Resource Return on Investment under Markup Pricing

In the (very) long run, a sustainable economy must rely on renewable resources. Until that time, an economy can be based on either renewable resources alone or a mix of renewable and non-renewable resources, but the particular mix may constrain the types of economic structures that are possible. A particularly important consideration is the quantity of resources required to extract the resources on which the economy is based, whether it is seeds retained for planting or petroleum used to extract oil. In the case of energy this is called “energy return on energy investment”, or EROI. More generally, it can be considered “resource return on resource investment”, or RROI. EROI has drawn attention lately both because the EROI of fossil fuels is falling and because the EROI of some renewable alternatives – especially for liquid fuels – is low compared to fossil fuels. In conventional economic analysis it is not clear what the relation between EROI, energy price, and macroeconomic outcomes might be. However, it raises immediate concerns within an Ecological Economic framework, in which resources – which may contribute only a small amount to GDP – are viewed as essential to the functioning of the economy. Resources are pictured as sitting at the base of an inverted pyramid, with the rest of the economy balanced on top of them. In this paper we show that when prices are set by markup, a standard Post-Keynesian assumption, then the “inverted pyramid” picture of the economy emerges naturally. We use this result to develop a computational framework for a “markup economy”, and apply it to the question of the macroeconomic impact of changes in resource prices and resource return on investment. We use the resulting model to explore several macroeconomic questions, demonstrating that the model is quite useful for exploring the role of natural resources in the macroeconomy. We then show our main result, that RROI has a surprisingly limited effect on real wages until it reaches quite low values.