I focused on the rust and energy basis in the above comment and ignored the local aspect and some others, indeed treating it as a national currency.
There was also some confusion about when and where the stamps where issued.

The local aspect has some interesting ramifications, some financial and others psychological.

First, lets look at the stamps. These are effectively a tax on money. Not a tax on earning money (income tax) or a tax on spending money (sales tax). In essence, this is equivalent to simply printing more money (straight inflation) each month. One difference is there is a hidden tax, that of the hassle of getting the money stamped which may have helped, beyond the inflationary aspect, in discouraging hording though end the end somebody was holding money at the end of the month and had to get it stamped. It isn't clear whether, if you failed to get the money stamped for, say, 3 months whether it was worthless or whether you had to buy three stamps.

Now, look at the 98% exchange rate to non-local currency. This encourages local consumption. An equivalent would be to tax non-local transactions (effectively an interstate or intercity commerce tax). In the US we have the opposite system. Local retail is taxed (sales tax) but interstate commerce can to some extent escape that (in states where they don't have offices). There are proposals to fix that with the original ones being objectionally onerous by requiring businesses to file returns with every state and now getting more reasonable in having a central clearinghouse. One could easily extend that regime to tax interstate commerce at a higher rate. There is also a non-governmental tax on interstate commerce - shipping cost/fuel but fuel has traditionally been at an artificially low cost. Assuming one had a interstate sales tax, a municipality could charge 2% less tax for local transactions; this could be justified in a revenue sense because since the money stays local they get to tax it again and again. But sales tax is still fundamentally different from a money tax. And one could argue that it was taxing money's existance rather than its movement (income tax from employment and sales tax from commerce) was the key aspect (or at least a significant one) that ultimately gave it velocity. Income tax, sales tax, capital gains tax, corporate income taxes all tax money for moving (something the flat tax people should take note of). Property tax is different in that it doesn't tax movement of money but taxes hoarding of certain tangible assets.

There is another aspect of a local currency: trust. The local currency was a fiat currency just as a national currency but its issuance was local. It rarely went very far out of your sight. Complicated contrivances like the stock market and arcane financial instruments that people don't really understand probably didn't exist for that currency and thus it was easier to understand and have confidence in and harder for people to charge money out of proportion to their services. Some of these complicated financial systems, however, do serve actual purposes.

The local currency was issued by the local government rather than being mostly issued by banks and was initially less leveraged (if you overlook the questionable stability of the national currency held as collateral).

The local currency was essentially facilitating a barter system. National currencies do this as well. If a local currency had not been issued, people would have had to resort to barter. The local currency provided a way to tax the barter system and use it for things like keeping government employees employed, aiding those who needed it most, and creating infrastructure (which ultimately creates wealth). Taxes on the money (within reason) is a small price to pay for the increased efficiency of barter. The government basically takes a percentage of the GDP gain and uses it for government services which is a win-win proposition.

The local currency was more likely to be embraced by those who did or could use local products, such as someone who made food products from local harvests. Thus it was easier to spend on local goods. And this lowered transportation costs and other parasitic costs. For every "dollar" spent on imports to your town, you probably see less money coming back for your exports. The further goods and money traveled, the more prone they would be to legitimate and illegitimate parasitic costs.

Ultimately, you do have to have interstate and international commerce. If you want to manufacture a wind turbine, for example, you need copper which will probably come from Chile. You need steel, concrete, and electronic components. If you want to install one, you need to buy a wind turbine that probably isn't going to be available from a local manufacturer. The local currency in this example allowed this, it just taxed it at 2%.

Both confidence in the local currency and lack of confidence may have contributed to its success. On the one hand, one could be reasonably confident that if you accepted the currency today for goods or services you could immediately turn around and spend it. On the other hand, there was less confidence you could spend it tomorrow. You were guaranteed that it would be worth less next month (and this was perhaps more psychologically apparent than inflation) and it might be worth nothing tomorrow or in a few days. Thus it was a hot potato. You were better off spending it on something you needed, or at least had intrinsic barter value, than holding it but you were better off holding it or exchanging it for something tangible than to buy something of little value. So, maybe they hit on the right balance of confidence.

Hoarding of goods may have been significant but at least that kept the money in circulation and the economy running (though it could lead to resource shortages). And as long as the money is circulating there is some confidence. In a depression, there isn't (necessarily) a shortage of materials or labor, there is just a failure of the economic system. People still need goods and services and need the jobs that producing those entail.

Thus, a couple key aspects that are different than our current economy seem to have been that money was taxed rather than the movement of money and that non-local commerce was taxed. The first aspect is similar to inflation but inflation is the result of governments printing money out of proportion to the growth of productivity - which is ok if you spend it on infrastructure that causes productivity to grow.

At the very least, energy dollars could provide a way to help keep the electric on. They utility could pay their workers in energy coupons which could be traded for things the workers need to live with people who then use those coupons for trade or to reduce their electric bills. Additional money is still needed for fuel, but people have an easier time coming up with the reduced amount of money if they can grow food in their garden or rent a room in exchange for energy coupons.