Despite being available for over 50 years, the true energy saving potential of variable speed drives can often be overlooked, especially by a new generation of engineers. As David Hughes, ABB UK’s Managing Director argues, the arrival of net-zero could be the catalyst that increases the uptake of the technology.
Recent research reports indicate that the global market for variable speed drives (VSDs) will exceed an estimated $33 billion by 2025. One of the most powerful arguments behind this growth is the global interest from governments in achieving a net-zero energy goal. In 2019 the UK became the first major economy to pass a net-zero emissions law specifying a new target that will require the country to bring all greenhouse gas emissions to net-zero by 2050.
What is net-zero? The UK government says “net-zero emissions means the total of active removals from the atmosphere, offsets any remaining emissions from the rest of the economy. Sometimes “net-zero” is used to refer to CO2 only and sometimes it refers to all greenhouse gases.”
This has massive implications for the public sector where keeping its offices, hospital wards, swimming pools and leisure centres heated, ventilated and air-conditioned is a costly business. For example, according to The Carbon Trust, the annual gas and electricity consumed by the UK’s NHS Trusts is an estimated £400 million. Barts Health NHS Trust, with a turnover of over £1.5 billion and a workforce of 16,000, typically spends £13 million on energy. Manchester University NHS Foundation Trust comes a close second with in excess of £11 million.
For those in the know, a VSD and high efficiency motor is the most sustainable and cost-effective method to reduce energy consumption, lower CO2 emissions and achieve energy efficient targets. A VSD is used on a motor powering a pump or fan to regulate their flow rate by precisely matching motor speed to load demand. Running an application at the lowest possible motor speed, while maintaining performance requirements, can lead to energy savings from 20 to 60 percent and with payback, in many instances, between one to three years. Varying the speed also reduces mechanical stress on the pump or fan and motor wear and tear, requiring less maintenance and prolonging system lifetime. As such, VSDs are one of the most cost-effective ways to maximise efficiency and reduce operational costs, with the savings benefiting the bottom line.
Yet the problem is that those who know about VSDs and motors would appear to be few and far between. In an ABB survey, engineers and the financial community were asked what they perceived to be the most effective way to save energy. The top answer was “change energy supplier”. However, this does not save energy long term, it only moves the energy pricing challenge from one energy supplier to the next, as wholesale energy prices rarely vary that much. The most effective way to save energy is to install VSDs and high efficiency motors, yet this answer languished well down the list, even behind turning off the lights. In fact, one third of the world’s industrial electrical energy is consumed by electrical motors and yet approximately 10 percent of the installed base are fitted with VSDs. This highlights an incredible opportunity for energy efficiency improvements through VSD retrofit installations.
There is clearly a need to raise awareness. A new breed of engineers is entering the building services arena, many of whom have not been trained in the benefits of using VSDs and motors. Apart from this skills gap, there is also a lack of energy efficiency engineers which is hindering the ability to find savings and the best way to implement reduction initiatives. To help overcome this, my own company has devised a 2-hour training course which is CPD-certified (Continuous Professional Development). The course shows how to spot those pump and fan applications that can save the most energy and money and, more importantly, how easy it is to make the savings happen. There is even an option, by way of an Energy Snapshot, to have an ABB-certified engineer accompany building services staff and show them how to spot up to five best money saving opportunities in just half-a-day.
The improvement in education extends to building services consultants. All too often, the advanced capabilities of the VSD are not reflected in today’s building services’ specifications. Even the choice of electric motor is more extensive than ever ranging from permanent magnet, induction and synchronous reluctance, with each offering a different mix of benefits, depending on the application. Previously a powertrain, comprising VSDs, electric motors, bearings, couplings and loads such as fans or pumps, were inherently dumb: none of the component parts communicated with each other, let alone the wider world.
This results in inefficient maintenance schedules. For instance, many electric motors are often rewound, as this is considered a cost-effective solution as opposed to replacement. There are two schools of thought about whether an electric motor should be replaced or repaired, depending on whether you are a motor manufacturer or a rewind company. A motor manufacturer argues that rewinding a motor loses efficiency and the cost of repair can be as much as the price of a new motor. Rewind companies, disagree, saying a rewind today delivers equal or improved efficiency levels at a competitive cost compared to new. So how does the end-user decide?
The arrival of smart sensors will go some way to alleviating uncertainties. Smart sensors convert traditional motors, pumps and mounted bearings into smart, wirelessly connected devices. It measures key parameters from the surface of the equipment which can be used to gain meaningful information on the condition and performance of the equipment, enabling users to identify inefficiencies within their system and to reduce risks related to operation and maintenance. Maintenance can now be planned according to actual needs rather than based on generic schedules. This extends the lifetime of equipment, cuts maintenance costs and reduces or prevents unplanned downtime due to breakdowns.
Finally, a word of warning. Don’t always look for a magic bullet to save the energy day. Innovation doesn’t have to mean new technology. There are some well-established technologies out there that are more than capable of saving the planet and which are under-utilised. Today’s variable speed drive may just be one of those technologies. It may be time to take a closer look.
ABB (ABBN: SIX Swiss Ex) is a pioneering technology leader with a comprehensive offering for digital industries. With a history of innovation spanning more than 130 years, ABB is today a leader in digital industries with four customer-focused, globally leading businesses: Electrification, Industrial Automation, Motion, and Robotics & Discrete Automation, supported by its common ABB Ability™ digital platform. ABB’s market-leading Power Grids business will be divested to Hitachi in 2020. ABB operates in more than 100 countries with about 147,000 employees.