Posted by Chloe Fletcher on , last updated
Is FM radio more energy-efficient than DAB? Do transmitters or audio devices consume the most electricity? What effect will switching off certain radio platforms have on energy use? As part of our work to improve the environmental impact of BBC services, we now have the answers to these questions and more.
Today, we are publishing our research which explores the energy footprint of BBC radio services, both as it stands now and how it may change in the future. This work is the first of its kind in analysing the novel area of radio energy use and forms an extension to the research we released back in September looking at the environmental impact of BBC television.
In our study, we considered the energy use across all available platforms, namely AM, FM, DAB, digital television (DTV) and via internet streaming services (such as BBC Sounds), revealing which ones have the largest footprints. We also compared energy use at various stages in the radio chain - not just looking at what the BBC is directly responsible for, such as preparation (playout, encoding and multiplexing) and distribution (transmitters and internet networks), but also in the consumption of our content by audiences. This highlighted the key energy hotspots in the BBC radio system and where best to focus our efforts if we want to reduce our energy footprint.
BBC radio attracts over 30 million listeners in the UK per week through live stations, podcasts, and other on-demand content. These radio services can be accessed on a range of consumer devices in the home, in-vehicle, at work and outside, including radio sets, smart speakers, smartphones, tablets, laptops, computers, TV sets and set-top boxes.
Unlike TV, which completed its digital switchover in 2012, the BBC still provides analogue radio services that continue to make up a sizeable proportion of listening. Over the last decade, there has been some debate over whether or not radio should undergo its own digital switchover. This is currently under review by the Department for Digital, Culture, Media and Sport after deciding not to proceed with plans back in 2013. Separately, the media industry have been investigating the possibility of migrating television and radio services to internet-only distribution. Either of these approaches would have inevitable impacts on the environment which are yet to be quantified - until now. We have evaluated the effect both a radio digital switchover or transition to IP-only services could have on energy consumption as well as two other scenarios.
As a whole, the main areas our research focused on were:
- How much electricity is currently used by BBC radio services,
- The comparative energy use per platform,
- How this use may change over time under four illustrative scenarios,
- Which parts of the system are consuming the most energy.
With such a complex system and unavoidable uncertainty regarding future behavioural and technological changes, modelling can be a challenge. That’s why we have used statistical techniques such as the Monte Carlo method - where model parameters are represented by distributions which are random sampled from over a number of simulations - to combat this. We have also undertaken sensitivity analysis to evaluate the confidence we have in our results. You can read more about our methodology and how we handle uncertainty in our paper.
The total energy required to prepare, distribute and consume BBC radio in our 2018 baseline was estimated to be 325 GWh, equivalent to 0.1% of UK electricity use that year. Of all five platforms, FM was found to have the biggest footprint overall at 100 GWh (31%) and AM the lowest at 25 GWh (8%), with IP (79 GWh; 24%), DAB (65 GWh; 20%) and DTV(56 GWh; 17%) falling in-between.
However, not all radio platforms are consumed equally. Listening hours on FM and DAB were found to be up to 11 times higher than on AM and DTV. As a result, we also calculated the electricity consumption per device hour to find the energy intensity of each platform. This painted a slightly different picture where DTV had the largest footprint at 81 Wh/device-hour, followed by AM (29 Wh/device-hour), IP (23 Wh/device-hour), FM (13 Wh/device-hour) and lastly DAB which had the smallest at 9 Wh/device-hour.
Overall, we found consumption had a much bigger footprint than preparation and distribution almost threefold. Consumer devices used around 73% of the total energy in 2018 compared to 27% for distribution, with preparation using less than 0.1% overall. Despite similar findings in our television research, we were again surprised by this result as the transmitter networks for radio services collectively use more power than that for digital terrestrial television. However, with the tens of millions of consumer devices which can access radio across the UK, even low-power audio devices add up.
With a clearer understanding of current energy use, it was also important for us to consider how this may change over time. Therefore, we explored four ‘what if…?’ scenarios over 20 years, from 2018 to 2037, which were:
- Business as Usual - All platforms retained
- Digital Only - Switching off AM and FM from 2030
- DAB/IP Only - Switching off AM, FM and DTV radio from 2030
- IP Only - Switching off AM, FM, DAB and DTV radio from 2030
Whilst these do not represent specific plans for the BBC, they allowed us to test our modelling capability and identify potential future hotspots within the radio chain. With such a range of different scenarios, we gained insight into how best to mitigate negative environmental impacts in the future.
All switch-off scenarios showed energy-saving potential compared to ‘Business as Usual’. Out of the scenarios modelled, the ‘DAB/IP Only’ case led to the largest energy reduction of 599 GWh, which was almost twice as much as the second-largest saving from ‘IP Only’ at 301 GWh. For the ‘Digital Only’ scenario, we estimated the smallest reduction of 176 GWh compared to ‘Business as Usual’. However, our results were sensitive to which devices people migrated to after switch-off. For example, a greater uptake in listening via television sets reduced the energy-saving potential in some scenarios.
The hidden power of standby
Our most notable finding, demonstrated in both the baseline and scenario results, was that the biggest factor driving energy use was the standby power of radio sets and smart speakers - more so than the power of devices when they are turned on. Therefore, as a potential intervention, we simulated the removal of this standby energy across all our scenarios from 2021. In practice, this would mean people unplugging devices from their power source when not in use.
By testing this, we found an average energy saving of 38% across our scenarios, which was unprecedentedly large. Although this intervention may be unfeasible in practice, it highlights that any reduction in standby power could lead to vast energy savings. This could be effected through audience education, tighter regulations on consumer electronic devices, and manufacturers reducing the power consumption of their products.
Choose what you would like our engineers to explain in an interactive experience discussing the environmental impact of the BBC's television services - and how they might look in years to come.
Sharing our work
This work forms part of our commitment to reducing the environmental footprint of media services and technology through the BBC Greener Broadcasting strategy. By taking a system-wide approach, we have highlighted the complexities across the radio chain and potential interventions to reduce the negative environmental impacts within it.
We are sharing our findings far and wide to educate the community and seek change through industry collaboration. In November, we will be presenting at conferences, including the WorldDAB General Assembly and Radio TechCon, as well as with other stakeholders across industry and government.
If you have any questions or comments, please do get in touch.
This post is part of the Broadcast and Connected Systems section