More recently, Campbell et al. (2014) performed emergy evaluations
of the global biogeochemical cycles; Watanabe and Ortega (2014) used
emergy for estimating the monetary value of ecosystem services
provided by the Taquarizinho river basin in Brazil while Campbell and
Tilley (2014) used emergy to assess the biophysical value of forest
ecosystem services in Maryland and introduced new emergy-to-dollar ratios,
termed eco-prices, to convert the emergy values of ecosystem services
to dollars