Electricity pricing reflects its real-time cost
Severin Borenstein
Long before US electricity restructuring began in the 1990s there was
a recognition that the marginal cost of producing electricity could
change significantly hour to hour. Combined with the high cost of
storing electricity, this meant that the true opportunity cost of
consuming electricity also would vary constantly. For many decades
economists have argued that retail electricity prices should fluctuate
accordingly - this is known as real-time pricing (RTP) - but the
technology to meter hourly consumption and to communicate fluctuating
prices was quite costly.
Business hours
In the last half of the twentieth century, the industry created a
system meant to approximate RTP with standard technology: ‘time-of-use’
priced that varied systematically by time of day and day of the week,
usually with a higher price Monday through Friday during business hours
and a lower price at all other times. The two prices (or sometimes
three, with an added ‘shoulder’ pricing period) were set months in
advance, however, and did not change to reflect system demand/supply
balance on a daily basis. Because of the cost of even this simple
pricing and metering scheme, it was used only for large commercial and
industrial customers.
In a regulatory environment, two additional factors worked against
adoption of RTP. Under regulation, the utility nearly always charges
prices that are based on some notion of average cost, including the
accounting amortization of long-term capital expenditures. Such an
approach is targeted at cost recovery, not efficient pricing. Also,
regulated utilities may be less likely to appreciate one of the main
attractions of RTP, the effect it has in shaving demand peaks and
reducing the need for capital investment. If regulators allow utilities
to earn generous returns on investment, or if the utility management
simply wants to grow the company, a pricing strategy that constrains new
capital investment is unlikely to be popular with managers.
It is not that utilities did not understand or calculate their
marginal cost. In fact, engineers tasked with minimising production
costs were constantly calculating ‘system lambda’, the value of the
production constraint, which corresponds directly to economic marginal
cost. They needed this information in order to choose among different
production resources. The information was just not used on the
consumption side.
RTP program
As metering technology improved, a few utilities began to experiment
with RTP. The pioneer and still a leader in this regard is Georgia
Power, a company that was, and remains, a traditional regulated utility.
GP introduced its first RTP program in 1991 for large industrial
customers. By 2000, nearly one-third of its entire electricity demand
was on RTP.
Wholesale electricity markets were deregulated in many parts of the
United States in the late 1990s. The idea was that electricity
generation could be a competitive industry with many generators vying to
sell their output into a common power market.
Infra-marginal units
The underlying economic model for this market, however, required that
prices occasionally rise to well above the marginal cost of producing
most units of output in order for firms to earn operating profits on
infra-marginal units, operating profits that allowed the firm to cover
its capital cost, at least in expectation. In some simple framework of a
constant marginal cost of each generator up to its capacity, this meant
that the market had to sometimes clear ‘on the demand side’.
That is, high prices would occur at times of high demand or reduced
supply and those high prices would cause quantities demanded to decline
until they were in line with system capacity.
Such price-responsive demand would constrain prices from jumping too
high, whether the tight market was caused by a true supply shortage or
an artificial shortage caused by some firms exercising market power.
What went largely unnoticed at the time was that the technology and
market organization to enable RTP was not in place in any of the markets
headed towards deregulation. My own pre-deregulation work with Jim
Bushnell, which forecast market power problems in deregulated
electricity markets, just assumed that there would be some degree of
real-time price response.
When deregulated markets launched in California, Pennyslvania - New
Jersey - Maryland, and New England in the late 1990s, retail customers
could choose among retail providers who were buying power out of the
wholesale power market.
Since electricity is a homogeneous good delivered over a
common-carrier infrastructure of transmission and distribution wires,
there was no ability to differentiate the product sold. In nearly all
cases, the final delivery and metering of usage was also left to the
still-regulated utility that was providing transmission and distribution
services. The centralization of the metering service meant that even if
a retailer wanted to offer new time-varying retail pricing structures it
was difficult to actually do so.
Still, because these markets were in a period of excess capacity,
prices remained low and steady at first, with the primary complaint
coming from producers who argued that prices were too low to justify new
investment.
Courtesy: NBER Reporter |