Optimised water heating and upgrade for meeting house

I have been very involved in maintaining my Quaker Meeting House in Damariscotta, Maine for many years.  I have helped to "green" the building in many ways, from adding a modest solar power system, to many efficiency upgrades.  The building was constructed in 1995 and was built with "traditional" construction and heating system.  This means that it uses an oil fired boiler like many buildings and homes in New England.  So about 10 years ago we decided to switch to a B20 (20% biofuel) mix that became available in our area.  Higher biofuel ratios do not work well in frigid temperatures because it can congeal and also corrode seals.

But then we realized that the water heater is tied in to the huge oil boiler and the boiler was running during the warm seasons to heat a 30 gallon tank located in the cool basement.  In this environment the tank loses heat and needs to be "topped up" fairly often wasting a lot of fuel oil to heat water that was not being used.  So we came up with a work-around.  We had a small 4 gallon electric heater installed after the hot water tank.  Then we installed a timer that only runs the oil "boiler-mate" for hot water on Sundays when we need more for dish washing and events.  When the tank is not being heated by the boiler, the stored water is tempered by the ambient environment, thus raising the temperature of the well water from a nominal 45-50F to 50-60F.  This reduces the load on the small electric heater a little.

Now the modest weekday hot water needs are met by this small electric heater.  Due to the Regional Greenhouse Gas Initiative (RGGI) in New England, the electric supply is supplied from at least 45% renewable sources such as hydro, solar and wind.  So this is a win from a cost, carbon footprint and efficiency standpoint.

All this came up when someone noticed rusty water coming from the hot faucets.  I drained water from each tank and determined that the small electric unit had rusted out inside.  Our local plumbing company wanted $400 for a new heater, plus labor.  This seemed unreasonably high so I found a nice Bosch unit on Amazon Prime (free delivery of a 20+ lb package!) for under $200.  It took me about 20 minutes to replace the unit.

Fix it - don't toss it

 I have had this handy dual power (solar/battery) Radio Shack calculator for decades.  Recently it started producing weird results - reminding me of my series of artworks that deliberately satirize our implicit trust in electronically represented numbers.  Here's an example of a recent one:

"Digital Numeric Relevator Mk XXXIV - Hexadecimal Blues"

My "Relevator" series all look like Sharper Image products from the Twilight Zone and they just show senseless numbers that dance, fade, or de-construct in interesting ways.

It is disconcerting when a calculator shows wrong results!  So I opened it up to see what I could learn/do.  All it took was a miniature Phillips screwdriver:

... and there in the corner was a replaceable watch battery!  

It turned out I happened to have a spare battery laying around and "Presto!" it worked fine and the display was even more readable than it had been.

Being a geek, I always test a calculator by entering 22 / 7 since pi is a good exercise for the electronics and I happen to have memorized the first 5 digits.  So it's working fine now.

The point of my sharing this simple repair story is that it is often much simpler than you think to repair something.  So I saved this little item from the landfill and expect it to last a few more decades.  This is the essence of living sustainably.

Previous posts in this series showed:

How I repaired a broken torchiere lamp base

How I repaired my microwave oven

How I repaired my trash can lid

These repairs were simple and easy to do repairs, requiring minimal tools and basic ingenuity.  You can often find detailed help for repairing just about anything on the web and YouTube.

En konstruert energikrise: løsninger

av Lars Kåre Grimsby, PhD Candidate, Noragric, University of Life Sciences, Norway

Status

Siden 1970-tallet har man forsøkt å utvikle og forsyne mennesker i utviklingsland med mer effektive vedovner, enkel biogass- og gassifiseringsteknologi, mikrovannkraft og solcellepaneler. Gjennom disse årtiene med bistandsintervensjoner har det etterhvert utviklet seg en kontrasterende todeling i tradisjonell og moderne energi (Goldemberg og Teixeira Coelho 2004). På den ene siden har man de ønskelige egenskapene som ren energi, høy virkningsgrad og mulighet til å levere kraft til nye teknologier og behov i industri og husholdninger i utviklingsland. På den andre siden har man tradisjonell energi, typisk billedliggjort ved en kvinne med rødsprengte øyne som sitter med ei gryte over et rykende bål eller kvinner som bærer tunge bører med ved.

Figur 1. Ingen røyk uten ild. Mikrokjøkken fyrt på lokal fornybar energi
(Lars Kåre Grimsby)

Kriser

Energifattigdom kom for alvor på den internasjonale dagsordenen i kjølvannet av den internasjonale oljekrisa i 1973. Den raske prisstigningen på olje gjorde at folk flest tok innover seg i hvilken grad samfunnet hadde blitt avhengig av en ikke-fornybar ressurs. I Norge tok Kong Olav trikken og bensin ble rasjonert med kuponger. Radikale aktivister som Ivan Illich (1974) skrev om hvordan alle verdens fartsgrenser burde senkes til sykle-fart for å jevne ut forskjellene på fattig og rik, og å bruke energi mer fornuftig. Samtidig fikk FN og bistandsorganisjasjoner øynene opp for «den andre energikrisa»: ikke-bærekraftig bruk av ved i utviklingsland (Eckholm 1973). FNs organisasjon for ernæring og landbruk (FAO) sine vekstmodeller for skog projiserte at med fremtidig økende uttak av biomasse til ved og rydding av land for jordbruk, så ville enorme soner i vestlige og østlige Afrika, og India være tilnærmet avskoget innen år 2000 (for et historisk innblikk, les Arnold et al. 2003). Dette ville bety økt byrde på kvinner som måtte bære ved over lengre avstander, samt økt bruk av enda skitnere brennstoff enn ved; for eksempel tørket kumøkk og andre biprodukter fra landbruket.

Der oljekrisa i 1973 åpnet øynene for energifattigdom, utløste 2000-tallets oljepriser på over 100 US dollar fatet interesse for alternativ energi. Biodrivstoff ble gjenstand for enorm interesse som oljesubstitutt for transportsektoren i Europa og USA, men også som et tiltak for forsyning av lokal, miljøvennlig og rimelig energi i avsidesliggende områder i utviklingsland (FAO 2020). Planteolje kan med relativ enkelhet drive dieselgeneratorer som leverer elektrisitet til små samfunn uten tilknytning til strømnettet (TaTEDO 2020). På samme måte som forbedrete ovner ville kunne forbedre kvinners hverdag og det lokale miljøet i utviklingsland, ble også biodrivstoff promotert for å kunne styrke kvinners plass i samfunnet gjennom tilgang på leselys, mekanisering av kverning av mais og pumping av vann. Denne moderniseringstanken, samt sterkt internasjonalt fokus på behov for å bekjempe energifattigdom i lys av økende oljepriser, gjorde at prosjekter for å levere planteoljebasert elektrisitet ble prøvd i land som Mali, India, Indonesia og Tanzania.

Energibistand

Bistandsarbeidere og forskere har siden den første oljekrisa grublet over hvorfor moderne energiteknologi ikke i større grad aksepteres av lokalbefolkninga. Det var generelt akseptert at fattigdom var den viktigste hindringen for utvikling av energibruk, og det var derfor overraskende da man etterhvert begynte å se at mennesker ikke moderniserte energikonsumet i takt med økende inntektsnivå. Istedet førte bedret livssituasjon til at man tilegnet seg og brukte et større mangfold av energiteknologier og -bærere. Masera et al. (2000) skriver at denne strategien åpner muligheter for effektiv og økonomisk allokering av energibærere og dermed balanserer flere behov hos folk mer effektivt enn det én energikilde ville kunne gjøre.

Dette utfordrer den etablerte sannheten blant FN og bistandsaktører om modernitet, ikke minst sett fra et lokalt perspektiv. Et lite dykk inn i testing av forbedrete ovner, biodrivstoffbasert el-produksjon og biogass viser at det ikke nødvendigvis er folks hoder det er noe galt med. I avhandlingen jeg håper å forsvare i september i år stiller jeg spørsmålstegn ved dikotomien tradisjonell-moderne som jo har vært effektiv for å reise midler til bistanden, men som kanskje ikke resonnerer like bra med brukerenes erfaringer. Som et eksempel er man avhengig av svært mye og svært rimelig arbeidskraft for å sanke oljefrø som forsyner lokalsamfunn med planteoljebasert elekstrisitet. Denne jobben er det marginaliserte kvinner som gjør i et prosjekt jeg har studert i Tanzania (Grimsby et al. 2020). - Det er lite som har endret seg fra sanking av ved til sanking av oljefrø for å levere «moderne» energi. I tillegg kan det være andre egenskaper enn prosjektutvikleres syn på modernisering som er viktige for brukerene.

Figur 2. Oljepresse, Maismølle og generator på planteolje i Tanzania
(Lars Kåre Grimsby)

Alternativ

Energifattigdom er først og fremst et spørsmål om ulik ressurstilgang. At marginaliserte kvinner fortsetter å sanke ved og biodrivstoff er ikke en konsekvens av teknologien, men av strukturelle problemer i samfunnet. Heller enn å argumentere mot bistand orientert mot forsyning av energiteknologi vil jeg snarere tvert imot avslutte med å oppfordre til økt innsats men med en reorientering for formidling av alternativ energi i utviklingsland. Nettopp det at folk tenderer mot på kløktig vis å tilegne seg og bruke et mangfold energiløsninger åpner for mer satsing, men muligens mindre opphengt i resultater målt ut fra bistandsaktørenes målsetninger og mer ydmyke for lokale behov. Dette legger grunnlaget for å tilgjengeliggjøre energiporteføljer som husholdninger, industri og annet næringsliv kan velge blant.

Referanser

Arnold, J. E. M., Köhlin, G., Persson, R. & Shepherd, G. (2003). Fuelwood revisited: What has changed in the last decade? Bogor: CIFOR. 47 pp.
Eckholm, E. P. (1975). The other energy crisis: Firewood. Washington, D.C.: Worldwatch Institute. 22 pp.
FAO. (2020). The state of food and agriculture. Biofuels: Prospects, risks and opportunities. FAO Agriculture Series (SOFA). Rome. 240 pp.
Goldemberg, J. & Teixeira Coelho, S. (2004). Renewable energy—traditional biomass vs. modern biomass. Energy Policy, 32(6):711-714.
Grimsby, L. K., Aune, J. B. & Johnsen, F. H. (2020). Human energy requirements in Jatropha oil production for rural electrification in Tanzania. Energy for Sustainable Development, 16(3):297-302.
Illich, I. (1974). Energy and equity. London: Calder & Boyars. 95 s. pp.
Masera, O. R., Saatkamp, B. D. & Kammen, D. M. (2000). From linear fuel switching to multiple cooking strategies: A critique and alternative to the energy ladder model. World Development, 28(12):2083-2103.
TaTEDO. (2020). Bio-fuel powered energy service platforms for rural energy services. Dar es Salaam: Tanzania Traditional Energy Development Organization. 87 pp.

Who killed the vampire loads loads in my entertainment system?

In a recent post I wrote about replacing my dead 37" LCD TV with a new 50 inch unit.  I didn't realize I was buying into an entirely new AV ecosystem.  I got talked into purchasing a sound bar for the TV which completely replaced my old-style stereo amplifier that I originally used for the sound system for my TV.  So I have completely restructured my entertainment system and in the process I have taken detailed measurements of its power consumption using a Kill-A-Watt meter.  The biggest take away I have gotten from this experience is that over the last 10 to 20 years new appliances have dramatically reduced their phantom loads.  A phantom (or vampire) load is the power an appliance consumes when you think it is "off".  In an entertainment system this includes all of the devices that you can turn on remotely.  They have an internal circuit that sits there all day waiting for a signal from your remote control and that consumes a certain amount of power - sometimes several Watts.

My original entertainment system consumed around 9 W in standby mode not counting the DVR and I used a timer to turn everything off from midnight to 6 PM thus reducing the load to the timer itself which is only 1 W:

My new entertainment system is significantly more efficient, not only when everything is on, but also when all of the devices are turned off.  My Kill-A-Watt could not get a valid reading for the TV, sound bar or Fire TV (streaming video) box because it is below its measurement threshold of 1 W.

I have recycled the DVD player, stereo amp, and CD player because I no longer need them.  The new sound bar lets me play my music via Bluetooth from my tablet or from the cloud using the Fire TV, and who uses CDs anymore these days?  So now my power consumption when watching TV has dropped from 223 W to around 102 W.  A 50% reduction.  Here in Maine we pay approximately $.14 per kilowatt hour, and if we assume I watch TV for five hours a night which is considered average then the monthly cost drops from about $4.68 to $2.14.  So I am saving over $2.50 on my electric bill every month.  (Actually I don't pay for electricity during the summer months because my solar array generates a surplus!).  If you extrapolate this across all the entertainment systems worldwide, this energy savings is really significant.

By the way, in the process of setting up and configuring the new TV, I learned that by adjusting the brightness setting I could reduce its power consumption from around 73 W down to around 50 W without any significant compromise in image quality.  You may want to dig into the settings on your TV and see how low a brightness setting you find acceptable.  If you do this while the TV is plugged into an energy meter, you can balance brightness versus power consumption.  It may take a period of adjustment to get used to a slightly less bright TV, but the default settings are usually much brighter than is necessary.

I think the drop in power consumption has a lot to do with advancing technology, but also some push back from consumers who want more efficient appliances.  Over the last several decades televisions have dramatically improved their operating efficiency as they transitioned from old-style CRT tubes to cold cathode backlit LCD screens to LED backlit LCD screens.  Similarly, engineers have found a way to reduce those pesky vampire loads in the entertainment systems.

So if you are overcome by "consumer-itis" and decide you need to upgrade your entertainment system, you may find that your electric bill drops significantly while your viewing experience is enhanced.  Guilt free TV! - who knew?  Just don't forget to recycle your old equipment.

My artwork that inspired an Invention that became a successful Business

I am going to start by going off topic for this post and tell you about a surprising success I had back in 2002.  At that time I was making turned wood artworks that took the form of undulating shapes supported by legs.  I have sold most of those pieces, but here is a good example:

"Ground Effect" by Guy Marsden

These artworks created a sense that the central lighter colored piece of wood was floating and eventually I decided that I  wanted to create a piece in which the wood actually levitated.  The result was this piece:

"The Mother And Child Reunion"
by Guy Marsden
(this piece is available)

The large yellow "mother" section is actually attached to the tusk shape in the back, while the smaller "child" element hovers just below:

"child" suspended in thin air!

The "child" moves around slightly in air currents but remains about a quarter inch away from the upper section at all times.  When I decided to embark on this project I researched magnetic levitation and eventually decided to develop my own circuit that would accomplish the levitation for this artwork.  (I design electronic products for a living: http://www.arttec.net/Industrial/Design.html). There is a small powerful magnet embedded in the lower section, and an electromagnet with control circuitry that I designed in the upper section.  It took me about two weeks of research and development to come up with an ideal circuit.

Having completed the artwork, it occurred to me that other electronic hobbyists might enjoy building the circuit that I came up with.  So I approached the hobby electronics magazine: "Nuts and Volts" to see if they would like me to run a construction article.  They approved enthusiastically and my article was published in 2003.  

Authors who publish construction articles often offer a kit of parts along with a circuit board and instructions to make it easier for people to build their design.  So I designed a circuit board, ordered parts and created instructions comprising a total investment of around $500.  I hoped that I would sell several dozen kits over the next few months after the article was published.  Here's a photo from the article showing the original kit levitating a matryoshka doll:

Original levitation kit assembled

I was quite surprised by the response to my kit and in my first full year I sold over $9,000 worth of them!  It was delightful that my email inbox went from: "you've got mail" to: "you got money" as order confirmations came in via PayPal.  Since then, sales have tapered off somewhat but I still sell several thousand dollars worth of them every year through my website: http://www.arttec.net/Levitation.  I offer kits and fully assembled versions and often hear from people that have made amazing projects with the kit - like this wonderful flying bird:

click here to see more projects

I often look back and reflect on the unusual sequence of events that began with creating an artwork that transitioned to designing an electronic circuit that became a successful product.  I think the lesson to be learned here is to always be open to the possibilities and to recognize and take advantage of every opportunity that presents itself.

To bring this blog post back around to the topic of sustainability, a few years later this experience inspired me to market another product that I originally designed for my own personal use.  This is a solar differential temperature controller used to improve the performance of my off-grid solar thermal heating systems.  I was equally surprised at how easy it was to start the business and how successful it became - I guess I have a knack for starting small businesses.  I eventually developed more sophisticated versions of this basic product and market them from a separate website: http://ArtTecSolar.com/

ART TEC SolarSolar Differential Temperature Controllers

There are now hundreds of my products out there in the world improving the performance of off-grid solar heating systems and I feel good that I am making a contribution to this important renewable energy market segment.

The importance of biofuels in our current society

The excessive net carbon dioxide emissions and the serious geo-political implications associated to fossil fuels, makes the replacement of these conventional fuels by alternative energy sources an urgent need. Biomass, as a clean renewable energy source, will certainly play an important role. Biomass presents advantages over other sustainable sources such as solar, hydro, wind and geothermal. On the one hand, biomass and the processed products can be easily stored. On the other hand, biomass is the only renewable source of carbon, hydrogen and oxygen and therefore it is suitable, besides heat and power, for the production of chemicals and transportation fuels. When looking at the transportation sector, liquid fuels produced from biomass, namely biofuels, will particularly be essential in aviation, ships and truck traffic, where the energy needs to be stored very efficiently. Biofuels are often divided into so-called first, second and third generation biofuels. The former ones originate from crops whereas second generation and third generation biofuels are produced from lignocellulosic materials and algal/aquatic biomass, respectively.

The use of first generation technology has been the subject of considerable media attention and a significant part of our society is concerned about the environmental and social impacts of these types of biofuels, originating from food crops.
In Europe, the main focus is on the production of second and third generation biofuels from sustainable feedstocks such as agricultural residues, algae, forest residues, etc. Norway does not produce first generation biofuels. Among the different second and third generation biofuels, Norway produces bioethanol and biogas from lignocellulosics. Biodiesel, instead is not produced. Although these materials may be more sustainable and do not compete directly with food, as it occurs with the first generation biofuels, they do compete for land use. In this context, there are several ongoing projects on algae for biofuel production in Norway, to overcome the concerns related to the second generation biofuels. Although biofuels production is being developed in Norway to a significant extent, there are still no environmental or sustainability demands on the use of biofuels, in contrast to the countries of the European Union. In order to implement biofuels in Norway, regulations and incentives will be essential.

Upgrading my TV and recycling the old one

A few days ago I went to turn on the TV and it would not turn on either using the remote control or the button on the side.  This TV does not owe me much because I bought it over six years ago on clearance from the now defunct Radio Shack store nearby and I had since repaired it by replacing the motherboard.  It was a 37 inch LCD flatscreen with a nominal rated power consumption of 140 W.

I found another clearance deal at Sears for a 50 inch LED TV that is rated around 60 W.  It is impressive that this larger TV uses much less power and has a very favorable Energy Star rating compared to other TVs in its class (actual label shown at left) and I am quite pleased with its quality overall. 

Incidentally, as an engineer I need to point out that TVs are marketed as "LCD" (Liquid Crystal Display) or "LED" (Light Emitting Diode).  The current crop of TVs are all sold as "LED TVs" yet they are still really using LCD imaging technology but LEDs as the back light which is what helps to make them thinner.  Older style "LCD" TVs used fluorescent lamps for the back light that used more power and added more bulk to the back of the TV.  My old TV was this latter style.

The Sears salesman also suggested that I replace my old style stereo amplifier and speakers that I use for the sound system for the TV with a new sound bar and subwoofer.  I declined, but ended up being curious about the idea since it might simplify the whole setup.  Eventually I drove down to Best Buy since they had a big selection of them and ended up purchasing a relatively affordable sound bar that fits very nicely right below the TV on our stand.  The salesman reminded me that Best Buy accept old appliances and recycle them so I just got back from dropping off the old TV to Best Buy.  I am so pleased that major retailers are stepping up and offering to recycle old equipment.  Most electronics appliances contain a variety of toxic chemicals that do not belong in the landfill.  I have also returned computers and printers to Staples.

I made the 32 mile round-trip in my solar charged Chevy volt (note the license plate is SUN PWRD!) with no carbon emissions.  

Solar water heater tank failure

A few days ago I was showing someone my solar domestic water heating system and when I opened the utility closet I was confronted with a quarter inch of standing water.  Clearly my solar heated water tank had sprung a leak.

The tank is a Whirlpool 40 gallon electric water heater that had a warranty of six years and by replacing the anode rod I extended that out to nine years or so.  My system is designed so that I can change the position of three gate valves to isolate the solar tank and continue to use hot water from our tankless water heater.  I did a web search to try and find a direct replacement for this tank because of its unique properties of having additional ports on the side and eventually found one in a Lowe's store about 40 miles away.  Fortunately it barely fit in the back of my Chevy Volt and I was able to spend the following day removing the old tank and replacing it.

I am an experienced plumber and engineered this system myself (I have a background in photo processing engineering from the 1970s) so it was relatively easy - yet time-consuming - to swap out the tanks.

I was quite disappointed that the water leak alarm that I had installed at the bottom of the tank (at bottom right in the top photo) did not alert me to this issue.  Perhaps it had run its battery down while I had been out of the house for a day.  Or perhaps I could not hear it in the rest of the house considering that the water heater is in a utility closet in a corner of the basement.  As part of the replacement and upgrade I have installed a deep drip pan under the tank and will find a better/louder leak alarm.  Lessons learned!

The old tank will find its way to the landfill eventually next time I do a major dump run with the help of a neighbor's pickup truck.  It bothers me that water heater tanks have a planned obsolescence of 6 to 10 years, but at least they don't contain any toxic materials!

Ti gode grunner til å jobbe med solcelleforskning

Jeg begynner om under en måned i ny jobb, som PhD-stipendiat skal jeg forske på solceller på Institutt for energiteknikk (IFE) på Kjeller. Jeg skal jobbe med det som kalles for tandemceller, basert på vanlig silisium, men med et spennende lag oppå. For dem som lurer på hva tandemceller er for noe, er det kort forklart en dobbel solcelle, der hver av de to cellene tar opp forskjellige frekvenser (farger) av lyset fra sola. Slik kan effekten til solcellene i teorien nesten dobles. Problemet er at det blir litt dyrere enn vanlige solceller. Denne typen teknologi er i dag stort sett i bruk kun i satelitter, og til en viss grad i "vanlige" solenergiverk med konsentratorspeil.

Her er ti grunner til at solceller appellerer så mye til meg:

1. Det er nesten magisk.
Det tok meg over tre år med universitetsstudier for å forstå hvordan en fotovoltaisk solcelle faktisk fungerer, og jeg syntes at det rett og slett er ganske fantastisk at vi klarer å lage elektrisk strøm direkte fra lys, uten å gå via noe som helst form for tradisjonell generator eller annen mekanikk.

2. 10.000 ganger mer enn vi trenger.
Solenergien som treffer jorda til en hver tid tilsvarer ca. 10.000 ganger menneskenes energiforbruk. Det er med andre ord nok å ta av, og i mange land vil bare det å dekke taket på alle bygninger med solcellepaneler teoretisk sett være nok til å dekke hele landets energiforbruk.

3. Nesten null CO2.
Når solceller først er produsert og installert, slipper de ikke ut noe som helst forurensing i løpet av sin levetid. Produksjonen vil nødvendigvis forårsake en del utslipp, en NTNU-studie anslår at CO2-utslippene forbundet med produksjon av solceller er på ca. 24 gram per produsert kWh. Men dette er lite i forhold til andre energikilder, gjennomsnittet for elektrisitetsproduksjon i Europa ligger på rundt 500 g/kWh.

4. Solceller lages av stein.
Dagens kommersielle solceller lages stort sett av silisium. Silisium er, etter oksygen, det grunnstoffet det finnes mest av i verden.

Det utvinnes i dag fra kvarts, som er verdens nest mest vanlige mineral (etter feltspat). Det er med andre ord ikke grunn til å forvente at vi støter på peak solar innen de nærmeste ### milliarder årene.

5. Sollyset er rettferdig.
Selv om solen skinner mindre i Trondheim enn i Oslo, kan sollyset sies å være ganske jevnt distribuert over kloden i forhold til andre energikilder som vannkraft, olje, gass, vind, og så videre. Mange utviklingsland egner seg spesielt godt for utnyttelse av solenergi, og det kan tenkes at de kan utnytte fordelene med å ikke ha en godt etablert infrastruktur for energi til å gjøre utbyggingen av solenergi enklere.

6. Det er enkelt.
På tross av at det tok oss mange hundre år med vitenskaplig utvikling før man klarte å lage en solcelle, er teknologien i bruk kanskje den enkleste av alle måter å generere elektrisitet på. Hold solcellen opp i sola, koble den til en motor, og motoren går. Bare batteriet er enklere, det trenger ikke lys for å fungere. Men det går jo tomt, da.

7. God ny teknologi.
Verdens første solcellepaneler ble satt sammen i laboratorier for litt over 50 år siden. De hadde en effektivitet på rundt 6%. I laboratorier i dag testes solceller med effektivitet på opp til 41% energi-effektivitet. Utviklingen har gått fort, og ikke minst innsatsen som har blitt gjort innen produksjon av solcellematerialer har gjort at strøm fra solceller i dag nærmer seg prisen på strøm fra fossil energi.

8. Norges eksport av fornybar energi i fast form.
Norge har i dag verdens mest klimavennlige elektrisitetsproduksjon. Vårt elektrisitetsforbruk dekkes i dag stort sett av vannkraft, og når produksjonen øker fremover, må vi bruke strømmen til noe. Den kan enten eksporteres som ”råvare”, eller vi kan bruke den til å produsere mer solceller og solcellematerialer. Slik kan vi eksportere vår rene, fornybare energi i fast form til land som har bruk for mer fornybar energi fra sola. En solcelle plassert i Sør-Europa produserer i 20-40 ganger mer energi i løpet av sitt livsløp enn det som går med til produksjonen.

9. Framtiden er lys.
Mens teknologien blir bedre og produksjonskostnadene går ned, øker prisen på konkurrerende energikilder (fossile). Samtidig øker oppmerksomheten rundt klimaproblemer, og mange land har problemer med egen energisikkerhet. Dette gir gode argumenter for at solenergi vil fortsette den voldsomme utviklingen vi har sett over de siste ti årene.

10. Norge er i front.
Til tider lite sol, men Norge har en sterk industri for solceller. Norge er i verdenstoppen når det gjelder produksjon av silisium til solceller, og det norske selskapet REC er et av verdens største selskaper innen solcelleproduksjon. Sammen med Elkem, Norsun, Fesil Sunergy, Norsk Solkraft og en hel rekke andre industriselskaper, står de for en levende industri som stadig vokser. Sammen med forskningsinstitusjonene NTNU, SINTEF, IFE og UiO kan vi fortsette seiersløpet inn i fremtiden, og ta med oss resten av verden!

Roof mounted solar panels cool inside the building

I was looking up at my solar panels on a very hot sunny day recently.  I noticed that they were shading the roof and wondered if they were having a cooling effect and thus reducing the air-conditioning load in my office below.  So I set up 4 temperature sensors connected to my data logger to look at a days worth of data on a clear sunny day when the ambient temperatures peaked at around 100°F in the shade.

Click image to enlarge

As you can see, the shaded roof temperature averaged about 10°F cooler than the exposed roof.  I expected the solar panel surface temperature to be significantly hotter, but it was only about 10°F above ambient.  I'm not certain that my methodology was perfect.  All I did was tape a sensor onto the back of the solar panel and secure the others to the roof with duct tape.  The ambient temperature sensor was in the shade away from the roof.

The take away here is that solar panels do have a cooling effect when covering an asphalt roof.  This is clearly an advantage when the rooms below that roof require air conditioning in the summer.

Another way to reduce air conditioning costs is to install a solar powered ventilation fan in the attic.

I installed a SunRise Solar Attic Fan many years ago and it reduced my attic temperature by up to 60°F.  These clever designs use a 10 W solar panel directly connected to a fan.  You can add a thermostat to ensure that it is not running when the attic is cool.

So one can definitely say that solar panels are cool!

Wind Assisted Propulsion of Ships

av Zhenju Chuang, ph.d., recently graduated from Institute of Marine Technology, NTNU

Reducing CO₂ Emissions from Shipping

SkySails towing kite

Climate changes have been given a large attention in the media lately. The general opinion is that the recent climate changes are mainly caused by human activities. This together with fluctuations in the oil prices has led to a great focus on energy conservation in the marine industry [1]. Shipping is responsible for more than 90% of world trade, creating   greenhouse gases, like COx, NOx, SOx. Fig 1 shows global CO₂ emissions. It seems that emission from shipping is not as big as other manufacturing industries. However, if we do nothing from now, according to EU prediction, by 2020, SOx will increase 40%, NOx will increase 50% and even more to PM2.5 being 55%.

So now we are facing a big opportunity to explore renewable energy. Wind is the best solutions for shipping since it is sustainable, easily accessible, cost and emission-free.

Wind assisted ship propulsion is becoming more and more popular now. Several main devices will be introduced here. Like sail (soft sail and rigid sail), Flettner rotor, wind turbine and kite.

Figure 1 Global CO₂ emissions

 

Soft Sail

Figure 3 (a) Square rig 

Figure 3 (b) Fore-and-aft rig

Soft sail was originated from ancient times, and its history is as long as human civilization. Two main categories of softsails are shown in Fig 3. They are square rig and fore-and-aft rig. The rigs are made of soft material, such as canvas, cloth which are rigged across masts [3]. Performance comparisons between two kinds of soft sails are shown in Table 1.

Table 1. Performance comparison between square rig and fore-and-aft rig

Rigid Sail

Figure 4 shows two examples of rigid sails. They are all consisted of self-rotating aero foils standing on an end to meet wind direction. They are made of hard material, so structure reliability is higher. Flaps can be included to increase its efficiency. Also rigid sail can reduce ship motion and thus reduce ship resistance. [4]

Figure 4 (a) rigid sail on deck

Figure 4 (b) rigid sail with flap

Flettner Rotor

Anton Flettner made the first comprehensive research on modern lift generating devices for auxiliary ship propulsion in the early 1920s. He came up with the Flettner rotor, which is a rotating cylinder that makes use of the Magnus effect to create large cross-forces in the direction of propulsion. These forces can be very large. [5]

Figure 5 E-Ship 1 – first voyage with cargo in 2020

The Flettner rotors are compact and made of high-tech materials. The technology used by these rotors is familiar to ship operators. They are suitable for retrofitting to slow speed vessels working in side winds. They may, however, have higher maintenance costs and they require an external energy source. If the external energy source breaks down, the rotors will not contribute to any thrust. When they are sailing windward, high drag forces are developed. There is also no way to reduce the aerodynamic force from the rotors in strong winds. These drawbacks concerning this wind assistance solution can be critical at unfavorable wind directions or if problems with the external energy source occur, and there are not many ships equipped with Flettner rotors today.

Wind Turbine

It is also possible to create propulsion by using wind turbines. The power generated by the wind turbines do not need to be used directly, but can be stored and used to drive for instance a propeller. Two categories of wind turbines, namely horizontal axis wind turbine and vertical axis wind turbine are shown in fig 6. [2]

Fig 6 (a) Horizontal Axis wind turbine

Fig 6 (b) Vertical Axis wind turbine

Kite

The German company SkySails has developed an example of a kite system for cargo vessels. The system is used parallel to the main engine if the wind conditions are favorable. It consists of three main components:

· Towing kite with a rope

· Launch and recovery system

· Control system for automatic operation

A kite can be actively controlled in order to create its own flying speed and thereby increasing the apparent wind speed. This leads to increased traction force per sail area. [6]

Conclusion

Wind assisted ship propulsion has great potential. Practical driven from international polity are more and more focus on green shipping and dwindling oil reserves. In order to develop more advance technology to investigate wind assisted ship propulsion, several uncertainties should be taken into account. For example, sea surface effect, atmospheric turbulence and wind vertex shedding of superstructure. Even more frame work for optimal combination of merchant ship type, wind assisted system and weather routine should be worked out.

References

[1]  Angvik, I., Wind Assisted Ship Propulsion, master thesis, NTNU, 2020
[2] Bøckmann, E., Wind Turbine Propulsion of Boats and Ships, master thesis, NTNU, 2020
[3]C. T. Nance. Outlook for wind assistance. Journal of Wind Engineering and Industrial Aerodynamics, 19:1-17, 1985.
[4] Silvanius, M., Wind assisted propulsion for pure car and truck carriers, master thesis, KTH Center fro Naval Architecture, 2020
[5] Craft, T. J., H. Iacovides, and B. E. Launder. Dynamic performance of Flettner rotors with and without Thom discs. Proc. 7 th Symp. on Turbulence & Shear Flow Phenomena. 2020.
[6] Naaijen, Peter, and Vincent Koster. Performance of auxiliary wind propulsion for merchant ships using a kite. 2nd International Conference on Marine Research and Transportation. 2007.