Abstract
Emissions associated with hydropower are often forgotten. Lifecycle assessments of greenhouse gas emissions emanating from hydropower must count embedded carbon, emissions from reservoir lakes and the loss of carbon sinks, as well as backup diesel generation emissions when dependence on hydropower fails to deliver energy. Using Zambia as a case study, we estimate using a bottom-up approach that the emissions associated with backup diesel generation from Zambia’s power utility ZESCO and three largest sectors of consumers were up to 27 000 tonnes of in the worst months of drought in 2019. This is significantly higher than what a previous top-down approach would have estimated.We worked out ZESCO’s diesel generation attributable to drought using trend analysis. We worked out the mining sector’s emissions using copper production data, on-grid electricity consumption and calculated electricity intensity to infer off-grid electricity consumption in years of drought. From our household survey we learned average duration of generator use, average capacities of generators and acquired household income and generator use data which we ran in a Tobit regression. These together with labour force survey data helped us infer the level of diesel generation by households of different income brackets. For manufacturing firms we surveyed 123 firms. We collected rich diesel generation use data covering years of drought, input this into an OLS regression to identify predictors of diesel generation use (installed capacity of generator in kVA, in litres and whether generation was in a drought year) which we then used to extrapolate implied diesel generation for the firms for which we had less rich data.As global average temperatures and the frequency of El Niño droughts rise in hydropower dependent countries which account for a fifth of the world’s population, backup generation emissions have implications for the formulation of low carbon energy policy.
Highlights
Hydropower dependency can lead to the release of greenhouse gas emissions in another way: when rainfall is low, hydropower ceases to be the dependable source of energy that the grid operator has used it for, and end-consumers resort to generating their own energy using diesel generators
This study aims to highlight the significance of backup diesel generation emissions in a hydropower dependent context using recent data and a bottom-up approach with Zambia as a case study
Where we found respondents to be aged 25 or less and in the lowest income brackets, we discarded their responses as those who were 25 or younger and in the lowest income bracket and were using generators may have been doing so with support from their parents, and so should have been counted in their parents’ households, or were getting the benefit of diesel generators thanks to their university accommodation – the survey had reached University of Zambia students
Summary
Introduction cri ptLooking at proposed hydropower dams and the associated distribution infrastructure required in Chilean Patagonia, Mar (Mar, 2009) forecast that the carbon impact of construction equipment and machinery, transport of labour, material embedded energy, and land-use change would be 48x the impact of natural gas plants that would deliver an equivalent amount of energy. El Niño events have been forecast to increase in frequency with global warming (Wang et al, 2017) This will necessitate the governments and power utilities of those countries, largely located in southern Africa, southeast Asia, Australasia, and northern South America (FAO, 2015, 2018; Hao et al, 2018; Vidal, 2016), to think about how to make their energy generation infrastructure more climate resilient. It will necessitate thinking on how to avoid contributing to the global warming that is making their hydropower infrastructure increasingly redundant. We show that unreliable hydropower infrastructure paradoxically results in increased purchases and use of high-greenhouse gas emitting diesel generators
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