Solar Agroprocessing, Aug 2014 Making Energy Affordable
Why focus on solar agroprocessing? UN Target: "Access to Energy" for all by 2030 Lighting + phone charging "access" Need more than 2-10W solar lamps/kits Possible "Access to Energy" package: Residential, mostly night-time needs: Lighting, phone charging, radio, fan and/or TV Community/business, mostly day-time needs: Refrigeration (especially for clinics), communications for market access, productive power for processing crops, carpentry, others? = "Tier 2+" service package = 75-150 kwh/year/house, or 25-50W/house
Tiers of Energy Service Current view of "access to energy" is still uncertain, and current thinking is based on tiers of services. However, very focused on consumers / households Does not account for clinic needs for health community mills school equipment, comms solar water pumping and similar mostly community-scale needs. Source: https://www.climateinvestmentfunds.org/ Hence, "Tier 2+" suggested which includes these needs.
Benefits of solar agro-processing Reduced expenditure on diesel, which dominate offgrid milling now Staple crops Globally, it is mostly mostly women and children who currently spend 30-60 minutes per day manually processing food that is consumed each day by 250 million offgrid rural households that do not have electricity. Mechanized agro-processing reduces time spent on basic labour Saved time leads to more time spent in the fields increasing food security Saved time leads to non-agricultural income-generating activities/opportunities Saved time can also increase parents' contribution to childrens' education Cash crops Processing cash crops at the village level can earn more value for households (eg. coconut oil produced instead of copra, edible rice instead of unhulled) Saved time leads to more time in fields growing/harvesting, increasing income Agro-processing is commonly part of microhydro, grid and diesel rural electrification projects, but rarely part of solar electrification projects.
Crops of the poorest 1 billion Over 1 billion people lack electricity 15 crops make up 90% of all food consumed on the planet 3 crop groups make up 50-60% of all food consumed Rice Maize Wheat and other cereals (sorghum, millet, barley, rye, etc) Other major crops are roots (cassava, yams, potato, taro) and in the Pacific, coconut Meat is a larger food group for the rich than the poor. Chicken and pork dominate the rural meat markets of poor countries.
Staple Crops of the World World production Average world yield Processing 2008 2010 required Rank Crop (metric tons) (tons per hectare) 1 Maize/Corn 823 million 5.1 thresh, grind, winnow 2 Wheat 690 million 3.1 thresh, grind, winnow 3 Rice 685 million 4.3 thresh, hull, winnow, (polish for white rice) 4 Potatoes 314 million 17.2 wash, peel 5 Cassava 233 million 12.5 peel, grate or slice 6 Soybeans 231 million 2.4 thresh, dry, clean, press 7 Sweet potatoes 110 million 13.5 peel, sometimes slice 8 Sorghum 66 million 1.5 thresh, grind, winnow 9 Yams 52 million 10.5 peel, sometimes grate 10 Plantain 34 million 6.3 peel Source: Staple food - Wikipedia, the free encyclopedia.htm
threshing maize pounding = grinding corn/cassava or hulling rice winnowing grating cassava / yams grinding flour grating coconut
Opportunity of Productivity Saving 1 hour per day for 250 million women globally that lack electricity = 100 billion hours/year of productivity = 50 million peoples' worth of 8-hour days = entire workforce of the UK or France by reducing time spent processing crops, fetching water and collecting firewood
Mechanized offgrid agro-processing Diesel 2-20 kw engines directly driving mills via belts Consume 1-7 L/hour of fuel, costing $1-7/hour, serves 200-2000 households at 200 kg/hr 1-4 hours/day operation means $300-3000/year on fuel Solar 0.2-2 kw solar systems drive mills directly or via batteries. Panels $1-2/watt = $300-2000 Batteries 0-300Ah = $0-2000 Controllers, other = $100-500 Solutions can be delivered for $500-5000 for 25-250 kg/hour, but may be slower than diesel 2-5 year paybacks on diesel
Transport: the hidden cost Diesel mills are rarely found in small villages of < 50 households One household eats 1-2 kg/day of staple food, so a 200 kg/hour mill can serve 100-200 households per hour of operation - this is the typical size of village in which mills are found (or in larger towns as well) However, most rural villages are 20-50 households. Many villagers travel 1-10 km to access a mill outside their village This can cost $0.20-$1.00 for the return trip, with a 25-50 kg bag The cost of milling is typicall $0.02-0.05/kg or $0.50-2.00 per bag Thus, travel can increase agro-processing costs for small villages by 50-100% and so they tend to not use mills even if they could afford it. Small solar mills can penetrate these markets that diesel mills do not now reach.
Case Study - Maize flour grinding Base Case Manual flour grinders, used 30 mins/day, cost $30 and are bought by offgrid villagers in central / south America. These break every 6 months. Solar solution A 1/3 hp (250W) electric mill that can process 30 kg per hour and thus can serve 15-30 households with 1 hour of use per day. Assuming there are 3-4 hours of sun per day, the following system can serve this need. 1 x 100W solar panel for 1 hour/day use = $100-200 1 x Nixtamatic mill = $250-400 1 x 40Ah battery for 1 hour/day use = $ 80-150 1 x 2000W Whistler Pro inverter = $150-250 Controller, wires, other = $ 20-100 TOTAL COST = $600-1100 Current annual cost: = $30 x 2 grinders/house/year x 15 houses = $900/year 1-2 year payback possible
Case Study - Rice hulling Base Case Rice hulling costs $0.50 to process a 25 kg ($0.02/kg) bag which lasts 12-25 days. Once transport costs are added, this can be $1/bag or $0.04/kg. A small village wishes to have a solar mill installed instead of traveling to the large rice mill in a nearby town. Solar solution A 1/2 hp (375W) micro rice mill can process 40 kg/hr, so serve 40-80 households with 2 hours/day of use. 2 x 150W solar panel for 2 hours use = $300-500 1 x micro rice mill without polisher = $500-700 1 x 80Ah battery for 1 hour/day backup = $150-250 1 x 2000W Whistler Pro inverter = $150-250 Controller, wires, other = $ 50-100 TOTAL COST = $1150-1800 The micro rice mill can process 80 kg/day, or 400-500 kg/week (8-10 bags). More panels = more households. Revenue = $10/week, or $500-2000 per year. 2-4 year payback possible, or 3-6 years if a small operator salary is drawn from gross revenue.
Case Study - Coconut Grating Base Case In South-East Asia, freshly grated coconut is available in local markets as well as whole coconuts, whereas in the Pacific, only whole coconuts are available. Periurban households can grate coconut for time-poor urban housewives or restaurants. Solar solution A 1/4 hp (175W) electric coconut grater can process up to 50 nuts per hour (typically 10-20 nut), producing 250g of grated meat per nut or 2.5-10 kg per hour. 1 x 80W solar panel for 1 hour/day use = $100-150 1 x 175W coconut grater with DC motor = $100-200 1 x 24Ah battery for 1 hour/day use = $ 50-100 Controller, wires, other = $ 0-50 TOTAL COST = $250-500 Whole coconuts sell for $0.10 each while one 500g of coconut milk (1 nut worth) sells for $1, so the selling price of grated coconut is set at $0.25 per nut (250g). Profit = $0.15 x 20 nuts/day = $3/day = $1000/year Of this, $0.05/nut is charged for mill use = $1/day Hence, 1-2 year payback possible
Case Study - Coconut Oil Base Case Coconut oil can be used to displace fuel in remote islands, or as a cooking oil, or for other uses. It is usually made in centralized mills, and villagers supply dried coconut meat (copra). Small scale oil expelling may also be possible to add local value to this crop. Solar solution A 1/4 hp (175W) electric coconut grater can process up to 50 nuts per hour (typically 10-20 nut), and a 150-500W oil expeller can produce 3-5 L/hour. 1 x 150W solar panel for 1 hour/day use = $150-250 1 x 175W coconut grater = $100-200 1 x 150W electric cold oil press = $400-600 1 x 40Ah battery for 1 hour/day use = $ 80-150 1 x 2000W Whistler Pro inverter = $150-250 Controller, wires, other = $ 20-50 TOTAL COST = $900-1500 Coconut oil value $1-5/litre, depending on use. Production = 4 L/day x 250 days/year = 1000 L/year Gross revenue $1000-5000, payback period <2 years
Case Study - Cassava grating Base Case Manual cassava and yam graters are used 15-30 mins/day are used across the Pacific, at a rate of around 5 kg/hour. During large festivals, up to 30 women process 200-500 kg over many hours. Solar solution A 2/3 hp (500W) electric drill has a grating attachment added, or more sophisticated graters can be purchased, that can process up to 150 kg / hour serving 75-150 households with 1 hour of use per day. 3 x 80W solar panel for 1 hour/day use = $250-350 1 x electric grating machine = $100-200 1 x 40Ah battery for 1 hour/day use = $ 80-150 1 x 2000W Whistler Pro inverter = $150-250 Controller, wires, other = $ 20-50 TOTAL COST = $600-1000 If paid in cash, $0.05/kg generates $7-8/hour revenue If paid in kind, one $10/house/month local handicraft can be exchanged for supply of the service, and sold Revenue = $1000/year, 1-2 year payback possible