ASSESSMENT OF ALTERNATIVE WATER

Transcription

1 Restricted dissemination (Service contract No /2008/496501/SER/D2) ASSESSMENT OF ALTERNATIVE WATER SUPPLY OPTIONS FINAL SUMMARY REPORT (SHORT VERSION) Author(s): Paul Campling (VITO), Leo De Nocker (VITO), Wim Schiettecatte (VITO), Ayis I. Iacovides (IACO), Thomas Dworak (Ecologic), Eleftheria Kampa (Ecologic), Manuel Álvarez Arenas (TAU), César Cuevas Pozo (TAU), Owen Le Mat (ACTeon), Verena Mattheiß (ACTeon), Fabienne Kervarec (ACTeon) Study undertaken for the European Commission DG Environment ACTeon 2008/IMS/R/ N97DO/PCA VITO December 2008

2 All rights, amongst which the copyright, on the materials described in this document rest with the Flemish Institute for Technological Research NV ( VITO ), Boeretang 200, BE-2400 Mol, Register of Legal Entities VAT BE The information provided in this document is confidential information of VITO. This document may not be reproduced or brought into circulation without the prior written consent of VITO. Without prior permission in writing from VITO this document may not be used, in whole or in part, for the lodging of claims, for conducting proceedings, for publicity and/or for the benefit or acquisition in a more general sense. 2

3 EXTENDED SUMMARY In 2008 DG Environment of the European Commission launched a project Assessment of alternative water supply options to assess four alternative water supply options in Europe, with the specific objectives to: Task 1 - assess the risks and impacts of four alternative water supply options (desalination, wastewater re-use, ground water recharge, and rainwater harvesting); Task 2 - assess the extent to which the possible negative effects from these water supply options in terms of environment and human health can be mitigated; and, Task 3 - identify conditions for the sustainable development of alternative supply options This Final Summary Report (short version) provides the main results and conclusions of the Task 1, 2 and 3 Reports, that are provided as annexes. Desalination is a proven alternative water supply technology that is growing in importance in and outside of Europe. It can be a replacement for potable mains water supply, but its supply regime is rigid and inflexible, and so is best suited for supplying a fixed amount of water according to its design specifications. There remains in particular environmental and economic concerns about the high energy use of the desalination process meaning that mitigation measures are needed to either improve efficiency or incorporate the use of renewable energy resources. In addition, there are also concerns about the impact on the environment of disposing brine meaning that adequate mitigation measures have to be incorporated to deal with brine disposal. Wastewater re-use is a proven alternative water supply technology, that is particularly important in Southern Europe. It is not a direct replacement for potable mains water supply, and so is used for non-potable uses, such as irrigation and watering landscapes. This means that wastewater re-use is most important in terms of reducing the demands for freshwater. If the end use of waste-water reuse is for non-potable requirements then the capital costs and energy use are relatively low. The main concerns are the need to have strict quality controls to minimise the risk of environmental contamination and health problems. Currently there is no European Union legislation concerning the quality controls and standards for wastewater re-use. Mitigation measures are needed to ensure that the environmental contamination risk is minimised. Rainwater harvesting is a proven alternative water supply technology, that is used in different situations across Europe. However there is not much information on the uptake of the technology, as it is carried out usually at the household or industrial plant level. It is an indirect replacement of mains potable water supply in the sense that is used within the house or industrial plant for non-potable purposes. The main factor that effects the uptake of the technology is the investment cost of installing the RWHS, especially if retrofitting is involved, because a double internal water distribution system has to be installed. In addition the rainfall distribution may not be evenly spread across the year meaning that a relatively large and costly rainwater storage tank needs to be installed. Mitigation measures are needed therefore to reduce the financial burden of this technology to improve the rate of uptake. Groundwater recharge is a proven technology that is used primarily in Northern Europe. The technology is quite wide ranging compared to the other technologies as it can include recharging with tertiary treated waste water or primary treated surface or rain water. When wastewater used is used for ground water recharge there is a need to 3

4 have strict controls to ensure that the wastewater is sufficiently purified the effect could be catastrophic on the groundwater if a calamity occurs and contamination is the end result. This means reliable mitigation measures and procedures have to be more or less guaranteed. If surface or rain water is used for groundwater recharge then only primary treatment is necessary and the environmental risks are much lower than using wastewater. Although these are all proven and reliable technologies there remains a difference between the mitigation requirements for drink water use in comparison to non-potable uses for households (e.g. rainwater harvesting for toilet flushing, washing machines, gardening), industry (e.g. wastewater re-use and rainwater harvesting for cooling, manufacturing processes) and agriculture (e.g. wastewater re-use for large-scale irrigation, rainwater harvesting for small-scale greenhouse irrigation). The case studies in Task 2 confirm that the list of environmental, economic and social issues identified in Task 1 covers the main issues. The case studies indicate that the mitigation measures used were successful to address potential and locally specific environmental concerns. Potential problems and mitigation options differ between locations and technologies meaning that mitigation measures have to be designed to deal with local conditions. The case studies therefore do not provide a single set of best available mitigation options or recommendations for good practise, but rather provide check-lists of potential problems and a catalogue of potential mitigation options, with illustrations about successful applications. The mitigation options are very diverse. They include case specific choice of location and ex-ante procedures (e.g. environmental impact studies) to define the framework and conditions for the water supply to operate. The following issues need to be addressed : Potential land-use and noise impacts from desalination and wastewater treatment plants; Impact of brine discharge on coastal and marine ecosystems; Contamination of soil and groundwater from treated wastewater which is re used. The added investment in distribution networks to transfer treated waste water from UWWT plants to agricultural land for irrigation, desalinated water from desalination plants to the mains water supply, harvested rainwater to toilets and washing machines (dual household distribution system). This last issue needs extensive monitoring and control. One point of note is that there is still no EU wide directive on the use of treated wastewater for irrigation. Mitigation measures to avoid public health impacts from misuse of rain water or treated waste water not intended for potable use include the setting up of national or local standards for water to be used or for equipment and installation procedures, defining guidance for good practise, labelling of tap points, information and education, The case studies give examples of implementing monitoring or control, also in cases where many users are involved. Compared to conventional water supply sources, some alternative water supply options require more energy (desalination) or more materials for equipment (rainwater harvesting) per m³ of water. This leads not only to higher costs, but also a higher burden on the environment. These issues are difficult to solve in the context of water supply decisions, and therefore need to be addressed in a wider environmental framework. 4

5 As desalination requires more energy compared to other conventional water supply sources, it will result in a higher carbon footprint, if it uses energy from fossil fuels directly or electricity from the mains grid generated by fossil fuel power stations. Although the designated use of renewables, such as solar or wind energy, may reduce the carbon footprint of desalination this problem, the current total costs of renewable energy per kwh are significantly higher. During 2008 the market price of crude oil peaked at 147 USD per barrel in July and then fell to 40 USD per barrel by December. Comparisons therefore between the short and long term economic costs of renewables and fossil fuels remain uncertain. It should also be remembered that desalination plants need a steady supply of energy to function optimally - this means that renewable energy supplies from wind and solar, which fluctuate depending on wind and solar conditions, and therefore need to be backed up by the mains electricity grid (or a fossil fuel powered generator). An alternative set up is to power the desalination plant continuously from the mains electricty grid, that is powered partially by renewables connected by a "smart" grid. Therefore, the costs of renewables and the need for a steady energy supply have to be considered. Rainwater harvesting systems require a relatively large investment in rainwater tanks, which is not only reflected in being an economic obstacle, but also in the relatively high environmental life cycle impacts embedded in material and energy use. There are no mitigation options to deal with this apart from guidelines to promote an optimal sizing of RW tanks. Alternative water supply options may be more expensive then more conventional options, especially if water prices do not recover all private and environmental costs. The case studies illustrate that in these cases the promotion of alternative water supply options are likely to use subsidies to compensate for price differences. However, these may in the long term not be the best way to deal with this situation, as it does not promote overall efficiency of water use. Therefore, it is recommended that promotion of more expensive alternative water supply options is accompanied by a revision of water pricing towards a full recovery of all private and environmental costs. Higher water prices give rise to concerns about the affordability of mains water for the low income groups. Furthermore, higher water prices also raise concerns about the affordability for agriculture and industries that have been used to having access to cheap, high quality water. Although subsidies can help these users in the transition towards a more sustainable use of water resources, the final goal should be to have sustainable water use where price of water reflects its true cost, efficiencies are improved, and water demand reduced. The case studies illustrate that the mitigation measures addressed have allowed alternative water supply options to be established. However, as the knowledge and experience on a number of issues is limited, further research on potential impacts and mitigation options are required. This is the case for: Discharge of brine into marine and coastal ecosystems Accumulation of boron from desalinated water in the water system and ecosystems; Contamination of soil and groundwater from treated wastewater; Scopes to improve energy efficiency of desalination; Scope for more cost-efficient use of rainwater harvesting systems, including upgrading of existing tanks and use in collective systems; Net costs of rainwater harvesting systems, accounting for short- and long term impacts on investments for mains water supply and distribution, sewage and sewage treatment and storm water management; Risks for human health of dual water supply systems and re-use of treated wastewater for irrigation; 5

6 Capability of mitigation options to adapt to climate change scenarios The main conclusion from the five case studies described in the Task 3 report is that alternative water supply options can be successfully used to solve water management problems, both related to droughts, storm water management and water quality issues. For some of the regions studied, alternative water supplies are becoming the largest contributors to meeting water demand. Due to the overriding importance of local factors there is a need to find local solutions to local problems. Therefore a European wide ranking of appropriate alternative water supply options and sustainable development issues is not possible. However, a number of interesting lessons can be learned from the case studies evaluated. The case studies provide a mixed picture related to the economics of alternative water supply options, but illustrate the need for appropriate price stetting of water systems. Some cases such as ground water recharge with treated wastewater illustrate that an alternative water supply option may be more cost effective compared to water transfers (for example, the coastal region of Belgium case study). In some cases an alternative water supply option may be cost effective because the environmental and resource costs of traditional water management are reflected in the price system, as is illustrated for rainwater harvesting in Berlin. In other cases, alternative water supply options are more costly than current mains water prices and so are difficult to introduce without subsidies, especially if current water prices do not reflect all costs (including environmental and resource costs) (for example, the case studies in Cyprus, Malta and Southern Spain). The requirements of the WFD to implement integrated water management and cost recovery programmes will contribute to a better appreciation of the benefits of alternative supply options. However ready to use tools and data are missing to facilitate the analysis of local problems and account for the full costs and benefits of all options. 6