-90% efficient with a power factor of >0.85.
However, drivers contain electronic components that can raise the temperature of the LED system. Any excess heat in an LED lighting system could result in accelerated lumen depreciation, colour shift and reduced rated life and so all LED lamps require an effective heat sink. A heat sink is a thermally conductive material attached to the LED printed circuit board (PCB) assembly. Heat sinks are specifically engineered to remove heat from the LEDs and the driver in order to ensure longer life, better lumen output and accurate colour temperature. Often, a ‘finned’ design is used to increase the surface area available for heat transfer (dissipation). Therefore, a well designed heat sink can result in lower housing and junction temperatures, as well as improved lumen maintenance over time.
Environmental benefits
Disposal is also a key factor to consider. As LEDs contain no mercury or other hazardous substances, users should see a reduction in disposal costs at the end of the lamp’s life, which in turn means a reduction in future liabilities. As well as meeting more stringent environmental standards, this also helps to reduce energy costs and a company’s CO2 footprint.
