The utilization of biogas produced from organic materials such as agricultural wastes or manure is increasing. However, the raw biogas contains a large share of carbon dioxide which must be removed before utilization in many applications, for example, using the gas as vehicle fuel. The process – biogas upgrading – can be performed with several technologies: water scrubbing, organic solvent scrubbing, amine scrubbing, pressure swing adsorption (PSA), and gas separation membranes. This perspective presents the technologies that are used commercially for biogas upgrading today, recent developments in the field and compares the technologies with regard to aspects such as technology maturity, investment cost, energy demand and consumables. Emerging technologies for small‐scale upgrading and future applications of upgraded biogas such as liquefied biogas are also discussed. It shows that the market situation has changed rapidly in recent years, from being totally dominated by pressure swing adsorption (PSA) and water scrubbing to being more balanced with new technologies (amine scrubbing) reaching significant market shares. There are significant economies of scale for all the technologies investigated, the specific investment costs are similar for plants with a throughput capacity of 1500 Nm3 raw biogas per hour or larger. Biogas production is increasing in Europe and around the globe, and so is the interest in the efficient use of upgraded biogas as vehicle fuel or in other applications. The market for biogas upgrading will most likely be characterized by harder competition with the establishment of new upgrading technologies and further optimization of the mature ones to decrease operation costs. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd

We present quantitative reconstructions of regional vegetation cover in northwestern Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present (BP)] at a 1° 9 1° spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, Correspondence: A.-K. Trondman, tel. + 46 (0)480 44 61 98, fax + 46 (0)480 44 73 40, Global Change Biology summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k BP and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k BP is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover-climate interactions, biodiversity and human resources.

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