Energy efficiency is a key element of the modern economy, affecting production costs, greenhouse gas emissions and sustainable development. Why are the efficiency and performance of internal combustion engines and electric motors so closely linked to energy efficiency? In this article, we answer that question and outline the steps you can take to assess how the engines and motors used in your company affect energy efficiency, and what can be improved to make that impact more favourable.
What do we mean by the efficiency of internal combustion engines and electric motors?
The efficiency of internal combustion engines and electric motors describes how effectively these devices convert the energy contained in fuel or electricity into mechanical work. For internal combustion engines, efficiency is usually measured as the ratio of the mechanical energy obtained from combustion to the chemical energy contained in the fuel. Their efficiency is constrained by the fundamental laws of thermodynamics and typically ranges from 25% to 30%, although modern engines can reach up to 40%. Most of the remaining energy is lost as heat.
The efficiency of electric motors, by contrast, is measured as the ratio of output power to the input power drawn from the electricity grid. Thanks to advanced technology and precise control, modern electric motors achieve efficiencies of 90-95%. Their higher efficiency results from fewer energy-conversion stages and lower energy losses. When the two types of drive are compared, differences in efficiency have a significant influence on drive selection for different applications, particularly where sustainable development and emissions reduction are priorities.
Motor efficiency and energy efficiency
Motor efficiency is a key indicator of energy efficiency, defined as the ratio of useful work performed by the motor or engine to the energy supplied as fuel or electricity. The higher the efficiency, the more energy is converted into mechanical work and the less is wasted as heat or through other losses. In practice, achieving high efficiency requires advanced technology, precise design and high-quality materials.
Modern electric motors, for example, can achieve efficiencies above 90%, significantly exceeding those of conventional internal combustion engines. Improving motor efficiency directly reduces energy consumption and operating costs while also lowering emissions of harmful substances into the environment. For this reason, optimising motor efficiency is one of the priorities of modern efforts to support sustainable development and conserve energy resources.
The link between motor efficiency and an energy efficiency audit
The efficiency of both internal combustion engines and electric motors is directly related to an energy efficiency audit. This is often confused with an enterprise energy audit, which involves a detailed analysis of a company’s energy consumption. In Poland, this audit is mandatory and is intended to identify areas where savings are possible and the measures needed to achieve them. It indicates what can be changed and improved within a company to reduce costs.
An energy efficiency audit, which is the type discussed in this article, is used to assess whether implemented measures have been carried out correctly. This audit provides an opportunity to reduce a company’s energy costs. It focuses on areas of potential savings identified earlier and assesses ways to improve energy efficiency.
During an energy efficiency audit, specialists analyse the technical and operating parameters of engines and motors, such as rated power, load, fuel or electricity consumption and efficiency. This makes it possible to identify inefficient equipment that causes high energy losses. The findings can then be used to recommend corrective measures, such as upgrading or replacing old motors with newer, more efficient models, using variable-speed drive systems, or implementing programmes for regular maintenance and optimisation of motor operation.
Efforts to improve motor efficiency through an energy efficiency audit lead to significant energy and financial savings and also contribute to reducing greenhouse gas emissions. The audit can also reveal the potential to implement innovative technological solutions, such as energy recovery from industrial processes, which further improves the energy efficiency of the entire system. An energy efficiency audit is therefore an indispensable energy-management tool that supports sustainable development and business competitiveness.
