Restricting urban biomass: A chance to improve city air quality

Reducing the volume of emissions for real estate activities and subsequently improving air quality is something EVORA Global supports clients in committing to. Often, this involves changing the way factors such as energy and heat consumption are managed. Switching from traditional fossil fuel to cleaner means is a great way to start, however, alternative means of heating still need to be carefully considered in terms of the overall impacts tied to them. 

Biomass systems are an example of an alternative heating source requiring such attention, due to implications for air quality from what they emit. In this blog we explore the potential issues with biomass and what the alternatives are for asset owners looking to move towards renewable heat. 

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UK non-domestic renewable heat

The topic of renewable heat has been rising up the agenda as a key part of UK decarbonisation and net zero targets. According to BEIS it is estimated that a third of energy consumption in the UK is from heating, with  a substantial portion of this stemming from fossil fuel sources. 

Traditionally heating has been sourced predominantly from gas (~78%) in the non-domestic space, with only a small proportion from electricity (~8%) and even less from alternative sources (~6%) according to an Imperial College London and Vivid Economics analysis in 2018. As a result, to advance decarbonisation efforts, subsidy schemes such as the Renewable Heat Incentive (RHI) have been introduced. 

The Non-domestic RHI serves organisations that use alternative heating, incentivising the switch by paying generators for generated heat. In this way, renewable heating systems can be paid for in the long term, due to bill savings and cash flow from set tariffs lasting 20 years. Biomass, organic matter used for fuel, has been the most popular alternative, leading the way in terms of the RHI’s contribution to energy system decarbonisation. In fact, as of the end of August 2019, biomass accounted for 16,776 accredited systems across GB, with a capacity of approximately 4.1GW. This represents around 85% of the total number and generating capacity under the non-domestic scheme as shown in Figure One.

Biomass is a carbon neutral fuel as carbon emitted is offset by that absorbed during the growth of the fuel (assuming that a sustainable supply chain is created with a continuous carbon sink and replenishment strategy in place). When compared to other fuelled boilers in Figure 2, data from the UK Houses of Parliament in 2016 suggests that the direct emitted carbon from biomass is lower than other conventional systems. This builds a strong case for using it in heat intensive settings.

Issues with air pollution

However, biomass has come under scrutiny due to other emissions which result from the combustion of the wood pellet fuel. Fine particulate matter (PM 2.5), ammonia (NH₃), nitrogen oxides (NO_X), sulphur dioxides (SO₂) and other harmful substances have been found in high volumes on average from biomass systems. 

PM 2.5 is an air pollutant that is a major concern for people’s health and wellbeing due to reducing the quality of the air we breathe, causing respiratory difficulties and affecting lung function in the long term. This is primarily from the particulates themselves, however, PM 2.5 can act as a sink for other toxic substances which are produced from transport and industry which can also be drawn into the lungs. Therefore, it is of interest that the volume of PM 2.5 emissions is reduced in urban areas, due to the general proximity of the public to sources of emissions, as well as the relative density of pollution in these regions and other toxins that can be mixed in.

Data from EMEP/EEA air pollutant emission inventory guidebook 2016 illustrates the issue that biomass presents in Figure 3 below, with PM 2.5 emissions being the second highest of the comparative boiler fuels. When these systems are concentrated in an urban area, the issue is only exacerbated.

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A BEIS consultation – restricting urban biomass

Due to issues arising from the continued rise in popularity around biomass and potential to impact air quality, Government outlined in an October 2018 consultation – Renewable Heat Incentive: Biomass Combustion in Urban Areas – the potential to restrict biomass facilities in urban areas. In effect, this will remove the financial incentive for all new biomass installations including combined heat and power (CHP). It has been a year since this consultation was introduced and Government has yet to provide a public response, however it is be speculated that the commitment to restrict urban biomass will follow through, as the Clean Air Strategy 2019 published in January 2019 reiterated the intention to do so.

These restrictions are aimed at steering potential installers of RHI systems away from biomass toward different measures, namely, those with a zero PM 2.5 emission status, as well as energy efficiency measures. As a result, BEIS suggest that the potential net present value of banning urban biomass from January 2019 could be as much as £89mn, with £23mn sourced from air quality impact savings alone due to lower social resource costs. Furthermore, carbon saving of 0.6MtCO2e per annum could also be achieved if other RHI technologies are deployed instead such as heat pumps and solar thermal.

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Alternatives for asset owners to consider

Despite heating systems being a staple in all buildings, the reliance on them is still up for debate. It can be considered that in a temperate region like the UK, the need for external heating systems providing heat to buildings is unnecessary, especially in new builds where most new installations are likely to be targeted. In the case of biomass systems, they may not even need to be considered if energy efficient measures can be designed into a construction in the first instance. Furthermore, when looking at older structures energy efficiency and heat dependence can be improved through retrofitting. 

New build thermal efficiencies are expected to increase in the next decade or so, with the tightening of Part L Building Regulations and promotion of better standards such as Passivhaus including improved insulation, reduced air flow and intelligent design to take advantage of solar thermal energy. This could, in the longer term, negate the need for external heating completely, biomass or otherwise as room temperatures are maintained through the day. Therefore, alternative heating arrangements can be put in place, these being smaller and possibly modular RHI accredited systems which can adapt to a growing company throughout the year. This would promote flexibility, energy savings and reduced emissions overall.

…alternative heating arrangements can be put in place, these being smaller and possibly modular RHI accredited systems which can adapt to a growing company throughout the year. This would promote flexibility, energy savings and reduced emissions overall.

However, for existing buildings, which make up most of the real estate stock, external heating will still be required regardless of energy efficiency measures put in place. But real estate within urban regions can still tap into the benefits of renewable heat while avoiding localised air pollution by investing in other generator types. Air source, ground source and water source heat pumps, solar thermal arrays and geothermal installations are RHI accredited systems that do not combust material and therefore have zero PM 2.5 or carbon emissions as a result. 

Utilising these technologies therefore help investors to contribute to sustainability standards, improve health and wellbeing overall and act as an alternative to sometimes expensive energy efficiency retrofitting as well as receiving subsidy for their contribution. 

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In summary, though biomass is a good alternative to carbon emitting fossil fuel boilers, in the urban environment emissions of PM 2.5 are problematic and undesired. As a result of the BEIS consultation, newly installed urban biomass is likely to lose subsidy. However, there are alternatives in place which can keep buildings warm but will help to improve air quality, through either complete replacement of biomass systems, or by using intelligent design to negate the need for large external heating in the first place. 

For more information surrounding urban RHI systems or energy efficiency measures, please get in contact with the team.