Power saving for home patients
As dialysis is a power-hungry process, and as electricity costs rise, home patients are inevitably faced with higher electricity costs – the extent of which are largely determined by the dialysis regimen.
For home haemodialysis patients, longer and more frequent dialysis regimens – while likely beneficial to clinical outcome and general health and well-being –also demand a higher electricity use and generate a proportionately larger power bill!
Home peritoneal dialysis patients, if using a peritoneal dialysate cycler system (e.g. a Baxter Home Choice 2™ or a Fresenius Liberty™ cycler), will face a more modest power bill, but nevertheless, an additive cost.
As part of a study to document the carbon footprint of an Australian suburban dialysis service, the Barwon Health Renal Service has reported that the annual power requirements of a standard single-pass haemodialysis system providing 3 x 4 – 4.5 hr dialysis treatments/week plus the power that is consumed by the RO system for those treatments is ~½ the weekly power requirement of an average Australian 4 person home in 2011 (8,9,10).
For the home patient, where both dialysis duration and dialysis frequency are likely to be significantly greater, power consumption would be expected to be even higher. While this has not yet been measured or reported from Australia, a UK study has shown exactly this.
Power consumption will also depend on the equipment used for home care. The UK study of the carbon footprint left by the NxStage system (= not used widely in Australia but a common home system in the US and, to a lesser extent, the UK), is only ~25% of the power used by a single pass system + RO.
Home patients should critically seek to lower their overall power usage. There are two primary steps to consider:
- Follow the usual and well publicized standard steps to reduce excess household power use. Look critically at home power consumption.
- Consider the power used in lighting, heating and cooling, by computers, TVs, and other appliances – all or many of which remain ‘switched on’ or in ‘stand-by’ mode, 24 hours a day.
- Consider energy-saving globes: e.g. LED lighting.
- Consider timer switches that turn household electrical equipment off at the power-point.
- Consider renewable power-assisted options… e.g. solar (or wind) power.
Alternative power-assisted home HD
There is now some limited trial data surrounding the use of solar panels in augmenting the power usage of haemodialysis (7). While this data was collected in a home training facility, this model can also be applied to augment the power requirement for home dialysis.
Data obtained from the Barwon Health solar-assisted HD pilot (Agar JWM et al. Solar-assisted HD. CJASN: 2012: 7 (2); 310-314) reports the capital and installation costs of a solar array sufficient to provide all power needs for an alternate nightly 8-9 hour home haemodialysis regimen = $3,400 (AUD) (12/2011).
A Geelong home haemodialysis patient, at his own expense, installed a solar array sufficient to provide all home HD power needs ($3,500). He reports that he now pays up to 80% less for his entire household power expenses … the ‘solar experiment’ at Barwon Health continues.
While clearly the additional once-off installation cost must be factored against the potential for a home patient to later be transplanted, to fail at home, or to suffer a significant deterioration in health leading to facility return, the cost may still be supportable, given that the annual health-care savings of home dialysis vs. facility-based care are ~AUD$30,000.
At a minimum, services should assess the potential benefits for individual home patients of home solar-assisted HD, depending upon the solar insolation data for their region and the local cost profiles for solar generation.
How to work out your home haemodialysis solar power requirements?
- Apply a standard electrical industry power-meter to your dialysis equipment – both dialysis machine and reverse osmosis.
- Measure the average hourly power draw (kWh) of your dialysis system(s).Do several measurements on several machines and mean the data.
- Determine the daily average solar insolation at the latitude and longitude of your home using the following method:
- Go to: www.wunderground.com/calculators/solar.html enter your city (eg: Geelong) and country (Australia).
- Check the ‘Give raw insolation data’ box.
- Scroll down to ‘Submit’ and click.
- A graph will appear, showing the raw monthly insolation data for your location (eg: Geelong) in kWhr/m2/day.
- The average kWh/m2/day is calculated (Geelong = 6 kWh/m2/day).
This means that each m2 of panel will generate ~6 kWh/day power. NEXT…
- Select a ‘panel model’ (eg: a Sanyo HIT Power 205) any number of potential solar arrays can be modelled at this Internet site. Check your local solar power suppliers for their range of products and apply.
- The ‘generative efficiency’ will be automatically determined.
- If the chosen/preferred array is unlisted, (eg: the array used for the Barwon Health trial was a Conergy 175), the efficiency rating for that array can be supplied by the chosen manufacturer.
- Finally, a predicted potential cost/benefit outcome can be calculated, based on power requirements, array size, and installation cost.