May 2015


Recycling23 May 2015 02:53 pm

CapsOnRoad

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

TeslaPowerwallGreenerhouse
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.