Green Purr

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

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 it 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 🙂

February 6, 2014
by Helen

Renewable Energy Festival – Green Point Urban Park, Cape Town

Firstly, a Happy and Wonderful New Year!  Personally and professionally, last year was a year of great change.  This year is going to be one of challenge and growth, which I’m incredibly excited and optimistic for.

To start off the new year (or rather, ease into it) a “renewable energy festival” will be taking place in the beautiful Green Point Urban Park in Cape Town.  Its a clever initiative to educate the general public about renewable energy in a friendly, fun, entertaining and relaxed space.  The organisers have ingeniously taken advantage of the great summer weather and the lovely accessible park to educate adults and kids about climate change and sustainable energy sources.   I’m sure it will be enlightening for many.

Renewable Energy Festival 8 Feb 14


Happy Weekend!