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2015/09/16 1
Renewable Energy in Agriculture Brief technology overview
AgriSETA Annual Seminar
Ulrich Terblanche 17 September 2015
AgriSETA
The Centre for Renewable and Sustainable Energy Studies was established in 2007 to facilitate and stimulate activities in renewable energy study and research at Stellenbosch University. The Department of Science and Technology has been funding the Renewable and Sustainable Energy (RSE) Hub at Stellenbosch University since its establishment in August 2006. The aims of the RSE Hub are to develop human capital, deepen knowledge, and stimulate innovation and enterprise in the field of RSE. Currently the DST is still sponsoring the work of the Centre with an annual grant administrated by the National Research Foundation. Stellenbosch University was designated as the Specialisation Centre in Renewable Energy Technology as part of the Eskom Power Plant Engineering Institute (EPPEI). The research and teaching activities sponsored by Eskom focus on concentrating solar power (CSP) and wind energy and also includes the Eskom Chair in Concentrating Solar Power. The Sasol Technology group sponsored the new facilities for the Centre for Renewable and Sustainable Energy Studies as well as the work and facilities of the Solar Thermal Energy Research Group at Stellenbosch University.
Index
• Introduction • Electricity in South Africa • Renewable Energy Technology
– Hydro – Solar – Wind – Biomass – Other
• Way forward • Incentives • Conclusion
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Introduction
• Ulrich Terblanche – B.Eng Mechanical Engineer at Stellenbosch University – M.Sc Sustainable Energy Engineering at the Royal Institute of Technology,
Sweden Former work experience includes project engineering in the oil and gas refining sector, analyses on using excess heat for district heating and electricity generation in the cement manufacturing industry as well as PV-hybrid systems and energy efficient design in the renewable energy sector. I currently works as a research engineer and project coordinator at the Centre for Renewable and Sustainable Energy Studies at Stellenbosch University.
• Centre for Renewable Energy Studies – Post graduate studies in Renewable Energy – Short courses in various Renewable Energy fields for students and industry – Contract research for industry, focus on feasibility studies for solar energy – Technology transfer through policy and decision briefs and assisting the public – Public awareness through schools programs, conferences and events
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5
South African electricity landscape
South African electricity landscape
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The useful life of the ESKOM generation fleet is at 60% on average (design life of 50 years) The required Maintenance duration (corrective or preventive) of the power plants is growing
7 Age of Eskom generation fleet (source: RE Policy mapping Study of RSA)
Factors affecting supply
8
Factors affecting Supply: SA power situation beyond 2030
Since thermal power stations last around 40-50 years, most of SA’s existing thermal power stations must be replaced by 2030
Electrical Energy Demand (250 TWh)
9
Integrated Resource Plan (IRP2010)
10
Wind: 800 MW (2010-2013) * 2 400 MW (Total to 2019) CSP: 200 MW (2014-2015) * 400 MW (Total to 2019) Solar PV: 2 400 MW (2012 – 2019) * Pevious IRP
Updated IRP for Comment (Nov 2013)
11
REIPPP - Costs
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Photovoltaic Letsedi 64MW Postmasburg Letsatsi 64MW Bloemfontein
Jeffreysbaai Windfarm 138MW
Khi Solar One Central Receiver 50MW Upington
SA Renewable Energy Power plants
Upington KaXu Solar One Parabolic Trough 100MW
Cookhouse Wind Farm 135MW
De Aar Photovoltaic 50MW
Hopefield Windfarm 66MW
Hopefield Windfarm 65.4MW
Kalkbult Photovoltaic 75 MW De Aar
Droogfontein Photovoltaic 50MW Kimberley
Renewable Energy Resources
• Energy is required for any work being done • Energy can be obtained from various sources:
– Gas for heating – Electricity for electrical machines – Diesel for vehicles – Chemical reactions in body for manual labour
• Renewable Energy (RE) resources has the ability to replenish itself, whereas non-renewable energy sources do not
• No single RE resource is the solution, a combination of systems most often required
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Hydro Power
• Mature technology
• Efficient technology (~90%)
• Available in large and small scale
• Suitable for base load
• Suitable for energy storage (pumped hydro)
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Hydro Power
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Hydro Power
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Pumped Storage
• Pumped storage (Hydro energy as storage)
• Life cycle efficiency between 73% and 78%
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Pumped Storage
• Pump storage usage – Turbine activated during peak demand periods which
is in line with highest tariffs – Pump activated during low demand periods which is
in line with lowest tariffs
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Pump
Generate
Hydro Power
• The power of water dependent on the following: – How far the water falls (vertical head)
– Amount of water falling (volume flow) • Power = Eff . ρ . Q . H . g
Eff – Efficiency
ρ – Density of water
Q – Volume flow
H – Head (height)
g – Gravitational constant
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Hydro Power
• Seasonal Variation
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Micro Hydro
• Small scale hydro applicable to farms with rivers:
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www.powerspout.com www.zmsa.co.za
Micro Hydro
• Maintenance skills requirements: – Mechanical workshop skills:
• Servicing of turbines, shafts, motors, piping, etc.
– Electrical skills: • Installation and maintenance of switches, cables, electrical
motors, etc.
• Qualified electrician for issuing a Certificate of Compliance (COC)
– Civil engineering: • Building of dam, understanding hydrology, concrete
structures, etc.
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Pico Hydro
• Example: Driekoppen
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Turbine head: 30 m Flow rate: 4 L/s Power output: 1.6 kWp (690 W) Storage capacity: 100 000 L System cost: R 88 000 Monthly saving: R 450 Payback: 20 years
Solar Energy
• The energy from the sun can be captured in multiple ways, the two best known technologies are:
– Concentrated solar power (CSP)
– Solar thermal technology
– Photovoltaic (PV) technology
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Concentrated Solar Power
• Focus direct sunlight onto a central receiver using heliostats, troughs or dishes (variations of mirrors)
• “Old” technology being improved, some existing plants over 30 years old
• Applicable for large scale power plants and some industrial processes
• Can be combined with thermal storage to extend operation beyond sunset
• Resource ideal in desert like areas (areas with no or little agricultural activity) 2015/09/16 30
Oldest CSP Plants in the USA
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SEGs plants built in 1984, still operational.
Latest CSP Plants in the USA
32
Solana (Abengoa) now in operation
250 MWe, 6 hours storage (molten salt), Solar field 2.2
km2, Area 1 200 ha, Annual energy production of 980 GWh
.
Latest CSP Plants in the USA
33
Crescent Dune, Solar
Reserve, 110MWe, 10
Hour Storage
Ivanpah, Bright-
Source, 377MWe,
No Storage
Solar Thermal
Solar thermal:
• Uses the heat from the sun to heat up a gas or fluid, cook food or dry produce
• E.g. Solar water heaters, solar cookers, solar ovens and solar dryers
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Solar Thermal
• Solar Water Heaters – High and low pressure systems – Reduce electricity consumption by replacing element
geysers or provide hot water where there were none
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Solar Thermal
• Solar Water Heater types:
– Flat plate collector
– Evacuated tube collector
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Types of swh - HP
Types of swh – LP (Kuyasa)
Solar Thermal
• Solar Water Heaters for Industrial Processes
– Textile industry Hangtshou, Chinea (13 000m²)
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Solar Thermal
• Solar Ovens & Cookers – Used for food preparation – DIY or available off the shelf – Uses concentrated solar energy principles
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Solar Thermal
• Solar Drying – Food processing through dehydration
– Industrial and small scale potential
– System design dependent on the food being processed
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www.solarfooddryer.com www.muktienergy.com www.pen.solar
Solar Thermal
• Maintenance skills requirement: – Mechanical workshop skills
• Manufacturing of parts for solar dryers such as wooden structures, steel drawers, fittings, etc.
– Plumbing • Copper piping, geyser installation, hot water systems, etc.
• Qualified plumbers to issue Certificate of Compliance (COC)
– Electrical skills • Mostly for disconnecting existing systems
– Basic understanding of solar physics • System orientation, shading effects and mounting
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Solar PV
Photovoltaic panels:
• Absorbs light (photons) from the sun and releases electrons, thus direct electricity generation
• Electricity generation only when the sun shines
• Used to offset electricity from the grid or for off-grid systems if used in conjunction with batteries
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South Africa Global Horizontal Irradiance
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GHI: Global Horisontal Irradiance used for PV and SWH resource assessments
Durban 1 600 kWh/m2/annum
Freiburg 1 300 kWh/m2/annum (best in Germany)
Solar PV
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• Equipment – Panel (generates DC electricity)
– Inverter (converts DC to AC)
– Cabling (connects to grid)
Solar PV
• Rooftop PV systems – Rapidly growing industry – Decreasing price of technology – Scalable technology – Simple installation with “plug-and-play” operation – Increasingly popular for households and businesses
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Solar PV
• PV systems generate electricity which can be used in existing electrical systems or implemented with electrical equipment, such as pumps
• Reasonably affordable technology • System active while sun shines
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www.allsolar.co.za www.hgomezgroup.com
Solar PV
• Majority of PV systems (excl. REIPPPP) are rooftop systems for self consumption
• Currently not allowed to feed electricity back into Eskom’s grid
• Some municipalities do allow feeding into their grid at predefined purchase rates (embedded generation)
• Most projects provide payback period of between 8 and 15 years (long term investment with a project life of +-20 years)
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Solar PV
• Maintenance skills requirement: – Electrical skills
• Electricians with knowledge of PV electrical operation, due to unique safety risks
• Qualified electrician to issue Certificate of Compliance (COC)
– Basic understanding of solar physics • Panel orientation and operation
– Labour • Washing of panels
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Solar PV
• Lourenford Wine Estate, Somerset West (500kW system)
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Wind Power
• Wind energy can be used for mechanical pumping or electricity generation
• Mature technology already used in agriculture
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www.adventurepower.co.za
South Africa Wind Energy Resource
52
Wind Power
• Wind turbines for electricity: – Well established and proven technology – Economically feasible on large scale (low cost per
kWh) – No water consumption – Low space uptake (allow for mixed land use) – Require constant wind at specified speed – Less predictable resource
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Wind Power
• Power Curve
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Wind Power
• Maintenance skills requirement:
– Electrical skills for electricity generators
• Electricians with knowledge of wind turbine operation, due to unique safety risks
• Qualified electrician to issue Certificate of Compliance (COC)
– Basic understanding of wind power systems
• Safety risks and troubleshooting
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Wind Power
• Example: Umoya wind farm – Hopefield, Western Cape – 66 MW (x37 1.8MW VESTAS turbines) – Start of construction end of 2012 – Fully operational in February 2014
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Biomass
• Through photosynthesis plants convert sunlight energy into chemical energy
• Biomass is chemically stored solar energy and can be converted to:
– Electricity, Fuel, Heat and Fertilizer
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RE Resources - Biomass
• Biomass can be used directly, gasified or liquidized to use as fuel
• Feedstock includes the following:
– Sewerage
– Food scraps
– Manure
– Landscape offcuts
• It is only renewable if harvested sustainably.
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Biomass
• Harvesting and processing
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Transport to Bio-Energy Plant
Combustion
Fermentation
Anaerobic Digestion
Mechanical
Bio-Energy Plant Processing
Bio-Ethanol
Heat
Electricity
Biogas
Oil
Bio-Energy Primary Products
Chemicals
Fuel
Bio-Energy Secondary Products
Biomass
• Maintenance skills requirement: – Highly dependent on the type of process undertaken, can
vary between process engineering to basic masonry
– Basic system operations understanding • Biogas digesters can be very sensitive to timing, temperature and
material used as feedstock
• Understanding the principles of sustainability to prevent over exploitation when using natural material such as wood
– Health and safety training • Flammable/explosive chemicals and material as part of the
process
• Depending on the fuel used, harmful bacteria can be found in sewage and manure
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Biomass
• Example: Stellenbosch University “proefplaas” biogas digester – Used for waste processing, manure feedstock broken up into cleaner
water, methane gas and fertilizer cake – Research into methane gas utilization – Manure feedstock from milk farm
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Biomass
• Example: Fort Hare University biogas digester – Cattle manure feedstock
– Uses bag system
– Methane gas used for cooking
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Biomass
• Example: Biogas digesters from around the world
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Dominican Republic, www.bio-gas-plant.blogspot.co.za
Kenya, www.darajkenya.com Germany, www.oekobit-biogas.com
Biomass
• Solaris Biofuel (Jet fuel) plant – Modified Tobacco crop (50 Ha)
– Target 20 mil Litre by 2017
– Jet fuel for Boeing airplanes operated by SAA
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Boeing.mediaroom.com
Other – Geothermal
• Geothermal Energy
– Not feasible in SA context
– No active plate boundaries and low thermal gradient
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The Nesjavellir Plant in Iceland 120 MW @ 190°C
Other – Ocean Energy
• Ocean Energy – Includes currents, wave energy, temperature differences and salinity
gradients – Farming activity not near coastal areas – Early stages of technology – Very high cost systems
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Way Forward
• Improve your knowledge – Read up on the subject – Attend short courses – Consult with experts
• Energy management has better results than renewable energy – The less energy you need, the smaller the system and the
lower the costs – Very short payback for energy efficiency initiatives,
compared to Renewable Energy – Documents available on energy management, e.g.
Winetech energy management guidelines
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Way Forward
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Way Forward
• Know your usage
– Start by installing electricity meters to record your data (you need at least 1 year worth of data to capture seasonal variation)
– Keep track of gas supplies
– Identify your waste and quantify it
– Employ an expert consultant to determine feasibility (CRSES) or use a student
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Incentives
• Rebates – Residential solar water heater (on hold) – Standard offer / standard product (on hold)
• Tax incentives – Accelerated depreciation (write off of system after 3 years) – 12 L, Energy efficiency tax incentive (per kWh tax deduction)
• Grants – Manufacturing Competitiveness Enhancement Programme (MCEP) – DTI – Green Fund – DEA/DBSA
• Loans – Green Energy Efficiency Fund – IDC
• Remove capital expense through power purchasing agreements – External organization provides capital and installs system, selling electricity
back to the user
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Incentives
• List of Available Funding:
http://www.sanedi.org.za/welcome-to-sasefid/
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Conclusion
• The use of renewable energy is rapidly growing in South Africa
• Various technologies exists that is applicable to agricultural use of renewable energy
• Technology is constantly improving and costs reducing
• Funding models and incentives available
• Long term benefits
• Job creation and local manufacturing potential
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Research Areas @ Stellenbosch
73
• Solar Thermal Energy Research Group
– Heliostat development
– Thermal energy storage
– Dry air-cooling
– System modelling
• Wind Energy
– Direct-drive permanent magnet generators
– Grid integration
– Conditioning monitoring of large wind turbines
• Bio-Energy
– 2nd Generation – Lignocellulose to bio-ethanol
– Thermal conversion (Pyrolysis, gasification, combustion)
– Bio-diesel
• Ocean Energy
– Wave energy
– Ocean current (Agulhas)
– Resource and technology assessment
• Photovoltaics
– Focus on PV systems and feasibility studies for industry
