It has often been said that renewable energy needs a different infrastructure than fossil or nuclear energy. Here is an attempt to spell out what this means.
Right now electricity generation can be split into base load, load following, and peak load generators. Base load is always turned on (except for maintenance) and covers the minimum demand. It must have high reliability and low marginal cost, ie cheap (dirty) fuel and it must be large scale to get economies of scale, which requires heavy equipment. This makes it difficult to increase or decrease electricity output on the fly. But since its capacity factor is high it can have high capital outlays. It is typically coal and nuclear. Load following plants can easily be started and regulated to account for the variability of the load. This requires lighter equipment and since it is not always on, its marginal cost is not so important, it can be simpler equipment using more expensive fuel. It is typically natural gas. Peak load power plants cover exceptional needle peaks in demand, but most of the time they are turned off. They are typically diesel. More information about this at http://www.grist.org/renewable-energy/2011-05-26-how-to-get-to-a-fully-renewable-power-system and http://en.wikipedia.org/wiki/Load_following_power_plant Some renewables are base load (hydro and geothermal) or dispatchable (hydro and biofuels), therefore they fit into the above framework. But the main renewables, wind and solar, are neither base load (because they are intermittent) nor load following (because they are not dispatchable). On the other hand they have practically zero marginal costs and high capital costs. With increasing penetration of wind and solar energy, a series of things happen: (1) Since it becomes more difficult to adjust electricity supply to demand, it becomes more important to adjust demand to supply, i.e. demand side management (DSM). DSM is already relevant today for peak shaving, will become even more relevant in the future and it will require a smart grid and smart appliances. (2) base load will become more and more uneconomical because it will happen more and more often that all demand is covered by renewables, which have lower marginal cost than base load. In the future energy system base load plants are of little use. (3) Instead of base load or load following, fossil fuels (especially natural gas) will be needed for "residual load" which is highly dispatchable. It is like peak load because it only takes a minute or two to start up or shut down, in order to cover demand when the sun does not shine or the wind does not blow, but it must be more efficient and cleaner and cheaper than diesel because it will be needed much more often. (4) More and more often, total renewable electricity generation will exceed total demand. This electricity will be available for energy storage, so that in the long run the residual load does not come from fossil natural gas but from energy stored during the times of excess renewable supply. Now energy storage can take many forms, some of them unexpected. (5) Transmission: With the present fossil-fuel-powered system, transmission lines from the large-scale fossil fuel or nuclear power plants to the consumers are needed. This transmission and distribution network has tree structure: electricity always flows in one direction, from the generator to the consumers. Some renewables are distributed, they are close to the consumption and need no transmission at all but a more intelligent distribution system; others are large scale (concentrating solar, offshore wind), they need transmission to get to the consumers, but instead of a one-way tree-shaped transmission net, a more interconnected net which at night may bring wind energy from Nebraska and during the day bring solar energy from Arizona. With better local storage options and higher penetration of renewable energy, these transmission lines may not have to be very long or thick. It is not clear at this time how everything will play out, this will depend on how technology develops. (6) Transportation fuels. So far we only talked about electricity. Transportation must either be electrified (electric railroads, electric cars) or must use biofuels or hydrogen produced by electrolysis from renewable electricity. (7) Space heating and air conditioning, water heating, cooking: New buildings will be much more energy efficient, they will not need natural gas for heating and cooking but electricity (ground-sources heatpumps) and water will at least be pre-heated by the sun. (8) Combined heat and power will become the rule instead of the exception. Natural gas facilities for residual power will be smaller and cleaner than today's large scale base load generators; therefore they can be located in populated areas and the waste heat from the electricity can be used for area heating, greenhouses, etc. Initially this will use fossil natural gas, but over time it will switch to biofuels. (9) How all these things will play out depends on technology: whether and when there will be a breakthrough in battery technology, various storage technologies, fuel cells, also energy saving technologies for end users (LED lights). For climate reasons it will also be necessary to extract CO2 from the air and sequester it, i.e. CCS may play a role even after all coal-fired power plants have been phased out. (10) It will also depend on political constellations. The fossil fuel and nuclear industries are fighting tooth and nail against being superseded by renewables. They try to maintain the fairy tale that there is not enough renewable energy or that it is too expensive. Not true. The construction industry is fighting against stricter home efficiency standards and higher in-home technology which will make pre-fab homes necessary, the auto companies will fight against electric vehicles because electric motors last 20 times longer than internal combustion engines, etc. (11) There is absolutely no need to use nuclear energy, neither fission nor fusion. It is too expensive and too dangerous (especially in times of political turmoil). This is how I see it. I may have overlooked things. Please comment. Hans _______________________________________________ pen-l mailing list [email protected] https://lists.csuchico.edu/mailman/listinfo/pen-l
