Optimized Hybrid Wind-Solar Energy System Structures for Irrigation Pump Load Sites in Kenya

Abstract

The world’s Sustainable Development Goals as clearly presented by the United Nations Department of economic and social affairs has zero hunger, and affordable clean energy. In the global struggle to meet both energy and sustainable agriculture, emerges the complex Energy-Water-Food (EWF) nexus. Kenya has initiated large-scale irrigation projects to ensure zero hunger. However, the energy required to run the pumps is very high, since diesel pumps and diesel generators are extensively used. This translates to high food production costs. In this research, optimized affordable clean energy systems required for irrigation were modeled and studied. Optimized hybrid wind and solar energy solutions for irrigation projects were presented. Five potential large-scale irrigation sites in Kenya were considered namely: Galana-Kulalu, Lotikipi, Rahole, Wei Wei, and Perkerra. The results showed that the energy requirement scenarios depended majorly on on-site conditions; crop water need cycles and rainfall patterns. Average Wind Speed to Global Horizontal Irradiance ratio influenced the structure of hybrid energy systems. Based on this ratio, longer cycle crops like sugarcane, maize, and cotton required systems with higher wind energy penetration compared to shorter cycle crops like radish and spinach. When this ratio changed in selected other irrigation sites, wind to solar power production was greater than one, and up to 500 times greater than one in sites with relatively stable sufficient wind like Lotikipi. Wind energy systems for areas with higher ratios contributed to smaller system structures as a result of a lower number of solar photovoltaic panels installed.

Adapted Irrigation Pump Load in Solar PV and Wind Energy Systems through Stepped Variable Frequency Drives

“…In second phase, detailed analysis of pump model so that pump load profile matched with pump power. The uniqueness of this research was proper irrigation load modeling done in many crop situations as well as for different irrigation sites in Kenya [1]. The irrigation water needs modeled from the agricultural parameters [22] given in Equation 1 below.…”

“…2 was used. It was a typical physical irrigation site as postulated by [1]. It was possible to install at least solar PV panels and wind turbines in the sites selected.…”

“…The figure above was extracted from [1], in the research for "Optimized Optimized Hybrid Wind-Solar Energy System Structures For Irrigation Pump Load Sites In Kenya". This research conducted in the first phase where the optimal structure of wind and solar PV system corresponding to irrigation sites and crops was prerequisite.…”

“…Note that the discharge required defined in the term kQkHfe 3 in the model was key point in the research. This term represented the Head (H) and Discharge (Q) as shown in affinity laws (Equation 5) [1]. The difference between the generated and utilized power gave the surplus or deficit.…”

“…Kenya has put in place strategies to shift focus from rain-fed agriculture to irrigation agriculture. Kenya has earmarked several irrigation projects and corresponding sites some of which are: Galana-Kulalu, Lotikipi, Perkerra, Rahole, and Wei Wei for this purpose [1]. The project's main purpose is to address the food security problem although significant commercial interest still exists, especially if cash crops can be grown there.…”