Renewable Energy Sources for Electrical Generation

and Hot Water Production

Introduction to Renewable Introduction to Renewable Energy SourcesEnergy Sources

“Capturing the energy from on-going natural processes”

Hydroelectric power now supplies about 715,000 MWeor 19% of world electricity (16% in 2003).

HydropowerWind powerSolar power

http://people.howstuffworks.com/hydropower-plant.htm

http://www.innovation-brennstoffzelle.de/e/energie/haupt4b.html

Applicability of RE sourcesSOLAR ENERGY APPLICABILITY

Solar Energy

ElectricityWater HeatingPassive Heating Cooling

•Thermal Power Plants•Photovoltaics

•Passive Solar Cooling•Adsorbtion refrigeration•Absorbtion refrigeration•Solar Evaporative Cooling

•Direct gain•Thermal Storage Wall•Sun space

Applicability of RE sourcesWIND ENERGY APPLICABILITY

World wind energy generating capacity in thousand MW, 1980-2002

Source: http://www.mindfully.org/Energy/2003/Wind-Power-GrowthMay03.htm

Applicability of RE sourcesWIND ENERGY APPLICABILITY

– Mechanical Pumping– Electricity generation

Source: http://www.buddycom.com/holland/holland/windmills.jpg

Applicability of RE sourcesBIO-ENERGY APPLICABILITY

– Power generation from burning biomass and waste

– Power generation from animal manure

Applicability of RE sourcesHYDRO-POWER APPLICABILITY

Source: http://www.eere.energy.gov/windandhydro/hydro_plant_types.html

http://www.sas.usace.army.mil/lakes/hartwell/works.htm

Renewable Energy Renewable Energy TechnologiesTechnologies

Technologies for Cyprus:• Solar Photovoltaic (PV)

Systems• Wind Energy Conversion

Systems• Mini and Micro

Hydroelectric Systems• Solar Water Heating

Systems

Constraints of RE Constraints of RE ApplicabilityApplicability

Constraints of Solar Electricity Applications– Capital Cost is too high:– (Today it costs approx. €20,000 for a normal

house to have a stand alone solar photovoltaic system)

– Lack of incentives– Lack of know-how

Constraints of RE Constraints of RE ApplicabilityApplicability

Constraints of wind-energy applications

– In general noise can be a problem– Wind data is not fully available in Cyprus– Lack of incentives for small applications

Constraints of RE Constraints of RE ApplicabilityApplicability

Constraints of hydro-power applications

– Flooding of areas may cause environmental damage

– Rainfall shortages– Limited availability of water movement in

Cyprus

Solar Photovoltaic (PV) Systems

Photovoltaics

Solar Photovoltaic (PV) Systems

• Electrical energy can be produced directly from solar energy using photovoltaic cells.

• PV cells are thin layers of a semiconductor -usually crystalline silicon - that convert photons of sunlight directly into DC electrical energy.

• PV cells and systems are quite costly to purchase, but they have no fuel cost.

• PV systems provide clean, noiseless electrical energy from renewable solar energy.

• PV modules are quite expensive (about $6/watt).

• They are usually cost effective only for remote or difficult to access locations where utility power is unavailable or it is too expensive to install the utility lines.

PV System Properties

• Individual PV cells are built up into panels with outputs from a few watts to 100 watts.

• These panels are modular and can be configured into larger arrays that can match almost any load requirement.

• PV systems are a proven technology and are made by numerous manufacturers.

• PV systems range in cost from $8000/kW to $13,000/kW installed. The high cost is for PV systems with battery storage and inverters.

Some Cost-Effective Urban Applications• Emergency telephones for roadways,

bike paths, parks, and parking lots• Lighting for signs, billboards, and

flagpoles • Traffic counters• Traffic hazard warning flashers • School crossing flashers • Security lighting for parks, playgrounds, parking

lots, paths, outdoor stairways, and equipment yards

• Irrigation controls for ball fields, median strips, and landscaping

A Typical Stand Alone PV System

A Packaged PV System

Comparison of Flexible and Rigid PV Modules

Source: United Solar Systems Corp., DOE/NREL

Where to Apply PV Systems

• Small loads are located in remote or difficult-to-access sites

• Long power lines to small loads need to be rebuilt

• Only high voltage transmission lines are available (large step-down transformers are very expensive)

• Utility line construction is very costly due to terrain, lack of easements, stringent building codes, or environmentally sensitive locations

Where to Apply PV Systems (cont)• Engine generators are currently being used• Stringent air quality, fuel transportation, or

noise regulations prevent the use of engine generators

• Delivery of fuel for generators in difficult-to-access locations is a problem

Where to Apply PV Systems (cont)

• Old livestock-watering windmills need to be replaced

• Water has to be hauled for livestock or wildlife

• An application needs to be portable or temporary

– Powering telecommunication receivers and transmitters at remote areas, where the electricity grid does not reach

– Solar cells on telephone kiosks which are not easily accessible by the electricity grid

Solar Energy in Cyprus Remote Applications

Cost of PV Systems• A mid-sized packaged DC system with 100 to

600 watt PV arrays averages about $14/watt.• A larger packaged AC system with 900 to

1800 watt PV arrays averages about $18/watt.

• A recent 10 kW PV system installed near Gainesville, FL cost $85,000.

• Very large PV arrays (utility size) without batteries or charge controllers average about $6/watt installed.

The Photovoltaic Effect• Sunlight is composed of photons—discrete

units of light energy.

• When photons strike a PV cell, some are absorbed by the semiconductor material and the energy is transferred to electrons.

• With their new-found energy, the electrons can escape from their associated atoms and flow as current in an electrical circuit.

Photovoltaic Cells• PV arrays require cleaning of

the surfaces if they become soiled or are used in dusty locations.

• They must be kept clear of snow, weeds, and other sources of shading to operate properly.

• PV cells are connected in series; if even one cell in a module is shaded, the output of the entire module will decrease appreciably.

The Photovoltaic Effect (cont)

Light energy

Electrical energy

n-Type semiconductor

p-Type semiconductor

Photovoltaic device

Solar Photovoltaic Suppliers• Astro Power, Inc• Cell Si Co, Inc• Advanced Systems Mfg, Inc• Amonix, Inc• Canrom Photovoltaics, Inc• EDTEK, Inc• EMCORE Corp• EBARA Solar, Inc• Energy Conversion Devices, Inc• Evergreen Solar• Global Solar Energy, Inc• Gratings, Inc

Solar Detoxification

• Solar Photocatalysis is today the most successful photochemical application of solar photons.

• Solar detoxification is well-suited to environmental conservation

• It is non-selective and can be employed with complex mixtures of contaminants.

Solar Detoxification TechnologyTreatment of Non-Biodegradable

Chlorinated Water Contaminants• A European industrial consortium was created to

design, manufacture, install and set-up turnkey SOLARDETOX(R) plants used to treat hazardous and non-biodegradable water contaminants using solar light.

• The process is based on the solar photo-catalytic mineralization of organic compounds dissolved in water.

• It is to be used to treat persistent industrial contaminants.

Solar Detoxification (cont)

• A full demonstration plant has been constructed at an industrial environment.

• There are a promising number of possible applications to this remarkable environmental technology.

• It has been validated even in non-sunny regions such as the West of Germany.

• The analysed results show that this technology could be fully competitive against conventional wastewater treatment processes.

Other Solar Detoxification Projects

• Detoxification of water for recycling and potabilization by solar photocatalysis in semi-arid countries (Morocco, Tunisia and Egypt)

Conceptual design of the final stand-alone solar photo-reactor for disinfection and decontamination to be tested in rural locations of Morocco, Tunisia, and Egypt

Other Solar Detoxification Projects

• Environmental collection and recycling of pesticide plastic bottles using an advanced oxidation process driven by solar energy (Spain)

• Solar photocatalytic water detoxification of paper mill effluents (Germany)

• Cost effective solar photocatalytic technology for water decontamination in rural areas of developing countries (SOLWATER)

• A coupled advanced oxidation-biological process for recycling of industrial wastewater containing persistent organic contaminants (CADOX)

Other Solar Detoxification Projects

• Solar detoxification of distillery waste (India)• Solar detoxification of contaminated water and

liquefied gas (Spain)

Solar water detoxification technology at the Plataforma Solar de Almería, Spain

Wind Energy Conversion Systems

Wind Energy Conversion Systems

• WECS - or wind turbines - are another one of the DG technologies using renewable energy sources.

• Wind turbines contain propeller-like blades that turn the energy in the wind into rotational motion to drive a generator.

• There are two general classifications of wind turbines:– HAWT - horizontal axis wind turbine– VAWT - vertical axis wind turbine

Three-Blade HAWT

Source: Tom Hall, DOE/ NREL

Darius Rotor Type VAWT

Source: Sandia National Laboratories, US DOE/NREL

Electrical Generators• Most wind turbines use asynchronous

generators that operate at variable speeds and produce DC power. An inverter is required to produce 50 Hz (or 60 Hz) AC.

• Low speed rotors usually turn at 15 to 60 rpm. A gear box is often used to drive higher speed generators. Gear ratios of 20:1 to 80:1 may be needed.

• AC is produced with an induction generator. Direct drive and variable speed generators are in prototype.

WECS Properties• Sizes range from a few watts to >1 MW

• Costs range from $1000/kW to $3000/kW.

• Proven technology

• Available from several manufacturers

• Use renewable energy input

• Applications

– small scale residential or commercial

– remote power systems

– up to utility scale power generation

Wind Turbine Performance• The maximum power available from a wind

turbine is given by:

• For P/A in W/m2 and V in m/s

where A is the area normal to the wind in m2

• As a practical matter, only 20-40% of this wind power can actually be captured.

3V21

AP

ρ=

3V625.0AP=

Classes of Wind Power Density at 33 ft (10 m) and 164 ft (50 m)

Source: DOE, Pacific Northwest National Laboratory (Battelle) Classes of Wind Energy for the World Resource Maps

Wind ExamplesFind the power in watts per square meter that can be produced from a 10 m/s wind. Assume a practical capture of 40% of the maximum value.

How would this change if the wind speed were 20 m/s?

Note that doubling the wind speed increased the power output by a factor of eight.

23 m/W250)10()625.0()40.0(AP

==

23 m/W2000)20()625.0()40.0(AP

==

Wind Turbine Suppliers• Atlantic Orient Corp• Bergey Windpower Corp• Dutch Pacific, LLC• GE Wind Energy• Jacobs• Northern Power Systems• Pacific Wind, LLC• Specialized Power Systems• SUZLON Wind Energy Corp• TMA, Inc• TOKO ASIA Enterprises• US Wind Turbine, LLC• Wind Turbine Company• Windstream Power Systems, Inc

Mini and Micro Hydro Generation

Reference for this Section

Micro-Hydropower Systems – A Buyer’s GuideNatural Resources of Canada 2004

Available on the Internet atwww.canren.qc.ca

What Is Mini or Micro Hydropower?• Flowing and falling water have potential energy.

Hydropower comes from converting energy in flowing water by means of a water wheel or through a turbine into useful mechanical power.

• This power is converted into electricity using an electric generator or is used directly to run milling machines.

• Small-scale hydropower systems are receiving a great deal of interest as a cost effective, renewable source of electrical power for homes, schools, commercial buildings and especially in remote communities.

A waterwheel in action

Micro-hydro systems have the following components:

• a water turbine that converts the energy of flowing or falling water into mechanical energy that drives a generator, which generates electrical power - this is the heart of a micro-hydropower system

• a control mechanism to provide stable electrical power

• electrical distribution lines to deliver the power to its destination

What May Be Needed• an intake or weir to divert stream flow from the water

course • a canal/pipeline to carry the water flow to the forebay

from the intake • a forebay tank and trash rack to filter debris and

prevent it from being drawn into the turbine at the penstock pipe intake

• a penstock pipe to convey the water to the powerhouse

• a powerhouse, in which the turbine and generator convert the power of the water into electricity

• a tailrace through which the water is released back to the river or stream

Principal components of a micro-hydropower system

Run of River Systems

• Many micro-hydropower systems operate "run of river," which means that neither a large dam or water storage reservoir is built nor is land flooded.

• Only a fraction of the available stream flow at a given time is used to generate power, and this has little environmental impact.

• The amount of energy that can be captured depends on the amount of water flowing per second (the flow rate) and the height from which the water falls (the head).

A typical micro-hydropower weir in Cherry Creek, British Columbia

How to Identify a Potential Site

• The best geographical areas for micro-hydropower systems are those where there are steep rivers, streams, creeks or springs flowing year-round.

• There is some micro-hydropower potential in the mountains of Cyprus.

Advantages of Micro Hydro• The energy to run hydropower systems is almost free

once they are built, even though they usually cost more to build than systems that generate electricity using fossil fuel or natural gas.

• Hydropower systems are inflation-proof because the cost of using the water in the river and stream is not likely to increase, and the cost of fuel for other systems could increase over the years.

• Hydropower systems last 20 to 30 years - longer than most other kinds of generating systems.

• Small projects such as micro-hydro systems can be built relatively quickly.

Advantages (Cont)• As a renewable resource, a micro-

hydropower system does not depend on oil, gas, coal or other fossil fuel in order to operate.

• It promotes self-sufficiency because its development occurs on a much smaller scale, and most adverse environmental and social effects of large energy development projects are eliminated.

• There is no need for long transmission lines because output is consumed near the source.

How to Measure Potential Power and Energy

• The first step is to determine the hydro potential of water flowing from the river or stream. You will need to know the flow rateof the water and the head through which the water can fall, as defined in the following:

Flow Rate and Head• The flow rate is the quantity of water flowing

past a point at a given time. Typical units used for flow rate are cubic metres per second (m3/s) or litres per second (lps).

• The head is the vertical height in metres (m) from the level where the water enters the intake pipe (penstock) to the level where the water leaves the turbine housing (see Figure 5).

Head of a micro-hydropower system

Power Calculations• The amount of power available from a micro-

hydropower system is directly related to the flow rate, head and the force of gravity. Once you have determined the usable flow rate (the amount of flow you can divert for power generation) and the available head for your particular site, you can calculate the amount of electrical power you can expect to generate. This is calculated using the following equation:

• Pth = Q x H x g– Pth = Theoretical power output in kW

Q = Usable flow rate in m3/sH = Gross head in mg = Gravitational constant (9.8 m/s2)

Consider System Efficiency

• Small water turbines rarely have efficiencies better than 80 percent.

• Potential power will also be lost in the penstock pipe that carries the water to the turbine because of frictional losses. Through careful design, however, this loss can be reduced to a small percentage; normally, the losses can be kept to 5 to 10 percent.

• Typically, overall efficiencies for electrical generation systems can vary from 50 to 70 percent, with higher overall efficiencies occurring in high-head systems.

• Generally, overall efficiencies are also lower for smaller systems.

Efficiency (Cont)

• As a rule, the "water to wire" efficiency factor for small systems (for example, up to 10 kW) could be taken as approximately 50 percent.

• For larger systems (larger than 10 kW) the efficiency factor is generally from 60 to 70 percent.

• Therefore, to determine a realistic power output, the theoretical power must be multiplied by an efficiency factor of 0.5 to 0.7, depending on the capacity and type of system.

Example• P = Q × H × g × e

e = efficiency factor (0.5 to 0.7)– Power output (in kW) = Q (m3/s) × H (m) × g × e

• Example A turbine generator operates at a head of 10 m (33 ft.) with a flow of 0.3 m3/s. How many kW will it deliver if the system efficiency is 50%?

• The solution is given by P = (0.3) × (10) × (9.8) × (0.5) = 14.7 kW

• These calculations will give you an idea of how much power you can obtain from your water resource.

Typical Power Output (in Watts) With Various Head and Water-Flow Rates

Cost of Micro Hydro Systems• How much will a micro-hydropower system cost?

There is no standard answer to this question because costs depend on site conditions and on how much work you are prepared to do yourself.

• In general, with current technologies the total cost can range from $1,500 to $2,500 per kilowatt of installed capacity, depending on the system's capacity and location.

• For systems that are less than 5 kW in power output, the cost per kW is approximately $2,500 or higher because of the smaller size and the cost of additional components such as a battery bank and inverter.

Approximate Micro-Hydropower System Costs: AC-Direct Systems

Additional References

• Mini/Micro Hydropower for the Mountains. ... Such considerations bring to the fore the attractiveness of the mini/micro-hydropowerdevelopment path. ...

• www.icimod.org/focus/energy/energy_mmhp.htm -... Hydropowersystems are classified as large, medium, small, mini and microaccording to their installed power generation capacity. ...

• www.canren.gc.ca/prod_serv/ index.asp?CaId=196&PgId=1305 ...New improvements in technology are widening the scope for small hydropower, particularly for mini-, micro- and pico-hydro applications. ...

• www.eurorex.com/ugtoges/Glossary/smhypage.htm - ... of canals, tributaries of main river Karnafuli, Shangu, Matamuhurias well as tiny waterfalls having potentials for setting up mini/micro hydropower unit in ...

• lged.org/sre/microhy-sre.htm -...File Format: PDF/Adobe Acrobat - View as HTML

• www.hrcshp.org/en/world/db/fiji.pdf -... surveys and analyses of mini-hydro projects ... analysis software Training on micro-hydro technology ... for exploiting ultra-low head hydropowersites, particularly ...

• www.itpower.co.uk/MMHC.htm -

Solar Water Heating

Solar Water Heating Applications

• Swimming pools

• Hot tubs and spas

• Domestic hot water– Offices, malls, hotels, motels– Large laundries and kitchens– Facilities in remote areas– Jails, hospitals and dormitories

Solar Water Heating Applications

• Process hot water– Food processing, hot water cleanup– Hot water rinses– Pre-heat boiler makeup water

Value of Solar Water Heating• Solar water heating systems

– Directly substitute renewable energy for conventional energy

– Reduce the amount of heat that must be provided by conventional water heating

– Reduce the use of electricity or fossil fuels by as much as 80%.

Status of Solar Water Heating

• Today’s solar water heating systems are well proven and reliable when correctly matched to climate and load.

• Solar water heating systems are most likely to be cost effective for facilities with expensive energy, or facilities with large hot water requirements.

Solar Water Heating in Cyprus• In 1999, well over half of the households and

about half of the hotels had solar water heating systems.

• Cyprus is one of the leading countries in terms of installed solar collectors per capita.

• Cyprus currently has a number of small and large solar water heater manufacturers, employing hundreds of people and producing thousands of m2 of solar collectors annually.

Solar Energy - Hotel• Hawaii's Mauna Lani Bay

Hotel installed a system of insulating PV roofing tiles.

• The system covers 10,000 square feet and generates 75 net kilowatts of electricity.

• It will reduce the hotel's utility bills enough to pay for itself in five years.

Types of Collectors• Low temperature – to 32ºC

– Unglazed absorbers• Mid temperature – to 70ºC

– Glazed flat plate collectors– Integrated collector systems (ICS),

thermosiphon, antifreeze, drainback• High temperature

– Evacuated tube – to 175ºC– Parabolic trough – to 300ºC

Flat-plate Collector

Passive, Indirect Thermosiphon System

Evacuated Tube Collector

Efficiency Aspects of Solar Water Heating

• Colder water supply temperatures increase system efficiency, since the fluid being heated loses less heat to the surrounding air until it reaches higher temperatures.

• Colder air temperatures reduce system efficiency by increasing the loss of heat from the collectors to the air.

• Potential for system freezing is a serious problem, and many solutions result in reducing system efficiency.

Two Main Types of Passive Systems

• Integrated Collector Systems (ICS) – store the water in the collector itself

• Thermosiphon Systems – have a separate storage tank directly above

the collector

Two Main Types of Passive Systems

• Good insulation of the collector and/or tank helps prevent heat loss at night, and helps prevent freezing.

• Connection pipes are the most critical parts for concern over freezing. Good insulation is necessary, but still does not totally solve the problem.

• The most frequently used systems for large facilities – antifreeze systems – are active, indirect systems.

• System configurations may utilize one storage tank or two tanks.– Single tank – conventional h/w heater– Single tank – wrap-around heat exchanger– Two tank – convection flow

General System Design Philosophy

• Combine solar water heating cost effectively with conventional water heating.– Use solar water heating systems to provide

about 2/3 of the annual need, and use conventional systems to provide the other 1/3.

– Use conventional water heating systems for backup.

• The most cost-effective size for a solar water heating system is typically to meet the full summer demand, but to meet only 2/3 of the year-round demand.

• Meeting the full winter demand with the reduced solar resource is very costly.

• Experience with commercial buildings seems to show that maximum cost-effectiveness occurs at a solar supply of about 50% of the year-round demand.

First Things First

• Conservation is usually the most cost-effective way to reduce water-heating bills. – For example, a low-flow showerhead

costing $9 saves 275 kWh of electrical energy and $27.50 per year for a five-month payback.

First Things First• Other hot-water saving measures:

– faucet aerators, – timed or optical-sensor faucets, – water-saving clothes washers, dishwashers or

other appliances, – water heater insulation, – lower-setting or timed water heaters, – swimming pool covers.

First Things First

• These energy efficiency measures are all compatible with solar water heating, and often reduce the size of the systems needed.

• Reducing hot-water use saves on water and sewage as well as energy.

Installation Issues

• Collectors are typically mounted on a roof–-facing south–and with a tilt angle equal to the latitude of the site.

• Latitude plus 15º maximizes winter heat collection, and latitude minus 15º maximizes summer heat collection.

Installation Issues

• Mounting orientation is not extremely critical. At most, a 10% loss of heat collection occurs for – ± 45º off southern orientation with a latitude

-15º tilt, or– ± 25º off latitude tilt with a true southern

orientation.

Installation Issues

• Weight on roof is not usually a problem, but check any structural requirements coming from earthquake or hurricane danger.

• Comply with standard plumbing and local building codes. Check for special regulations regarding solar water heaters.

Installation Issues

• In the U.S., quality assurance and performance rating standards have been developed by SRCC – the Solar Rating and Certification Corporation.

• SRCC standards address health and safety, code compliance, and durability and reliability.

Application of Small Systems(less than 10 square metres of collectors)

• Consider four small systems approved by SMUD*:– A 4 m² indirect thermosiphon system– An evacuated tube integrated collector

system– A 6 m² antifreeze system– A 4 m² antifreeze system with wrap-around

heat exchanger (using one less pump)* SMUD – Sacramento (California, US) Municipal Utility District

• System costs vary from $2,860 to $3,180• Systems meet 61% to 74% of 220 litre per day

hot water demand• For a 20-year life, 0.5% per year O&M for the

two passive systems, and 2% per year O&M for the two active systems, the delivered cost is $20 to $23 per GJ (278 kWh) of hot water.

• Or, cost is around $7.20 to $8.30 per 100 kWh of hot water. Or 7.2 to 8.3 cents per kWh.

Table 1. Typical Energy Cost for Water Heating

Energy Cost Average Efficiency

Effective Energy Cost

electricity $0.10/kWh (10¢/kWh) 91% $0.11/kWhLPG $ 0.173/kWh ($1.23/kg) 65% $ 0.27/kWhfuel oil $ 0.09/kWh ($1.00/L) 63% $0.14/kWhnatural gas $ 0.029/kWh ($8.00/GJ) 65% $ 0.044/kWh

Maintenance Issues• Solar water heating systems are long-lived (20-30

years), and generally require relatively little attention.

• All systems should be inspected and checked out at least twice a year. – Sensors and controllers in active systems

should be tested for proper operation. – Pumps should be checked and tanks checked

for leaks. – Relief valves ($10) need replacement about

every 15 years.

Maintenance Issues• If water is hard – check for scale (usually

calcium carbonate). – Consider installing an extra anode rod in the

water heater tank. – Clean potable water side of heat exchangers.

• Replace antifreeze every 5-10 years.

What Makes Solar Water Heating Cost-Effective?

• High-cost conventional water-heating system (more than about $15 to $20/GJ)

• High daily volume of very hot water use (such as for laundries or industrial processes)

• Steady demand throughout the week and year, or highest need in the summer

What Makes Solar Water Heating Cost-Effective?

• Relatively greater daytime hot-water use• Unshaded, south-facing roof space or sunny,

nearby grounds • Good solar resource • Cold-water supply • Soft water