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Title Environmental Assessment of Enzymatic Biotechnology
Author Kløverpris, Jesper
Andersen, Jens Toftegaard
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2004
Abstract The purpose of the project has been to perform a general environmental assessment of enzymatic biotechnology. The conclusions have been drawn on the basis of 11 case studies performed and presented separately in a Case Study Report. The case studies constitute comparative life cycle screenings performed on different applications of enzyme products produced by the Danish biotech company Novozymes A/S. The life cycle screenings have mainly focused on primary energy but other impact categories have been considered in supplemental qualitative impact assessments. It has been investigated whether the environmental performance of an enzyme product is related to specific characteristics of the enzymatic application. The enzyme product applications represent a range of net savings of around 350 to 43400 MJ/kg. Furthermore, the ratio between the avoided and induced primary energies represents a range of 1.4 to 60. The investigated enzyme products have been categorised in six groups and are ascribed so-called cradle to gate primary energy in the range of around 22 to 234 MJ per kg of formulated product. Induced primary energy of the enzyme products are in all cases seen to be of minor importance for the net savings. The primary energy of the enzyme products only reduce the net savings by 0.2 to 13 percent. Besides the induced primary energy of the enzyme product itself, the enzyme applications have generally been associated with a number of system changes, being decisive for the environmental characteristics of the enzyme product. Some enzyme products cause raw material savings. This is considered a main system change and it results in avoided primary energy. In some cases, the raw material savings may lead to an induced flow of another raw material, which results in induced primary energy reducing the net savings. Some enzyme products directly substitute auxiliaries, partially or totally. The case studies have shown that this type of application typically has a simple set of system changes. Some enzyme products provide savings of process energy. This leads to avoided primary energy. In systems with heat recovery, energy savings may be accompanied by induced process energy. This leads to induced primary energy. In one of the 11 case studies the net savings of primary energy are associated with an environmental trade-off. In order to characterise an enzyme product as environmentally superior, the product must result in positive net savings of primary energy and not be compromised by significant environmental trade-offs. In case of raw material savings, this means that it must be meaningful to ascribe a specific primary energy to the avoided raw material seen in a consequential life cycle perspective. In case of direct auxiliary substitution, the exchange ratio between the avoided auxiliary and the enzyme product must be higher than the ratio between the primary energy of the enzyme and the auxiliary, respectively. If an enzyme product reduces the need for process energy, positive net savings are obtained if the primary energy savings per kg of enzyme exceeds the primary energy related to one kg of the enzyme product. Furthermore, the primary energy of the avoided process energy must be higher than the primary energy of a possible induced energy flow. Based on the findings in the project, it is concluded that enzymatic solutions generally can be considered environmentally superior to their conventional alternatives.
Pages 250
Admin Creation date: 2006-06-22    Update date: 2007-02-24    Source: dtu    ID: 177827    Original MXD