Monday, December 13, 2010

Cradle to Grave -- The Holistic View for Sustainability

I am from Waipahu High School. May I ask you a question about hydropower for my science project? In your opinion, will hydropower energy be a successful alternative energy in the future? Will it prevent global warming?
Donnalynn Agpaoa

Donnalynn's question is important and almost universal. Its generic version is: Will Technological Option X be a successful alternative? I'll get to the generic form later, but first, here is my answer to her.

Hydro-power can be very powerful. Its electricity generation is clean, and reliable for 100+ years, if designed properly. Kauai has a small but successful hydro-power generator.

Now lets take account of the negatives.

Hydro-power can destroy ecosystems, and in some cases villages, cities and regional cultures may disappear, as they become submerged in the reservoir (lake) behind the dam.

The dam itself may be viewed as an eyesore. Also it is somewhat risky. If it fails, there will be catastrophe downstream.

One important consideration in the total picture is the amount of steel and concrete that's needed to build the dam. The amount is massive and the manufacture of the necessary steel and concrete will create a lot of pollution. Similarly, the machinery that will build the dam will pollute as it works to build the dam, and the machinery itself created pollution when it was built.

So, say, a Caterpillar front-loader has a life of 30 years and will work at the dam site for 1.5 years. Therefore 5% of the resources and pollution that went to manufacture the front-loader need to be "billed" to the dam project.

We have to take into consideration all these cradle-to-grave sustainability impacts in order to correctly derive the total impact of the proposed hydro-power infrastructure.

As for your hydro-power question, the correct answer is that it can be green but not necessarily. We need to evaluate each and every proposed project, add all its pluses and minuses, and then decide if it is a good project.


In general now, in several cases what appears "green" or "good" is the opposite when all its impacts are accounted for. For example, electricity produced by coal or oil is neither clean nor green.

That's one of the reasons that I oppose the city's elevated heavy rail plan. The promoters call it green, the engineering calls it dark black!

And that's one of the reasons environmentalists dislike the new EPA ratings for electric cars. For example, the Nissan Leaf gets 106 mpge (or MPG-equivalent). Quoting the LA Times:

"Things got hairy with the Leaf. The EPA worked out a formula in which an electric car using 33.7 kilowatt-hours of electricity was considered equivalent to a standard vehicle using a gallon of gasoline.

[On the other hand, a better] process would consider all the greenhouse gases released from the time the electricity is first generated until it is sent through transmission lines to charging units. Based on such measurements, the Leaf would rack up more than 250 grams of CO2 and other emissions every mile, according to data from the Energy Department's Argonne National Lab. Gasoline-fueled cars on average release 450 grams a mile.

The fact that the emissions came from a coal plant producing electricity in Utah is just as bad as if they came out of the tailpipe."

Sustainability is often misused for marketing purposes but in the right hands it provides a mindset and tools to get a holistic view of the impacts of a technological option as small as a solar panel or a household appliance, and as large as a hydro-power dam or a transportation system.

1 comment:

. said...

What're your thoughts on solar water panels and PV panels?

They are often touted as a way to reduce electricity bills and dependence on fossil fuels, but i wonder -- doesn't it take a lot of refining and heavy metals to make the panels in the first place? How long is their useful life? Do the larger cradle-to-grave costs outweigh the purported benefits?