The costing of carbon credits from ocean nourishment plants

Ocean nourishment is a process for stimulating the sequestration of atmosph eric carbon dioxide in the deep ocean by providing the nutrients needed to enhance the production of phytoplankton. The carbon dioxide sink thus creat ed, can be used to generate tradeable carbon credits. The costs of sequeste ring carbon by the process of ocean nourishment have been estimated using a s a basis, the previous experience in nitrogen fixing of Toyo Engineering C orporation. While there are uncertainties about the biological uptake effic iency, these introduce only a moderate uncertainty in our overall estimates of costs. The major determinants of the costs are the interest that must b e paid on capital and the cost of the feedstock, natural gas. We have used for discussion purposes, an interest rate of 4-8% per annum and natural gas costs of US$0.5-$2 per GJ. The costs of carbon credits lie in the range US $6.70-$12.40 per tonne of carbon dioxide emissions sequestered. It should b e noted that we have adopted the measure of carbon avoided by non-emission, because of the complex partitioning of anthropogenic carbon between the at mosphere, land and ocean. (C) 2001 Elsevier Science B.V. All rights reserve d.