Overview and Rationale  System Components Approach Costs Site Data Energy Demand Calculations Background Materials  Electrical Grid Generators Inverter Rectifier Batteries Photovoltaic Cells Definitions Additional Resources

Overview and Rationale 

Healthcare delivery in one of the most remote places on earth requires a high-quality, reliable, safe, clean, and sustainable supply of energy.  Nyaya Health is pioneering the delivery of effective medical care in rural Nepal, and part of that is developing a model for electrical generation. Renewable energy technology in particular provides an opportunity to improve healthcare outcomes and enhance overall community development.  Renewable energy can itself improve public health outcomes by decreasing carbon emissions and pollution. For rural populations who suffer from a lack of access to reliable traditional energy sources, solar energy is an important strategy for long-term economic and energy self-sufficiency.  Finally, a reliable energy supply is essential for our growing telemedicine applications. Our overall goal, as with any program or technology we deploy, is to develop and test models of delivery in areas affected by poverty, war, and isolation.  

System Components

The following diagram provides an overview of the rural energy generation system.

Approach

The capital costs of energy systems are significant.  They are also among the rural health technologies most prone to breakdown.  As such, we take a phased approach to scaling up our energy system.  This approach itself will serve as a model for other rural healthcare facilities as they, like us, first meet their preliminary needs and then layer on additional energy capacity as they expand.  The key is to cost-efficiently add new components while building upon previously purchased technologies.  The phased approach additionally provides for opportunities to collaborate with corporate donors as we develop our capacity.  Currently, Bayalpata hospital utilizes a battery and inverter system to store energy and have a generator on-site for backup power in emergencies. The hospital is connected to the public electric grid, which is operational approximately 30% of the time owing to load-shedding and other outages.  

The phased approach that we take is as follows: 

Throughout, during periods of excess solar energy, we will sell unused solar electricity to the utility company or donate to our other educational and community activities.

Costs

Site Data

Coordinates of the Hospital

Longitude East: 81 degrees 14 minutes, XX seconds , 

Latitude North : 29 degrees 13 minutes, XX seconds

The hospital is situated on a plain with unobstructed sunlight.   The buildings are arrayed in a line, with sides of the triangular roofs facing in the north-south direction.   This may facilitate placement of solar panels on the south facing side of the roof, depending upon whether this is structurally feasible.  See pictures of the site below.   For solar, there are approximately 5000 sq meters on the government plot itself that we could potentially use to place panels.  We can hire and train any additional staff as needed for the new system.

Solar data for Bayalpata from HOMER Energy's software ( http://www.homerenergy.com/  which imports data from NASA's surface solar energy data set http://eosweb.larc.nasa.gov/sse/ ): 

 

Temperature

Average/Typical During the Day: From 15-30 degrees Celsius, varying by season.

Max: 45 degrees Celsius at peak-day during the summer

Min: 5 degrees Celsius in early morning during the winter

 

Rainfall

Rainfall is approximately 1250mm per year. Nepal experiences monsoon rains from June to September.  

During this time, it can rain non-stop up to 2-3 days.  Rains can be very hard and persistent.  The fields where the solar PV arrays would be located are not prone to flooding, however.

 

Energy Demand Calculations

There are two main considerations for determining electrical load: surge (start-up) and maintenance (typical) loads. The surge load is the start-up load, so for example starting a 400 watt centrifuge may instantaneously draw 1000 watts. The maintenance loads are those that, once the machines have started, are continuously drawing that amount of energy.

Background Materials 

Electrical Grid

The grid is the AC electricity provided by the utility company over power lines. The clinic is connected to the grid, but owing to load-shedding, it is 40% on in good times; and has been out for stretches of entire two weeks. Some organizations can get exemptions on the load shedding from the utility company since they provide essential clinical services. In our setting, however, the load shedding occurs by entire areas within the district, making getting load shedding exemptions more difficult. 

Generators

Despite rising fuel prices, fossil fuel generators (kerosene, petroleum/gasoline, diesel) still play a prominent role in any emergency power system. The most important role of a generator is that it can provide electricity in serious emergencies, such as when there are long periods of grid outages. This can provide direct electricity to AC loads, or can pass through the rectifier to charge the batteries. In small clinics, it is often the only additional emergency power source. The cost-efficiency of generator systems is related less to load provided than by the daily run-time; longer run-times typically make for a much more costly system:

Source: "Renewable Energy for Rural Health Clinics", National Renewable Energy Laboratory, 1998.

http://www.nyayahealth.org/Library/energy_rural_PHC.pdf

That is, as a supplemental resource, diesel generators can be cost-effective. But if you are starting to use the generator non-stop owing to an unavailable or uncertain grid, you should quickly consider investing in solar or wind, since the operating costs of the generator will quickly catch up to the up-front costs of the alternative energy sources.

We presently have a 5 kW diesel generator at our clinic to provide additional power. We chose diesel over petrol because it is safer, more reliable, more durable, and more fuel efficient. Here are some good resources on the subject:

http://thewattshop.co.nz/generators.php

http://www.enable.nu/publication/D_1_1_RETs_overview.pdf

http://practicalactionconsulting.org/docs/technical_information_service/diesel.pdf

There is also mention here about the utility of water-cooled over air-cooled systems, perferable if cost/availability is equivalent.

In some cases, a clinic may be faced with a choice between a cheaper 2.5 kW petrol and a more expensive 5 kW diesel, which makes the decision somewhat more difficult. You have to determine what the typical cost per liter, and the liters per kW-hour for both. determine the difference between petrol and diesel at one year of operation where we are burning an estimated 20*360 =7200 kWh. it is quite possible that a 5 kWh diesel engine will be less costly than a 2.5 kWh petrol engine. See http://spreadsheets.google.com/pub?key=p-TJjzE7A-O7M4RGBq80mGA for our rough calculations. 

Inverter

An inverter converts DC electricity (from photovoltaic cells or batteries) to AC, which is what most appliances require. One important aspect for most medical centers, certainly those with lab equipment, is that the inverter produces pure sine waves rather than square waves or modified sine waves. Many of the sensitive electronic devices require pure sine waves from the inverter.

The size of the inverter is determined by the electrical load of the clinic. It is important when sizing the system to wire properly to avoid overloading the inverter. So for example a 5 KVA inverter cannot be powering 6 KW of machines, or else it will burn out. 

Rectifier

A rectifier operates in the reverse, converting AC electricity from the grid or generator into DC that can be stored for later use by the battery system. It typically is part of the same machine/box as the inverter. 

Batteries

Batteries store energy for later use. Input and output current is DC, so they require an inverter to power AC loads. The size of the battery system is typically computed in Amp-Hours, which is determined by the amperes of each device and their run time. To convert from your KW-hrs per day to Amp-Hours, you can either use the amps ratings for each of your devices, or just devide the KW-hrs by the Voltage of the batteries (often 12V). So as to preserve the life of your batteries, you're not going to want to drain your batteries all the way down. Hence you might size your system based on draining 80% of the way. 50% might be even better, but would require a larger system that might be cost prohibitive.

You can see our calculations here:

http://www.nyayahealth.org/Library/sanfe_energy_calcs.xls 

Photovoltaic Cells

The up-front costs of PV are often sizeable, but in many areas with adequate solar exposure, they represent an excellent long-term solution. 

Definitions

Kilovolt-amps (kVA): The amount of power in an alternating current (AC) circuit equal to a current flow of one ampere at an elecrtomotive force of one volt.

Kilowatts(kW): equal to one thousand watts. 1 Watt = 1 Volt x 1 Amp. Work is done at  a rate of one watt when one ampere flows through a potential difference of 1 volt.

Amperes(amp): SI base unit (short form: amps) of electric current or amount of electric charge per unit time, in coulombs per second.

Direct Current (DC): Unidirectional flow of electric charge. Direct current is produced by sources such as batteries, solar cells etc. Direct current is used to charge batteries, and in nearly all electronic systems as the power supply.

Alternating Current (AC): An electric current whose direction reverses cyclically. The usual waveform of an AC power circuit is a sine wave which also results in the most efficient transmission of energy. Used generically AC refers to the form in which electricity is delivered to businesses and residences.

Kilowatt hour (kW.h/kW h/kWh): The unit used to express energy delivered by electric utilities. Energy in kilowatt hours is the product of power (delivered by the appliance)  in kilowatts multiplied by time in hours (amount of time appliance is used.)

Source: http://en.wikipedia.org/wiki/   

Additional Resources

Calculating energy needs (USAID)

http://www.usenix.org/event/nsdi08/tech/full_papers/surana/surana_html/index.html

http://home.howstuffworks.com/emergency-power.htm

http://en.wikipedia.org/wiki/Uninterruptible_power_supply

http://www.scienceinafrica.co.za/2008/february/backuppower.htm

http://www.powerstream.com/battery-capacity-calculations.htm

http://www.powervar.com/Eng/ABCs/CalcVAWATTS.asp

Members' Notes:

Solar Photovoltaic

Basics of Solar PV technology from SELF website: http://www.self.org/shs_tech.asp

SELF's 1994 project in Pulimarang, Nepal: http://self.org/nepal.asp

Solar PV vendors in Nepal: http://energy.sourceguides.com/businesses/byP/solar/pvM/byGeo/byC/Nepal/Nepal.shtml

Solar Energy Data is available here (Sanfebagar Latitude: 29N ; Longitude: 81E): http://eosweb.larc.nasa.gov/cgi-bin/sse/sse.cgi?+s01#s01

Possible Funding Sources/Partners:

1. DC-based Solar Electric Light Fund (SELF) funded PIH to put in solar panels in Rwanda. A hybrid energy system combining diesel and solar power was built. The system uses diesel generators as back-ups but generates 90% or more of the power used  for providing the clinical services from solar energy. See and read more about the project: http://pih.org/inforesources/newsletters/PIH-Newsletter-2007Summer.pdf

2. Himalayan Light Foundation: http://www.hlf.org.np/index.html.

3. After installation, government subsidies may be available: http://www.energyhimalaya.com/policies/gov-plans-n-policies.html

Solar Thermal

Biogas

duncan says there's a decent amount of livestock in the area, which is

what we need for biogas. basically, you throw animal dung and water

into a pit. methane and co2 are produced, which are channeled into

heating, lighting, cooking utilities in a home, clinic, etc. i'm

looking into the different types of supplies we would need for this

(how much dung, what type of pit, connections to homes, etc).

pros off the top of my head:

- relatively cheap and easy to install/maintain with the right training

- free fuel (animal dung) once installed

- fuels several things (heating, lighting, cooking stoves...)

- provides energy for wide range of places, from individual houses to

larger structures and communities based on size of pit, etc.

- we can eliminate indoor air pollution from stoves, since this is a

clean fuel, thus somewhat reducing respiratory infections

- good for environment

- many examples of successful implementation in resource poor settings

- end product is a good fertilizer

downside is that temperature is important - the pit needs to be in a

warm environment, which may be difficult in nepal year-round...any

thoughts? there are some other downsides, but this is a big one.

here's a link for a brief article about biogas if you don't know much

about it. i glanced at it quickly:

http://practicalaction.org/practicalanswers/product_info.php?cPath=21_32&products_id=42

Energy-Efficient Appliances

We also are looking for an inexpensive, energy-efficient option for refrigeration, such as:

Sun Frost Energy-Efficient Refrigerators

There's some information about this also at:

http://www.polarpowerinc.com/products/refrigerator/reliable-vaccine-ref.htm

http://www.polarpowerinc.com/products/refrigerator/consider_solar_ref.htm

If we have a positive answer from SELF this can be incorporated in the same project...

Discussions and Suggestions on Configuring a Power System http://www.polarpowerinc.com/info/y2k-year2000.htm