Assignment 1: Solar Powered Irrigation Systems

Assignment 1: Solar Powered Irrigation Systems

Assignment Overview

You will calculate the size of a photovoltaic (PV) panel for a solar powered irrigation system (SPIS) in this assignment. The main goal is to estimate the size (capacity) of a SPIS located in close proximity to a site that is significant to you personally or professionally. Make sure to choose parameters suitable for the specific local requirements.

You will carry out this assignment in teams of about ten people. Upon completion your team admin will submit your group’s report (online upload). In case you have difficulties to find a team, please ask us the Online-Tutors for support. You can reach the Tutors by directing a post to @poweringag or by sending a private message to PoweringAg. The Tutors are happy to assist you by finding a team. First, your peers (fellow MOOC-Participants from the other teams) will review your report upon submission. Second, the course instructor will review your report as well. The course instructor will evaluate your team’s submission regarding it’s eligibility for obtaining the Assignment One Badge. The instructor will also upload a summarized common feedback for Assignment One. The Instructor’s Feedback will address all the relevant issues observed in the individual reports.

In order to simplify the review process of your report, please follow the structure outlined below (chapter 1 to chapter 5). Providing your team’s draft within the marked fields below is the easiest way to use this template.

Please note that the deadline for uploading this assignment is the 21st of February. Please note that the last day to complete the peer review is the 28th of February.

Group’s name
Africa Unite Team Assignment 1 / Names of all contributing group members
1.  Jamie Krovontka
2.  Nawa Sililo
3.  Ngombo Kalimbwe
4.  Fuh Michael Apolonius
5.  Sean Rumage
6.  Victoria Solbert
7.  Hillary Allison Cirka
8.  Alberto Serena
9.  Salwa Bouadila
10. Julius Magala
11. Laura Serena

Chapter 1: Case study location

The proposed solar powered irrigation system will be located in the following area:

Continent / On which continent is your case study
Africa
Country / In which country is your case study located?
South Africa
Region / Please describe the site of your case study.
Mpumalanga Province, South Africa
Coordinates / Please provide the coordinates of your site:
nn°nn'nn"N/S nn°nn'nn"E/W (e.g. take it from google map)
Mpumalanga Province
Geographic latitude:29° 48’ 46" (29° 48’ 77) S
-29.81292 in decimal degrees
Geographic longitude:30° 38’ 11" (30° 38’ 18) E 30.63646 in decimal degrees
Site:Nelspruit
Latitude/longitude:25°28′28″S30°58′13″E
Decimal coordinates:-25.4745 30.9703
Short description about the socio economy of the region (max. 500 words) / Please incorporate the following information into your description:
Population size, main agricultural productions (staple food, cash crops, fruits, vegetables, etc.), main irrigation mechanisms, electricity supply (grid connected or off grid), main economic activities, market access for the agro products, climate conditions – temperature, precipitation, seasons, etc.
Mpumalanga Province with its capital, Nelspruit, has an area of 78 370 km² or 6, 4% of South Africa’s total area and a population of approximately 3 million.
Mpumalanga is located on the high plateau grassland known as Highveld and deep valleys of the Escarpment in the north-east.
The climate of Mpumalanga can be quite diverse. The Highveld has moderate summers with a rainy season and cold, frosty winters. The Lowveld experiences has a subtropical climate with mild winters. During winter, the Highveld and Escarpment can sometimes experience snow.
The variations in climate due to altitude can be observed by comparing average winter to summer temperatures in the capital, Nelspruit. Nelspruit averages: January maximum: 29 °C (min: 19 °C), July maximum: 23 °C (min: 6 °C), annual precipitation: 767 mm
Mpumalanga has a wide variety of crops. Citrus and tropical fruits are produced in the Lowveld. Grains like maize and sorghum (main crops and staple food) are produced in the Highveld. The Highveld also produces exotic trees. Gum and wattles plantations can be found in the Escarpment.
Other crops include wheat, barley, sunflower seed, soybeans, macadamia's, groundnuts, sugar cane, vegetables, coffee, tea, cotton, tobacco, and deciduous fruit. The main vegetable crops produced are beetroot, cabbage, carrots, onions, spinach and pumpkin.
Livestock products are the second largest income of the province, which include cattle, sheep, goats, pigs, horses, donkeys, as well as poultry.
Mpumalanga has about 4.675 commercial farming units with the total of 101.051 farm workers, indicating that the farming industry creates many jobs in Mpumalanga. In addition, subsistence farmers dominate the agricultural sector in Mpumalanga.
The cultivated permanent commercial rain fed areas cover approximately 13, 9% of the area of Mpumalanga, while cultivate irrigated land covers only 1, 7%.
Most farmers use water from the rivers for crop irrigation which is pumped into reservoirs and then collected by water-cans for irrigation purposes. In this area, sometimes rivers run dry leaving farmers without water to irrigate their crops.
Mpumalanga mainly uses traditional furrow and overhead sprinkler systems. Modern water distribution technologies such as sprinkle and trickle irrigation are replacing more traditional surface methods in order to reduce wastage.
Agricultural production under irrigation in South Africa receives water from groundwater and surface water sources. Groundwater irrigates 24% of irrigable area as compared to surface water which irrigates 76% (VAN TONDER & DENNIS, 2000).
Mpumalanga accounts for 83% of South Africa's coal production. 90% of South Africa's coal consumption is used for electricity generation and fuel.
Mpumalanga’s economy is mainly based on Agriculture, mining and tourism. The area has a well-developed network of roads and railways, making it highly accessible for market products to the rest of Africa and other continents.
Sources
1.  Irrigation technology in South Africa and Kenya, Rodrigo Otávio Câmara MonteiroI 2010
2.  MPUMALANGA AGRICULTURAL EDUCATION AND TRAINING REPORT DEPARTMENT OF AGRICULTURE, CONSERVATION AND ENVIRONMENT, MAHLANGU E & SEKGOTA M G B
3.  Free encyclopaedias, November, 2015
Optional / Satellite photo of location map (e.g. google map or Google Earth) or other images of the site
Map of South Africa ( in red color is Mpumalanga region)

Chapter 2: Farming system and water requirement

Farming system (maximum 200 words) / 1.  Please provide a description of the types of crops that can be found on your selected site (including the crops that are already practiced and new crops that will be produced after the implementation of the proposed irrigation scheme) (maximum 200 words)
Agriculture in Mpumalanga is characterized by a combination of commercialised, subsistence and livestock farming. As such, the area’s crops are diverse in nature, ranging from more water-intensive crops, such as cotton, wheat, and potatoes, to a number of subtropical fruits and nuts. The goal of this system is not necessarily to introduce any new crops, but rather to increase the yield and water efficiency of pre-existing crops, especially when it comes to the thirsty crops listed above. The production of a number of other crops – tobacco, vegetables, sunflowers, and maize – could also be expanded as a result of this new irrigation system.
Water requirement (maximum 1000 words) / 1.  Please provide information on the existing irrigation systems (water availability for irrigation purpose, e.g. ideally per day (m3/day), or per month (m3/month) if daily data is not available)
Water available for irrigation purposes come from various routes. Mpumalanga receives seasonal rainfall every year. The rainfall is used mainly for seasonal crops in agriculture.
Below is the graph showing the annual rainfall in this region.

The White and Crocodile Rivers flow along the region, with three irrigation dams. White River lies 20km north of Nelspruit and is located where it neither excessively hot in summer when rainfall is at its highest, nor overly cold during the sunny winters. The farms tend to be relatively small but the agriculture is intensive with various crops in abundance, including vegetables readily available.Some of the waters come from Olifants Free-flowing rivers: Elands; Mbyamiti; Nwanedzi-Sweni Interbasin Transfer Systems: Usutu to Olifants Basin; Komati to Olifants Basin Dams: Kwena; Da Gama; Vygeboom; Witklip; Klipkopjes; Blyderivierspoort, Inyaka; Ohrigstad; Buffelskloof; Klaserie;
Below: chart shows the source of water and availability per month
Source of water / Availability per month (m3/ month)
Precipitation
Rivers
Wells (?)
TOTAL
The Mpumalanga area needs on average an estimated 67 mm net irrigation per month after rainfall has been taken into account. This equates to 667 cubic metres per hectare per month.
Drag line irrigation is defined as an overhead sprinkler system, where sprinklers are connected by means of portable hoses and permanent or semi-permanent pipes to a pressurized water supply. Drag line irrigation can be well adapted for the irrigation of large areas of big estates or for smallholder irrigation with plot sizes as small as 1 hactare and less. It can be successfully integrated with a conservation contour lay-out as required in hilly areas for erosion control.
Pivot (Wobbler) irrigate, different soil types with sprinklers using high wind speeds, irrigation of high and low profile crops, and more.
Floppy Irrigation is a South Africa-based irrigation technology which has developed low cost sprinkler system that reduces management and input costs, reduces water loss and improves yield. The Floppy Sprinkler is installed as a solid set system with variations according to the irrigated crop's cultivation practices. The sprinklers are available in two varieties: floppy overhead system or the floppy short/tall riser system.
Drip Irrigation is a technique in which water flows through a filter into special drip pipes, with emitters located at different spacing. Water is distributed through the emitters directly into the soil near the roots through a special slow-release device.
South Africa introduced these irrigation systems due to water shortage and it has proved by farmers and the government that they are efficient and cost effective.
Therefore farmers use different systems of irrigation with availability of water as follows:
Irrigation System / Million cubic metres for the area / Hactares
Dragline / 436,364 / -
Pivot (Wobbler) / 320,000 / 14,545
Floppy / 320,000 / 14,545
Drip / 252,632 / 22,967
2.  Please develop the crop water requirement profile, e.g. water demand per day (or month) for each crop type and total water demand for all crops together
Maize needs 450 to 600 mm of water per season, which is mainly acquired from the soil moisture reserves. About 15, 0 kg of grain are produced for each millimetre of water consumed. At maturity, each plant will have consumed 250 l of water. The total leaf area at maturity may exceed one square metre per plant.From sowing to harvest, a corn seed takes 55 to 95 days to grow, depending on what type of corn is planted as well as the climate it is grown in.
Sorghum is grown mostly in an annual rainfall range of 300 to 750 mm. It is grown in areas which are too dry for maize. Most sorghum plants take 90-120 days to mature.
Wheat needs between 12 and 15 inches of rain over a growing season to produce a good crop. How much water a particular wheat crop will need will depend on how much water is stored in the ground and how much natural rainfall an area gets. In most cases, irrigation levels will range from no required irrigation to 16 inches of water. It takes wheat 110 days to grow.
Sugarcane production takes up about 31,000 hectares in the area, which means a monthly net demand of 20 million cubic metres of water per month.
Sunflowers grow as annuals, with some varieties only living for two months. They thrive in hot weather with full, all-day sunlight, but they require 34 inches of water annually for best growth. Some of that water comes from rain and natural water in the soil, but most is dependent on regular watering. Harvest usually takesplace 50 to 60 days fromplantingand 15 to 18 days after the full bloom stage.
3.  In this step, please calculate the water requirement (from SPIS) for the irrigation by subtracting the available water from the total water need. You may present the results graphically (y-axis: water quantity ((m3/day) or (m3/month)) and x-axis days or months)
Note: if you want to calculate the water need for livestock as well, you could develop the daily water demand profile for livestock and combine it with the irrigation water demand profile to obtain the total water demand profile. However, for this assignment, you do not need to consider the livestock water demand profile in the following steps.
Calculations of water requirement (from SPIS)
Crop / Water requirement per month / Area under cultivation / Number of months from planting to maturity / Total Water requirement
Maize / 1 square m / 55-95 days / 450-600mm
Sorghum / 90-120 days / 300-750
Wheat / 110 / 12-15 inches
Sugarcane
Sun flower / 50-60 days / 35 inches
Fodder crops
Total
Water requirement (from SPIS) = b - a

Chapter 3: Pumping head (height) calculation

Pumping head (maximum 500 words) / 1.  Please calculate the height difference between the water level in the well or basin (or ground water pumping level) and the water storage tank (of your irrigation system). To simplify matters, we do not go into details of frictional and other losses here (in reality, these losses need to be accounted for while calculating the total head).
The main factors affecting the selection of the pump and system are: required head, water source, available electrical power (peak) and energy (distribution over time), water requirement.
After determining the water requirement for the considered crop (size the pump to cover the most demanding periods), the main water source has been detected.
CHOOSE SOURCE
Depending on the water source, configuration and mounting can be submersible, surface mounted or floating.
Add a figure for the typical layout.
See pump curves. Positive displacement or centrifugal depending on the flow-rate vs head requirements.
The system layout is designed as follows:
Drawing with locations and heights of: water source (decide well or surface), pump (submersible?), PV panel, tank, users and pipeline connection.
Since the solar energy production peak is rarely in phase with the crops irrigation requirements, a dedicated tank is used to store enough water to provide a possibly regular supply of irrigation water during cloudy weather or in case maintenance issues with the power system. This component is sized to store at least (CHOOSE NUMBER OF DAYS) day water supply. Multiple tanks may be required if a very large volume of water is to be stored.
If freezing days are possible, care should be given to drain the entire system upfront.
The pump target flow rate is obtained dividing the daily water needs by the number of peak sun hours per day, this considering the month when the irrigation requirements are the most critical.
The total head available at the irrigation system intake sums the following contributions: well/reservoir pressure, pump increase, storage tank elevation (if present). The majority of the losses are of frictional nature and depend on the delivery system layout (piping, restrictions). They are, therefore, not taken into account in this first design attempt.
CALCULATIONS
The pump is powered by a DC motor directly connected to the PV system.
System improvements:
- use of a high operating voltage improves the efficiency – consider in the connection of the solar panel arrays.
- the installation of a filter upstream of the pump intake has to be considered, especially in case sand and contaminants are present in the well.
Note: Here, in order to decide the position (height) of the water storage tank from ground (land to be irrigated) you need to choose a proper water distribution type (irrigation type) for your site. You may choose the following heights for different schemes: Flood Irrigation: 0.5 m, Open channels: 0.5-1 m, Drip/trickle: 1-2 m and Sprinkler: 10-20 m.

Chapter 4: Sizing of the SPIS