Big question

BQ10 - How do we remove more carbon than we emit by 2050?



The areas that this Big Question covers include:

  • Energy & Transport – decarbonise through avoidance, efficiency and alternatives to fossil fuels
  • Process Emissions – minimised emissions through prevention, optimisation or capture
  • Land Use & Carbon Capture – carbon sequestration potential maximised
  • Investment & Procurement – minimised emissions in materials, consumables, products & services, credible offsets
  • Customers – reduced emissions related to customer behaviour
  • Cross-Cutting – low carbon, sustainable water cycle management

Have a look at the route map – this is a plan as to how we will answer our Big Question through research.

The route map has a number of key elements. At the top is our Big Question and then the Outcomes we need to achieve from the research programme -if we can achieve all these Outcomes we can answer the Big Question. You can also see the Key Benefits that will come from achieving the desired Outcomes.

Click on the Research Outcomes below to see the Projects that have been completed or are underway. 

Scroll down further to see Case Studies explaining the impact of our research.

Current Project Summary 


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Integrating and producing hydrogen.

Project Status - Project Commenced

The UK’s latest hydrogen strategy, published in August 2021, states that hydrogen is a new low carbon solution that is critical for the UK’s transition to net zero. There are a range of solutions to create hydrogen but it is likely that electrolysis of water will feature prominently in this. Research is required to establish the impact on water resources and to identify alternatives to electrolysis of water relevant to the water sector.


In light of the governments ambition to delivery 5GW of production to meet our net zero commitments, the water industry needs to understand and develop its position in the supply chain.

There is significant challenge in that there is little or no hydrogen production in the UK at present and therefore the implications on infrastructure and supply chain are currently unknown. This may well be an opportunity for the water sector but will need careful management to maintain water supply to customers.


Air pollutant emissions across wastewater operations.

Project Status - Project Commenced

Justification – Problem
In Defra’s 25 Year Environment Plan, “clean air” features as one of the 10 goals to achieving the ambition of being the first generation to leave the environment in a better state than we found it. Building on this, Defra has published a Clean Air Strategy in 2019 to tackle air pollution, “making our air healthier to breathe, protecting nature and boosting the economy”.  The strategy sets out existing policies and a programme of new actions to reduce emissions of five of the most damaging air pollutants (NH3, PM2.5, NH3, NOx, SO2 and NMVOCs). In the upcoming Environment Bill, air quality is listed as a priority area for setting long-term targets, including for PM2.5, the pollutant with the strongest evidence of health effects.  The Irish government’s “Statement of Strategy” also commits to substantially reduce air pollution and promote cleaner ambient air, moving towards the World Health Organisation (WHO) air quality standards. 

The World Health Organization estimates that air pollution kills an estimated seven million people worldwide every year . Air pollution also has negative impacts on the environment e.g. effecting the acid and nutrient status of soils and waters. The UK and Irish governments and the devolved administrations are committed to delivering clean air, with an increasing focus being given to tackling air pollution and improving air quality due to the negative impacts on human and environmental health. The recent focus on air pollution signals a broadening of government attention, which has previously concentrated primarily on greenhouse gases. 

There are gaps in our knowledge on sources of air pollutants from water company operations and activities that this project would seek to address.  The focus of this project would be on wastewater operations and activities as opposed to looking at all water company operations and activities which include water treatment; catchment; energy; waste disposal; property services; commercial; fleet; and capital projects.  By establishing the impact of wastewater operations and activities it will help form a baseline and understand the potential impact of the remaining water industry operations and activities. 

Justification – Problem Impact
The water industry is just one sector with a role to play in understanding how air pollutant emissions are released into the environment, and the potential solutions to tackle this challenge.  Across our operations and activities, there are a number of ways in which we can emit and be exposed to external sources/inputs of the targeted air pollutants.  There is a risk that the growing focus on air pollution will result in new regulatory standards for emissions to air being imposed on water companies in the future.  The likelihood of this has sharply increased in recent months due to the suggestion by researchers that air pollution has significantly worsened the Covid-19 outbreak and led to more deaths than if pollution-free skies were the norm , . Whilst at the same time lockdown ways of working and the resultant improvement in air quality through reduced transport has increased the awareness of society to the potential benefits of improved air quality. In England the Environment Agency is already taking steps to control the release of air pollutants on some water company assets. Therefore, it is important that we take steps now to understand our impact on air quality and ensure that it is appropriately managed.  

Justification – Addressing the Problem
The overall aim of the project is to identify and quantify the risk of air pollutant emissions (NH3, PM2.5, NH3, NOx, SO2 and NMVOCs) across wastewater operations and activities. This will provide the water industry with a better understanding of the sources and associated risk of air pollutants from wastewater operations and activities. 

It will also inform the need for future research into effective controls to minimise the risk of air pollutant sources from water industry operations and activities, enabling the industry to be proactive in anticipating future regulatory requirements and lead to more efficient and innovative solutions being ready for application should new standards be applied.

The project will also seek to develop an air pollution accounting workbook, similar to the carbon accounting workbook, to provide water companies with a consistent and transparent approach for accounting air pollutant emissions form the identified sources. 

Justification – Project Outputs
•    Present a clear picture of the sources and associated risk of air pollutant emissions across wastewater operations and activities. Identify future research projects into effective controls to minimise the risk of identified sources. 
•    Establish an air pollution accounting workbook, similar to the carbon accounting workbook,  to provide water companies with a consistent and transparent approach for accounting air pollutant emissions form the identified sources. 


Biosolids to land - carbon emissions and carbon capture.

Project Status - Project Commenced

The reuse of biosolids to land has the potential for notable greenhouse gas emissions, or significant carbon storage – depending on the form of the biosolids and the recycling method used.

The increasing prominence of the sector’s net zero carbon work, the impacts on biosolids reuse of the farming rules for water, and growing interest in soil carbon, mean that it is timely to review and challenge assumptions about positive and negative carbon effects of this activity. This will be needed to help inform judgements on the most environmentally sustainable methods of sludge reuse.

A few emissions factors for biosolids reuse on land are available via the carbon accounting workbook. These emissions factors are rather old, and it would be timely to understand whether they should be revised or not.

Currently, emissions from biosolids to land are outside the reporting boundary used for regulatory reporting; they are assigned to the owners of the land where the biosolids are being spread. However, some companies include biosolids to land in their calculations for parallel wider carbon reporting, and it could be argued that there are reasons for good quantification from a producer responsibility point of view.

The Water UK carbon network has identified this topic as a priority for the next year of the carbon Big Question.


Calculating wholelife / totex carbon.

Project Status - Project Commenced

Category - Carbon

Over the last 15 years the water sector has been developing tools for different aspects of its carbon footprint. Through UKWIR the Carbon Accounting Workbook provides a consistent approach for annual operational emissions. Also focused on operational emissions, the Water UK Net Zero routemap programme will culminate in the provision tools for estimating carbon reductions of different options over a given period of time, and the cost per tonne of CO2 avoided.

Now, growing attention is being paid to the embodied carbon of capital schemes and the sector’s supply chain. Already, various tools are available for estimating capital carbon emissions for new assets, (some of which include operational carbon) and with developments such as PAS2080 they are becoming more standardised. But uptake has been variable across the sector.

Two interconnected risks remain. Firstly, that embodied / capital carbon continues to receive less attention than operational emissions and that capital and operational carbon are not assessed in the round – contrary to totex thinking. Secondly, that the sector lags behind regulator and other stakeholder expectations on measuring capital carbon and building it into decision making and reporting


Converting sewage sludge to biochar - a review of options & feasibility.

Project Status - Project Completed

Category - Sewerage

Please note -  a submission has been made to the Water Breakthrough Challenge which will cover this project's objectives if it is successful. If it isn't then the BQ team feel that this piece of work is still important to progress. So please vote for it on the basis of whether it is of interest to you or not.

Achieving net zero carbon by 2030 is going to be very challenging. Reduction options will likely involve many small to medium scale interventions, and a small number that could yield large carbon reductions.  However, we face significant residual emissions in 2030 in scenarios unless investment in technological solutions is greatly accelerated.

The specific issue that this proposal relates to – converting sewage sludge to biochar – is closely related to the problem of reducing our carbon footprint by sequestering carbon within char and also providing reducing emissions associated with digestion and sludge recycling. It is also related to issues around the land route for biosolids, due to the presence of microplastics and persistent organic compounds, and whether thermal technologies have a role to play in response.

Projects coming soon.


Carbon accounting workbook update v15.

Project Status - Project Completed

To avoid inconsistent greenhouse gas emissions reporting we need a common method and accounting system. This is achieved through the carbon accounting workbook (CAW).

The CAW requires annual updating - at the very least to incorporate revised emissions factors issued by BEIS. Previous updates have also included broadening the scope of items that are quantified, and improving functionality.