The workshop on Mathematical Modelling and Mathematical Methods in Energy was held in COPEL Building, Curitiba, Brazil from 29 November to 1 December 2004 with more than 100 participants. The scientific programme consisted of 20 invited talks and 20 contributed papers. All talks were well attended with deep discussions. The participants came from Brazil, Canada, China and U.S.A. The following mathematical modelling and methods applied in energy area such as petrol and electric energy were discussed: partial differential equations, singular value decomposition (SVD), eigenvalue problems, preconditioning techniques and optimization. All participants, especially people from energy engineering, recognized the importance of participation and collaboration with mathematicians for their researches. The present volume contains seven selected papers essentially devoted to numerical linear algebra with applications in energy area. We thank the referees who helped us in doing the editorial work. Their efforts and suggestions made it possible to publish scientific papers with high quality. We appreciate the support of the Scientific Committee of theWorkshop consisting of Jose Luiz Alqueres (ALSTOM, Brazil), Ricardo Biloti (UFPR, Brazil), Mario Jorge Dias Carneiro (UFMG, Brazil), Paulo Afonso Bracarense Costa (CGEE-MCT, Brazil), Djalma M. Falcao (UFRJ, Brazil), Clovis Gonzaga (UFSC, Brazil), Sergio Granville (PSR, Brazil), Fernando Gruppelli (COPEL, Brazil), Dan Marchesin (IMPA, Brazil), Claudia Sagastizabal (IMPA, Brazil), Robson Luiz Schiefler (COPEL), Jurandyr Schmidt (PETROBRAS), Carlos Tomei (PUC-Rio, Brazil), Lei Wang (PowerTech Labs, Canada), and Jin Yun Yuan (UFPR, Brazil). The workshop was sponsored by Araucaria Foundation, Brazilian National Agency of Electric Energy, Brazilian Society of Mathematics, COPEL, Global Progress of Brazilian MathematicsMillennium Institute (IM-AGIMB), Ministry of Education, Federal University of Parana and Federal University of Santa Catarina. Last, but not the least, we thank all participants for their contribution and efforts in making the Workshop an interesting, pleasant and successful event.