Today, lighting accounts for approximately 19% of electricity consumed in the world. Around 67% of all lighting currently installed is based on less energy-efficient technology, probably developed before 1970. However, with increasing energy costs many companies are seeking more efficient alternatives.
Reducing the total cost of ownership 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 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.
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 affect the total cost of ownership.
The benefits of LED lighting
The initial cost of an LED light fitting is higher than an HID or fluorescent equivalent, but there are 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 /W compared to traditional lighting technologies (compact fluorescent, HID, incandescent). 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.
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.
Moreover, because solid state devices have no filaments or glass components that can break, this significantly reduces the risk of premature failure of LED light fittings. LED lamps do not emit ultraviolet (UV) or infrared (IR) radiation and provide immediate start up and instant, 100% illumination. The colour temperature of LED lighting can also be varied to suit the particular requirements of the customer. LED lighting provides a high colour rendering index, which results in crisper, more natural light.
Efficiency and operating
The expected lumen maintenance L70 of an LED lamp is 50,000 to 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, heatsink, 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 to 90% efficient with a power factor of at least 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 heatsink. A heatsink is a thermally conductive material attached to the LED PCB assembly. Heatsinks 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 heatsink can result in lower housing and junction temperatures, as well as improved lumen maintenance over time.
Disposal is also a key consideration. 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.
Cooper Crouse-Hinds has constructed an LED R & D centre in the USA. With this, the company is able to ensure that LED lighting components and systems such as drivers, heatsinks optics and controls, are developed and tested according to the relevant international lighting standards and that these products are also certified for use in hazardous areas. The company says it can guarantee the future compatibility of its products, even as new SSL technologies are developed. On an oil platform, where many CEAG fluorescent fittings are installed, having a future-proof light fitting with readily available replacements, is critical to the customer’s operation.
Economic payback on LED lighting is being driven by lower energy consumption, longer life and reduced maintenance over the complete product lifecycle. The performance and safety benefits of LED lighting should also be considered, including instant on/off, cold temperature operation and good resistance to vibration and impact