Increasing energy efficiency with resistor technology

At COP28 in November 2023, 119 countries signed the Global Renewables and Energy Efficiency Pledge, committing to triple renewable energy capacity and double energy efficiency improvements by 2030. While shifting to largely renewable sources is important, this pledge recognises the importance of using existing energy sources efficiently too. Here, Mike Torbitt explains how resistor technology supports energy efficiency mechanisms for existing and future resources

The pledge has the objective of reaching eleven terawatts (TW) of installed renewable energy generation capacity and an annual rate of more than four per cent of energy efficiency improvements globally by 2030. 

With average global temperatures between February 2023 and January 2024 over the 1.5˚C above pre-industrial levels goal outlined by the Paris Agreement, the pledge aims to tackle global warming by reducing fossil fuel usage and carbon emissions. 

The goal of tripling renewable energy capacity should be within reach for the signatory countries. Energy think tank Ember analysed data from the EU bloc and 57 other countries, finding that an annual renewables deployment growth rate of 17% is required to meet the 2030 target. Renewable capacity grew at this level in the seven-year period between 2016 and 2023, meaning a continuation at the same rate would see the pledge achieve its aim.  

Efficiency issues

However, the prospect of the energy efficiency objective being met is less promising. Increasing energy efficiency is essential to making total energy consumption lower, which will result in fossil fuels making up a smaller share of the energy mix and reduce greenhouse gas emissions. 

Unfortunately, the rate of progress for energy intensity, the main measure for the global economy’s level of energy efficiency, fell from 2% in 2022 to 1.3% in 2023. Energy intensity measures how much energy is needed for a given activity, so its progress increases when energy efficiency is improved. 

Currently, the projected rate of energy intensity improvements is between now and 2030 is 2.2%, just over half of the required four per cent. So, why does energy efficiency prove a challenge? 

Since energy efficiency improvements need to be made across a range of industries such as construction, industry and transport, it requires a complex and coordinated approach that is more difficult to oversee than power generation.  

Targeting transport 

With the transport industry responsible for around 30% of global energy use, the highest of any sector, an increased focus on energy efficiency is key to meeting the COP28 pledge. To improve the sector’s efficiency, automakers must consider technologies that reduce a vehicle’s energy output.

A key way of doing this is through regenerative braking, which recycles excess kinetic energy to recharge the vehicle’s battery. This principle is already widely applied to hybrid and electric vehicles (EVs), the latter of which convert 77% of energy into power, compared with between twelve and 30% for petrol and diesel vehicles.  

However, EVs are not the only mode of transport that can benefit from regenerative braking, with high-speed trains using this principle to decelerate when approaching stations. By reversing the current in the electric motors, the kinetic energy is recycled and can be used for other parts of the rail network. Consequently, high speed railways applying this principle can increase their level of energy efficiency, with the UK’s HS1 saving enough energy to power over 375 homes each year.  

For both of these applications, dynamic braking resistors play a crucial role in ensuring that any excess energy is safely reused or dissipated in the case it cannot be recycled. Cressall has over 60 years of experience in providing dynamic braking resistors for transport applications, with the EV2 for electric and hybrid vehicles, and a range of traction resistors for locomotives.  

As 2030 draws closer, the signatories of the Global Renewable and Energy Efficiency Pledge can feel assured that their efforts to increase renewable capacity is largely on track. However, to ensure that the pledge is met, a coordinated approach of using the latest technology to ensure the continued growth of energy efficiency is key. 

Mike Torbitt is managing director of resistor manufacturer Cressall.