Mixed-use Systems Research Articles

Divide and Prosper? Impacts of power-distribution feeder separation on household energy-use, irrigation, and crop production

Subsidized access to electricity is important to meet increasing demand for irrigation and reducing reliance on dirtier diesel pumps. Feeder Separation (FS) is an engineering-solution which can ration supply to farmers, curtail power theft, and upgrade the power-grid network. However, limited evidence exists if and how FS actually benefits farmers, other consumers, and the environment.We compared effect of FS to traditional mixed-use feeder system using a quasi-experimental design with 2451 households from 12 districts in Madhya Pradesh, India. While the duration of supply remained the same as the mixed-use system, FS resulted in more regular (42% vs 49%) and better voltage (13% vs 19%) supply. Consequently, households shifted away from kerosene for lighting. Farmers reduced diesel-pump use by 41 h, increased electric-pump use by 45 h, and the net irrigation reduced by 12 percent without adversely affecting crop yields.FS can be a useful template for Low and Middle Income Countries that seek to expand irrigation with affordable access to electricity. Use of dirtier diesel pumps will persist to the extent grid power is unable to meet need of farmers for mechanised irriggattion. Therefore, FS combined with subsidized power for sustainable irrigation and full-priced power-supply beyond that limit can effectively curtail groundwater exploitation and reduce environmental impacts of diesel-pumps.

Carbon costing for mixed-use greywater recycling systems

Urbanisation in the twenty-first century is accompanied by higher water demands per unit area of available space. The ability of water providers to meet these demands long term will require sustainable innovations in terms of water supply. Previous research by the authors has shown that urban mixed-use systems that share greywater (GW) between high-rise domestic dwellings (where GW production exceeds non-potable demands) and high-rise offices (where non-potable demands exceed GW production) could overcome these difficulties. This paper explores the carbon costs (embodied and operational) of such an urban arrangement by investigating the influence of membrane bioreactors (MBRs), constructed wetlands (CWs), building heights, floor plate areas and cross-connection distances. Five water supply scenarios are considered: scenario 1 (conventional mains treated offsite); scenarios 2a and 2b (individual GW treatment via CW/MBR); scenarios 3a and 3b (shared GW treatment via CW/MBR). Over a 15-year period it is shown that shared CW treatment had the lowest carbon dioxide emissions, saving up to 11% compared with conventional mains, whereas a shared MBR increased carbon dioxide emissions by up to 27%. Furthermore, most carbon dioxide savings occur when the ratio (height or floor area) of office building to residential building is 2:3.