Climate Change: Implications for Hydropower Sustainability HSAF Meeting 5 Itaipu Dec. 8, 2008
Without climate change, we might not be in this room: Renewed interest in renewable energy for climate change mitigation is one of the factors behind the current surge in hydropower development. Several climate-related issues are relevant for us: Hydrological Variability impacts on safety, reliability, economic viability, reservoir management, environmental flows etc. Greenhouse Gas Emissions from Reservoirs impacts on environmental impact assessment, location & design of new projects, reservoir management, eligibility for participation in carbon trading Carbon Markets impacts on economic viability, incentives for adoption of sustainability standards Currently the word climate is mentioned only once in the SAP, as part of the definitions under Aspect C1 (governance of existing projects).
Issue 1: Hydrological Variability
Runoff is a key input parameter for power generation and is determined by three components: - natural physical cycles - trends - random influences With longer time series and more sophisticated models, water managers and infrastructure planners have become used to ever better predictive abilities. Much of water management is about managing variability expected variability within natural cycles, changes due to trends (some well known, others emerging), plus random fluctuations around expected flows, the range of which may be changing as well. Some of the climate-change induced trends are secondary effects e.g. increased upstream abstraction for irrigation.
In describing the forecasts of changing hydrology, the report said its studies had high confidence that, by mid-century, annual river runoff and water availability were likely to increase in high latitudes and some tropical wet areas but decrease in some dry regions in the mid-latitudes and tropics. The IPCC said there was also high confidence that there would be reduced water resources in semi-arid areas, such as the Mediterranean basin, western US, southern Africa and North east Brazil. The only reference to a rise in specific regional risk for hydropower the report pointed to the Mediterranean basin. With regard to North America, the report says: Warming in western mountains is projected to cause decreased snowpack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources. While the report mentions hydropower specifically in a few instances, especially as a mitigation technology to help stabilise emissions, it also mentions in many areas the broad disruptive effects to food and health and security from the change in climate patterns. The increase in hydrological risk presents a broader challenge to water resources, and the roles of dams and reservoirs in irrigation, water supplies and flood management.
Science, February 2008
Lake Mead could be dry by 2021..
Projected changes in runoff: on major rivers.. Discharge at mouth, average 1960s - 1990s, in km 3 / year Discharge at mouth, 2050s, in km 3 / year Percentage change Amazon-Orinoco 6803 5537-19% Ganges-Brahmaputra 1187 1388 +17% Yangtze 955 1122 +17% Amur 331 413 +25% Danube 216 192-11% Indus 121 175 +44% Zambezi 120 105-13% Nile 76 65-14%
.. at regional levels..
.. and at project scales Climate Change & Water Infrastructure Jörg Hartmann WWF Dams Initiative tel +49 69 79144 131 mob +49 162 291 4438 hartmann@wwf.de
plus: Seasonal Shifts
Changes in runoff (total / seasonal) Why does this matter? determine appropriate dimensioning of power station and reservoir (exante) and load factor (ex-post) Changes in frequency / magnitude of extreme events determine storage requirements and outflow capacities (ex-ante) and utility and safety of existing structures (ex-post) Secondary effects, e.g. changes in erosion and sedimentation rates determine storage requirements, sediment management facilities (ex-ante) and life expectancy of reservoir (ex-post) climate change imposes hydrological and therefore financial and safety risks on hydropower (but may also create hydrological opportunities)
Options for Managing Hydrological Risks Four generic categories of response to risks treatment / reduction / mitigation termination / avoidance / elimination toleration / retention / acceptance transfer Example: The risk of low flows / low load factors can be mitigated by adding storage capacity or by pooling generation assets, avoided by abandoning a hydropower project, accepted by going ahead with designs based on historical hydrology, transferred by buying insurance (such as weather insurance) or concluding PPAs without firm delivery commitments
Treatment of climate-induced hydrological changes in the SAP Quality of the analysis and management of the hydrological resource is currently a consideration under B4 ( planned operational efficiency and reliability ) and C5 ( operational efficiency ), C6 ( operational reliability ). Hydrology touches upon many issues incl safety, reliability, economic viability, reservoir management, environmental flows and other aspects. Should there be one overall aspect that captures a credible approach, or should it be mentioned as a requirement under a variety of aspects? Challenge: how to measure how well planning, design and operations deal with uncertainties and adaptation to ongoing changes? Suggested lead questions: - Do project owners understand risks (and opportunities), and have they assessed all management options? - Does infrastructure permit flexible operations? - Is there an active monitoring program in place to inform an ongoing adaptation process?
Issue 2: Greenhouse Gas Emissions from Reservoirs Sadly, although the technical issues appear tractable, the unfolding dispute seems unlikely to spawn the normal mechanisms for scientific resolution.
Full Accounting of GHG Emissions Reservoir emissions result from the decomposition of the biomass that was submerged, that enters the reservoir later, and that grows within the reservoir itself. Reservoirs are classified as land-use changes under IPCC Guidelines for National Inventories and countries should reduce uncertainties surrounding emissions, following a recommended methodoloy. Reservoir emissions are only one component of the GHG footprint of hydropower. Other components include - the GHG footprint of materials and transport during construction - emissions due to displacement of settlements and agriculture, deforestation near access roads and transmission lines - the carbon content of sediment released at decomissioning - the changes to carbon uptake in the river basin (by holding back water, sediment, nutrients, trace elements etc.)
Reservoir and River Biogeochemistry Focus on net changes in the carbon cycle imposed by reservoirs: - Reservoirs replace a natural carbon source or sink. - By creating anaerobic / anoxic conditions, reservoirs may convert carbon which would otherwise have been emitted as CO 2 into CH 4. - By storing carbon in the sediment, reservoirs keep it temporarily out of circulation.
Shallow tropical reservoirs are most likely to emit significant amounts of GHG as they tend to develop anaerobic conditions and have significant amounts of biomass available. Options for reducing GHG emissions: 1. Vegetation management prior to flooding 2. Catchment management initiatives 3. Multiple off-take 4. Site selection 5. Water residence time 6. In-reservoir oxygenation systems 7. Off-set sequestration program 8. Methane capture
Current and future treatment of GHG emissions in the SAP Direct and indirect GHG emissions over the life of the scheme are covered under A19-A20 for the comparison of different energy supply options. Reservoir management is covered under generic aspects B18, C16. Objective: GHG emissions of new and existing projects should be evaluated, and options for reducing them should be used as far as feasible we are looking at quality of analysis and quality of mitigation. Methodological guidance required (IHA/UNESCO process, IPCC, independent scientific process) Guidance to be translated into clear eligibility / accounting rules for carbon trading.
Current Power Density Rules in the CDM Power density is defined as installed capacity in proportion to flooded area. At low power densities below 4 Watts/m 2, hydro projects cannot be registered for the CDM. Between 4 W/m 2 and 10 W/m 2, projects have to assume an emission of 90g CO 2 equivalent per KWh, and above 10 W/m 2, emissions do not need to be taken into consideration.
Issue 3: Carbon Markets