Energy Production (iv) Efficient Energy Production

Chapter 3: CLEAN

Energy Production (iv) Efficient Energy Production

Part 4: Producing Energy Efficiently

The process of producing energy consumes energy. In fact, the energy transformation sector uses about a third of all primary energy. Given that in most conventional power stations, only about 30-50% of the energy consumed is converted into electricity (older coal stations are the worst culprits), there obviously is potential—in at least two key areas—to produce a lot more energy with the resources we import.

Firstly, there is opportunity to modernise the large power plants, the installations that feed the high-voltage grid, powering up entire cities. This is at least partly (the other reason is to control emissions better) why Electrabel is investing a great deal of money in its existing infrastructure. The technology used can make a substantial difference. For example, the efficiency of an older coal-fired power plant is only about 30-35%. Compare that to Siemens’ newest gas turbine, currently the largest of its type in the world. This 444-ton machine has a capacity of 530 MW (if combined with a downstream steam turbine), which is enough to power a city of 3 million residents. Its efficiency is a world-record at approximately 60%. Coal is cheap and reasonably abundant, however, which is why coal plants continue to be built. Modern coal plants also are more efficient than older types, and should carbon-capture technology become effective then we can expect a lot more coal plants to be built. All eyes are on E.ON, for example, with its controversial plan to build a new 1100 MW coal-fired plant in Antwerp that it claims will be 46% efficient and ‘carbon-capture ready’.

Secondly, there is opportunity to produce a great deal more energy at a decentral level, in smaller scale, using cogeneration technology. Cogeneration is a technique that allows for the production of heat (steam or hot water) and electricity in a single process. While traditional power plants release their exhaust gases direct into the atmosphere, a cogeneration plant will use those hot gases to produce hot water or steam. Most cogeneration plants today can be found at large industrial sites, where the heat generated is used in the factory’s industrial processes. Typically driven by natural gas or biogas, cogeneration facilities can achieve energy efficiency levels of around 90%. That is a tremendous difference with even the most efficient electricity-only power plants. As a result, there has been tremendous growth in the adoption of this technology in Belgium. Looking at the total power capacity installed, however, the bulk can be ascribed to a handful of massive installations in the chemical industry. But rolling the technology out to smaller scale contexts, to smaller industrial sites, buildings or even residential areas, is proving difficult. Even though cogeneration is supported by a green power certificate system, there are a number of key limitations that hamper growth in the future.

Firstly, the heat generated needs to be used in some way or other. While it makes sense for a chemical plant to use cogeneration given the need for electricity and heat in its production processes, in many other settings one first needs to build a district heating system of sorts. Places like New York City and many Scandinavian and Eastern European cities have such district heating systems in place (where large cogeneration plants push steam through a district- or city-wide network of pipes, into the heating systems of apartment buildings and office buildings). In Belgium we do not have such infrastructure in place. New infrastructure is gradually being built, however, with these principles in mind. Electrawinds, for example, has projects on the cards where newly established commercial zones will have access to a central heating system powered by a cogeneration plant. Also, there has been much success (albeit largely due to the feed-in tariffs) in linking cogeneration installations to greenhouse agriculture.

A second limitation is that the excess electricity generated needs to be injected back into the grid. While a large industrial site will typically already have dedicated links to the grid, smaller industrial sites and greenhouse agriculture do not. The vision of decentralised power production, where thousands of small industrial sites and residential zones alternate between being power consumer and producer, implies that the grid needs a major revamp. More on this in the next section: ‘Fixing the Grid.’

Thirdly, it is proving difficult to develop efficient small-scale cogeneration systems for use in smaller companies, buildings or even homes. The problem is that the heat demand profile needs to be reasonably consistent (i.e. consume a consistent amount of heat continuously). That is not the case in smaller buildings or homes. Nevertheless, it is likely that cogeneration technology for the home will eventually become available.