Lifecycle Assessment of Solar Thermal Collector

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  • All goods and services have an environmental impact along their life cycle. On this concept

    the European countries have focused their attention, considering the improvement of

    Renewable Energy 30 (2005) 10311054$ - see front matter q 2004 Elsevier Ltd. All rights reserved.Life cycle assessment of a solar thermal collector

    Fulvio Ardente, Giorgio Beccali,Maurizio Cellura*, Valerio Lo Brano

    Dipartimento di Ricerche Energetiche ed Ambientali (DREAM),

    Universita` di Palermo, Viale delle Scienze, 90128 Palermo, Italy

    Received 9 March 2004; accepted 13 September 2004

    Available online 23 November 2004


    The renewable energy sources are often presented as clean sources, not considering the

    environmental impacts related to their manufacture. The production of the renewable plants, like

    every production process, entails a consumption of energy and raw materials as well as the release of

    pollutants. Furthermore, the impacts related to some life cycle phases (as maintenance or

    installation) are sometimes neglected or not adequately investigated.

    The energy and the environmental performances of one of the most common renewable

    technologies have been studied: the solar thermal collector for sanitary warm water demand. A life

    cycle assessment (LCA) has been performed following the international standards of series ISO

    14040. The aim is to trace the products eco-profile that synthesises the main energy and

    environmental impacts related to the whole products life cycle. The following phases have been

    investigated: production and deliver of energy and raw materials, production process, installation,

    maintenance, disposal and transports occurring during each step. The analysis is carried out on the

    basis of data directly collected in an Italian factory.

    q 2004 Elsevier Ltd. All rights reserved.

    Keywords: Life cycle assessment (LCA); Renewable energy; Solar thermal collector

    1. Introductiondoi:10.1016/j.renene.2004.09.009

    * Corresponding author. Tel.: C39 91 236 131; fax: C39 91 484 425.

    E-mail address: (M. Cellura).

  • pro

    The need to strengthen the green market has been successively confirmed in another

    F. Ardente et al. / Renewable Energy 30 (2005) 103110541032official document named the green paper on Integrated Product Policy (IPP) [2]. Once a

    product is put on the market, there is relatively little that can be done to improve its

    environmental characteristics. The IPP approach seeks to reduce the environmental

    impacts occurring throughout the entire life cycle of the product since the early stages

    of product design and development. Furthermore, the diffusion of the green public

    procurement should induce the producers to investigate the environmental impacts of

    their production and to disseminate the environmental information adopting scientific data

    format as the environmental product declaration (EPD) [3].

    For IPP to be effective, life cycle thinking needs to become second nature for all those

    who come into contact with products [4]. The cognitive process is at the basis of the

    environmental performances improving. It is necessary to have detailed and reliable data

    on which to base assessments regarding each life cycle step. Life cycle assessment (LCA)

    represents an important support tool for IPP and the the best framework for assessing the

    potential environmental impacts of products currently available [4]. To obtain reliable

    results, data should be collected and managed following standardised procedures. The

    international standards of series ISO 14040 represent a widespread accepted methodology

    [57]. The best way to demonstrate the advantage of the life cycle thinking concept is by

    demonstrating its practical application. The present paper focuses the attention upon one

    of the most common renewable technologies: the solar thermal collectors for warm

    sanitary water demand. Renewable energy sources are often presented as clean energy,

    not considering the environmental impacts related to their manufacture. The production of

    the renewable plants, like every production process, entails a consumption of energy and

    natural resources as well as the release of pollutants [8].

    Many authors have deeply investigated the benefits related to the employment of solar

    systems [913] including studies regarding LCA of solar collectors and comparative

    analyses of different collectors typologies [1419]. However, the studys assumptions or

    data references are often not clearly shown. In addition, results are often presented as

    aggregated indexes [1517] making difficult the comparison among different studies or the

    dominance analysis of each life cycle step are difficult. Furthermore, some life cycle steps

    (as, for example, installation or maintenance processes) are generally not investigated in

    detail or are simply neglected. Some studies, in fact, consider the full LCA of a solar

    collectors as too much expensive and time consuming [17] or suppose as significant only

    the impacts related to materials processing and collectors assembling [18,19].

    On the other hand, the principles of eco-design suggest to employ disaggregated

    information to identify the steps with the greatest impacts and with the largest

    improvements potentials [20,21]. The aims of this paper are:

    to trace an eco-balance of an exemplary equipment, referring to a passive thermal. The

    research refers to a passive thermal solar collector produced in Italy

    to grant transparency of assumptions, system boundaries and data sources in order tothegramme [1]. In other words, global environmental problems can be met only if the use of

    energy and the raw materials per product unit will be reduced, i.e. eco-efficiency increased.the eco-performances of products/services as a key point of the European environmentalallow comparability to other studies

  • to present results as much disaggregated as possible, in order to show the incidence of

    each component and life cycle step and to avoid uncertainties related to weighting

    processes and impacts assessment









    2. Impacts per unit of collector area. This alternative may be misleading. Enlarging the

    collector surface S, the specific environmental impacts (as, for example, the CO2/S)

    F. Ardente et al. / Renewable Energy 30 (2005) 10311054 10331

    watcould decrease. So, two collectors with the same total impacts could have different

    specific ones. In fact, the collector with the greater surface would be considered as more

    ecological not necessarily being. Furthermore, a greater extension does not imply a

    proportional growth of the energy harvest, due to the non-linear relationship between

    the collector surface and the collected energy.

    3. Impact per unit of energy output. This alternative is generally chosen for energy

    systems [23,24], because it refers to the environmental impacts of the energy

    performances of the plant. However, it is difficult to apply this FU to the LCA of solar

    collectors. The output of this system is an extremely variable data, depending on

    The first one represents the normal flat collector whose thermal fluid is moved by a pump towards a separate

    er tank. The second is a compact collector strictly connected to a smaller water tank, and the fluid is naturallysame product category. The choice of the FU is not always immediate. In our case study

    three different alternatives were checked [3]:

    1. FU equal to the entire equipment. The results are presented as global quantities

    concerning the whole collector. Probably, this is the most intuitive choice but it could

    cause misunderstanding. In fact, there are various typologies of collectors, which can

    be roughly divided in two main categories: collectors with forced circulating flow and

    collectors with natural circulating flow.1 Performing the LCA related to these two

    collectors types, the results could be not comparable.uni

    asmoThe choice of the functional unit (FU)

    The first phase of the LCA is the goal and scope definition. It includes an important

    p: the clear statement of the functional unit (FU). The FU is defined as the reference

    t expressed as quantified performance of the product system [5]. The FU is important

    basis for data collection and for the comparability of different studies referred to theta regarding the production, the installation and maintenance phases have been directly

    llected; thanks to the collaboration of an Italian firm [22]. The data collection has been

    o referred to the Environmental Management System active in the production site. Data

    arding raw materials and energy sources have been referred, when possible, to Italian

    an values. When not available, data of other European databases have been employed.durThe presented results are extracted from the case study CS2 performed within the

    rks of Task 27Subtask C of IEA (International Energy Agency) about Performance,

    ability and sustainability of advanced windows and solar components for buildings.ved by the difference of density caused by the solar heating.

  • the solar energy input. Confusion could arise referring the impacts to the energy output

    because the same collector could have a different eco-profile depending on the location.

    Our LCA case study refers to the first FU alternative, and the environment