Skip to content
Grist home
All donations doubled!

Past Umbra

  • Umbra on speed limits

    Dear Umbra, I was babbling about the ’70s energy crisis, gas rationing, and the nationwide 55 mile-per-hour speed limit at work the other day, and found myself explaining to a group of younger people how you save gas if you drive slower. They had never heard such a thing! Could you refresh my memory about […]

  • Umbra on why we shouldn’t waste energy

    Dear Umbra, I am doing a big geography project at school on saving energy and recycling. My part is to comment on what will happen if we keep wasting energy. I know the basic information, but I am not sure what to write, as it is to be given out to adults (and I’m only […]

  • Umbra on offsetting emissions from flatulence

    Dear Umbra, I was wondering if there is any information about the average CO2 emissions from human flatulence. My friend (and I really do mean my friend, I’m not just trying to hide that it’s for me) has a birthday coming up, and I think it would be a fun and meaningful gift to get […]

  • Umbra on biodiesel vs. straight veggie oil

    Dear Umbra, I have the opportunity to convert a 1979 non-turbo Mercedes into a non-diesel. The question I have is: to which should I switch, biodiesel or vegetable oil? I can’t seem to find out which one is best, just that these two are better than any petroleum-based fuels, which we already know (thanks for […]

  • Umbra on true hybrids

    Dear Umbra, I read the New York Times article that reported auto manufacturers are using hybrid technology to boost power rather than improve mileage. It specifically mentioned the Honda Accord, claiming that the mileage difference between the six-cylinder and the hybrid is minimal. What are the facts here? Is there a hybrid that really, actually, […]