A study of farming could be ideal for a student living in a rural environment (and who may even have a farming background). An investigation that is focused upon change will almost certainly question the impact of government policies and changing consumer preferences. However, it may also be possible to inquire if weather conditions over recent years have had any impact upon decision-making: have any new crops been introduced in response to warmer weather, for instance? For such a study to be successful, a student will need full cooperation from the farmer(s) being surveyed, as they will be personally providing much of the data.
A study of a supermarket as a site of consumption could provide a local study whose analysis will connect with plenty of interesting global issues. Where is food sourced from? How are store supply patterns changing? Are fewer or more products shipped over long distances than in the past? Alternatively, an investigation could contrast the supply networks of two different suppliers, perhaps an organic store and a supermarket.
London-based students could investigate the impact of the London congestion charge on local businesses (one stated aim of the charge has been to reduce London’s carbon emissions).
Other suggestions: