The Ultimate Post

I have decided to end my Optimistic Engineer blog (at least for the time being). It’s mainly due to the time commitment a project like this deserves, which I have struggled to live up to.

However, I learnt a lot and hope others did too. Hopefully I’ll continue to learn (not least through my day job) and find new ways of sharing my knowledge with others.

Thanks to all who subscribed/commented/offered words of encouragement – this really was much appreciated.

Bye for now!

O. E.

Half way to 2050…

One of the first things to strike me about the 2050 Calculator from DECC (earlier post and direct link) was how to know if you have matched supply and demand. This seems to be done as part of the model, because if you change the demand side significantly you can see the supply graph changing. However, at a glance it looks like supply is higher than demand…

…It’s been an hour and I still haven’t worked out exactly why this is! The more I learn the more I realise I don’t know.

So, sorry for the half-post. I will attempt to learn more and know less (?) by next time!

2050: What are our options?

While I’m on the topic of cool online gadgets, I thought I would link you to the UK Department for Energy and Climate Change’s 2050 Calculator. It has a number of options for both the demand and supply of energy over the next 40 years, so you can play around with each of them and see the effects.

This sort of model brings up a whole host of issues, which I’ll start trying to address in a few future posts. For now, please just have a look (click here!) and a play. If any specific questions arise, let me know so I can be sure to cover them in my posts.

Green for “Go!”

Someone at work showed me a cool online gadget which can help you decide when to do laundry, or bake cookies (in an electric oven!). It’s a page on the Ecotricity website which shows live gCO₂/kWh values for the UK electricity grid.

As I mentioned in an earlier post, matching electricity supply and demand at all times is difficult and requires some not-so-efficient power plants at peak times. So, at high demand (and/or low renewable input) times, the grid will emit more CO₂ per unit of electricity than at low demand times.

The Ecotricity gadget demonstrates this with a traffic light – red is bad, amber OK, and green good, or “green“!

It also implies that non-time-critical use of electricity should be done when you get the green “go” rather than red “stop” light. I baked cookies at 11pm on Sunday, which was probably a relatively low carbon choice, though I have to admit it didn’t occur to me at the time!

There are plans to sell “smart” appliances in the future which know the electricity price (approximately proportional to CO₂ emission levels) and turn on when demand is low, but still get the job done by a deadline you set. So using the traffic light website is a bit like becoming a “smart” appliance yourself…

A second attempt at a first post

In one of my earlier posts I went a bit close to the climate change debate, which I generally try to stay away from on this blog. My reason for this is that I don’t think a full understanding of the science is necessary to realise that action is a much safer choice than inaction.

As I had some trouble expressing this last time, I re-found the video which helped me realise it in the first place and thought I’d share that. Maybe this should have been my first post!

Diesel – Dirty or Divine?

As with everything else, there are pros and cons to diesel engines.

The ones I’ll focus on are to do with emissions. Diesels are sometimes referred to as “dirty” because they produce more oxides of nitrogen and sulphur (NO_x and SO_x), which have negative environmental and health effects.

To reduce SO_x emissions, ultra low sulphur diesel (ULSD, or “clean diesel”) is used. To reduce NO_x emissions, NO_x adsorbers are used. Interestingly, these NO_x adsorbers only work properly with ULSD as otherwise they become poisoned by sulphur.

So diesel has problems, which can mostly be overcome, but what’s the “divine” bit about? Apart from the fact that it starts with a “D” which I thought would make a catchy title…

Well, diesel engines are more efficient than petrol engines (mostly due to high temperature combustion, which is the same reason for NO_x and SO_x production). Typical diesel engines are above 30% efficient whereas petrol engines tend to have efficiencies around 25%.

Note: The difference in efficiency seems apparent when comparing miles per gallon (MPG) values for diesel and petrol cars. However, in terms of CO₂ emissions it is (unfortunately!) not that simple. This is because diesel fuel is actually denser than petrol, so one gallon (measure of volume) contains more carbon than a gallon of petrol (2.8kg compared to 2.4kg). So, in terms of grams of CO₂ emitted per mile, this has to be taken into account as well as the MPG.

Pump it up!

On the weekend I did something for the first time, so thought I’d share my experience… I put air in my car’s tyres! Of course, many people have done this many times, and I should have done it quite a few times in the year I’ve owned my car. I suppose the point is that lots of people don’t do it as often as they should, even though it can save them money (and the world CO₂), and is free.

The numbers I found suggest that I’ve been using about 2% more fuel than necessary due to my tyres being under-inflated. As driving emissions are such a large proportion of a driver’s carbon footprint, this is quite significant – I’d have to change a lot of lightbulbs to get a similar effect.

So, for those who haven’t inflated tyres before, I actually found it quite fun. For those who have, and think I’m mad and will find the novelty soon wears off, I have a suggestion: Try taking someone with you and take bets on what the pressure will be in each tyre as you go. (Disclaimer: I do not condone gambling! Maybe the loser could just buy the winner a chocolate bar at the petrol station?).

In case you’ve misplaced the manual, this website tells you what your tyre pressures should (probably) be, if you give it your registration number.

Just like with batteries, I’m now going to start trying to practice what I preach, so I’ll check my tyres again in about a month’s time (and this time I’ll win that chocolate bar…).