The basic features of an efficient short-term wholesale market design do not need to change to accommodate a significantly larger share of zero marginal cost intermittent renewable energy from wind and solar resources. A large share of controllable zero marginal cost generation does not create any additional market design challenge relative to a market with a large share of controllable positive marginal cost generation. In both instances, generation unit owners must recover their fixed costs from sales of energy, ancillary services, and long-term resource adequacy products.

We show that the negative demand shock due to the COVID-19 lock-down has reduced net-demand system demand less the amount of energy produced by intermittent renewables and net imports that must be served by controllable generation units. Introducing additional intermittent renewable generation capacity will also reduce the net-demand, which implies the lock-down can provide insights about how electricity markets will perform with a large share of renewable generation capacity. We find that the lock-down induced demand shock in the Italian electricity market has reduced day-ahead market prices by 23 EUR/MWh (-45%) but re-dispatch cost have increased by 9 EUR/MWh (+103%) per MWh of load, both relative to the average to the same magnitude for the same time period in previous years. Relating the actual re-dispatch cost to a non-COVID-19 re-dispatch cost counter-factual derived from a deep-learning model estimated using pre-COVID-19 data yields an increase of 40%. We argue that the difference between these two re-dispatch cost increases can be attributed to the increased opportunities for suppliers with controllable units to exercise market power in the re-dispatch market in these low net-demand conditions. These results imply that an increased intermittent renewable energy share is likely to increase significantly the costs of maintaining a reliable grid because of the low levels of net-demand.

Small businesses are typically committed to providing a positive customer experience and therefore may exhibit a response to dynamic electricity prices different from residential or industrial customers. We conduct a field experiment to determine the extent to which small businesses respond through re-configuration of typical routines throughout the experiment period versus through adjustments to specific dynamic pricing events. Using a customer-level survey of appliance ownership, we estimate the hourly response patterns of individual appliances to participation in the experiment versus individual dynamic pricing events. Consistent with our re-configuration hypothesis, small businesses primarily curtail electricity usage throughout the experiment period, although we also find a small imprecisely estimated response to dynamic pricing events on top of the re-configuration effect. Appliances not critical to a positive customer experience such as dish dryers, food storage units, lights, electric motors & pumps, and industrial heaters are the major sources of the energy savings from the re-configuration actions of these small businesses.

We report on an economic experiment that compares outcomes in electricity markets subject to carbon-tax and cap-and-trade policies. Under conditions of uncertainty, price-based and quantity-based policy instruments cannot be truly equivalent, so we compared three matched carbon-tax/cap-and-trade pairs with equivalent emissions targets, mean emissions, and mean carbon prices, respectively. Across these matched pairs, the cap-and-trade mechanism produced much higher wholesale electricity prices (38.5% to 52.6% higher) and lower total electricity production (2.5% to 4.0% lower) than the \equivalent" carbon tax, without any lower carbon emissions. Market participants who forecast a lower price of carbon in the cap-and-trade games ran their units more than those who forecast a higher price of carbon, which caused emissions from the dirtiest generating units (Coal and Gas Peakers) to be signicantly higher (15.2% to 33.0%) than in the carbon tax games. These merit order \mistakes" in the cap-and-trade games suggest an important advantage of the carbon tax as policy: namely, that the cost of carbon can treated by rms as a known input to production.

To maximize environmental benefits from the rollout of its cap-and-trade program for greenhouse gas emissions, California should focus on achieving a positive demonstration effect from the program by doing as little as possible to harm the state's economy, as transparently as possible and as fast as possible.

If regulators and utilities want to avoid future consumer backlash from smart grid investments, they should adopt retail pricing policies best suited to maximizing the consumer benefits from smart grid technologies.