solar powered air conditioning for elderly, low income houstonians robert l. howard, jr., ph.d....

Solar Powered Air Conditioning for Elderly, Low Income Houstonians

Robert L. Howard, Jr., Ph.D.

National Society of Black Engineers

Houston Space Chapter

August, 2003Chapter Technology Seminar

NSBE – Houston Space Chapter

Introduction

The Need– Air conditioning can be as high as 25-40% of

a household’s annual energy costs– Many low-income residents cannot afford this

and go without air conditioning– 60,000 homes in Houston without power in

2001; only 14,443 in all of Texas received assistance

– Senior citizens accounted for 14 out of 20 heat-related deaths in Houston in 2001



Introduction

The Need– CDC reports fans are useless at temperatures

above 90 deg F with humidity above 35%• Spur movement of hot, humid air

• Causes increased heat stress – accelerates body hearting and raises internal body temperature

• Essentially turns room into convection oven

• Should not be used for preventing heat-related illness in areas of high humidity



Introduction

Problem persists despite local efforts to help– Window air conditioners donated, but wiring

in many homes cannot handle added load– 1998 fatality: widower had turned off air

conditioner to save money– Houston libraries and multipurpose centers

open as cooling centers, but inaccessible to some: elderly less mobile, afraid to leave home, lack transportation



Introduction

Excellent opportunity for NSBE and NASA to come together in mutual fulfillment of charters

NSBE-Houston Space Chapter can make a positive impact by installing solar powered air conditioners in as many elderly, low income households as possible



Introduction

Provides a cool zone within home – elderly do not have to leave homes to be safe

Does not interfere with limited house wiring

Will not increase household electric billTechnology available off the shelf, but not

accessible to these communities – cost and unfamiliarity; we will bring it to them



Introduction

Harmony of NSBE and NASA objectives– NASA vision is “to improve life here, to extend life

there, to find life beyond.”– NSBE mission is “to increase the number of culturally

responsible Black engineers who excel academically, succeed professionally, and positively impact the community”

Solar power system improves life here in a culturally responsible way that positively impacts the community

If we don’t do it, who will?



Introduction

Service project may well save lives; at minimum it will increase the comfort of our elderly

Also benefits chapter members by providing hands-on technical experience many will not encounter in day-to-day job responsibilities



Brief Survey of Solar Electric Power

More than just a set of solar panelsVariety of components required for proper

functioningPhotovoltaic Panel

– Three basic types: single crystal silicon, polycrystal silicon, and thin film/amorphous

– Convert sunlight directly into DC electricity




Inverter– Converts DC electricity into AC electricity

– Most home appliances require AC power

Battery– Provide energy storage for use when solar panels

cannot receive sunlight

– Also supplement panels to smooth power level

– Most are Lead-acid (30% sulfuric acid)

– Absorbed Glass Mat (AGM) type recommended – requires no maintenance and cannot leak




Charge Controller– Used in any solar power system that includes

batteries– Blocks reverse current (solar panels draining

batteries) and prevents battery overcharge– May also prevent battery overdischarge,

protect from electrical overload, and display battery status and flow of power




Power Outlets and Wiring– Proper gauge wiring essential to avoid poor

performance of appliances and possible fire risks

– Power outlets sometimes include circuit protection

Frame/Structure– Hold solar panels in place; roof or pole

mounts; some pole mounts track sun



Overview of Mars Testbed Solar Recharge Station

Some in-house JSC experience with solar power systems– Environmental Office (COD) and Advanced

EVA Group built a solar recharge station as part of a Mars testbed activity

– Used commercially available components from Solarcraft (Stafford, TX)

– Purpose was to demonstrate how state-of-the-art technology can improve life on earth as well as explore space




Reads like a prelude to this projectHSC will seek to tap into their expertise

and possibly their relationship with Solarcraft

Will also seek to coordinate with MOD and Engineering Directorate organizations involved with solar power



Solar Powered Air Conditioning System

Two main options exist:– Daylight-only system (no batteries)

• Simpler, significantly less expensive• Offers no cooling between sunset and dawn

– Continuously operating system (requires batteries)

• Provides constant temperature• More expensive and complex

– Presentation will explore both options, but will not choose between them




Daylight-only Configuration




Continuous Operation Configuration



Subsystem Data

In order to conduct a preliminary sizing, data was compiled on commercially available solar power subsystems and air conditioning units– Voltage, wattage, amperage, BTU cooling

capacity, price, vendor, etc.



Preliminary System Sizing

Complete solar-powered air conditioning system sized based on current vendor prices

Should not be construed as an exact specification of what the system will look like or cost– Prices, component availability subject to

change– Chapter may decide to construct items in-

house rather than use commercial equipment




Should be viewed as a ballpark estimateBoth options (daytime vs. continuous) sizedFor simplicity, continuous system assumes:

– 12 hours charge time; 10 hours discharge time

Overcast conditions not modeled in this analysis




Both options assume cooling for a 300 to 350 square foot area, which includes a kitchen

Rule of thumb suggests 8,000 BTU air conditioner for this square footage, with additional 4,000 BTU to account for kitchen heat

Selected 1140 W Kenmore 12,300 BTU Multi-Room Air Conditioner



Preliminary System Sizing – Option 1 (Daytime-only)

Photovoltaic Panel– SAPC-165 multicrystalline module– 156 W per module, $612– Total of seven required, for cost of $4284

Panel Mounting– UTRF64 Passive Tracking Mount– Tracks sun passively (no electric power)– Holds all seven SAPC-165, costs $989




Inverter– Sized based on power generated– Using Powerstar 1300 inverter, but requires

DC Converter• Powerstar operates at 12 V, photovoltaic panels

operate at 24 V

• Powerstar costs $540, converter costs $285 for total of $825.00




Wiring and Receptacle– Length will vary with each house; impossible

to specify in advance– Assuming generic value of $200

Total cost for Option 1: $6,698One unresolved concern: uneven power

supply levels may damage air conditionerChapter will need to resolve concern



Preliminary System Sizing – Option 2 (Continuous Operation)

Batteries– AGM batteries chosen - 12V Concorde PVX-

2120L offers the best value (2520 W-hrs)– Six batteries required to meet power goal– Cost $304.95 each, for a total of $1,829.70

Photovoltaic Panels– 15 SAPC-165 providing 2400W at $5,999.85

Inverters– Two Powerstar 1300 Inverters at $1,080



Preliminary System Sizing – Option 2 (Continuous Operation)

Charge Controller– Trace C35: three units used – one for every

two batteries– Total cost: $337.05

Tracking Mounts– Two UTRF64 tracking mounts used at cost of

$1,978– Total cost for Option 2: $11,819.64



Preliminary System Sizing –

Difference in price visually shows why Option 1 remains a preferred choice– $6,698 vs. $11,819.64

Limitations in Option 1 must be solved before it can be considered valid, however



Fundraising

Chapter cannot pay for this project from dues, shirt sales, and dinners

Will seek to partner with JSC, contractors, and solar power companies in hopes of equipment donations

Will pursue grants and contracts from foundations, government agencies, businesses, nonprofits, etc.



Fundraising

Need chapter members to join Finance Zone to help Marlo in this area

Need new members from business directorates within JSC and contractors, especially B, H, and L mail codes



Engineering Roadmap

This paper is only a first step, not a complete analysis

Need for additional studies - engineering work continues– Deepen understanding of solar power systems– Resolve outstanding technical issues– Generate

• Finalized specifications• Safety reviews• Implementation procedures



Engineering Roadmap

Need for electrical engineers in the chapter to step up and get involved

New members especially needed from DF7, DT4, EC, EP, and JA13

Room for other chapter members – engineers and non-engineers to contribute



Engineering Roadmap

Paper studies likely to continue through fall and into early spring

Build hardware experience prior to assembling air conditioner units– Conduct series of smaller, less expensive solar

projects (e.g. solar fans, other low wattage devices)

– Side benefit: many of these may have outreach uses

Goal: first operational unit completed in time for summer 2004



Candidate Selection

No mechanism in place yet to select recipients – must be accomplished prior to first delivery

Churches, United Way, etc. work routinely with the types of elderly we wish to serve

Coordinating with such organizations will help us to identify responsible elderly with genuine need



Conclusion

We can’t help everyone suffering in HoustonWe will make a differenceWe will pioneer a roadmap other organizations

can followEnhance image of NASA, NSBE, contractors,

partnersGain sense of satisfaction – we will have used

our skills to change the lives of people



Questions?

solar powered air conditioning for elderly, low income houstonians robert l. howard, jr., ph.d....

Documents

chapter members

space slide

flow of power slide

nsbe mission

art technology

community solar power

possible slide

current solar panels