Conceptually, each payment in a LETSystem comprises an LT component and "green money" component even when the former is zero. Whatever the price P, the payment comprises NP in LT and (1 - N)P in “green”, where N ranges from 0 to 1. In this sense, the “green” component is a complementary1 currency for LT.
The LT + “green” combination might be thought of as a very simple “vector currency” - a vector having only two components - but we can add more. Indeed, we can add as many as we find useful.
In contrast, a currency that merges everything into a single measure - a price, a “value”, a weighted sum - is a scalar quantity. The “value” (price) of anything bought or sold using a scalar currency can be equated to some multiple of the “value” of anything else, and that includes the price (exchange rate) or other such currencies - whether dollar, euros, yen, bitcoins or cowrie shells. There is nothing to distinguish one such currency from another other than the technology used to make payments or store the numbers. Such currencies preserve very little information. The unconstrained currency pools they form invariable settle into something close to a power law distribution. That such distributions occur naturally not a valid argument in their favour. If we wish to create a sustainable abundance for all humankind (and for everything else on “spaceship earth”1) then we need more richly information-retentive economic systems.
Other measures (1): human time (my 1 hour = your 1 hour)
An important practical measure, and one very different from that used to define LT, is human time - a person-hour1. This is not productive time (given that individuals have different productive capacities at different times) but time given up for the benefit of others. In practice, such measures are used in schemes used for the following purposes:
- To encourage socially marginalized individuals to accept help from others and to accept that their own contributions, even if not financially compensated, are valuable in turn to others in their community. This is a function of time banks, one-to-one services-to-needs matching by tightly controlled brokers supported by rich information systems. Such services are expensive to run and can only be sustained in the longer term if funded from within a larger closed system, i.e. by creating a loop from costs saved elsewhere through the beneficial effects of the time bank. Such a loop calls for a diversity of measures.
- To encourage socially marginalized groups (often younger people in deprived areas) to undertake organized remedial or development activities activities collectively, rewarded in time credits. Such time credits extend the concept of those used in time banks, providing access to learning resources, community resources (computers, workshop space, performance space, etc.) and social activities. Such “rewards” generally incur a cost which has to be covered by completing the loops in a similar way to the case of time banks, but time-value resources can also be donated within the local community (e.g. otherwise empty seats in a cinema or musical event (one hour of seat time for each hour of time credit earned).
Other measures (2): energy (ML2T-2)
Energy is a constant in its capacity to move, heat, drive or illuminate. The efficiency of energy conversion may improve over time, but energy remains constant in its capacity. Therefore it's the closest thing we have to a true store of value “currency”. Accounting for energy generated, stored, transferred, lost or converted provides valuable supplementary information within a vector currency.
Other measures (3): closed pools - like for like services or goods
Mutual child care (among trusted friends)
Car-sharing and car pools
Land-work parties
House-building parties
Other measures (4): semi-closed circular processes
“Fertility circles” - … growing, harvesting, distribution, (putrescible) waste collection, composting, ground preparation, planting, growing, …