Category Archives: Energy

Shocking: GM is recalling all 2017-2019 Bolt EVs, will cut range by 10% to prevent fires

This is an huge blow to the Chevy Bolt EV line – they have confirmed five vehicles had their batteries spontaneously catch fire. And they do not know why, yet.

GM is recalling 68,667 of the cars globally from the 2017 through 2019 model years, including nearly 51,000 in the U.S.

Source: GM recalling Chevrolet Bolt EVs due to fire risks amid federal probe

GM dealers will update the software to prevent full charging of the batteries, cutting range by about 10%, as an interim solution. Alternatively, they ask owners to not fully charge their batteries or to not park inside garages or car ports. The latter may be tough – many people charge their vehicles at  home, inside the garage and might not have 220 v access available outside. Many who live in apartments and condos only have “carport” or “garage parking” – and have no place to park their vehicles outside. Plus, being winter time, range is already reduced by cold temperatures. This is a bit of mess.

All of the fires involved nearly fully charged batteries so they assume (but don’t know) that this is the cause.

They do not expect to have a real solution until sometime in 2021 – and it is not clear that this interim solution solves the problem, either.

What is the most power efficient (least electricity use) programming language?

Can energy usage data tell us anything about the quality of our programming languages? Last year a team of six researchers in Portugal from three different universities decided to investigate this question, ultimately releasing a paper titled “Energy Efficiency Across Programming Languages.” They ran the solutions to 10 programming problems written in 27 different languages,…

Source: Which Programming Languages Use the Least Electricity? – The New Stack

With some exceptions, this problem is a hard one to sort out – yet it matters when using battery operated portable devices.

The paper took a hard look at the common assumption that a faster program will always use less energy, pointing out that it’s not as simple as the law of physics that says E(nergy) = T(ime) x P(ower).

I proved this in my Masters in Software Engineering thesis eight years ago. Software developers have long operated on the belief that a “fast” and efficient program would use less energy. But ultimately it depends on how their high level code is translated into compiled code or pseudo-code, or interpreted, and the underlying implementation of any virtual machines that execute the pseudo-code.

Paradoxically, less efficient algorithms can indeed use less electric energy – it ultimately depends on how the hardware is put to use. And in the case of pseudo-code – this means a power optimized app running on one Android phone might even be less – or more – efficient when run on a phone from a different manufacturer using a different virtual machine to execute the pseudo code!

There is a complex, and non-obvious trade-off between algorithm efficiency, memory usage, and power consumption – and it varies by language, and by device.

On phones, the big power users tend to be the display, and GPS, and the camera – and of course, the CPU. Most power reduction strategies work to keep hardware turned off, or in a low energy state, as much as possible.

Claim: Electrify America has a charger within 150 miles of 96% of people in America

In this CNBC news video, the CEO of Electrify America says they have a charger within 150 miles of 96% of Americans.

Well …

  • Their nearest charger from us is across a mountain range, 122 miles away, to the west.
  • Nearest to the north is 129 miles.
  • Nearest to the south is 293 miles.
  • Nearest to the east is 330 miles.

Using their network we certainly could not travel in an EV to the east or south. I guess that makes us kind of special!

Using other CCS compatible chargers, there is now a single 50 kwh DC charger 120 miles to the east (and it’s free!); but if that single charger is in use, you’ll have a long wait. In the past few weeks, a single DCFS has been added 195 miles to our south. Which is better than none but again, if in use, it could be a long wait.

Obviously, these build outs will take time. In the interim, EVs (other than Tesla) might not make sense where I live.

California to ban sale of new gas-powered cars in 2035 

California will ban the sale of new gasoline-powered cars to combat climate change starting in 2035, a move that could help reshape the nation’s automobile market and its output of greenhouse gases.

Source: California to ban sale of new gas-powered cars in 2035 under Newsom order – SFChronicle.com

The State that is currently unable to provide sufficient electricity to its people, will require that all new vehicles sold after 2035 be – basically – electric. Will be interesting to see how they solve the infrastructure challenge in just 14+ years. The State is presently building just half of a high speed rail system over a period of 25 years.

Related: I do not understand the full concept of Executive Orders. The report notes this mandate is done via Executive Order in order to bypass the Legislature and public input. That is not a democracy in action – that is an authoritarian and undemocratic government.

Separately, the SF Bay area Metropolitan Transportation Commission has voted to mandate that 60% of all workers must work from home – with exemptions for work that cannot be done from home.

Issues have been raised as to how this creates social isolation, difficulties for many people who do not have homes suitable for work, and wipes out large numbers of businesses and jobs that support workers downtown. It also treats those who already walk or take public transport to work the same as everyone else – they too would be required to work at home.

Continue reading California to ban sale of new gas-powered cars in 2035 

Wildfires and Solar Panels – Solarponics

Wildfires-and-solar-panels: The heavy ash sediment has been known to reduce power production by as much as 30% or more if not washed off.

Source: Wildfires and Solar Panels – Solarponics

I’ve been losing up to 20% of power production every day for the past couple of weeks due to drifting wildland fire smoke. While the smoke is billowing clouds on a few days, or the sky looks visibly smoky, most days are just “slightly hazy”. In the morning and evening, the sun is noticeably orange but we otherwise have blue skies.

Yet with these conditions we have dropped from about 30 kwh to 24-26 kwh power production each day.

I had to hose off the panels last week – there had been a few days with pretty heavy smoke in the air and that seemed to have deposited ash on the panels.

The Adjustment Factor Tesla Uses to Get Its Big EPA Range Numbers

EPA mileage estimates are sort of bizarre. In EVs, once the range is 200+ miles, the more important factor is probably speed of fast recharging and availability of DC fast charging networks.

But looking at the “range” value is probably what most consumers focus on when making decisions. Tesla has mastered the “Adjustment factors” to get higher EPA ratings.

Source: The Adjustment Factor Tesla Uses to Get Its Big EPA Range Numbers

I used an online tool to calculate charging options for several EVs traveling over a specific route. One model, we will call Model 1, required 3 stops for 30 minutes each, plus one stop for about 45 minutes, to reach the destination. It’s maximum charging rate is about 50 kwh. That’s just over 2 hours of charging time.

One of the other cars is the Tesla Model 3 – which has access to high current DC fast charging stations along the route at up to 150 kwh.

Clearly, the Model 3 can be re-charged at a much faster rate than the “Model 1”.

In fact, the Model 3 required about three 10-12 minutes DCFS stops at 150 kwh stations, followed by one 25 minute charge near the end.

“Model 1” had over 2 hours of charging time on the route while the Model 3 had just under one hour.

The ability of the vehicle to accept the truly high powered chargers – and the availability of fast charging networks at high current makes a big difference.

Another factor is EVs do their fastest charging in sort of the bottom half of the battery capacity. Once the charge cycle refills past 50-60%, the charge rate starts to drop. It takes longer – a lot longer – to charge up the last 20% than it did to charge from 20-40%!

This means you’ll recharge to 70%, drive down to 20%, recharge back to 70% – and so on, to minimize charge time. But that is only possible if DC fast chargers are located in the right places along your route.

Battery capacity, the charging rate and charge curve, and availability of fast charging stations – all factor into your ability to drive long distances in a given amount of time.

I’ve concluded a charge rate of at least 75 kwh is going to be an important feature to make EVs practical for my sort of long distance travel here in the west where distances can be quite long. The vehicles charging rate, the charging curve, and your availability of fast chargers should all be considered when evaluating EVs.

Hypothesis, not conclusion: “In the US, switching to EVs would save lives and be worth billions”

With a confidence interval between zero and infinity:

A team led by Northwestern’s Daniel Peters decided to have a particularly detailed look at this issue, examining several scenarios of grid generation and EV adoption in the US. The results show that even with today’s grid, switching to EVs produces significant benefits.

The researchers used simulated hourly air pollution data from vehicles around the country, along with emissions data for power plants. This went into a model of weather over the course of a year (2014, as it happens), which also simulated important chemical reactions and natural emissions of compounds that interact with pollutants. The resulting air quality simulations were applied to an EPA population health model to show the expected impact on human health.

Source: In the US, switching to EVs would save lives and be worth billions | Ars Technica

And this was pushed through climate models afterwards.

No matter how you slice it, when your model is based on assumptions, simulated values, multiple models, all applied on top of one another, you have created an interesting video game simulation.

Perhaps you can use it to produce multiple hypotheses. But one thing you cannot do – in any way, shape or form – is produce a useful forecast of anything. Claiming this pile of models produces definitive conclusions is scientific fraud.

Continue reading Hypothesis, not conclusion: “In the US, switching to EVs would save lives and be worth billions”

Renewable energy confronts reality in California

Millions of homes in California are enduring rolling black outs. The power system operator acknowledged that as demand spiked, due to high temperatures and AC demand – they lost 1 gigawatt of wind energy and nearly 1/2 gigawatt of a conventional power plant.

Peak energy use occurs late in the day – when solar power production is in decline relative to peak demand. Related – the internal resistance of solar panels goes up in high temperatures. From personal experience, I lose up to 10% of potential solar array power production during extreme heat events versus “normal” temperatures.

Because solar and wind cannot be “revved” up on demand, like conventional power plants, the utilities have to reduce demand by shutting off power to customers.

This is a well known engineering problem –  one that California  pretends does not exist. This week reality and physics intervened and they discovered that it does actually exist. Yesterday, Gov. Gavin Newsom acknowledged that California’s heavy reliance on renewable energy is a significant factor in their current rolling shutdowns.

Continue reading Renewable energy confronts reality in California