Recycling23 May 2015 02:53 pm


On the road again

When I told a sustainability expert at My Green Home that we should advise people to remove bottle caps before recycling, I received an incredulous response: “How could that possibly matter? Why should we make recycling more complicated for people?”

The picture above answers those questions better than any words.

I recently snapped this photo on my block, late on rubbish collection day. Clearly a street recycler has pulled the bottles out of this bin, twisted the caps off, dropped them on the road and tossed the flattened, lid-less bottle into his trolley. When the next rain arrives, the caps will be washed into the nearest storm drain and start a journey to the Braamfontein Spruit, the Jukskei River, the Crocodile River, Hartbeespoort Dam, and on to the Limpopo River before perhaps hitting the beach as plastic pollution along the Indian Ocean.

Cool-drink and water bottles are made of PET plastic, which is quite valuable for recyclers. Lids are usually made of high density polyethylene (HDPE) and polypropylene (PP). They can also be recycled, but they’re not as valuable. Obviously the guy who dropped these on the road didn’t think they were worth pulling around all day in his trolley.

If the picture hasn’t convinced you, here are answers to common cap questions:

But why make recycling more effort? When you drank the last drop from that bottle, the lid was off. Twisting it back on is effort. Leaving it off is not.

But don’t milk bottles stink with the lid off?
Rinsed with a very small amount of water, empty milk bottles do not stink. Milk bottles stink to high heaven when the lid has been on for a while and then come off, as it inevitably must. And with the lid off they can be flattened right away to take up less space.

So let your bottles and lids part ways on the way to the recycling bin. Bottle caps should never see the sea.

Solar05 May 2015 02:15 pm

People keep stopping me to talk about Tesla’s new battery for solar-powered homes. It’s obvious from their excitement that Elon Musk has succeeded in giving the impression that the Powerwall is something totally new, especially for South African homeowners desperate for a solution to load shedding. I shouldn’t be surprised. Solar batteries have never made international news before.

But the Powerwall is hardly the first battery designed to store electricity from solar photovoltaic (PV) panels. So here are a few key points about what is and is not new in the announcement:

Solar batteries are already in South Africa and have been for many years.
The vast majority are deep-cycle lead-acid batteries, much like car batteries, but with improvements that help them endure heavier use. They are heavy and relatively bulky, need to be charged fully and discharged only partially, and they tend to last just three to seven years, depending on how they are used. (Photovoltaic panels, by contrast, can easily last 25 years.) But lead-acid solar batteries work, and many South African homes already use them to avoid load shedding or even to go off the grid.

Lithium-ion solar batteries like the Powerwall are also already in South Africa. It’s safe to assume that Tesla will make high-performance batteries, but there is nothing in the announcement to suggest a revolution in battery technology. Whatever the brand, lithium-ion batteries have several advantages over their lead-acid cousins. They are smaller, lighter and longer lasting. You don’t have to charge them fully and you can discharge them somewhat further than lead-acid batteries. But they are so much more expensive that most solar homeowners who want storage still opt for lead-acid batteries.

Powerwall lithium-ion batteries will be less expensive than other lithium-ion batteries. Tesla is using its size and manufacturing prowess to bring lithium ion much closer to lead-acid pricing. In fact over the long term, Powerwall may work out to be less expensive for American homeowners than lead-acid.

Powerwall will not be available in South Africa for at least a year and will cost more here. The wholesale price of $3,000 for the 7 kWh model of Powerwall is already R36,000 just converting at the current exchange rate. High-tech products that are easy to ship frequently cost 25 percent to 100 percent more here than in the US. Powerwall is bulky to ship from the US, where it will be built. Expect to pay well over R36,000 at first.

You don’t have to wait to find a solar-battery solution to load shedding. Perhaps you wish to have all of your lights, computers, television and other electronics working all day, every day, with or without load shedding, but you know that you should avoid a certain nameless option that is noisy, releases poisonous soot, contributes to global climate change and requires regular refueling and maintenance. (See my 2008 article comparing generators with solar PV here.) You can install a solar PV system today using lead-acid solar batteries. In a few years, when those batteries are ready to be retired and recycled, Powerwall and other lithium-ion batteries will be widely available and more affordable in South Africa. You can swap your storage technology while leaving the rest of the solar system in place. Of course you can always install the batteries alone and charge them off the grid to protect you from load shedding until you can afford the PV panels to go with them.

Solar PV with batteries is not cheap. As I wrote in a recent post, only over the very long term does solar PV without a battery save money compared to paying Eskom for that electricity during the daytime. Add batteries and recouping the costs purely on lower electricity bills becomes even harder. But when compared with the expense and inconvenience of load shedding—or of diesel generators—a solar battery solution can be priceless. With or without Tesla’s Powerwall.

Recycling27 Apr 2015 01:48 pm

In honour of Freedom Day, I present my photo of a South African flag made from used bottle caps. De La Salle Holy Cross College in Victory Park, Johannesburg, is a school committed to all things green, and the grade R children last year showed their colours by creating this magnificent flag on a wall at the school.

©  2015 Don Boroughs

© 2015 Don Boroughs

Hot Water &Solar27 Mar 2015 02:35 pm

Solar Hot Water Panels

If you are considering whether to install a solar water heater, you might want to move fast. Eskom’s rebate programme has been extended to cover solar systems installed by the end of April 2015 as long as applications are submitted by the end of May. The rebates can reduce the up-front costs of a solar water heater by up to R11,000.

This isn’t necessarily the end of solar rebates. A plan was in place to shift the responsibility for the rebates from Eskom to the Department of Energy. The extension is a stopgap measure because it appeared that the DOE was not ready to launch its rebates, and the prospect of halting incentives at a time when the grid needs all the help it can get was exactly the wrong message to be sending. The DOE has not made public all of the details of its rebate programme, but has warned that it will place a heavy emphasis on requirements for South African manufacturing content. If you can afford to install now, at least the rules are public and the rebates well-established. Better the devil you know . . .

In this era of load-shedding, there is an extra consideration to take into account when deciding on a solar system. The most efficient solar water heaters use a circulation pump between the panels and tanks, but when the electricity is off, not only does the water stop heating, but the panels can overheat. So opt for either a thermosiphon system, which needs no pump, or a pumped system that is powered by solar cells. Some hot water panels are even sold with a miniature photovoltaic panel built in to run the pump.

To help you get started, read the Guide to Solar Hot Water that I wrote for the My Green Home website.

Finally, Eskom has extended the rebate but not their solar hotline. Direct any questions to the ordinary customer service line 08600 ESKOM.

Lighting13 Mar 2015 08:34 am

candle LEDs and incandescent candle bulbs in chandelier

A candle in the wind

Four years ago, I set out on a journey to replace all of the incandescent lights in my home with modern LEDs. The final stumbling block in this quest was a candelabra in my dining room, pictured above. Candle-shape bulbs with narrow screw bases, known as “E14” bulbs, were a great source of frustration for me. Well after LED equivalents of 60 watt and even 100 watt standard-shaped bulbs became available, I couldn’t find dimmable, bright, LED replacements for these 40 watt candle globes.

My wait is over. Last week I bought three Osram Superstar Classic B40 Advanced Frosted candle bulbs at my local Lighting Warehouse for R90 each. They use 6 watts instead of 40, so the three-globe candelabra has dropped from 120 to 18 watts. Since we use the dining room lights a few hours a day, I calculate that they will pay for themselves in less than two years. They come with a four-year guarantee and a 20 year-estimated lifetime, so my investment is safe.

You can judge the quality of the light for yourself in the picture above. I left the image’s colour balance at daylight, which makes incandescent and warm-white LEDs seem a little more orange than they actually appear when your eyes adjust to them. The bulb in the upper right is the new Osram LED. The other two are my old incandescents. In this fixture, the LEDs actually light the dining room table more brightly than the incandescents did. This is in part because they cast their light away from the base. The effect might be slightly less bright if the globes screwed into the chandelier base-down, shining up to the ceiling. I find the colour of the light adequate, so overall it has been an improvement in lighting a slightly dim room.

The only noticeable disadvantage has been that on our old rotary-dial dimmer, the bulbs only seem to work at two light levels, not a continuous range. In time I will replace the dimmer with an electronic dimmer recommended for LEDs. In the meantime, I am already satisfied with this bright purchase and happy to know that my last incandescent globes are now just candles in the bin.

Global Warming04 Mar 2015 07:40 pm

Why should you take steps to reduce your tiny impact on this great big world? I heard a convincing argument in a documentary about air pollution that has taken China by storm. Chai Jing has an uncanny ability to approach environmental issues with both her heart and her head. At the end of Under the Dome she observes how she was affected after getting involved in the installation of a filter to reduce the particulate emissions of a restaurant near her home in Beijing:

“I suddenly felt like my feet hit the ground. It’s a difficult feeling to describe—you know full well that in the grand scheme of things, this is actually a small impact. But knowing that when one person is able to make a small contribution, they are able to actually make things better, their heart feels grounded. In the war between human beings and air pollution, this is how history will be made: When millions of everyday people, stand up one day and say: “No. I’m not satisfied. I don’t want to wait. I will not sit back. I will stand up and do something. Right now, right here, right in this moment, in this life.”

Hot Water23 Feb 2015 05:55 pm

Switched off geysers

Switched off

I’m no party animal, but I attended four social events this weekend. My takeaway from a dozen or so conversations is that South Africans are seriously looking for ways to save energy. People were telling me about their new efficient fridges and gas stoves. A property developer explained how Standard Bank is saving thousands of tons of carbon dioxide by generating its own power from gas in Rosebank.

One question came up at two different parties: Does it save energy to switch off the geyser for part of the day? This is a query I’ve heard so often that one could be forgiven for thinking that it was the Number 1 issue in energy efficiency. People take passionate stands on either side of the debate. One person told me that he’s saving hundreds of rands each month by switching the geyser on and off. Another said she had heard that it uses more electricity to heat the water back up than to keep it hot.

Here’s the disappointing answer to the most-discussed issue in home energy conservation:

It’s no big deal.

You can save a little electricity with daily switching, but you could save a lot more by lowering the temperature of your geyser thermostat, buying low-flow shower heads, or insulating the tank—not to mention the even larger savings from installing a solar water heater or heat pump.

If your geyser were perfectly insulated, switching would save nothing. Because it is not, the element will reheat the water from time to time even if no one is using hot water. If the element is off, however, the tank loses heat more slowly as the water gradually cools. All of that water has to be reheated when you turn the geyser back on, but because overall tank losses were lower than if the tank had been kept hot, it requires a little less energy than repeatedly heating the water over that same period of time.

What about the guy who said he was saving hundreds of rands? If your geyser has been off for several hours and you switch it back on, any shower you take or dish you wash before the water has been fully re-heated is saving you significant energy, because switching off and on is effectively lowering your thermostat setting. These savings can be large, but you could have saved that same energy more consistently and easily by simply lowering the thermostat on the geyser. Unconvinced? You can read more here.

Electrical engineer TC Venter has a long, technical article on the subject of options for saving electricity with hot water heaters in Watt Now and comes to this conclusion: “short switch-off periods (less than a day) do not really contribute meaningfully to energy saving.” But Venter did bring up one exception to this rule.

There is one special situation, if one thinks it through carefully, in which a timer can be used daily to eliminate practically all standby power. If the occupant of the flat is single and a creature of habit, who only needs hot water to bath or shower at 07:00 each day, a small (50L) geyser could be run like an electric kettle: an electronic timer could be set to switch the geyser on for one hour at 06:00 every morning, to ensure hot water at 07:00, but not to reheat the geyser after its hot water has been used. The geyser remains cold until the next morning at 06:00, thus no standby power is required.

Of course switching off the geyser when you leave home on a trip can add up to real savings. Switching off during Eskom’s peak hours of 5 to 9 pm is also good for the country, if not for your utility bill. And timers are essential with solar water heaters to avoid using electricity to heat up the tank after morning showers, just before the sun has a chance to do its work. Finally, if you really want to switch your old-fashioned electric geyser on and off every day during idle hours, go right ahead. Just don’t imagine that your hot-water electricity consumption is solved.

Solar20 Nov 2014 10:33 am

I get a lot of questions about rooftop solar photovoltaic panels. Even people who haven’t really started investing in energy efficiency are eager to consider spending their savings on solar PV. I understand. There is something sexy about generating your own power.

I rarely write about the subject here because I haven’t purchased PV panels for one very good reason: photovoltaics should always be the last energy investment for a home, not the first. You can save more electricity at a lower cost with other expenditures: LED lighting, solar hot water, heat pumps and variable-speed pool pumps, to name a few.

But this is a good time to look closely at the numbers for two reasons.

1. PV panel prices have dropped significantly in the past few years.

2. My Green Home has given me a window on real-world results for a house with solar PV.

Not too many years ago, an executive in the solar industry in South Africa admitted to me that even at wholesale prices, it would not pay for him to put panels on his own roof. But for the past several years, PV module prices in South African have been falling by about 22 percent a year. Many installers are also keeping prices down by recommending systems with no battery storage, since batteries greatly increase costs both up-front and down the line. (Batteries generally do not last as long as PV panels.) Without batteries, you are not protected from load-shedding and blackouts, but you are supplying some of your own clean electricity at a more reasonable cost.

This is the kind of simple, grid-tied system installed for My Green Home at the Ngewanas’ home in Cape Town. I have access to detailed metering data from the house and have used it to calculate electricity production for the last three months and to extrapolate those results to create a projection for the annual kilowatt hours to be generated by the system. (Seasonal variability was factored in using the monthly data from this Soventix commercial PV installation at Blaauklippen Vineyards.)

The Ngewana family has a small system, with one 255 watt panel connected to a 230 watt inverter that creates AC current from the panel’s DC output. On every sunny day, it produces at least 1 kWh. My calculations project that it will produce 400 kWh in a year. The Ngewana family pays R1.54 per kWh, so the panel will save them R615 in the current year.

That’s mahala money for the Ngewana family, since the panel was sponsored by Citrine Energy. But if you had to pay for it yourself, Citrine would charge about R10,500, and the system would take 10 full years to pay for itself at the anticipated rates of tariff inflation. It’s a fairly safe investment, since polycrystalline silicon panels generally last much longer than 10 years. But you will need patience if you are counting the days until you’ve paid off your investment.

The rate of return would be better for South Africans who live in sunnier regions or pay a higher tariff, but at todays PV prices, it will take several years to cover the outlay under most circumstances. The situation will improve dramatically when South African utilities begin to pay homeowners for any excess electricity they feed into the grid, which is called a feed-in tariff. This will also allow homeowners to buy larger panel sets that cost less per watt. (Some homeowners do this already by running their disc meters backwards, but this is illegal.)

At My Green Home, we had to carefully size the system to produce no more electricity than the home would ever use during the sunny part of the day. (Approximately equal to their 300 watt variable-speed pool pump.) With the pre-paid meter at that house, kilowatt hours add up no matter which direction the electricity is flowing. They would have paid for any excess kWh they contributed to the grid!

So has the time arrived yet for generating electricity on your roof? It depends. If saving money is your only priority, wait a couple of years until prices fall further or your utility offers to buy your excess electricity with a feed-in tariff. If, however, you have already invested in making your home energy efficient, and it would give you pleasure to know that some of your electricity is clean and carbon-free, the time is now.

Global Warming28 Oct 2014 12:27 pm

17 kWh/m2/year. My Number.

17 kWh/m2/year. My latest “number.”

The 49M campaign for saving electricity has launched a new calculator that allows any South African household to Know Your Number. I tried it out and found that it is by far the easiest way to get a reasonable figure for your home’s kWh/m2/year, which is your “number.”

Earlier this year, I wrote a guide to calculating this figure for the Green Building Council’s My Green Home website. The guide is still worth using if you want a more precise calculation for a full year, and it can help you work out the square meterage of your home if you don’t already know it. The advantage of the 49M calculator is that you only need to know your m2 and kilowatt hour consumption for a single month. It works out an annual figure for you, taking into account the generally higher electricity use in winter.

I tried several months on the calculator and all results were within a reasonably accurate range of 16 to 20. My manual calculation for all of 2013 had been 21, and my consumption has fallen a little since then.

Why would you want to know your kWh/m2/year? For one thing, it’s the most reasonable way to compare two houses of different sizes. You can use it to benchmark and see how much you might be able to improve. Second, any effort to monitor your kWh will help you save, just as you are more likely to lose weight if you step on a scale from time to time. Greenerhouse has a spreadsheet that can also help you monitor your electricity from your meter.

On, you can save your results, track them month to month and even share them on Facebook. The website sets benchmarks for you in the form of letter grades. Mine was an “A”, two notches short of an A++. It seems I still have work to do.

What’s your number?

Lighting &Solar06 Oct 2014 03:13 pm

It’s official: electricity tariffs will not rise just 8 percent – as had been promised – for the next few years. The National Energy Regulator of South Africa (NERSA) has granted Eskom a 12.69 percent increase for next year. Supposedly it’s a once-off exception, but don’t count on it. An article in today’s Business Day quotes several economists predicting years of high electricity inflation. Here’s Azar Jammine, chief economist of Econometrix:

“I wouldn’t be surprised to see this rate increase being repeated in the following four years (after next year). To be fair, if we are to get over this energy crisis we do have to increase tariffs”

This is bad news for consumers’ wallets of course, but you could look upon it as good news if you are thinking about investing in energy efficiency. A tariff of R1.50 per kilowatt hour – a rough median for suburban South Africans today – reaches R2.72 after 5 years of such increases.

Consider LED lights, for example. If you spend R1000 on 10 LED downlighters to replace halogen bulbs that are used 4 hours a day, you would expect to save R5717 over 5 years with 8 percent electricity inflation. Bump that up to 12.67 percent tariff increases and the savings leap to R6274. A solar water heater that would normally take 4 to 6 years to pay for itself reaches the breakeven point a half-year sooner.

The news from Eskom gets worse and worse, but the prospects for saving energy just keep getting better.

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