Permaculture: Renewable

Energy

Permaculture: Renewable

EnergyKevin BayukKevin Bayuk

OverviewOverview Outline and brief description of renewable energy

technologies

General overview of technologies and applications integrated using permaculture design

Information on costs

Common barriers and issues limiting wide spread use/dissemination

Outline and brief description of renewable energy technologies

General overview of technologies and applications integrated using permaculture design

Information on costs

Common barriers and issues limiting wide spread use/dissemination

General Principles & Considerations

General Principles & Considerations

Thermodynamics EMERGY / EROEI Supply and Demand

Negawatts (Accept Feedback) Embrace Diversity Integrated Solutions Observe and Interact -

Scale

Thermodynamics EMERGY / EROEI Supply and Demand

Negawatts (Accept Feedback) Embrace Diversity Integrated Solutions Observe and Interact -

Scale

Terminology - Units of Measurement

Terminology - Units of Measurement

Ampere: Amps - A unit in which electrical current flow ismeasured.

Voltage: Volt - V unit in which electrical force is measured.

Wattage: Watts unit in which electrical power is measured and isobtained by multiplying Voltage and Ampere.

Watt Hours: Whrs is A unit in which electrical power consumption is measured and is obtained by multiplying the wattageby the number of hours of use.

ExamplesExamples

An electrical bulb burning on 220 volts draws 3 Amps. What is the Power consumption if it runs for two hours?

Power consumed will be

= watts x hours

= volts x amps x hours

= 220 x 2 x 3

= 1320 watt hours

i.e. 22000 watt hours = 22 kwh 1000

You pay for your household electricity

Kilowatt HourKilowatt Hour

as so much $

per kilowatt hour (kwh)

which is just the watt hours divided by a thousand.

Solar water heatingSolar water heating Heats your tap water not your

radiators 50% of hot water needs overall Roof should face between SE and

SW 3-4m2 array for households Need hot water tank 20-30 years useful life

Heats your tap water not your radiators

50% of hot water needs overall Roof should face between SE and

SW 3-4m2 array for households Need hot water tank 20-30 years useful life

Opportunity: Combine with re-roofing to reduce costs

Flat plate Evacuated tubeUnglazed

Increasing efficiency/cost

TypesTypes

How do they work?How do they work?Closed system Open (direct) system

Photovoltaics (PV)Photovoltaics (PV)

Convert light into electricity

Single PV Cell: 1.5 Watts

Typical Panel (30-40 cells): 40-60 Watts

Convert light into electricity

Single PV Cell: 1.5 Watts

Typical Panel (30-40 cells): 40-60 Watts

Opportunity: Captures photons at peak use periods

Polycrystalline SiThin Film

Increasing efficiency/cost

Monocrystalline Si

TypesTypes

How do they work?How do they work?

Load AnalysisLoad Analysis Household load analysis estimates the

peak and average power and energy required Mind the “Edge Events” like

refrigerator cycling on Some might be reduced or time-shifted

to decrease system costs A spreadsheet program like Excel will

speed analysis of the various loads, their use time, peak power, and energy required List the loads, enter the power, time per day,

and compute the rest From total energy required and total power,

one can compute the size of solar modules and batteries

Household load analysis estimates the peak and average power and energy required Mind the “Edge Events” like

refrigerator cycling on Some might be reduced or time-shifted

to decrease system costs A spreadsheet program like Excel will

speed analysis of the various loads, their use time, peak power, and energy required List the loads, enter the power, time per day,

and compute the rest From total energy required and total power,

one can compute the size of solar modules and batteries

Solar PotentialSolar Potential

Roof-top Solar Array Computations

Roof-top Solar Array Computations Find the south-facing roof

area; say 20 ft * 40 ft = 800 ft2

Assume 120 Wp solar modules are 26 inches by 52 inches; 9.4 ft2/120 watt; 12.78 W/ft2

Assume 90% of area can be covered, 720 ft2, ~9202 W

and that there are (e.g) 5.5 effective hours of sun/day; 51 kWh/day

The south-facing modules are tilted south to the latitude angle

76 modules would fit the area, but 44 would provide an average home with 30 kWh/day and cost ~$17600 for modules alone

Find the south-facing roof area; say 20 ft * 40 ft = 800 ft2

Assume 120 Wp solar modules are 26 inches by 52 inches; 9.4 ft2/120 watt; 12.78 W/ft2

Assume 90% of area can be covered, 720 ft2, ~9202 W

and that there are (e.g) 5.5 effective hours of sun/day; 51 kWh/day

The south-facing modules are tilted south to the latitude angle

76 modules would fit the area, but 44 would provide an average home with 30 kWh/day and cost ~$17600 for modules alone

Siemens Solar SM110

Maximum power rating, 110 W

Minimum power rating, 100 W

Rated current. 6.3 A

Rated voltage, 17.9 V

Short circuit current, 6.9 A

Open circuit voltage, 21.7 V

Battery Charge ControllerBattery Charge Controller Limits charge current to

protect battery from overheating and damage that shortens life

Disconnects battery loads if voltage falls too low (10.6 V is typical)

Removes charge current if voltage rises too high (14V is typical)

Regulates charge voltage to avoid battery water gassing

Diverts output of source to a secondary load (water heater or electric furnace) if battery is fully charged Saves energy wisely

Limits charge current to protect battery from overheating and damage that shortens life

Disconnects battery loads if voltage falls too low (10.6 V is typical)

Removes charge current if voltage rises too high (14V is typical)

Regulates charge voltage to avoid battery water gassing

Diverts output of source to a secondary load (water heater or electric furnace) if battery is fully charged Saves energy wisely

Soltek Mark IV 20 Amp

Regulator

“Big as a breadbox” for a 4 kW inverter

Storage BatteriesStorage Batteries Lead-acid (car) batteries

are most economical; but must be deep-cycle type

Critical rating is 20-hour value or Reserve Capacity (RC) in minutes at 25A load

Charge cycle is ~70% efficient -- rather wasteful

Requires maintenance to ensure long life

A home might have ten of these batteries

Need to know the length of time without full sun in days

Inverter must match series battery voltage

Lead-acid (car) batteries are most economical; but must be deep-cycle type

Critical rating is 20-hour value or Reserve Capacity (RC) in minutes at 25A load

Charge cycle is ~70% efficient -- rather wasteful

Requires maintenance to ensure long life

A home might have ten of these batteries

Need to know the length of time without full sun in days

Inverter must match series battery voltage

Soltek Deep-Cycle

BatteryAP-27

12 Vdc,115 A-hr 20-hour rate

BatteriesBatteries

So if a battery is rated at 24 Amp Hour Capacity we can draw -2 Amps from it for 12 hours or-12 Amps for two hours or-24 Amps for 1 hour etc.

The capacity of a battery can be given in watt hours

but this is very cumbersome,

and since the battery voltage is always fixedwe divide the watt hours by the voltage.

= volts x Amps x hours Volts

To get Amp hours.

InverterInverter The inverter converts low voltage (12V to 100s V) direct current to 120 Vac

Synchronous inverters may be “inter-tied” with power line to reduce billable energy

In “net metering” states, the energy is metered at the same rate going into and out of the electrical grid --- no storage required (except for outages)!

Loads can use 12 volt low-voltage directly at higher efficiency with special lamps

The inverter converts low voltage (12V to 100s V) direct current to 120 Vac

Synchronous inverters may be “inter-tied” with power line to reduce billable energy

In “net metering” states, the energy is metered at the same rate going into and out of the electrical grid --- no storage required (except for outages)!

Loads can use 12 volt low-voltage directly at higher efficiency with special lamps Trace

Legend 4 kilowatt Inverter

InvertorsInvertorsAn invertors is an electronic device that will convert D.C. Power into A.C Power i.e. 12 volt D.C. from a battery into 220 volt A.C. Smallest practical size for our application is 150 watt.One of 10 KW is large enough to power a 3 Bedroom House.

Invertors come in two basic types:

True Sine wave such as EDM Delivers

50Hz

Modified Sine Wave

50Hz

Disadvantage: Not as efficient as true sine waveEquipment such as specialized electronic medical instruments and measuring instruments might not perform, as they should.No problem with normal household and consumer electronic products.

Energy TransmissionEnergy Transmission

Solar power is expensive, so design wires for 1% loss instead of usual 3 to 5% for utility power

Use higher voltage (120Vac for long lines) instead of 12 Vdc

Spend more on larger wire than normal to reduce resistance loss

Battery and inverter wires might be AWG #0 or 2 or larger

Inverter output is 120Vac, so AWG#12 and 14 are common for 20A and 15A home service

Danger with batteries is not shock but flash burns and flying molten metal Special dc-rated fuses and circuit breakers are required

Solar power is expensive, so design wires for 1% loss instead of usual 3 to 5% for utility power

Use higher voltage (120Vac for long lines) instead of 12 Vdc

Spend more on larger wire than normal to reduce resistance loss

Battery and inverter wires might be AWG #0 or 2 or larger

Inverter output is 120Vac, so AWG#12 and 14 are common for 20A and 15A home service

Danger with batteries is not shock but flash burns and flying molten metal Special dc-rated fuses and circuit breakers are required

Some Important Electrical Information

Some Important Electrical Information P = E•I = E2/R = I2•R,

where P is power (instantaneous), E is electromotive force, I is intensity or current, and R is resistance

Energy = P•t, where t is the time that power flows V = I•R for a load or E = I•R for a source,

where V is voltage drop across resistor Wire size numbers roughly double the area and halve

the resistance for every three size number changes #18 AWG is used in ordinary lamp cord (zip cord) #18 AWG has a resistance of 6.385 ohms per 1000 ft #12 AWG has a resistance of 1.588 ohms per 1000 ft #9 AWG has a resistance of 0.7921 ohms per 1000 ft #6 AWG has a resistance of 0.3951 ohms per 1000 ft #3 AWG has a resistance of 0.197 ohms per 1000 ft

P = E•I = E2/R = I2•R,where P is power (instantaneous), E is electromotive force, I is intensity or current, and R is resistance

Energy = P•t, where t is the time that power flows V = I•R for a load or E = I•R for a source,

where V is voltage drop across resistor Wire size numbers roughly double the area and halve

the resistance for every three size number changes #18 AWG is used in ordinary lamp cord (zip cord) #18 AWG has a resistance of 6.385 ohms per 1000 ft #12 AWG has a resistance of 1.588 ohms per 1000 ft #9 AWG has a resistance of 0.7921 ohms per 1000 ft #6 AWG has a resistance of 0.3951 ohms per 1000 ft #3 AWG has a resistance of 0.197 ohms per 1000 ft

Solar Power ApplicationsSolar Power Applications

Technology type

System Application

PV (solar electric) Grid connected Supplementing mains supply

PV (solar electric) Stand-alone Small home systems for lighting, radio, TV, etc. Small commercial/community systems, including

health care, schools, etc. Telecommunications and navigation aids Water pumping Commercial systems Remote settlements Mini-grid systems

Solar thermal Connected to existing water and/or space heating system

Supplementing supply of hot water and/or space heating provided by the electricity grid or gas network

Solar thermal Stand-alone Water heating, i.e. for rural clinics Drying (often grain or other agricultural products) Cooking Distillation Cooling

PV systems: Strengths & Weaknesses

PV systems: Strengths & Weaknesses

Strengths WeaknessesTechnology is mature. It has high reliability and long lifetimes (power output warranties from PV panels now commonly for 25 years)

Performance is dependent on sunshine levels and local weather conditions

Automatic operation with very low maintenance requirements

Storage/back-up usually required due to fluctuating nature of sunshine levels/no power production at night

No fuel required (no additional costs for fuel nor delivery logistics)

High capital/initial investment costs

Modular nature of PV allows for a complete range of system sizes as application dictates

Specific training and infrastructure needs

Environmental impact low compared with conventional energy sources

Energy intensity of silicon production for PV solar cells

The solar system is an easily visible sign of a high level of responsibility, environmental awareness and commitment

Provision for collection of batteries and facilities to recycle batteries are necessary

The user is less effected by rising prices for other energy sources

Use of toxic materials is some PV panels

Wind PowerWind Power• Temperature differences create currents affected by earth’s rotation and land contours = wind

• A wind turbine obtains its power input by converting the force of the wind into a torque (turning force) acting on the rotor blades.

• The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed.

• Temperature differences create currents affected by earth’s rotation and land contours = wind

• A wind turbine obtains its power input by converting the force of the wind into a torque (turning force) acting on the rotor blades.

• The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed.

Wind TurbinesWind Turbines

Wind turbines start at 400 watts and go up to many megawatts

Only work when the wind blows Not easily installed on houses

Work better when at the top of tall towersDo not like turbulent airCan be noisy

Wind turbines start at 400 watts and go up to many megawatts

Only work when the wind blows Not easily installed on houses

Work better when at the top of tall towersDo not like turbulent airCan be noisy

Siting a TurbineSiting a Turbine

Requires** clearance without obstructions 200 yards from turbine within 20 feet of turbine height

Requires a good macro wind resource with good micro wind elements

Requires** clearance without obstructions 200 yards from turbine within 20 feet of turbine height

Requires a good macro wind resource with good micro wind elements

OrientationOrientationTurbines can be categorized into two overarching classes based on the orientation of the rotor

Vertical Axis Horizontal Axis

Turbines can be categorized into two overarching classes based on the orientation of the rotor

Vertical Axis Horizontal Axis

Performance: EnergyPerformance: Energy

•Based in kWh a month not rated power •Household sized turbine (10->23’ diameter)

Monthly kWh Production

0

100

200

300

400

500

600

700

800

900

5.6 7.0 7.9 8.9 10.0 11.2 12.3 13.4 14.5 15.6 16.8 17.9 19.0 20.2 21.2 22.4 23.5 24.6

Wind Speed Average - MPH

kWh

Tower HeightsTower HeightsAnemometors, to be accurate, need to be in the exact location for a yearTower height restrictions may apply but it is important to get the generator up as high as possible to maximize energy productionAvoid obstructions position turbine at least 30 feet above nearby features

http://rredc.nrel.gov/wind/pubs/atlas/

Wind Power ApplicationsWind Power Applications

Technology type System Application

Wind power - electrical

Grid connected Supplementing mains supply

Wind power - electrical

Stand-alone, battery charging

Small home systems Small commercial/community

systems Water pumping Telecommunications Navigation aids

Wind power - electrical

Stand-alone, autonomous diesel

Commercial systems Remote settlements Mini-grid systems

Wind power - mechanical

Water pumping Drinking water supply Irrigation pumping Sea-salt production Dewatering

Wind power - mechanical

Other Milling grain Driving other, often agricultural,

machines

Wind systems: Strengths & Weaknesses

Wind systems: Strengths & Weaknesses

Strengths Weaknesses

Technology is relatively simple and robust with lifetimes of over 15 years without major new investment

Site-specific technology (requires a suitable site)

Automatic operation with low maintenance requirements

Variable power produced therefore storage/back-up required.

No fuel required (no additional costs for fuel nor delivery logistics)

High capital / initial investment costs can impede development (especially in developing countries)

Environmental impact low compared with conventional energy sources

Potential market needs to be large enough to support expertise/equipment required for implementation

Mature, well developed, technology in developed countries

Cranage and transport access problems for installation of larger systems in remote areas

The Technology can be adapted for complete or part manufacture (e.g. the tower) in developing countries

Micro HydroMicro Hydro• water+gravity+turbine+generator = electricity

• Site dependent

• Can be most efficient renewable energy source (little environmental impact)

• Small scale

• Can cost as little as one tenth of a PV system of comparable output

• Low volume and high head systems work and high volume low head systems work

• water+gravity+turbine+generator = electricity

• Site dependent

• Can be most efficient renewable energy source (little environmental impact)

• Small scale

• Can cost as little as one tenth of a PV system of comparable output

• Low volume and high head systems work and high volume low head systems work

You need two things to make power

Head and Flow

You need two things to make power

Head and Flow

Measuring HeadMeasuring Head Pipe with

pressure gauge at the bottom (1 person)

2.31 feet = 1 psi This gauge reads

38 psi 38 psi x 2.31

feet/psi = 88 ft of head

Pipe with pressure gauge at the bottom (1 person)

2.31 feet = 1 psi This gauge reads

38 psi 38 psi x 2.31

feet/psi = 88 ft of head

5 gallon bucket5 gallon bucket

This may be tricky…

Small stream, little waterfall

Most typical method for microhydro

5 gallon bucket5 gallon bucket

If the measured flow using a 5 gallon bucket and a stop watch was 5 gallons in 1.5 seconds, how many GPM would this be?

If the measured flow using a 5 gallon bucket and a stop watch was 5 gallons in 1.5 seconds, how many GPM would this be?

GPMgal

200min1

sec60

sec5.1

5

Larger StreamsLarger Streams

Float MethodFloat Method Weir

Power EstimatePower Estimate

Power (watts) = Net Head (ft) * Flow (GPM)9-14 (use 10)

Power (watts) = Net Head (ft) * Flow (GPM)9-14 (use 10)

10 assumes a system efficiency of 53%

NozzlesNozzles

Flow through the pipe is controlled by the nozzle size

Mollies Branch Case Study

Mollies Branch Case Study

100 ft of net head Stream flow: 300 gpm Design flow: 85 gpm Penstock: 1200’ of 4” HDPE Turbine: Harris Hydro 4-

nozzle PM Power: 850 W for now Energy: .85 kW x 24 h/day

x 30 day/mon = 612 kWh/mon

Cost = about $16,000

100 ft of net head Stream flow: 300 gpm Design flow: 85 gpm Penstock: 1200’ of 4” HDPE Turbine: Harris Hydro 4-

nozzle PM Power: 850 W for now Energy: .85 kW x 24 h/day

x 30 day/mon = 612 kWh/mon

Cost = about $16,000

Measuring Flow

The 4” HDPE arrives in 50’ lengths

Fusing the pipe with the ASU Wind & Hydro Class

Fusion welder

• Shave pipe ends

• Heat with 500 degree iron

• Press ends together to fuse

• Makes a “double roll back bead”

The penstock gradually drops 100 feet along the 1200

feet of pipe. It is supported along the

bank with steel stakes and aircraft

cable

This log house is moved into place to house the turbine

The wire run and Balance of System is roughed in

A battery box is built to contain the eight Trojan L16 batteries (48V)

A silt trap/intake filter is built from a 55 gallon plastic

drum

The penstock is connected to the turbine house

A stand is constructed for the turbine.

A union and hinge allows the turbine to be tilted back for

servicing.

Screw-type gate valves insures slow operation

The water passes through the floor and returns to the

creek

Water is diverted from the creek to the silt trap

A second silt trap barrel is added to improve performance

The battery bank and inverter are wired. The electrician installs a subpanel for the hydro loads.

The log house does a nice job of reducing the sound level (sounds like a sewing machine)

Hydropower: Strengths & Weaknesses

Hydropower: Strengths & Weaknesses

Strengths Weaknesses

Technology is relatively simple and robust with lifetimes of over 30 years without major new investment

Very site-specific technology (requires a suitable site relatively close to the location where the power is needed)

Overall costs can, in many case, undercut all other alternatives

For SHP systems using small streams the maximum power is limited and cannot expand if the need grows

Automatic operation with low maintenance requirements

Droughts and changes in local water and land use can affect power output

No fuel required (no additional costs for fuel nor delivery logistics)

Although power output is generally more predictable it may fall to very low levels or even zero during the dry season

Environmental impact low compared with conventional energy sources

High capital/initial investment costs

Power is available at a fairly constant rate and at all times, subject to water resource availability

Engineering skills required may be unavailable/expensive to obtain locally

The technology can be adapted for manufacture/use in developing countries

Biomass BasicsBiomass Basics

-Biomass fuels have the potential of providing 4%-25% of the United States energy needs

-3.6% of United States Energy Consumption derived from Biomass Sources

-Biomass fuels have the potential of providing 4%-25% of the United States energy needs

-3.6% of United States Energy Consumption derived from Biomass Sources

Three major forms of biomass energy-Solid Biomass (Wood, Incineration)-Liquid Fuel (Ethanol, Biodiesel)-Gaseous Fuel (Landfills, Methane)

Solar Energy Conversion

Solar Energy Conversion

1 hectare = ~2.5 acres

Boiling 1l of WaterBoiling 1l of Water

Rocket Stoves and Mass Heaters

Rocket Stoves and Mass Heaters

Bioenergy Technologies

Bioenergy Technologies

GasificationGasification

Biomass heated with no oxygen Gasifies to mixture of CO and H2

Called “Syngas” for synthetic gas Mixes easily with oxygen Burned in turbines to generate

electricity Like natural gas

Can easily be converted to other fuels, chemicals, and valuable materials

Biomass heated with no oxygen Gasifies to mixture of CO and H2

Called “Syngas” for synthetic gas Mixes easily with oxygen Burned in turbines to generate

electricity Like natural gas

Can easily be converted to other fuels, chemicals, and valuable materials

PyrolysisPyrolysis Heat bio-material under pressure

500-1300 ºC (900-2400 ºF) 50-150 atmospheres Carefully controlled air supply

Up to 75% of biomass converted to liquid

Tested for use in engines, turbines, boilers

Currently experimental

Heat bio-material under pressure 500-1300 ºC (900-2400 ºF) 50-150 atmospheres Carefully controlled air supply

Up to 75% of biomass converted to liquid

Tested for use in engines, turbines, boilers

Currently experimental

Anaerobic DigestionAnaerobic Digestion

Decompose biomass with microorganisms Closed tanks known as anaerobic

digesters Produces methane (natural gas)

and CO2

Methane-rich biogas can be used as fuel or as a base chemical for biobased products.

Used in animal feedlots, and elsewhere

Decompose biomass with microorganisms Closed tanks known as anaerobic

digesters Produces methane (natural gas)

and CO2

Methane-rich biogas can be used as fuel or as a base chemical for biobased products.

Used in animal feedlots, and elsewhere

Methane DigestersMethane Digesters

BioFuelsBioFuels Ethanol

Created by fermentation of starches/sugars

US capacity of 1.8 billion gals/yr (2005) Active research on cellulosic

fermentation Biodiesel

Organic oils combined with alcohols Creates ethyl or methyl esters

Vegetable Oil

Ethanol Created by fermentation of

starches/sugars US capacity of 1.8 billion gals/yr (2005) Active research on cellulosic

fermentation Biodiesel

Organic oils combined with alcohols Creates ethyl or methyl esters

Vegetable Oil

Bioenergy ApplicationsBioenergy Applications

Fuel state Application

Biogas Supplementing mains supply (grid-connected)

Biogas Cooking and lighting (household-scale digesters) Motive power for small industry and electric needs

(with gas engine)

Liquid biofuel Transport fuel and mechanical power, particularly for agriculture

Heating and electricity generation Some rural cooking fuel

Solid biomass Cooking and lighting (direct combustion) Motive power for small industry and electric needs

(with electric motor)

Bioenergy: Strengths & Weaknesses

Bioenergy: Strengths & Weaknesses

Strengths Weaknesses

Conversion technologies available in a wide range of power levels at different levels of technological complexity

Production can create land use competition

Fuel production and conversion technology indigenous in developing countries

Often large areas of land are required (usually low energy density)

Production can produce more jobs that other renewable energy systems of a comparable size

Production can have high fertiliser and water requirements

Conversion can be to gaseous, liquid or solid fuel

May require complex management system to ensure constant supply of resource, which is often bulky adding complexity to handling, transport and storage

Environmental impact potentially low (overall no increase in carbon dioxide) compared with conventional energy sources

Resource production may be variable depending on local climatic/weather effects, i.e. drought.

Likely to be uneven resource production throughout the year

GeothermalGeothermal

Energy available as heat from the earth

Usually hot water or steam

High temperature resources (150°C+) for electricity generation

Low temperature resources (50-150°C) for direct heating: district heating, industrial processing

No problems of intermittency

Energy available as heat from the earth

Usually hot water or steam

High temperature resources (150°C+) for electricity generation

Low temperature resources (50-150°C) for direct heating: district heating, industrial processing

No problems of intermittency

TrompeTrompe

RE Applications: Summary

RE Applications: Summary

RE Technology Energy Service/Application

Wind – grid‑connected & stand-alone turbines, wind pumps

Supplementing mains supply. Power for low-to medium electric power needs. Occasionally mechanical power for agriculture purposes.

PV (solar electric) – grid- -connected, stand‑alone, pumps

Supplementing mains supply. Power for low electric power needs. Water pumping.

Solar thermal – grid‑connected, water heater, cookers, dryers, cooling

Supplementing mains supply. Heating water. Cooking. Drying crops.

Bio energy Supplementing mains supply. Cooking and lighting, motive power for small industry and electric needs. Transport fuel and mechanical power.

Micro and pico hydro Low-to-medium electric power needs. Process motive power for small industry.

Geothermal Grid electricity and large-scale heating.

Village-scale Mini-grids usually hybrid systems (solar-wind, solar-diesel, wind-diesel, etc.). Small-scale residential and commercial electric power needs.

CONCLUSIONSCONCLUSIONS

Renewables can be used for both electricity and heat generation. There is a wide range of renewable energy technologies suitable for implementation in developing countries for a whole variety of different applications.

Renewable energy can contribute to grid-connected generation but also has a large scope for off-grid applications and can be very suitable for remote and rural applications in developing countries.

Demand conservation is the key

Renewables can be used for both electricity and heat generation. There is a wide range of renewable energy technologies suitable for implementation in developing countries for a whole variety of different applications.

Renewable energy can contribute to grid-connected generation but also has a large scope for off-grid applications and can be very suitable for remote and rural applications in developing countries.

Demand conservation is the key