Understanding embodied greenhouse gas emissions in the water and sewerage sectors

Abstract

Embodied (or embedded) greenhouse gas emissions are commonly overlooked in corporate carbon accounting, although they can represent a large proportion of overall emissions. In this paper, we utilise embodied emission data submitted to Ofwat, the economic regulator of water and sewerage companies in England and Wales, as part of their review of price limits. This is the first time that water and sewerage companies have presented embodied emissions associated with their capital programmes. In total, embodied emissions add an extra 50% on top of companies' operational greenhouse gas emissions. We consider the drivers for embodied emissions and show that capital maintenance programmes are the largest source. We highlight the relationship between capital expenditure and embodied emissions, and discuss why there are significant differences in embodied emission intensities between companies. Many of the differences arise from the way the common methodology for estimating embodied emissions is applied.Understanding embodied greenhouse gas emissions M. Keil et al.

The ‘carbon footprint’ of sewer pipes: risks of inconsistency

“…For example, the UK construction industry's carbon dioxide emissions make only around 7% of the country's total 'carbon footprint' (CF) (Hertwich and Peters, 2009); however, the overall influence of construction can potentially reach up to 47% (BIS, 2010). The same applies to the UK water and sewerage sector, in which it is believed that embodied carbon dioxide emissions from assets make up around a third of water companies' CFs (Cisholm, 2013), reaching up to 2?32 MtCO 2 e (metric tonnes of carbon dioxide equivalent) per annum, of which around 0?46 MtCO 2 e are associated with sewerage capital maintenance and construction of assets (Keil et al, 2013). There is already evidence that water companies, under guidance from Ofwat (the water services regulation authority), are addressing operational as well as embodied carbon dioxide emissions.…”

“…The current embodied carbon dioxide calculation guideline for the water industry, published by UKWIR (UK Water Industry Research) in 2008 (UKWIR, 2008) and updated in 2012, was mainly based on a simplified method in which standardised emission conversion factors are multiplied by the quantity of materials used (Keil et al, 2013). With that simplified standardised conversion method employed, it is difficult to ascertain whether all data quality and representativeness requirements, as set out in ISO 14044, section 4.2.3.6 (ISO, 2006), are being followed.…”

“…With that simplified standardised conversion method employed, it is difficult to ascertain whether all data quality and representativeness requirements, as set out in ISO 14044, section 4.2.3.6 (ISO, 2006), are being followed. It is also noted that the ICE method and database was considered as the default method/data source at the UKWIR's guide (Keil et al, 2013). Considerable differences exist in CF values recorded by various databases and sources reaching up to 40% for some products: one example is the cradle-to-gate CF values for precast hollow-core flooring reported by Alexander et al (2003) and Vares and Hakkinen (1998), which were 207?2 kg CO 2 /t and 123?25 kg CO 2 /t, respectively.…”

Flexible design in water and wastewater engineering – Definitions, literature and decision guide

“…Environmental legislation and concern about resource shortage may stimulate research in this area (Kumar and Putnam, 2008). A first indication for this is the assessment of embodied greenhouse gas emissions of assets by the UK water sector in response to regulation (Keil et al, 2013).…”

Scenario analysis of embodied greenhouse gas emissions in UK construction

“…Further disaggregation of the infrastructure class in particular could build on projections of construction and future emissions submitted to regulators (e.g. Keil et al, 2013). Better statistics on physical outputs (i.e.…”