Future electricity grids: the rise of the prosumer

Unlike other commodities such as gas and oil, electricity cannot  be easily stored. It must be consumed almost as soon as it is produced.

Consumer demand follows a fairly predictable pattern. Electricity prices are higher on weekdays when “peaking” power plants come online to satisfy increased demand. The first demand peak occurs in the morning – when a high proportion of the population is getting ready for work or school.  A second peak occurs in the evening when consumers return home and start cooking dinner, or turn on the television.

Conventional power generators such as coal and gas turbines can respond quickly to variable consumer demand by increasing fuel input and ramping up output during the day. Nighttime is a cool-off period.

Intermittent renewables changed this model. We must now factor in unpredictable supply peaks and increased price volatility. In the UK and Germany consumers bear the brunt of these new costs. You can read more about how renewables are shaking up the traditional power model here. 

There are several ways to manage this new supply intermittency and smooth prices.

One is more interconnections. These reduce bottlenecks and diversify supply sources so that electricity-rich areas can service electricity-poor ones. Nations hoping to boost electricity production from renewable sources will need a well-connected grid, as an oversupplied area can experience shortages as soon as the weather changes. New power lines require public support and investment.

Short-term (spot) electricity trading can optimise electricity flows between areas and facilitate price arbitrage. Spot trading services are offered by EPEX Spot in Central Western Europe or ERCOT in Texas, for example. These services also permit renewable energy producers to rebalance their books if the weather forecast was inaccurate and they produce much more or much less electricity than predicted.

Smart grid technology uses real-time information about supply and demand to automatically adjust electricity flows curtailing price peaks (or negative prices). Again public money is needed to roll-out this infrastructure at the national level.

Another means is electricity storage.

Pumped hydro-storage has existed for a long time. It is the only large-scale storage technology used commercially. It involves pumping water uphill when electricity prices are low, then running water downhill, through turbines, during peak-price hours to generate electricity. Pumped hydro projects are nevertheless hugely dependent on local geography and rainfall, as well as regulations regarding water-use.

The lithium-ion batteries used in electric cars pack a lot of energy density for their size. They cost around US$10 000, even for a small vehicle, and can only run for about 175km before recharging. This could be better. Crucially, lithium-ion batteries do not suffer from “memory” issues. Meaning that don’t need to be drained before being recharged.

Battery manufacturers across Asia and the USA are struggling to cut costs and upscale their technology to plug into the electricity grid. Yet, electricity generation is decentralising. Small-scale industrial and household solar production is on the rise. Rather than selling their excess power back to the grid some could go off-grid.

Most experimental batteries would need to be bigger than a house in order to store enough solar electricity to power one household for a day. And they remain prohibitively expensive. However, Tesla caused a lot of excitement last month when it announced plans to market lithium-ion batteries at prices starting from US$3500. It costs a household a further US$5000 or so to install solar panels. Nevertheless, this much-anticipated battery is priced lower than any other technology on the market. The Tesla battery should be small enough and safe enough to install in your basement. Plus, you don’t need to be a rocket scientist to operate it.

How did they do it? It’s not new technology. Rather, Tesla is building a US$5 billion gigafactory in Nevada’s desert, where it hopes to realise enormous economies of scale. While the market is still waiting for a technological revolution – the step-change that would make batteries as portable and powerful as microchips which are continuously delivering ever cheaper computing power – Tesla intends to reduce manufacturing costs for current battery technologies.

There is a sizable market of homeowners prepared to fit out their homes with solar panels, battery storage and adopt other energy efficient technologies. These early adopters need enough cash to  invest upfront, before they reap the benefits in reduced or zero-cost electricity bills in the months and years that follow.

For most middle class homeowners US$8500 is no small fee. Companies such as SolarCity in the US provide another piece of the jigsaw. Financed by high net worth individuals, as well as Google and Goldman Sachs, the company pays for solar panel installations, aggregates the earnings from energy savings and grid buybacks, then sells bonds based on a predicted revenue stream. Such creative financing will hasten the prosumer revolution and eventually take some of us off-grid.

No one technology will solve all the problems intermittent renewable energies have introduced into electricity markets. A patchwork of different solutions looks likely to emerge – with some consumers taking matters into their own hands.

Renewables menace traditional power model

Lots of things are shaking up the traditional power model. A decade ago gas and coal power plants were very profitable. Retail companies, which distribute to industrial and household consumers, bought wholesale electricity at a price that always covered operating costs and got a healthy boost during peak demand hours. Even fairly inefficient power plants could expect to have enough profitable operating hours to keep in the money.

Electricity generated from renewable energy sources has altered this dynamic, most noticeably in Germany where Energiewende policies encourage renewable energy development. The upfront costs of new renewable energy projects are subsidised. Once operational wind or solar parks are given priority access to the distribution grid – they can always market the electricity they produce. Furthermore, the government pays out a “feed-in” tariff. That is, guarantees a certain price for every megawatt hour of electricity generated by a wind or solar farm.

These policies have discouraged private investment that might have brought more competitive renewable energy technologies, ones that do not require government subsidies, to market sooner. Nevertheless, Germany’s goal to get 60% of its electricity from renewable sources by 2050 is on track. The eventual success or failure of these policies is the experiment the entire world is watching.

However, the rapid expansion of renewables has upset the incumbents – traditional thermal power generators that use coal and gas as fuel. Renewables harm their profitability for a number of reasons.

First of all, the average wholesale electricity price is lower. Once a wind turbine or solar panel is installed operating costs are near zero because the wind and sun are both free fuel sources. The price of electricity depends on where inflexible consumer demand matches producers’ supply. The producers with the lowest operating costs are always called on first. Then the price of electricity creeps up the supply curve until consumer demand is satisfied. Every day, every hour, producers receive a price for the electricity they produce based on the last generator called up in the so-called “merit-order.” The graph below illustrates this.

meritorder

The last generator is always less efficient. This means that its operating costs are higher and it will only generate electricity when the price covers these operational costs. Now that renewables are part of the merit order, we don’t climb as high up the curve as before. On average, prices have decreased, implying the recurrent “last generator” is more efficient than a few years ago.

Second, thermal power plants’ operating hours are down. A lot of electricity is being generated from renewable sources replacing supply previously provided by gas and coal power plants. This point is obvious – money can only be earned when your power plant is online and generating electricity. This adds to traditional power plants’ woes. Prices are weakened, but their sale volumes are also harmed as renewable energy production grows.

Third, renewables are very variable. Already gas power plants have shut down and new projects have been cancelled because they could not survive the renewables’ economic shake-up. However, some days the sun does not shine, or there is no wind, and traditional generators are still needed. This can vary hour-by-hour, minute-by-minute. Only very modern gas facilities are capable of ramping up and down to balance unpredictable renewable production. Although, this is simply not profitable in a weak price climate where operating hours are down. So, these rapid-response power plants are no longer being built. This is called the “missing money” problem.

Fourth: the rise of the prosumer. Households and businesses have been installing solar panels with the hope of decreasing their electricity bills. In some countries, excess electricity that is generated can be injected into the grid earning you cash back from the local electricity retailer. This is how the word prosumer came about. Households connected to the distribution grid were traditionally pure consumers. Having installed solar panels the consumer is now a producer as well. They may even be electricity self-sufficient on sunny days or exceed their own electricity needs, affording them the opportunity to sell back to the grid.

Alone, one solar powered household cannot produce enough electricity to perturb the traditional power model. Yet, the arrival of hundreds and thousands of prosumers on the grid has the potential to be very destabilising as seen with commercial solar generation.

These four issues are part of a bigger problem: electricity infrastructure and markets are inflexible. They were not designed to manage decentralised and unpredictable electricity production. Nevertheless, this is the model we will have to manage in the future. Distribution lines also have ramping limits constraining how quickly power flows can be increased or decreased. Volatile prosumers and commercial wind and solar farms compromise the grid’s technical stability. And we still need back-up for the days and hours when renewable electricity production is low. Managing variable electricity production demands a model where this responsibility is shared by the market players.


Graph was found at www.powermarket.eu