Green Purr

February 15, 2017
by Helen
1 Comment

Western Cape Drought 2017

South Africa is experiencing its worst drought in living memory.  The Western Cape particularly, with its winter rainfall climate, is taking severe strain.  With dams at around 36% capacity in the Western Cape and rain only expected in another 3 or so months, mild panic is setting in. Weekly dam levels in the Western Cape can be tracked on the City of Cape Town’s website.

Below are a few ways to conserve water in all parts of our homes, adapted from the FLOW campaign (For the Love Of Water).  

Reduce water consumption

  1. Turn-off the tap while brushing teeth, shaving or soaping hands.
  2. Take shorter showers and use less water if you bath.
  3. Sweep outside areas, do not hose down with water.
  4. Use eco-friendly soaps and cleaning products.
  5. Fix leaks at home & report public water leaks to the Municipality.
  6. Always use a plugged-sink or bowl instead of a running tap.
  7. Insulate hot water pipes to reduce time waiting for water to heat up.
  8. Collect water with buckets while waiting for the water to heat up.
  9. Install aerators and flow-reducing valves on your taps.
  10. Install water saving devices on taps, toilets and showers.
  11. Install a water meter and monitor your use.


  1. Wash your car with a bucket and sponge only.
  2. Use a commercial car wash that recycles water.
  3. Use a commercial car wash that uses waterless cleaning systems.


  1. Shower instead of bath.
  2. Use less water in the bath.
  3. Bathe young children together.
  4. Flush the toilet only when odours make it necessary.
  5. Put a brick in your cistern to reduce water usage per flush.
  6. Install a low-flow shower-head.
  7. Install aerators and flow-reducing valves on your taps.
  8. Install a dual flush mechanism on your toilet.
  9. Install a geyser blanket for insulation.
  10. Insulate the copper pipes around the geyser.


  1. Cut back on washing your towels and linen.
  2. Match the size of your laundry load with water volume.
  3. Buy an eco-friendly wash ball.
  4. Buy a water-efficient washing machine.


  1. Only turn the dishwasher on when it’s full.
  2. Use a plugged sink to wash dishes instead of a running tap.
  3. Use less dish-washing liquid to reduce the need for rinsing.
  4. Use a plugged sink to rinse vegetables instead of a running tap.
  5. Use the water you used to rinse fruit and veggies to water plants.
  6. Keep a bottle of tap water in the fridge to avoid running the tap until the water is cold.
  7. Don’t use running water to defrost food.
  8. Install aerators and flow-reducing valves on your taps.
  9. Purchase water-efficient appliances and water-saving devices.

Plants & Garden

  1. Learn about water-wise gardening.
  2. Water plants at the coolest part of the day.
  3. Group plants together that have the same water requirements.
  4. Water plants with the water you used in the kitchen to rinse fruit and veggies.
  5. Choose local indigenous water-wise plants for your home and garden.
  6. Adjust sprinklers to water plants and not the pavement.
  7. Cover your pool so the water doesn’t evaporate.
  8. Check your pool for leaks.
  9. Put self-closing spray-nozzles on hosepipes.
  10. Use natural and organic garden products.

Methods to check your home is leak free

  1. Use your water meter to check for hidden water leaks. Read the water meter before and after a two-hour period when no water has been used. If the water meter doesn’t read exactly the same, then there is a leak.
  2. To check for toilet tank leaks, add food coloring to the tank. If the toilet leaks, the toilet bowl will have changed color within 30 minutes.
  3. Repair dripping taps by replacing the washer. If a tap is dripping at a rate of 1 drop per second, you could be wasting up to 10,220 Liters per year!
  4. If your toilet handle constantly stays in a downward position this means that water is constantly running. Replace or fix the handle to avoid wasted water.
  5. Insulate your water pipes. If you do, you’ll get hot water faster, avoid wasting water while it is heating, and also saving money on electricity!



City of Cape Town website


July 22, 2016
by Helen

The Inspiration that is Elon Musk

If you google fun facts about Elon Musk, this pops up:

  • Elon Musk was born in South Africa in 1971.
  • He became famous for starting Tesla Motors and SpaceX but he first made his fortune as a co-founder of PayPal.
  • Musk provided a large amount of inspiration for the Hollywood character Tony Stark (a.k.a. Iron Man).

Tony Stark, really? I guess Iron Man did spend a few moments in space while fighting the Leviathan and Chitauri during the Battle of New York – that must be the SpaceX link :-}.

He’s definitely a character and a visionary.  If our current consumption of natural resources and rate of carbon emissions continues, and we do have to start colonising Mars, he could even potentially be the saviour of the human race.

I haven’t read Ashlee Vance’s book about Musk yet, but this article  provides a great summary on a few of the lessons we can learn from his life.  Pretty inspirational for a 45 year old.

His life in info-graphic summary:




May 7, 2016
by Helen

Weekly finds – May 2016

This weeks finds:

  • The most obvious limiting factor to energy generation from solar panels is overcast weather.  Imagine if rainfall on solar panels could also generate energy?  A group of scientist have experimented with applying a graphene layer to solar panels and it seems this possibility exists!
  • Transparent solar cells is one of my favourite renewable energy innovations but its flaws – not really being 100% transparent and only being about 1% efficient (Greenpurr) – have prevented the tech from being commercial viable. Recent advancements though have guaranteed true transparency and an increased potential efficiency to around 5%. Still a long way off from being a green building or smart phone/tablet material.
  • One of the factors that contribute to nuclear power not being a clean or sustainable (I’m potentially repeating myself on this :-)) source of energy is the problem with its resulting high level radioactive waste. Because of the thousands of years the waste needs to safely decompose (250,000 years according to this Scientific American article) the current methods aren’t reliable and a permanent solution is simply not available. Most of the current methods involve burying it in sealed stainless-steel and concrete containers underground or in water-cooled pools onsite at nuclear power plants (yikes!). A new innovation in cement design could potentially increase the safe storage life of nuclear waste to up to 100,000 years (insert praying emoji here).



March 2, 2016
by Helen

Tesla Energy in Cape Town


Tesla Powerwall

Tesla Powerwall

Anyone living in South Africa will remember last year’s (2015) power outages.  With our sunny climate, the most obvious solution to this seemingly perpetual problem is to install a solar back-up system to negate grid down time.  Or if feasible, to go off grid completely.   The initial capital cost, maintenance and longevity of the systems require much analysis to determine if this is a worthwhile investment.  Other factors to consider are the physical size of the batteries and storage space, the frequency and replacement cost of the batteries, as well as where power will be received from if solar generation is weak (if off grid and during winter in the Western Cape for instance), cost and longevity of solar panels etc.

While there are local options to having a solar solution installed, the Tesla Powerwall has received much media attention and seems to be the go-to option.  The available advertised date in South Africa was January 2016 with Tesla approved distributors currently undergoing training for the systems.  

According to the four systems that will be available to the South African market through Rubicon are:

  1. Tesla Powerwall and 5kW SolarEdge inverter (part no. RUB-TES) — R116,000.
  2. Tesla Powerwall, 5kW SolarEdge inverter, and 3kWp solar panels (part no. RUB-TES3) — R169,000.
  3. Tesla Powerwall, 5kW SolarEdge inverter, and 5kWp solar panels (part no. RUB-TES5) —  R210,000.
  4. Two Tesla Powerwalls, 5kW SolarEdge inverter, and 5kWp solar panels (part no. RUB-TES5.2) — R272,000.

These prices all exclude VAT, installation costs and are subject to exchange rate fluctuations.  With the Rand dipping in the last few months, would the capital outlay be feasible? Luckily for me, Lawrence from did the rough calculations for easy evaluation.  See his calculations here.  My feeling is that it’s still too pricey for the average Joe.

So, what makes it different from other solar systems?  There may be some complex science to this (I’m open to some explanation!), but it is probably just great marketing.  The Powerwall isn’t built on cutting edge technology but is rather improvements on commercially available tech.  The battery is what seems to make it different:

  • it has a 10 year warranty (sourcing batteries in South Africa I couldn’t find warranties over 2 years)
  • the chemistry is different to other acid based options (lithium-ion, nickel-manganese-cobalt and nickel-cobalt-aluminum)
  • the storage design is slick and simple
  • built-in cooling system
  • easily scale-able for higher usage.

Another great development from the Tesla power solutions world is that they’re opening up an office in Cape Town – Tesla Energy – which will be headed up by Evan Rice, former GreenCape CEO.  I’m excited for the potential economic benefit to the Western Cape if a Tesla Gigafactory becomes a reality in the province!  




May 29, 2015
by Helen
1 Comment

Western Cape Bee Decline

I’m not sure about everyone’s position on bees.  This blogger obviously loves them and knows that they are essential to our food security.  Globally, they have been declining at scarily massive rates.

Did you know that in some places in the USA, massive hives are trucked from farm to farm to pollinate each one?  Not enough of these little creatures exist to pollinate all the sources of food for humans.  More bee facts can be viewed on this interesting documentary:

The bee population of the Western Cape has recently been exposed to a spore forming larvae which has killed about 40% of its numbers.  The only way to get rid of contaminated honey, hives and bees is to burn them – a necessary act that further decreases their numbers.

A creative way to help increase bee numbers is to buy a frame and some honey in support of the Frames for Bees Project!  Everyone can help our little food security enablers – check out this website on the how to

Happy Honey Hunting


May 28, 2015
by Helen

Weekly Finds 1 – May 2015

This weeks finds:

Happy last few days of May!


March 23, 2015
by Helen

Power from the people – City of Cape Town’s grid allows small scale electricity feed from consumers

Some semi-recent fantastic news:  Cape Town is allowing commercial, industrial and residential users to feed electricity back into the grid!  I may be wrong, but I think this is a South African first.    Small scale embedded electricity generators (SSEG) can now apply for compensation of electricity fed back into the Cape Town grid, if  they meet the conditions stipulated in the Guidelines for Embedded Generators.

Some of the conditions are that the generators may not be net generators of electricity (are only selling their excess electricity), install the necessary equipment for grid feedback at their own cost, apply for a generation license from NERSA for a generation capacity greater than 1MVA (no license for less than 1MVA capacity needed) and only sell back to the City of Cape Town grid and agree to the SSEG tariffs.

This is one of the ways the City of Cape Town wishes to achieve its goal of sourcing 10% of its electricity from renewable energy sources by 2020.



August 20, 2014
by Helen

Weekly Finds 2 – 2014

This weeks finds:

  • Grey water recycling systems for households can eliminate much wastage by reusing the water for garden irrigation or toilet flushing.  Some Turkish university students have furthered this concept and created a washing machine that cleanses and filters your shower water that is then directly used for washing your clothes. Their project is water efficient and won the Hansgrohe Special Award.
  • Germany, again, beats renewable energy generation records.
  • I’m not entirely sure this article captures the exact low carbon develop pathways the major polluting countries of the world will need to follow to prevent climate change, but the idea of negotiating technology to achieve a low carbon footprint per person without assigning the costs to a specific entity yet seems novel.  Perhaps if the outcome is great enough, the resulting cost won’t seem unaffordable?
  • Understanding the magic that happens when spinach proteins photosynthesize could lead to artificial photosynthesis and a new alternative energy source.
  • Ever wondered how photovoltaic systems worked and how to design one?  EdX offers an online course that teaches you exactly that.


July 28, 2014
by Helen

Weekly Finds 1 – 2014

7 months into the year and no weekly update?  I must be very busy 🙂